September, 2018
Inspection News and Views from the American Society of Home Inspectors

Inspecting Old Houses: Exteriors and Siding


With this article, I continue this series, “Inspecting Old Houses,” Which highlights the unique aspects of old homes and the importance of taking the age of the home into consideration during a home inspection. Inspecting the home exterior is an important part of the process; this is the third article of the series that explores this topic. 

The siding on any home should limit water and air infiltration into the structure. The current technique is to limit any water infiltration into a home and seal the home up so tightly that exterior air needs to be brought inside with mechanical means. Technology is now being used to achieve these goals with house wraps, sealants and tapes; however, in the past, people used common sense principles to achieve these goals and good enough was good enough. If a masonry wall became damp, the thinking was that it will dry out when it stops raining. If it kept raining, the wall would stay wet, no big deal. Walls could be protected with overhanging roofs if the nature of the climate dictated the need to keep the wall dry.

Wood siding is one of the simplest sidings to install and was most commonly used in parts of the country that were forested or, with the advent of rail transportation, in any place with a rail line. The virgin forests that were harvested produced siding with tremendous decay resistance. The sidings were installed to minimize water penetration naturally with the shapes and installation methods used. Horizontal sidings were lapped to shed water and vertical sidings had enough overlap to limit water infiltration on the vertical joints. Trim was lapped and beveled to drain moisture away from the building. In some situations, the wood siding was the exterior sheathing; in other situations, there was a board sheathing and possibly asphalt felt paper (remember that?) to provide additional water and air tightness. Air circulation was designed into many siding shapes to promote drying.

Log structures were chinked for weather tightness, but then, as soon as time and resources were available, they were covered with a wood siding. The wood siding protected the log walls, provided weather resistance and showed the wealth of the owner. Exterior log walls on a home were a sign of “new arrivals” or those who could not afford a better siding. 

Masonry exterior walls are found throughout the country on the oldest homes (adobe Indian pueblos) and in modern construction as veneer. Solid brick and stone walls are the earliest structural masonry walls, and the masonry was the siding. If you had clay and low-cost labor, it was relatively easy to make bricks in a kiln on the property. If you had stones (lots of stones, that is), it was logical to make your walls out of them, but I hardly think it was easy. How people and draft animals got huge stones high into the walls and chimneys is still mind-boggling to me. Still, if you were getting the stones out of your newly cleared field to plant crops, stacking them up to make your walls was the next logical step and the log house was passed on to the next generation of children or the workers on the farm. 

The permanence of masonry structures was a big consideration in their construction. When you built a stone or brick home, you were building it for many generations of your family to come, not just for a few years. If you decided that your home wasn’t large enough or fancy enough, you could construct an addition to accommodate your growing family or to showcase your increased wealth. 


Masonry walls were one of the earliest low-maintenance sidings. If you repointed the walls every 50 years or so, you were good to go for another generation or two in the home. Brick cavity walls were designed to reduce water infiltration into the home and use fewer bricks, but they were still structurally sound. Unless the cavities were filled with insulation, there was little increase in energy efficiency. With the advent of industrial building material production, people used concrete block or clay tiles for faster construction, which affected the home’s permanence and durability.

Stucco is a masonry siding that has been used for thousands of years all over the world. Putting a layer of mortar on the outside of a wood home provides the durability of masonry. Stucco on masonry walls is for decoration and greater weather-resistance. In the 1920s and 1930s, the “stucco man” came down the street selling low-maintenance exterior wall coverings to minimize the maintenance of painting the wood. The stucco could be made to look like almost anything (Formstone), so your house could have a completely different appearance from your neighbor’s house, but it would still have the same siding. In the southwest United States, the sun and heat are tough on wood and because there were fewer trees, masonry exterior walls were the most practical and durable. 

Metal, Asphalt and Vinyl
Metal (steel and aluminum), asphalt and now vinyl sidings were and are commonly used to cover older sidings or masonry to update and reduce the maintenance of the homes. Usually, these sidings are considered to be at least minimally breathable, but many times these sidings were installed over foam, plywood or oriented strand board (OSB) sheathing materials. These underlayments can trap moisture that potentially could move more than one direction in an exterior wall. Condensation problems can develop in the walls and these can be difficult to detect. If you suspect there may be an issue with hidden condensation trapped in walls, especially with damp basements or crawl spaces below, it is your job to raise the question and suggest that the client consult a specialist to further evaluate the situation. The consultation may involve thermal imaging or destructive testing (that is, opening up the wall to look from the interior or exterior). 

Flashing Details
Exterior flashing details are always critical issues, but they assume even greater importance when an older home has been re-sided. Details that permit moisture to infiltrate through a window sill and into a wall—especially behind foam exterior sheathing—can lead to significant damage, rot and the horrible “m” word, mold. These issues are similar to the problems caused by artificial stucco in newer homes. It is important to look for and call out these issues in your reports. Caulk is not a permanent repair for water penetration concerns.

Sidings extending below or close to grade are always a concern. I always note these situations as significant concerns, especially if the interior inspection is limited in these areas. 

If a situation turns out to be a non-issue, you may be labeled the “deal killer.” If the situation turns out to be significant, you are a hero—at least to your clients—and you have saved them from potentially thousands of dollars in repairs. If problems are found after closing without being called out in your report, no one is happy. 

In my next article in the “Inspecting Old Houses” series, I will describe antique roofing materials and systems. If you have any questions or comments on my articles or would like me to speak at your chapter’s educational conference, please contact me at 540-636-6200 or