Healthy House Siding

We chose aluminum siding for the outside of the house. Siding is painted at the factory. Aluminum doesn't corrode or rot or wear out, although it does dent. It shouldn't need to be painted again for 20 years or more, and it cleans up beautifully with just a hose. Surprisingly, it is widely used on the east coast, but it is not very popular in the west, where people seem to prefer stucco.

The exterior side of the wall framing was first covered with an aluminum foil wind barrier. I had originally planned on using a foil-kraft paper-foil sandwiched material. However, the contractor expressed a concern that over a period of years, the aluminum foil might cause the steel framing to corrode if they were put in direct contact (electrolytic corrosion). Rather than risk that, we decided to use regular builder's foil, with aluminum on one side, and kraft paper on the other. Having paper exposed toward the inside of the house wasn't ideal. However, the paper is relatively low odor, and it is isolated from the house by being on the outside of the airtight barrier. It is also covered by insulation.

The purpose of the foil is to minimize air movement in the wall cavity. It can also be a place where inside to outside temperature and humidity differences can meet, so water can condense there and flow down near the outside of the building, rather than near the interior wall.

The builder's foil was taped together using Polyken #339 aluminum foil tape. The #339 uses a low odor adhesive. For completeness, the builder's foil was also taped at its seams on the inside of the building (on the kraft paper side). A while back, Polyken changed their name to Tyco Adhesives.

The aluminum siding was attached on top of the foil, from the bottom up. Each segment of siding was screwed to the framing, creating a weatherproof seal from segment to segment. The screws used for X bracing mentioned on the page about framing turned out to not be a problem. However, because there was no plywood behind the siding, the vertical seams along each row of siding were more visible than they should have been. The installers took extra care to put bracing on the inside of the wall to push the siding out just a little, to make the seams less visible.

Unfortunately, siding does get dirty. We found that a hose works pretty well for light dirt, but that we really need a pressure washer for the heavier stuff. We also have a long brush with a water sprayer on the end of a pole that works pretty well for the walls that aren't up too high.