Rehabilitation: Possible Problems, Causes, Remedies

Paint deterioration

On wall surfaces, blistering and peeling often result from either a buildup of excessive moisture within the wall cavity behind the paint or from using an incompatible paint type. For example, if oil paint is applied over latex, peeling of the top coat can sometimes result. Some possible remedies which may help to alleviate moisture problems include: repairing leaky roofs; repairing and sealing walls and floors in damp basements to reduce or eliminate moisture penetration into wall cavities from this source; painting or wallpapering interior sides of the affected walls with products designed to act as vapor barriers; and, in extreme cases, installing a system of louvered upper and lower wall plugs designed to vent exterior wall cavities through natural convection. Once the problem has been remedied, the affected area should be thoroughly cleaned, scraped, and/or sanded, primed with a high-quality oil-based primer and repainted with latex or oil paint according to the manufacturer's specifications.

Excessive cracking of surface paint is usually caused by improper application techniques, such as painting a surface which is dirty or greasy or painting when it is too cold or damp. Cracking can also result when paint that is several layers thick becomes excessively hard and brittle with age and is no longer able to expand and contract with the wood siding in response to temperature and humidity changes. Cracking can usually be dealt with by thoroughly cleaning and carefully sanding the affected area, removing sanding residue, and repainting under weather conditions specified by the manufacturer. Remember, sanding should either be done by hand or with an orbital or reciprocating power tool. Avoid using rotary sanders; they can dig into the wood and leave marks which remain visible after painting. Stripping old paint completely should only be undertaken when the problem is extreme. If stripping is necessary, avoid using blowtorches, chemical strippers, and abrasive methods such as sandblasting; these methods can cause severe damage to the siding. Paint should be removed by hand with a wide putty knife or scraper and heat plates or guns designed for this purpose. When using this method, always take adequate precautions against fire and toxic fumes. 

For mildew problems, trim back trees or shrubs which may be inhibiting the evaporation process and repair leaky gutter systems. To remove mildew, scrub the affected area with a soft brush and a solution containing a cup of non-ammoniated detergent, a quart of household bleach, and a gallon of water (for stubborn spots, use and extra quart of bleach). Once the mildew is removed, thoroughly rinse the siding with a direct stream of water from a spray nozzle. After the surface is completely dry, repaint with primer and paint which are designed to be “mildew resistant.”

Wood Sidings

Splitting, warping, and rotting of wood sidings can be caused by a variety of factors, including excessive moisture levels within wall cavities, excessive weathering due to lack of paint, or poor-quality materials. A buildup of mildew or mold on siding surfaces is often caused by leaky gutters, or plantings which reduce air circulation along a wall. 

Split clapboards can often be repaired by gently spreading the two edges of the split slightly apart, applying wood glue along each edge and then forcing the two edges back together. The two sections can be held in place with finishing nails set above and below the split. After the glue has completely dried, remove the finishing nails, fill the holes with wood putty, and lightly sand the area smooth prior to priming and repainting. 

Warped clapboards can sometimes be straightened by drilling several holes through the board and inserting wood screws. Then tighten the screws until the warp flattens out. Caution: to avoid splitting the board, always tighten the screws in gradual stages over a period of several days. Wet boards as thoroughly as possible prior to tightening the screws. Putty over the screws and sand surface lightly before repainting.

For rotted or damaged clapboards, make a vertical cut on each side of the affected section with a small saw. Using a hammer and chisel, pull the nails which hold the top and bottom of the section in place and remove the section in pieces. Replace the section with a new piece, fill and joints with wood putty, and sand the surface smooth before priming and repainting. 

Rotted, cracked, or warped wood shingles can be replaced on an individual basis in the same manner outlined for clapboards, except there is no need for making cuts with a saw.

Masonry

Most mortar deterioration results from the combined effects of weathering and air pollution. Excessive spalling and cracking of bricks usually result from the combined effects of deteriorated mortar or improper repointing. Water gets inside cracks and joints. It expands and contracts with temperature changes, cracking and displacing the surrounding masonry. Air pollution contributes greatly to the buildup of dirt and deposits on brick wall surfaces. Mixed with water, these deposits often stain brick. 

