Above:  an overloaded outlet with no cover

It’s a Visual Inspection

A “visual” inspection means that a home inspection report is limited to describing conditions in those parts of a home that an inspector can see during the inspection. Obviously, parts of the home that are permanently hidden by wall, ceiling and floor coverings are excluded, but so are parts of the home that were inaccessible during the inspection for some other reason. Some reasons might include lack of an access point, such as a door or hatch, or a locked access point, or because an occupant’s belongings blocked access, or because of dangerous or unsanitary conditions.

There can be many more reasons. The point is that if an inspector can’t see a portion of the home, the inspector can’t assume responsibility for ensuring that a safe and proper condition exists or that systems are operating properly in that hidden space.

Safety

Safety can be a matter of perception. Some conditions, such as exposed electrical wiring, are obviously unsafe. Other conditions, such as the presence of mold, aren’t as clear-cut.

In the example of the possible existence of mold, it’s difficult to accurately call it out during a general home inspection because mold sometimes grows in places where it can’t be readily seen, such as inside walls, making its discovery beyond the scope of the inspection.  Also, the dangers to human health are from the inhalation of spores from indoor air.

Above:  the cutting torch and gutter system of roof drainage management

Inspectors will also examine the major accessible components of certain systems as required by the Standards of Practice. Furnace air filters are one example.

A home inspection is not technically exhaustive, meaning that systems or components will not be disassembled as part of the inspection. For example, an inspector will not partially disassemble a furnace to more accurately check the condition of the heat exchanger. Inspectors typically disclaim heat exchangers.

Hazardous Materials

Asbestos, mold, lead, water purity, and other environmental issues or potential hazards typically require a specialist inspection, and may additionally require laboratory analysis.

Home Inspectors are Generalists

Above:  the result of subfloor movement

Inspector Qualifications

Very few home inspectors have been in the inspection industry for their entire working lives. According to an InterNACHI poll, about half the home inspectors have a background in the building trades. Those with a construction background started with a general idea of the systems and components that they might find installed, as well as how those systems age and fail.

This doesn’t mean that inspectors with a background in something other than the building trades are not qualified — only that they started in the inspection industry at a relative disadvantage. Building the skills and developing the judgment to consistently recognize and interpret evidence correctly and make appropriate recommendations are things that can be improved with practice and continuing education.

Managing Expectations

Part of a home inspector’s job is to manage the expectations of their client. This is especially true when a client has never dealt with a home inspector before. Explaining the limitations of a home inspection to a client will help them develop realistic expectations concerning what to expect from a home inspection report, and what lies beyond the scope of the inspection.

When a home buyer is interviewing inspectors, the buyer should ask about how the inspector handles special safety concerns.

Disclaimers are portions of an inspection agreement or report in which an inspector notifies the client that the inspector will not accept the responsibility for confirming the condition of a portion of the home or of a particular system or component.

History

Asbestos cement first came into use as an exterior cladding after 1907, when Austrian engineer Ludwid Hatschek came up with a way to shape the material into sheets, allowing it to be manufactured as siding and shingles. By the 1920s, the National Board of Fire Underwriters recommended that asbestos cement replace wood as siding and roofing material because of its superior fire-resistant properties. This recommendation from a nationally known insurance board contributed to a boost in sales and, by the 1940s, hundreds of thousands of homes in the U.S. had been constructed using asbestos cement siding.

During the late 1960s and early ‘70s, however, the news media began to report on the health hazards associated with asbestos. As reports increased, concern grew, so the federal government took action and, in 1973, the EPA banned the use of asbestos in the manufacture of building products.

Health Risks Associated with Asbestos Cement

Asbestos fibers are a proven health hazard if inhaled. Asbestos dust is a known cause of a type of lung cancer called asbestosis. Mesothelioma, another deadly form of cancer that attacks internal organs, can also be caused by exposure to asbestos. However, asbestos cement siding that has been properly installed and is not in a state of decay presents no health risks as long as it remains undisturbed. This is because the cement binds the asbestos fibers and prevents their release into the air, under normal use and maintenance.

The EPA deems asbestos to be hazardous when it is in a friable state, meaning that it can be crumbled, crushed or pulverized by hand pressure. Crushed asbestos in a powdery form can allow its particles to become airborne and inhaled, causing potential health problems. Asbestos cement products that are not in a friable state are not considered hazardous. The only potential danger is when the cement is disturbed in a way that causes the asbestos fibers to become airborne.

If mechanical activities performed on the siding, such as chipping, sawing, grinding or sanding, allow particles to become airborne, then the cement is considered in a friable state and, consequently, hazardous. Deterioration can also lead to particles becoming airborne and potentially dangerous.

Advantages

• Asbestos cement siding is highly fire-resistant and will not burn or melt the way vinyl and wood siding will.
• It resists termite damage.
• It resists rotting.
• It has been manufactured with textures intended to simulate the look of other cladding materials, such as wood grain.
• It is fairly easy to clean and maintain.
• Unlike more porous siding materials, such as wood clapboard, asbestos cement siding will not quickly soak up paint, which allows it to be painted more easily.

Disadvantages

• Asbestos cement siding is very brittle and can be easily chipped, cracked or broken.
• The use of a pressure washer for maintenance can crack the siding and lead to moisture intrusion, if the pressure setting is high enough.
• Asbestos cement can be dangerous if pulverized by sawing, sanding, breaking, etc.
• It is difficult to find replacement siding for repairs.
• This product cannot be refurbished, unlike other forms of siding.  Wood clapboard, for example, can be sanded and re-painted, and cedar shake siding can be sand-blasted and re-stained.  Either of these methods can restore wood close to its original state.  But this is not possible with asbestos cement siding.
• It is no longer considered aesthetically desirable.

