Siding material and installation choices are often made without regard to local climates and conditions and/or a building's design. This often results in siding failure. The examples are numerous: LP and EIFS siding systems tend to fail in wet climates and exposed locations and yet work quite well in many types of building designs in dry climates. I recall a national seminar about such siding issues. Inspectors from areas with wet climates had all of the horror stories, the others only knew of these problems from the professional literature.

These choices are not just regional ones, they often depend upon "micro-climates" and specific design elements. For example: within the city of Seattle one can find a large variation in rainfall, sun exposure and wind patterns. As a result, the cedar shingle siding on an exposed building on the west side of Capital Hill will tend to require a great deal of maintenance and may experience siding failure. The shingle siding on the same building on the east side of the same hill will tend to last with minimal maintenance.

The use of vinyl siding on such a capital hill building might be a good alternative, but that will depend upon the design of the building. Vinyl siding tends to leak at structures without good roof overhangs or those with exposed decks and balconies.

If the building sits on a hillside and requires complex scaffolding for siding maintenance and repairs, then a lower maintenance siding product might be called for even if the original cost is a higher. If the building is on a wet and flat lot then adding a few inches to the height of the concrete foundation will save in future siding and other maintenance and repair costs. And, if one invests in quality wood siding at a seaside location, an investment in stainless steel nails will help prolong the life of the siding system.

Siding choices require a thorough understanding of local climates and conditions, the specific design demands of the building and the characteristics of siding materials.

A common misconception about houses with brick siding is that the bricks constitute a structural component of the home. In most houses, brick is used as a veneer and a siding product, with the actual structure of the house being a normal wood frame structure.

Good quality brick will withstand most of the forces which deteriorate siding products. The required maintenance is mostly in the area of the mortar used to hold the bricks together. Old fashioned mortar contained very little, if any, Portland cement, and becomes very brittle over time. Such deteriorating mortar needs to be scraped out between the bricks, and new grout tuck pointed into the joints. This is a labor intensive process, often costing between $10,000 and $30,000 for an average sized home. While newer mortar material may not require such restoration as often, it may require moss control, water sealing, and the correction of any deteriorating bricks or settling cracks.

Aluminum siding is a relatively low maintenance product over the first years of its life. While subject to dents and blemishes which are not easily correctable, a good craftsman can replace individual siding pieces with matching siding as needed. The siding does require careful washing and eventually repainting. A painting job on aluminum siding must be carefully prepared, using a primer specifically selected for the aluminum siding. Since certain patterns of aluminum siding are sometimes discontinued by the manufacturer, it might be a good idea to stock up on a few extra pieces of your pattern for future replacement.

Stucco is a very common siding material in areas with a "Mediterranean" climate, i.e. a relatively dry climate. Stucco is most often installed on masonry or adobe structures. It is made out of sand, lime and cement. As with EIFS siding, stucco siding has a high failure rate in wet climates. I don't recommend the use of stucco siding in such climates.

Here are some notes about the use of stucco:

• Stucco and similar products are not traditionally used in the wet Pacific Northwest, however, it is very common in dry climates like New Mexico - where it is the traditional siding product. Stucco can work in wet locations, but it must be installed with local conditions in mind.
• Good installation, includes a good quality tar-impregnated felt, wire mesh, expansion joints, flashings, and good overhangs, gutters, and down spouts. All of this must be accompanied by good quality material and professional installation. In wet climates, a very good roof overhang is of special importance, it helps protect the stucco siding from the rain.
• Older wood frame homes were often stuccoed over a wood lath. Such lath can deteriorate over time and allow for extensive cracking and separation from the wall structure.
• Stucco related problems are often identified by extensive cracking, moss and mildew growth, paint blistering, and noticeable repair patches.

There are a dozen different varieties of wood siding, all the way from the traditional bevel cedar siding to plywood products, cedar shingles, and vertical cedar siding. There are also various forms of re-manufactured wood siding, such as hardboards, oriented strand board, plywood, and masonites. Our experience suggests that good quality wood siding is one of the best choices for siding material in the Pacific Northwest. Properly installed, plywood siding, such as T1-11, results in a very economical, low maintenance, and long lasting exterior siding product.

Many turn-of-the-century homes in the Pacific Northwest are sided with the original clear cedar bevel siding. Such siding, when properly maintained, can remain in excellent condition for years. Wood siding, like all other products, needs to be properly installed and maintained. However, unlike many other siding products, it can be repaired and partially replaced. Most older styles of wood siding products are available on today's market.

Not all wood siding products are of equal quality. In recent years, we have seen the increased use of half by six, tight-knot cedar siding and other similar thin, bevel, tight-knot siding products. These products are typically manufactured from young trees. The wood from such trees does not have good dimensional stability; i.e., it shrinks, warps, and splits. In addition, such wood does not appear to have the characteristic of old growth cedar for resisting rot.