Deteriorated mortar should be repointed. Loose mortar should be removed from the joints by hand with a hammer and chisel to a uniform depth of ½ - 1”. To ensure a good bond, thoroughly flush chiseled joints with water prior to refilling them with new mortar. Important precautions: When removing old mortar, don’t chip the edges of the surrounding bricks. This will accelerate the deterioration of the brick. Make sure that new mortar matches the color and composition of the original mortar. Most older buildings have bricks designed for use with soft lime mortar; hard cement-based mortars can lead to damage to the surrounding bricks. If you’re unsure of what type of mortar to use, have some of the original analyzed at a high school or college chemistry laboratory to determine the proper mix. Finally, never refill a joint completely. Refinished joints should always be slightly recessed. 

Minor cracks in bricks can usually be repaired by filling them with tinted sealant designed for that purpose. Severely cracked, broken, or spalling bricks should be replaced by chiseling out the damaged brick and surrounding mortar, laying a shallow mortar bed on the top, bottom, and sides of the cavity, and inserting a brick “buttered” on all sides but the finish side with mortar prior to final pointing. The new brick should match the original brick in size, color, and texture as closely as possible. 

Proper removal of dirty deposits from brick can be accomplished in two ways: a) hand scrubbing with soft bristled brushes and rinsing with water sprayed under low to moderate pressure; or b) chemical cleaning. Chemical cleaning is a highly technical and potentially dangerous procedure which should be undertaken only by competent and knowledgeable professionals. Never utilize abrasive cleaning methods such as sandblasting on exterior brick; they can irreparably damage brick. Also, never coat brick with clear “waterproof” sealants such as silicone; it’s an unnecessary expense which can result in major maintenance problems in the future if moisture gets trapped beneath the sealant.

Roofs

Exposure to rain, sunlight, and air pollution eventually lead to the deterioration of roof surfacing and flashing materials and leakage. Your first step toward curing these problems should be to assess the existing condition of the roof. (You may want to contact a reputable roofing contractor to help with this.) If deterioration is extensive, complete replacement may prove more effective and economic than piecemeal patching. However, under certain circumstances, patching can be useful and cost effective. For example, as a temporary measure, existing leaks should be repaired immediately to prevent water damage in the rest of the building until the new roof is installed. 

For roof systems in which the bulk of the surface fabric and/or flashing is essentially sound, selective repair can often provide a long-lasting roof at moderate cost. For example, assume your house has a roof surfaced with asphalt shingles which are in good condition. However, the flashing which seals the edge of the roof at the juncture of a chimney stack has deteriorated and is leaking. It may be possible to carefully remove the shingles immediately around the chimney stack, replace the deteriorated flashing and reset or replace the removed shingles, thereby effectively solving the problem without replacing the entire roof.

Energy Conservation

Excessive infiltration (flow of air into and out of a building), inefficient heating/cooling systems, and lack of insulation are among the most typical reasons for high heating and cooling costs. 

Excessive infiltration can occur for 40 percent of the heating and cooling costs of old houses. To reduce infiltration, make sure that all doors and window openings are properly weatherstripped and caulked. Storm windows and doors should be installed and functioning properly. Cracks and crevices along foundation walls (especially where they meet wooden sills) should be sealed with appropriate caulking materials. 

Like infiltration, inefficient heating/cooling systems are a leading cause of high energy costs in older buildings. Have your system serviced at least once a year to ensure peak operating efficiency. Consider upgrading heating equipment with more efficient units. Automatic thermostats designed to raise or lower temperatures when a building is vacant are also helpful. In weather which is not too hot, consider turning air conditioners off and opening windows. 