Maintenance

Damage and deterioration can lead to structural and health issues, so proper maintenance of asbestos cement building materials is a primary concern.  Keeping the siding clean and performing any minor repairs as soon as they become necessary are both important.

Asbestos cement siding is fairly brittle and has little resistance to cracking, chipping and damage from impact, which can cause asbestos particles to become airborne.  Damage to the siding can also lead to other damage related to moisture intrusion.  Damaged areas that cannot be fixed can be replaced with non-asbestos fiber cement by a professional.  Specific fiber cement materials have been manufactured for repairs that are intended to mimic the look of asbestos cement siding.

Landscaping features, such as a row of shrubs, can be incorporated around the home to help protect the siding from impact damage.

Inspection Tips

Here are some common problems associated with asbestos cement siding that inspectors are likely to encounter:

• Chipping and cracking often occur with this brittle material.
• Fasteners used to hold the siding in place may deteriorate at a faster rate than the siding.
• Discoloration and staining may occur from corrosion or runoff from an adjacent material.  The discoloration may be normal, but it could also indicate a chemical reaction that has decreased the durability of the material.
• Like many other cement products, efflorescence may appear on asbestos cement siding.  This crystalline growth can indicate that water is passing through the material, promoting deterioration of the cement.
• Biological growth, such as moss and algae, can occur if conditions are favorable.  This growth may stimulate surface deterioration and staining.

The term “stucco” is used to describe a type of exterior plaster applied as a two- or three-part coating directly onto masonry, or applied over wood or metal lath to a log or wood frame structure. Stucco is found in many forms on historic structures throughout the United States. It is so common, in fact, that it frequently goes unnoticed, and is often disguised or used to imitate another material. Historic stucco is also sometimes incorrectly viewed as a sacrificial coating, and consequently removed to reveal stone, brick or logs that historically were never intended to be exposed. Age and lack of maintenance hasten the deterioration of many historic stucco buildings. Like most historic building materials, stucco is at the mercy of the elements, and even though it is a protective coating, it is particularly susceptible to water damage. Stucco is a material of deceptive simplicity; in most cases, its repair should not be undertaken by a property owner unfamiliar with the art of plastering. Successful stucco repair requires the skill and experience of a professional plasterer. Although several stucco mixes are representative of different periods, they are provided here for reference.  Each project is unique, with its own set of problems that require individual solutions.

Stucco has been used since ancient times. Still widely used throughout the world, it is one of the most common of traditional building materials. Up until the late 1800s, stucco, like mortar, was primarily lime-based, but the popularization of Portland cement changed the composition of stucco, as well as mortar, to a harder material. Historically, the term “plaster” has often been interchangeable with “stucco”; the term is still favored by many, particularly when referring to the traditional lime-based coating. By the 19th century “stucco,” although originally denoting fine interior ornamental plasterwork, had gained wide acceptance in the United States to describe exterior plastering. “Render” and “rendering” are also terms used to describe stucco, especially in Great Britain. Other historic treatments and coatings related to stucco, in that they consist (at least in part) of a similarly plastic or malleable material, include: parging and pargeting, wattle and daub, “cob” or chalk mud, pise de terre, rammed earth, briquete entre poteaux or bousillage, half-timbering, and adobe. All of these are regional variations on traditional mixtures of mud, clay, lime, chalk, cement, gravel or straw. Many are still used today.

Revival Styles Promote the Use of Stucco

The introduction of the many revival styles of architecture around the turn of the 20th century, combined with the improvement and increased availability of Portland cement, resulted in a craze for stucco as a building material in the United States. Beginning about 1890 and gaining momentum into the 1930s and 1940s, stucco was associated with certain historic architectural styles, including: Prairie; Art Deco and Art Moderne; Spanish Colonial, Mission, Pueblo, Mediterranean, English Cotswold Cottage, and Tudor Revival styles; as well as the ubiquitous bungalow and four-square house. The fad for Spanish Colonial Revival, and other variations on this theme, was especially important in furthering stucco as a building material in the United States during this period, since stucco clearly looked like adobe.

Although stucco buildings were especially prevalent in California, the Southwest and Florida, ostensibly because of their Spanish heritage, this period also spawned stucco-coated, revival-style buildings all over the United States and Canada. The popularity of stucco as a cheap and readily available material meant that, by the 1920s, it was used for an increasing variety of building types. Resort hotels, apartment buildings, private mansions and movie theaters, railroad stations, and even gas stations and tourist courts took advantage of the “romance” of period styles, and adopted the stucco construction that had become synonymous with these styles.

A Practical Building Material

Stucco has traditionally been popular for a variety of reasons. It was an inexpensive material that could simulate finely dressed stonework, especially when scored or lined, in the European tradition. A stucco coating over a less finished and less costly substrate, such as rubblestone, fieldstone, brick, log or wood frame, gave the building the appearance of being a more expensive and important structure. As a weather-repellent coating, stucco protects the building from wind and rain penetration, and also offers a certain amount of fire protection. While stucco was usually applied during construction as part of the building design, particularly over rubblestone or fieldstone, in some instances, it was added later to protect the structure, or when a rise in the owner’s social status demanded a comparable rise in his standard of living.

