Foam boards must be protected during installation. They are not designed or manufactured to be waterproof and can absorb water. If they are left outside overnight, their surfaces can get damp and lead to immediate and even severe warping. Warped boards should be discarded. Foam boards are very light and can be used, with a degree of success, to build up areas that collect water. This built-up method is much preferred over adding gravel to cover standing water.
It is not uncommon for membrane roofs to fail at the point where the insulation boards end and the overhang begins. A noticeable height difference can be clearly seen at this junction. The bending of roof membranes is less a problem than the expansion and contraction differential. Heat and cold are absorbed by the roof and gravel and forced to remain in the roof by the foam insulation. While one inch away, where there is no insulation, heat easily soaks through the overhang. This narrow line of roof membranes takes a constant beating.
Most roofing and insulation is made in a factory, and then installed by roofers. Sprayed foam is manufactured by the same workers that are installing it. Think of it as 'real-time' roofing. When choosing a spray foam contractor, proven ability to install durable roofs is paramount; a small, hidden mistake can later cause serious roof problems or failure. Sprayed foam fits exactly and adheres well to a cleaned surface. When applied, it rises in three seconds and solidifies in one minute. Foam is sprayed to a thickness that reaches the desired R-value, adding almost R-7 per inch. Low areas can be carefully built up with additional waterproof foam insulation. Additions and modifications are incorporated without compromising the original roof.
Cleaned tarpapers and other roof membranes make an ideal base for sprayed foam. This helps avoid the expense accompanying thousands of pounds of landfill from each roof replacement. Instead of being discarded, existing foam boards can remain in place and continue to contribute to energy savings. Clean gravel removed from roofs can be recycled.
Even though windows should not be overlooked in discussions of heat loss in an Eichler, they are secondary to the roof. After all, the biggest feature on any Eichler is the roof. Inside the house, underneath that huge surface, heated or cooled air constantly cycles at the ceiling. It continually costs real money and comfort as this treated air changes back to the outside air temperature.
When it's time to re-roof your Eichler, consider insulation. It will enhance your home's value and improve your quality of life.
Guest 'House Doc' Randy Feriante has operated Dura-Foam Inc., a family-owned business that installs polyurethane foam roofing, for nearly 25 years. Based in Menlo Park, Dura-Foam (650-327-3200) maintains a strong focus on the Eichlers.