We also find that when cedar shingles are used as a side-walls product, it is mandatory that good quality paint or stain is used to minimize the splitting and warping of these shingles. Typically, we will find the greatest amount of deterioration to the side-wall shingles on the south and southwest side: the weather side in this area. Replacement of the damaged shingles with a matching material is relatively easy, and a recommended process if it is followed by a good quality paint or stain application and proper maintenance.

A common problem seen with wood siding is associated with side-wall insulation and vapor barriers. Wood siding should be installed in a way which allows the siding to "breathe." Improper siding installation over a vapor barrier, and/or over insulation can result in a higher humidity content in the siding, and eventually add to paint and moisture deterioration problems.

Siding, manufactured from oriented strand board and other wood composites, have the advantage of being manufactured from relatively low cost wood and young trees, thus saving money and attempting at a more benign impact on the environment. Such siding products became more attractive as traditional wood siding decreased in quality and/or increases in cost. Unfortunately, most of the experience with such siding products have been poor. Most of these products have experienced moisture related problems.

Louisiana Pacific Corp. came out with an Inner-Seal Lap Siding (LP Siding). Masonite developed OmniWood, and a number of other companies launched other similar products. Of all of these products, LP is the best known, but for the wrong reasons. LP has been involved in a highly publicized legal action and has agreed to pay for some siding damage.

I actually don't think that LP siding is such a bad product, and I hope that one of these years, newer versions of these products will have fewer problems. However, as of now (fall of 2004) I have not seen the evidence that allows me to recommend such a product.

The key issues relating to the longevity of LP and other manufactured wood siding products seem to be as follows:

1. A better formulation of the materials and the manufacturing process.
2. Good quality installation and careful attention to manufacturers installation and maintenance instructions.
3. Low interior moisture levels, good venting systems, wide roof overhangs and the proper control of vegetation next to the house.

One of the problems with this type of siding is the requirement that it must be installed with "hidden fasteners", and not "face nailed." Each piece of siding is nailed along the top edge of the board, the nails are then covered by the next layer of siding. This requirement is intended to prevent water entry into the core of the material. Failure to follow these instructions has contributed to many of the damaged siding installations.

This "hidden fastener" requirement makes partial replacement of LP type siding very difficult. When replacing wood lap siding, a damaged piece is carefully removed and a new piece installed. The new piece is then face nailed into place. With LP siding repairs, such face nailing needs to be minimized and carefully caulked, or the siding needs to be glued into place.

Methods to reduce additional de-lamination - Before doing anything, it is very important to find out what if any help is available from the siding manufacturer. Following all of the manufacturers maintenance guidelines may be required in order to keep any warrantee in force.If the siding shows some swelling or thin fissures at the bottom edge, it may be possible to reduce further damage by priming the siding with "Permenizer Plus" or a similar primer and then repainting. The primer and paint may be applied with a spray gun, but the bottom edge and any other areas of defects must be brushed.

Premature paint deterioration is often the result of moisture and water vapor, which originates inside the home and penetrates through the wall and siding. For example, one of the most common ways to detect failing tub and shower walls is by the appearance of blistering and other paint deterioration at the outside of the wall in question. Such exterior paint damage cannot be corrected by any exterior painting process unless the cause of the moisture or water vapor is first eliminated and associated repairs are made. A careful inspection of the exterior and interior of the home should thus be performed before exterior siding and painting work begins. Poor quality painting is counter productive. A good exterior paint job should last 10-15 years. Good quality painting includes the following steps:

• Removal of any unused miscellaneous fittings, hooks, old electrical equipment, etc.
• Removal of tree limbs and other vegetation in contact with the house or overhanging the roof.
• Re-grading of the yard in such a way as to eliminate the possibility of any soil touching the siding or any portion of the wood framing of the house.
• Check that a proper drainage system exists and is functioning. Please see: Gutters, Downspouts, and Drains, and Downspout Drain Systems.
• Replacement or repair of any damaged siding and trim.
• Modification, or repair of the various venting systems in the house to assure low interior moisture.
• Washing, scraping, and sanding as required. Caution: Older paint products often contain high levels of lead. Paint chips and sanding dust from such buildings are often ingested or inhaled by small children. It can also contaminate the soil. For more information, you may want to contact the Washington State Department of Labor and Industries, Office of Health and Safety, (1-800-423-7233).
• Some siding products are best maintained with good quality stains. Check with a good painter, lumber yard, or full service paint store to decide on the best product for your home.
• Prime as required, including all raw wood, and damaged areas.
• Painting: use good quality paint and follow instructions on the can or manual.

Note: Painting rags, tools, and debris covered with some painting products can start fires through spontaneous combustion - be careful. Dispose of leftover paints and other household products in accordance with the law - call the Household Waste Information Hotline: (206-296-4692).

Note: Full service paint stores are usually available for technical assistance in preparation for good do-it-yourself exterior painting work, and/or referral to reliable painting contractors. As a rule of thumb, you should count on spending 80% of the total time required to paint your home in preparation, and only 20% of the time with the brush in hand.