Composition of Historic Stucco

Before the mid-to late 19th century, stucco consisted primarily of hydrated or slaked lime, water and sand, with straw or animal hair mixed in as a binder. Natural cements were frequently used in stucco mixes after their discovery in the United States during the 1820s. Portland cement was first manufactured in the United States in 1871, and it gradually replaced natural cement. After about 1900, most stucco was composed primarily of Portland cement, mixed with some lime. With the addition of Portland cement, stucco became even more versatile and durable. No longer used just as a coating for a substantial material like masonry or log, stucco could now be applied over wood or metal lath attached to a light wood frame. With this increased strength, stucco ceased to be just a veneer and became a more integral part of the building structure.

Today, gypsum, which is hydrated calcium sulfate or sulfate of lime, has, to a great extent, replaced lime.  Gypsum is preferred because it hardens faster and has less shrinkage than lime. Lime is generally used only in the finish coat in contemporary stucco work.

The composition of stucco depends on local custom and available materials. Stucco often contains substantial amounts of mud or clay, marble or brick dust, or even sawdust, and an array of additives ranging from animal blood or urine, to eggs, keratin or gluesize (animal hooves and horns), varnish, wheat paste, sugar, salt, sodium silicate, alum, tallow, linseed oil, beeswax, and wine, beer or rye whiskey. Waxes, fats and oils were included to introduce water-repellent properties, sugary materials reduced the amount of water needed and slowed down the setting time, and alcohol acted as an air entrainer. All of these additives contribute to the strength and durability of the stucco.

The appearance of much stucco was determined by the color of the sand — or sometimes burnt clay — used in the mix.  Often, stucco was also tinted with natural pigments, or the surface whitewashed or color-washed after stuccoing was completed. Brick dust could provide color, and other coloring materials that were not affected by lime, mostly mineral pigments, could be added to the mix for the final finish coat. Stucco was also marbled or marbleized — stained to look like stone by diluting oil of vitriol (sulfuric acid) with water, and mixing this with a yellow ochre, or another color. As the 20th century progressed, manufactured and synthetic pigments were added at the factory to some prepared stucco mixes.

Methods of Application

Stucco is applied directly, without lath, to masonry substrates, such as brick, stone, concrete or hollow tile. But on wood structures, stucco, like its interior counterpart plaster, must be applied over lath in order to obtain an adequate key to hold the stucco. Thus, when applied over a log structure, stucco is laid on horizontal wood lath that has been nailed on vertical wood furring strips attached to the logs. If it is applied over a wood frame structure, stucco may be applied to wood or metal lath nailed directly to the wood frame; it may also be placed on lath that has been attached to furring strips. The furring strips are themselves laid over building paper covering the wood sheathing.

Like interior wall plaster, stucco has traditionally been applied as a multiple-layer process, sometimes consisting of two coats, but more commonly as three. Whether applied directly to a masonry substrate or onto wood or metal lath, this consists of a first “scratch” or “pricking-up” coat, followed by a second scratch coat, sometimes referred to as a “floating” or “brown” coat, followed finally by the “finishing” coat. Up until the late 19th century, the first and the second coats were of much the same composition, generally consisting of lime or natural cement, sand, perhaps clay, and one or more of the additives previously mentioned. Straw or animal hair was usually added to the first coat as a binder. The third, or finishing coat, consisted primarily of a very fine mesh-grade of lime and sand, and sometimes pigment. As already noted, after the 1820s, natural cement was also a common ingredient in stucco, until it was replaced by Portland cement. Both masonry and wood lath must be kept wet or damp to ensure a good bond with the stucco. Wetting these materials helps to prevent them from pulling moisture out of the stucco too rapidly, which results in cracking, loss of bond, and generally poor-quality stucco work.

Traditional Stucco Finishes

Until the early 20th century when a variety of novelty finishes and textures were introduced, the last coat of stucco was commonly given a smooth, troweled finish, and then scored or lined in imitation of ashlar. The illusion of masonry joints was sometimes enhanced by a thin line of white lime putty, graphite, or some other pigment. Some 19th century buildings feature a water table or raised foundation of roughcast stucco that differentiates it from the stucco surface above, which is smooth and scored. Other novelty and textured finishes associated with the “period” or revival styles of the early 20th century include: the English cottage finish, adobe and Spanish, pebble-dashed or dry-dash surface, fan and sponge texture, reticulated and vermiculated, roughcast (or wet dash), and sgraffito.

Regular Maintenance

Because building owners knew stucco to be a protective, but also somewhat fragile coating, they employed a variety of means to prolong its usefulness. The most common treatment was to whitewash stucco, often annually. The lime in the whitewash offered protection and stability, and helped to harden the stucco. Most importantly, it filled hairline cracks before they could develop into larger cracks and let in moisture. To improve water repellency, stucco buildings were also sometimes coated with paraffin, another type of wax, or other stucco-like coatings, such as oil mastics.

Assessing Damage

Most stucco deterioration is the result of water infiltration into the building’s structure, either through the roof, around chimneys, window and door openings, or excessive ground water or moisture penetrating through, or splashing up from the foundation. Potential causes of deterioration include: ground settlement lintel and door frame settlement; inadequate and leaking gutters and downspouts; intrusive vegetation; moisture migration within walls due to interior condensation and humidity; vapor drive problems caused by furnace, bathroom and kitchen vents; and rising damp resulting from excessive ground water and poor drainage around the foundation. Water infiltration will cause wood lath to rot, and metal lath and nails to rust, which eventually will cause stucco to lose its bond and pull away from its substrate.

