Exterior Siding and Paint

Some homeowners re-paint the exterior of their home every few years only to find that the new paint does not last, others find that their siding has failed and that they need a new sidings system.

Here you will find the information you need to help you select and maintain the siding at your home. The information here-in will can save you the $$$ and the time to enjoy you summer.

All siding systems require regular maintenance. While some siding systems require more maintenance than others, any promise that a particular product is maintenance-free or permanent should be viewed with skepticism.

Siding failure is one part of the epidemic exterior envelope problems that have plagued many condominiums in British Columbia, the Pacific Northwest and other wet or moist areas. Siding failures have also plagued many residences. These problems have been due in part to material failure (e.g. LP, EIFS and poor quality wood products) but an equally important part has resulted from poor quality designs and installation practices (e.g vinyl siding).

The importance of siding design, material selection, installation practices and maintenance practices can't be overstated. Siding must perform a number of vital functions, including the protection from sun, wind, rain and moisture. It must also cope with moisture that emanates from the interior of the house.

Siding related decisions have always been important. They have become even more important with the advent of energy efficient construction practices, new materials and modern designs. Here you will find information to help with exterior siding related decisions.


  • The term "Exterior Envelope" is very useful when thinking about siding issues. It turns out that most siding problems are related to other parts of the exterior envelope of a structure. Siding problems are often related to the location and exterior design of a home, the roof, flashing systems, vents, drainage, wall insulation, windows, doors and all of the components that make up the exterior envelope of a structure.

    Here is an example. Log homes can last for centuries but some deteriorate in just a few years. Part of the problem maybe in the quality of the logs. The more important issues are often found in the design of the foundation, the log structure and the roof. If the bottom logs are anchored to a good concrete foundation and are not in contact with the soil, they will not rot. If the entire log structure is protected from the rain by a wide roof overhang the logs will not rot. But if some of the logs get wet and stay wet, they will rot and will not last no matter what the quality of the wood might be.

    Similar concerns exit with all siding systems. Almost all siding can last for a long time if it is part of a good exterior envelope. Conversely, most siding issues are part of a larger problem and not just the fault of the siding material, installation practices or maintenance.

  • 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.

  • January 2001

    I have just reviewed an advance copy of the March 2001 Fine Homebuilding (#137). On page 86 is an article called: Rain-Screen Walls: a Better Way to Install Siding by Mark Averill Snyder with some side bars by Joe Lstiburek.

    This is an excellent article with some equally fine illustrations and a 'must read' for anyone installing siding and/or experiencing siding problems.

    Not all houses require a rain-screen installation, many are doing just fine without. The problem is in predicting which house would benefit from such a systems. And so, the investment in a better siding installation system appears to me to be worth the extra cost. - George

    p.s. I find some of Joe's comments a bit strident, but his overall ideas are right on target.

    October 2004

  • 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.

  • This was one of the promised "permanent, no maintenance" siding products. When in good condition, it is best left alone. We have not come up with any acceptable materials which can be used to patch or repair this material. The cement asbestos board does become brittle and subject to cracking over time, and will most likely have to be covered or removed at some point by an asbestos abatement company at high cost (+/- $2.50/sq.ft.). For more information about cement asbestos siding, asbestos abatement, and guidelines for homeowners who wish to undertake the removal of cement asbestos siding themselves, please contact the Puget Sound Air Pollution Control Agency, (206) 343-8800.

  • 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.

  • If you are choosing new siding, don't choose vinyl siding. There are lots of better products that have fewer problems and last much longer. If you already have vinyl siding, read on and plan on replacing the siding - something that is not necessary with many other siding products.

    Vinyl siding does not rot or peel and it can work quite well in most standard home designs. But it's not fool proof and from what I see in the field, some of this siding is installed by fools. For example, most siding application instructions require a gap of 1" or more between the bottom of the siding and any horizontal surface. This is a common detail in almost all siding applications and is commonly done with most siding products. However, from what I can see many of the vinyl siding applications pay little attention to such details. As a result, water can wick up behind the siding. The siding will not rot, the wall behind it will.

    The bigger problems with vinyl siding occur at structures where the siding is not protected by a good roof overhang or where the siding is exposed to wind blown rain. For example, I have seen many serious leaks and damage at balconies with vinyl siding on the balcony railing walls.

    As I see it, the problem with the vinyl siding is related to it's promise of a "lifetime" and "no maintenance product". The product is being oversold and this hype seems to permeate the industry down to the installers.

    Vinyl is not a bad siding product on certain types of homes. It requires quality installation work and attention to manufacturers specifications. It does need to be washed from time to time. It gets damaged by heat from BBQs (yes it melts and burns). It also gets damaged by baseballs etc. and it can be very hard to repair because it is often very difficult to find matching replacement pieces.

    Note: Vinyl siding is made out of Polyvinyl Chloride - PVC. PVC has some potentially serious toxicity problems during manufacture and disposal. I don't recommend the use of PVC containing materials such as: pipes, vinyl siding and some roofing membranes.

  • 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.

  • EIFS siding systems involve the application of a plasticized cement stucco product on top of an exterior mounted polystyrene foam board insulation. This system is usually 'top coated' with an acrylic polymer sealant. The promise of the system has been: low cost, ease of application and a "clean" look. The reality is another matter.

    Reports from various parts of the country show that moisture can be trapped behind the siding and cause wood rot and other damage. This has lead a number of jurisdictions to ban EIFS siding. And, based upon by experience and industry reports, it appears that the failure rate of EIFS siding system is higher than that of any other siding system on the market. Some insurance companies are reported to be refusing to insure homes and buildings with this type of siding, and at least one leading manufacturer has stopped to produce a component product. For the EIFS industry point of view please call: (800) 898 2842, and (800) 294 EIMA (the EIFS trade association).

    In an attempt to solve some of the problems associated with EIFS siding systems, various special details and "water management" solutions have been developed by the industry. Some of the special details involve more complicated flashing and caulking systems. The "water managed" systems provide for a secondary "shield" behind the EIFS siding and for a way to drain any water which might have penetrated the "primary" water barrier.

    George's Tips In light of the extensive amount of damage associated with EIFS siding in wet climates, and in light of the frequency of design and installation errors found with these systems, I don't recommend EIFS siding in wet or moist climates.

    The special details and water managed systems that are being recommended in the trade journals for EIFS siding systems may turn out to be sufficient to make this siding product reliable. However, these special details are very complicated and require an unrealistically high level of work quality.

    My advice: don't use EIFS siding Systems.

  • 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.