Most owners today recognize the potential benefits of insulated walls and roofs; however, many are unaware of the potential dangers posed by improperly installing insulation in older buildings. A safe and effective way to insulate a side wall with interior wall surfaces which are already in need of replacement is to remove the interior wall surface, install fiberglass batt insulation between the exposed studs, cover it with an appropriate vapor barrier material such as polyfilm, and install a new interior finish surface directly over the vapor barrier. 

In order to avoid ripping out plaster, many property owners decide to have insulation blown into the wall cavities. Be careful! Blown-in insulation techniques rarely include provisions for effective vapor barriers. Without them, when warm water vapor from the interior comes in contact with cold insulation during the winter it will condense into water. The result is soggy and ineffective insulation. Since air can’t circulate through the wall, this moisture may become trapped and cause rot in the walls or peeling exterior paint. 

Remember, if you’re going to go to the trouble and expense of insulating, make sure it’s done right. Otherwise, you may wind up spending a lot and gaining little.

Exterior Paint Color

From a visual standpoint, exterior paint color is one of the most important character defining features of a building. Often, well-intentioned owners who have worked hard to repair, retain or replace historic exterior trim or sidings realize too late that the new paint color scheme they’ve used on a building is inappropriate for one or more of the following reasons: too many colors were used; not enough colors were used; the colors chosen are from the wrong historical era.

You can usually avoid this problem if you take the following steps. First, try to determine the original color scheme of the building; carefully scrape off the paint along the edges of sidings and trim features at several locations on the north side of the building until the bottom paint layer is exposed. When scraping, angle your knife slightly; this will help make the color of each layer of paint more visible. Then wet the scraped area; this will allow you to determine the original vase color more accurately. 

If this method proves unsuccessful, or you do not like the particular color scheme you have uncovered, consult publications which describe appropriate color schemes for the period in which your building was built. You can also refer to charts published by various paint manufacturers which describe documented historic colors and color schemes. Since some of these publications can be expensive to purchase, you may want to call a local or state historic preservation organization. Often, these organizations keep such information on file as a public service. These groups can also provide invaluable assistance if you have questions or want further assistance.

Exterior Trim

Like paint color, moldings, brackets, porches, and other ornamental trim features give special character to the exterior of the building. Whether you do the work yourself or have it done, retaining, repairing, or replacing these features will be a worthwhile investment in the total value of your property. 

For loose trim features such as moldings, carefully refasten the feature by drilling holes and countersinking and screwing the trim back on. Before scraping and repainting, fill the screw hole depression with putty and sand lightly. 

Epoxies, polyesters, and synthetic resins available on the market today often allow for repair rather than replacement of partially rotted or broken features such as porch posts and railings. With use of such materials, rotted sections can often be cut out and refilled; and broken or cracked brackets, balusters, moldings, doors, and other wooden features can often be re-glued. Features beyond repair can be reproduced with a jig or sabre saw and drill and stock lumber, using an intact, similar feature as a model. Intricate features such as brackets can often be made in sections and then glued together with waterproof epoxies. If exact reproduction of a feature such as a molding is not possible, approximate the size and shape of the original as closely as possible. If a major feature such as a front porch is missing entirely, try to locate an old photograph on which to base the design of the new porch. If you cannot find a photograph, look at similar nearby buildings which retain old porches; these may help to give you an idea of the size, shape, and details of the porch which was removed from the building.

Storefronts

Nineteenth/early twentieth-century mixed-use row building storefronts are characterized by display windows featuring large panes of glass. Often, these large display windows are topped by rectangular transom windows. When repairing storefronts, many well-intentioned owners go too far in attempting to make this feature look “historic.” The most common error most owners make is to “Colonialize” the front by installing multiple-pane display window grids. This treatment is not only historically inappropriate; often, it makes the store less desirable to potential tenants seeking large unbroken window areas in which to display their wares. An old photograph of the building showing an intact original or early storefront is usually the best design guide on which to base your repairs. If such a photograph is unavailable, you may find it helpful to contact a local or state historic preservation office for design assistance.

Text and drawings by Paul Loether and Preston Maynard