After the cause of deterioration has been identified, any necessary repairs to the building should be made first before repairing the stucco. Such work is likely to include repairs designed to keep excessive water away from the stucco, such as roof, gutter, downspout and flashing repairs, improving drainage, and redirecting rainwater runoff and splash-back away from the building. Horizontal areas, such as the tops of parapet walls and chimneys, are particularly vulnerable to water infiltration, and may require modifications to their original design, such as the addition of flashing to correct the problem.

Previous repairs inexpertly carried out may have caused additional deterioration, particularly if executed in Portland cement, which tends to be very rigid and, therefore, incompatible with early, mostly soft lime-based stucco that is more flexible. Incompatible repairs, external vibration caused by traffic and construction, and building settlement can also result in cracks which permit the entrance of water and cause the stucco to fail.

Before beginning any stucco repair, an assessment of the stucco should be undertaken to determine the extent of the damage, and how much must be replaced or repaired. Testing should be carried out systematically on all elevations of the building to determine the overall condition of the stucco. Some areas in need of repair will be clearly evidenced by missing sections of stucco or stucco layers. Bulging or cracked areas are obvious places to begin. Unsound, punky or soft areas that have lost their key will echo with a hollow sound when tapped gently with a wooden or acrylic hammer or mallet.

Identifying the Stucco Type

Analysis of the historic stucco will provide useful information on its primary ingredients and their proportions, and will help to ensure that the new replacement stucco will duplicate the old in strength, composition, color and texture as closely as possible. However, unless authentic, period restoration is required, it may not be worthwhile, nor in many instances even possible, to attempt to duplicate all of the ingredients (particularly some of the additives) in creating the new stucco mortar. Some items are no longer available, and others, notably sand and lime — the major components of traditional stucco — have changed radically over time. For example, most sand used in contemporary masonry work is manufactured sand, because river sand, which was used historically, is difficult to obtain today in many parts of the country. The physical and visual qualities of manufactured sand versus river sand are quite different, and this affects the way stucco works, as well as the way it looks. The same is true of lime, which is frequently replaced by gypsum in modern stucco mixes. And even if identification of all the items in the historic stucco mix were possible, the analysis would still not reveal how the original stucco was mixed and applied.

There are, however, simple tests that can be carried out on a small piece of stucco to determine its basic makeup. A dilute solution of hydrochloric (muriatic) acid will dissolve lime-based stucco, but not Portland cement. Although the use of Portland cement became common after 1900, there are no precise cutoff dates, as stuccoing practices varied among individual plasterers, and from region to region. Some plasterers began using Portland cement in the 1880s, but others may have continued to favor lime stucco well into the early 20th century. While it is safe to assume that a late-18th or early-19th century stucco is lime-based, late-19th or early-20th century stucco may be based on either lime or Portland cement. Another important factor to take into consideration is that an early lime-stucco building is likely to have been repaired many times over the ensuing years, and it is probable that at least some of these patches consist of Portland cement.

Planning the Repair

Once the extent of damage has been determined, a number of repair options may be considered. Small hairline cracks usually are not serious and may be sealed with a thin slurry coat consisting of the finish coat ingredients, or even with a coat of paint or whitewash.

Commercially available caulking compounds are not suitable materials for patching hairline cracks. Because their consistency and texture is unlike that of stucco, they tend to weather differently, and attract more dirt; as a result, repairs made with caulking compounds may be highly visible and unsightly. Larger cracks will have to be cut out in preparation for more extensive repair. Most stucco repairs will require the skill and expertise of a professional plasterer.

In the interest of saving or preserving as much as possible of the historic stucco, patching rather than wholesale replacement is preferable. When repairing heavily textured surfaces, it is not usually necessary to replace an entire wall section, since the textured finish, if well-executed, tends to conceal patches, and helps them to blend in with the existing stucco. However, because of the nature of smooth-finished stucco, patching a number of small areas scattered over one elevation may not be a successful repair approach unless the stucco has been previously painted, or is to be painted following the repair work. On unpainted stucco, such patches are hard to conceal, because they may not match exactly or blend in with the rest of the historic stucco surface. For this reason, it is recommended, if possible, that stucco repair be carried out in a contained or well-defined area, or if the stucco is scored, the repair patch should be “squared-off” in such a way as to follow existing scoring. In some cases, especially in a highly visible location, it may be preferable to re-stucco an entire wall section or feature. In this way, any differences between the patched area and the historic surface will not be so readily apparent.

Repair of historic stucco generally follows most of the same principles used in plaster repair. First, all deteriorated, severely cracked and loose stucco should be removed down to the lath (assuming that the lath is securely attached to the substrate), or down to the masonry if the stucco is directly applied to a masonry substrate. A clean surface is necessary to obtain a good bond between the stucco and substrate. The areas to be patched should be cleaned of all debris with a bristle brush, and all plant growth, dirt, loose paint, oil and grease should be removed. If necessary, brick or stone mortar joints should then be raked out to a depth of approximately 5/8-inches to ensure a good bond between the substrate and the new stucco.

To obtain a neat repair, the area to be patched should be squared-off with a butt joint using a cold chisel, a hatchet, a diamond-blade saw, or a masonry bit. Sometimes, it may be preferable to leave the area to be patched in an irregular shape, which may result in a less conspicuous patch. Proper preparation of the area to be patched requires very sharp tools and extreme caution on the part of the plasterer not to break keys of surrounding good stucco by “over-sounding” when removing deteriorated stucco.

When repairing lime-based stucco applied directly to masonry, the new stucco should be applied in the same manner, directly onto the stone or brick. The stucco will bond onto the masonry itself without the addition of lath because of the irregularities in the masonry or those of its mortar joints, or because its surface has been scratched, scored or otherwise roughened to provide an additional key. Cutting out the old stucco at a diagonal angle may also help secure the bond between the new and the old stucco. For the most part, it is not advisable to insert metal lath when re-stuccoing historic masonry in sound condition, as it can hasten deterioration of the repair work. Not only will attaching the lath damage the masonry, but the slightest moisture penetration can cause metal lath to rust. This will cause metal to expand, eventually resulting in spalling of the stucco, and possibly the masonry substrate, too.

If the area to be patched is properly cleaned and prepared, a bonding agent is usually not necessary. However, a bonding agent may be useful when repairing hairline cracks, or when dealing with substrates that do not offer a good bonding surface. These may include dense stone or brick, previously painted or stuccoed masonry, or spalling brick substrates. A good mechanical bond is always preferable to reliance on bonding agents. Bonding agents should not be used on a wall that is likely to remain damp or where large amounts of salt are present. Many bonding agents do not survive well under such conditions, and their use could jeopardize the longevity of the stucco repair.

A stucco mix compatible with the historic stucco should be selected after analyzing the existing stucco. It can be adapted from a standard traditional mix of the period, or based on one of the mixes included here. Stucco consisting mostly of Portland cement generally will not be physically compatible with the softer, more flexible, lime-rich historic stuccos used throughout the 18th and much of the 19th centuries. The differing expansion and contraction rates of lime stucco and Portland cement stucco will normally cause the stucco to crack. Choosing a stucco mix that is durable and compatible with the historic stucco on the building is likely to involve considerable trial and error, and probably will require a number of test samples, and even more, if it is necessary to match the color. It is best to let the stucco test samples weather as long as possible — ideally, one year, or at least through a change of seasons — in order to study the durability of the mix and its compatibility with the existing stucco, as well as the weathering of the tint, if the building will not be painted and color-match is an important factor.

After thoroughly dampening the masonry or wood lath, the first scratch coat should be applied to the masonry substrate, or wood or metal lath, in a thickness that corresponds to the original (if extant), or generally about 1/4-inch to 3/8-inch. The scratch coat should be scratched or crosshatched with a comb to provide a key to hold the second coat. It usually takes 24 to 72 hours, and longer in cold weather, for each coat to dry before the next coat can be applied. The second coat should be about the same thickness as the first, and the total thickness of the first two coats should generally not exceed about 5/8-inch. This second or leveling coat should be roughened using a wood float with a nail protruding to provide a key for the final or finish coat. The finish coat, about 1/4-inch thick, is applied after the previous coat has initially set. If this is not feasible, the base coat should be thoroughly dampened when the finish coat is applied later. The finish coat should be worked to match the texture of the original stucco.

Colors and Tints for Historic Stucco Repair

The color of most early stucco was supplied by the aggregate included in the mix — usually, the sand. Sometimes, natural pigments were added to the mix, and 18th- and 19th-century scored stucco was often marbleized or painted in imitation of marble and granite. Stucco was also frequently coated with whitewash or a colorwash. This tradition later evolved into the use of paint, its popularity depending on the vagaries of fashion, as much as a means of concealing repairs. Because most of the early colors were derived from nature, the resultant stucco tints tended to be mostly earth tones. This was true until the advent of brightly colored stucco in the early decades of the 20th century. This was the so-called “Jazz Plaster” developed by O.A. Malone, the “man who put color into California,” and who founded the California Stone Products Corporation in 1927. California stucco was revolutionary for its time as the first stucco/plaster to contain colored pigment in its pre-packaged factory mix.

When patching or repairing an historic stucco surface known to have been tinted, it may be possible to determine through visual or microscopic analysis whether the source of the coloring is sand, cement or pigment. Although some pigments or aggregates used traditionally may no longer be available, a sufficiently close color match can generally be approximated using sand, natural or mineral pigments, or a combination of these. Obtaining such a match will require testing and comparing the color of the dried test samples to the original. Successfully combining pigments in the dry stucco mix prepared for the finish coat requires considerable skill. The amount of pigment must be carefully measured for each batch of stucco. Overworking the mix can make the pigment separate from the lime. Changing the amount of water added to the mix, or using water to apply the tinted finish coat, will also affect the color of the stucco when it dries.

Generally, the color obtained by hand-mixing these ingredients will provide a sufficiently close match to cover an entire wall or an area distinct enough from the rest of the structure that the color differences will not be obvious. However, it may not work for small patches conspicuously located on a primary elevation, where color differences will be especially noticeable. In these instances, it may be necessary to conceal the repairs by painting the entire patched elevation, or even the whole building.

Many stucco buildings have been painted over the years, and will require re-painting after the stucco repairs have been made. Limewash or cement-based paint, latex paint, or oil-based paint are appropriate coatings for stucco buildings. The most important factor to consider when re-painting a previously painted or coated surface is that the new paint be compatible with any coating already on the surface. In preparation for re-painting, all loose and peeling paint, and other coating material not firmly adhered to the stucco, must be removed by hand-scraping or natural bristle brushes. The surface should then be cleaned.

Cement-based paints, most of which now contain some Portland cement and are really a type of limewash, have traditionally been used on stucco buildings. The ingredients were easily obtainable. Furthermore, the lime in such paints actually bonded or joined with the stucco and provided a very durable coating. In many regions, whitewash was applied annually during spring cleaning. Modern, commercially available, pre-mixed masonry and mineral-based paints may also be used on historic stucco buildings.

If the structure must be painted for the first time to conceal repairs, almost any of these coatings may be acceptable, depending on the situation. Latex paint, for example, may be applied to slightly damp walls or where there is an excess of moisture, but latex paint will not stick to chalky or powdery areas. Oil-based or alkyd paints must be applied only to dry walls; new stucco must cure up to a year before it can be painted with oil-based paint.

Contemporary Stucco Products

There are many contemporary stucco products on the market today. Many of them are not compatible, either physically or visually, with historic stucco buildings. Such products should be considered for use only after consulting with a specialist in historic masonry. However, some of these pre-packaged tinted stucco coatings may be suitable for use on stucco buildings dating from the late 19th and early 20th centuries, as long as the color and texture are appropriate for the period and style of the building. While some masonry contractors may, as a matter of course, suggest that a water-repellent coating be applied after repairing old stucco, in most cases, this should not be necessary, since color washes and paints serve the same purpose, and stucco itself is a protective coating.

Cleaning Historic Stucco Surfaces

Historic stucco buildings often exhibit multiple layers of paint or limewash. Although some stucco surfaces may be cleaned by water-washing, the relative success of this procedure depends on two factors: the surface texture of the stucco, and the type of dirt to be removed. If simply removing airborne dirt, smooth unpainted stucco, and heavily-textured painted stucco, may sometimes be cleaned using a low-pressure water wash, supplemented by scrubbing with soft natural bristle brushes, and possibly non-ionic detergents. Organic plant material, such as algae and mold, and metallic stains may be removed from stucco using poultices and appropriate solvents. Although these same methods may be employed to clean unpainted roughcast, pebble-dash, or any stucco surface featuring exposed aggregate, due to the surface irregularities, it may be difficult to remove dirt without also removing portions of the decorative textured surface. Difficulty in cleaning these surfaces may explain why so many of these textured surfaces have been painted.

When Total Replacement is Necessary

Complete replacement of the historic stucco with new stucco of either a traditional or modern mix will probably be necessary only in cases of extreme deterioration — that is, a loss of bond on over 40% to 50% of the stucco surface. Another reason for total removal might be that the physical and visual integrity of the historic stucco has been so compromised by prior incompatible and ill-conceived repairs that patching would not be successful.

When stucco no longer exists on a building, there is more flexibility in choosing a suitable mix for the replacement. Since compatibility of old and new stucco will not be an issue, the most important factors to consider are durability, color, texture and finish. Depending on the construction and substrate of the building, in some instances, it may be acceptable to use a relatively strong cement-based stucco mortar. This is certainly true for many late 19th and early 20th century buildings, and may even be appropriate to use on some stone substrates, even if the original mortar would have been weaker, as long as the historic visual qualities noted above have been replicated. Generally, the best principle to follow for a masonry building is that the stucco mix, whether for repair or replacement of historic stucco, should be somewhat weaker than the masonry to which it is to be applied in order not to damage the substrate.

General Guidance for Historic Stucco Repair

A skilled professional plasterer will be familiar with the properties of materials involved in stucco repair and will be able to avoid some of the pitfalls that would hinder someone less experienced. General suggestions for successful stucco repair parallel those involving restoration and repair of historic mortar and plaster. In addition, the following principles are important to remember:

• Mix only as much stucco as can be used in one-and-a-half to two hours. This will depend on the weather (mortar will harden faster under hot and dry, or sunny conditions).  Experience is likely to be the best guidance. Any remaining mortar should be discarded; it should not be re-tempered.
• Stucco mortar should not be over-mixed. (Hand mix it for 10 to 15 minutes after adding water, or machine-mix for three to four minutes after all ingredients are in mixer.) Over-mixing can cause crazing and discoloration, especially in tinted mortars. Over-mixing will also tend to make the mortar set too fast, which will result in cracking and poor bonding or keying to the lath or masonry substrate.
• Wood lath or a masonry substrate, but not metal lath, must be thoroughly wetted before applying stucco patches so that it does not draw moisture out of the stucco too rapidly. To a certain extent, bonding agents also serve this same purpose. Wetting the substrate helps retard drying.
• To prevent cracking, it is imperative that stucco not dry too fast. Therefore, the area to be stuccoed should be shaded, or even covered, if possible, particularly in hot weather. It is also a good idea in hot weather to keep the newly stuccoed area damp, at approximately 90% humidity, for a period of 48 to 72 hours.
• Stucco repairs, like most other exterior masonry work, should not be undertaken in cold weather (below 40 degrees Fahrenheit, and preferably warmer), or if there is danger of frost.

Historic Stucco Textures

Most of the oldest stucco in the U.S. dating prior to the late 19th century will generally have a smooth, troweled finish (sometimes called a “sand” or “float” finish), possibly scored to resemble ashlar masonry units. Scoring may be incised to simulate masonry joints, the scored lines may be emphasized by black or white penciling, or the lines may simply be drawn or painted on the surface of the stucco. In some regions, at least as early as the first decades of the 19th century, it was not uncommon to use a roughcast finish on the foundation or base of an otherwise smooth-surfaced building. Roughcast was also used as an overall stucco finish for some out buildings, and other less-important types of structures.

A wide variety of decorative surface textures may be found on revival-style stucco buildings, particularly residential architecture. These styles evolved in the late 19th century and peaked in popularity in the early decades of the 20th century. Frank Lloyd Wright favored a smooth-finish stucco, which was imitated on much of the Prairie-style architecture inspired by his work. Some of the more picturesque surface textures include: English Cottage or English Cotswold finish; sponge finish; fan texture; adobe finish; and Spanish or Italian finish. Many of these finishes and countless other regional and personalized variations on them are still in use.

The most common early 20th-century stucco finishes are often found on bungalow-style houses, and include: spatter or spatterdash (sometimes called roughcast, harling or wetdash), and pebble-dash or drydash. The spatterdash finish is applied by throwing the stucco mortar against the wall using a whisk broom or a stiff fiber brush, and it requires considerable skill on the part of the plasterer to achieve a consistently rough wall surface. The mortar used to obtain this texture is usually composed simply of a regular sand, lime and cement mortar, although it may sometimes contain small pebbles or crushed stone aggregate, which replaces half the normal sand content. The pebble-dash or drydash finish is accomplished manually by the plasterer throwing or “dashing” dry pebbles (about 1/8-inch to 1/4-inch in size)onto a coat of stucco freshly applied by another plasterer. The pebbles must be thrown at the wall with a scoop with sufficient force and skill that they will stick to the stuccoed wall. A more even or uniform surface can be achieved by patting the stones down with a wooden float. This finish may also be created using a texturing machine.

A wood-burning stove (also known as a wood stove) is a heating appliance made from iron or steel that is capable of burning wood fuel. Unlike standard fireplaces, wood stoves are typically contained entirely within the living space, rather than inset in the wall.

Wood stoves come in many different sizes, each suited for a different purpose:

• Small stoves are suitable in single rooms, seasonal cottages or small, energy efficient homes. These models can also be used for zone heating in large homes where supplemental heating is needed.
• Medium-size stoves are appropriate for heating small houses or mid-size homes that are intended to be energy-efficient and as inexpensive as possible to maintain.
• Large stoves are used in larger homes or older homes that leak air and are located in colder climate zones.

To ensure safe and efficient use of wood-burning stoves, inspectors can pass along the following tips to their clients:

Never:

• burn coal. Coal burns significantly hotter than wood, posing a fire hazard;
• burn materials that will emit toxic chemicals, such as wood that has been pressure-treated or painted, colored paper, gift wrap, plastic, plywood, particleboard, or questionable wood from furniture;
• burn wet wood. Generally speaking, it takes six months for cut, stored wood to dry out and be ready for use in wood-burning stoves;
• burn combustible liquids, such as kerosene, gasoline, alcohol or lighter fluid;
• let small children play near a lit wood-burning stove. Unlike standard fireplaces, the sides of which are mostly inaccessible, all sides of wood stoves are exposed and capable of burning flesh or clothing; or
• let the fire burn while the fire screen or door is open.

Always:

• use a grate to hold the logs so that they remain secured in the stove and the air can circulate adequately to keep the fire burning hot;
• keep the damper open while the stove is lit;
• dispose of ashes outdoors in a water-filled, metal container;
• check smoke alarms to make sure they are working properly; and
• periodically remove the stovepipe between the stove and the chimney so that it can be inspected for creosote. Homeowners may want to hire a professional to perform this service.

Efficiency and Air Pollutants

While federal and state governments crack down on vehicle and industrial emissions, they do relatively little to limit the harmful air pollution emitted from wood stoves. The problem is so bad that, in many areas, such as Chico, Caifornia (pictured at right), the smoke from wood stoves is the largest single contributor to that city’s air pollution.  Smoke from wood stoves can cause a variety of health ailments, from asthma to cancer.

To mitigate these concerns, the EPA sets requirements for wood-stove emissions based on the design of the stove: 4.1 grams of smoke per hour (g/h) for catalytic stoves, and 7.5 g/h for non-catalytic stoves. Some state laws further restrict airborne particulates, and many new models emit as little as 1 g/h. These two approaches — catalytic and non-catalytic combustion — are described briefly as follows:

• In catalytic stoves, the smoky exhaust passes through a coated, ceramic honeycomb that ignites particulates and smoke gasses. Catalysts degrade over time and must eventually be replaced, but they can last up to six seasons if the stove is used properly. Inadequate maintenance and the use of inappropriate fuel result in an early expiration of the catalyst. These stoves are typically more expensive than non-catalytic models, and they require more maintenance, although these challenges pay off through heightened efficiency.
• Non-catalytic stoves lack a catalyst but have three characteristics that assist complete, clean combustion:  pre-heated combustion air introduced from above the fuel; firebox insulation; and a large baffle to create hotter, longer air flow in the firebox. The baffle will eventually need to be replaced as it deteriorates from combustion heat.

The following indicators hint that the fire in a wood-burning stove suffers from oxygen deprivation and incomplete combustion, which will increase the emission of particulates into the air:

• It emits dark, smelly smoke. An efficient stove will produce little smoke.
• There is a smoky odor in the house.
• There is soot on the furniture.
• The stove is burning at less than 300º F. A flue pipe-mounted thermometer should read between 300º F and 400º F.
• The flames are dull and steady, rather than bright and lively.

To ensure efficiency, practice the following techniques:

• Purchase a wood-burning stove listed by Underwriters Laboratories. Stoves tested by UL and other laboratories burn cleanly and efficiently.
• Burn only dry wood. Wood that has a moisture content (MC) of less than 20% burns hotter and cleaner than freshly cut wood, which may contain half of its weight in water.
• Burn hardwoods, such as oak, hickory and ash once the fire has started. Softwoods, such as pine, ignite quicker and are excellent fire starters.
• Make sure the stove is properly sized for the space. Stoves that are too large for their area burn inefficiently.
• Burn smaller wood rather than larger pieces. Smaller pieces of wood have a large surface area, which allows them to burn hotter and cleaner.

InterNACHI inspectors should always disclaim knob-and-tube wiring during their inspections.

Facts About Knob-and-Tube Wiring:

• It is not inherently dangerous. The dangers from this system arise from its age, improper modifications, and situations where building insulation envelops the wires.
• It has no ground wire and thus cannot service any three-pronged appliances.
• While it is considered obsolete, there is no code that requires its complete removal.
• It is treated differently in different jurisdictions. In some areas, it must be removed at all accessible locations, while others don’t, but inspect it for safety reasons.
• It is not permitted in any new construction.

How Knob-and-Tube Wiring Works:           

K&T wiring consists of insulated copper conductors passing through lumber framing drill-holes via protective porcelain insulating tubes. They are supported along their length by nailed-down porcelain knobs. Where wires enter a wiring device, such as a lamp or switch, or were pulled into a wall, they are protected by flexible cloth or rubber insulation called “loom.”

Advantages of Knob-and-Tube Wiring:

• K&T wiring has a higher ampacity than wiring systems of the same gauge. The reason for this is that the hot and neutral wires are separated from one another, usually by 4 to 6 inches, which allows the wires to readily dissipate heat into free air.
• K&T wires are less likely than Romex cables to be punctured by nails because K&T wires are held away from the framing.
• The porcelain components have an almost unlimited lifespan.
• The original installation of knob-and-tube wiring is often superior to that of modern Romex wiring. K&T wiring installation requires more skill to install than Romex and, for this reason, unskilled people rarely ever installed it.

Problems Associated with K&T Wiring:

• Unsafe modifications are far more common with K&T wiring than they are with Romex and other modern wiring systems. Part of the reason for this is that K&T is so old that more opportunity has existed for improper modifications.
• The insulation that envelopes the wiring is a fire hazard.
• It tends to stretch and sag over time.
• It lacks a grounding conductor. Grounding conductors reduce the chance of electrical fire and damage to sensitive equipment.
• In older systems, wiring is insulated with varnish and fiber materials that are susceptible to deterioration.

Compared with modern wiring insulation, K&T wiring is less resistant to damage.  K&T wiring insulated with cambric and asbestos is not rated for moisture exposure. Older systems contained insulation with additives that may oxidize copper wire. Bending the wires may cause insulation to crack and peel away.

K&T wiring is often spliced with modern wiring incorrectly by amateurs. This is perhaps due to the ease by which K&T wiring is accessed.

Building Insulation:

K&T wiring is designed to dissipate heat into free air, and insulation will disturb this process. Insulation around K&T wires will cause heat to build up, and this creates a fire hazard. The 2008 National Electrical Code (NEC) requires that this wiring system not be covered by insulation. Specifically, it states that this wiring system should not be in…

hollow spaces of walls, ceilings and attics where such spaces are insulated by loose, rolled or foamed-in-place insulating material that envelops the conductors.

Local jurisdictions may or may not adopt the NEC’s requirement. The California Electrical Code, for instance, allows insulation to be in contact with knob-and-tube wiring, provided that certain conditions are met, such as, but not limited to, the following:

• A licensed electrical contractor must certify that the system is safe.
• The certification must be filed with the local building department.
• Accessible areas where insulation covers the wiring must be posted with a warning sign. In some areas, this sign must be in Spanish and English.
• The insulation must be non-combustible and non-conductive.
• Normal requirements for insulation must be met.

Modifications:

• Many homeowners adapted to the inadequate amperage of K&T wiring by installing fuses with resistances that were too high for the wiring. The result of this modification is that the fuses would not blow as often and the wiring would suffer heat damage due to excessive amperage loads.
• It is not uncommon for inspectors to find connections wrapped with masking tape or Scotch tape instead of electrical tape.

K&T Wiring and Insurance:

Many insurance companies refuse to insure houses that have knob-and-tube wiring due to the risk of fire. Exceptions are sometimes made for houses where an electrical contractor has deemed the system to be safe.

Advice for those with K&T wiring:

• Have the system evaluated by a qualified electrician. Only an expert can confirm that the system was installed and modified correctly.
• Do not run an excessive amount of appliances in the home, as this can cause a fire.
• Where the wiring is brittle or cracked, it should be replaced. Proper maintenance is crucial.
• K&T wiring should not be used in kitchens, bathrooms, laundry rooms or outdoors. Wiring must be grounded in order to be used safely in these locations.
• Rewiring a house can take weeks and cost thousands of dollars, but unsafe wiring can cause fires, complicate estate transactions, and make insurers skittish.
• Homeowners should carefully consider their options before deciding whether to rewire their house.
• The homeowner or an electrician should carefully remove any insulation that is found surrounding K&T wires.
• Prospective home buyers should get an estimate of the cost of replacing K&T wiring. They can use this amount to negotiate a cheaper price for the house.

In summary, knob-and-tube wiring is likely to be a safety hazard due to improper modifications and the addition of building insulation. Inspectors need to be wary of this old system and be prepared to inform their clients about its potential dangers. This article is from InterNACHI and can be found at https://www.nachi.org/knob-and-tube.htm.