Q: Last month, as part of my pre-move-in inspection, an inspector indicated that the duplex I was buying lacked air vents beneath the eaves, although there were vents on either end of the building near the peaks. Then the handyman who was making repairs told me he had just read that the under-eave holes weren't necessary; that, in fact, they would upset the flow of air if they were installed. The building is 20 years old. Is it necessary to have the vents put in?
Q: At a townhouse development, we are replacing 15-year-old cedar shakes with a high-profile composition product. As chairman of our roofing committee, I worry about blocked bird holes under the eaves where there is blown-in insulation. Also, in the case of vaulted ceilings, I am concerned that the often-protruding yellow fiberglass batt insulation should be tamped down. It has been exposed through the skip sheathing following tear-off of the old shakes. I am concerned it will affect the free airflow to the ridge vents. I have been told, however, that even if these things are not done consistently, it is not the end of the world. Am I making too much of the importance of this ventilation issue?
A: Venting (both attics and crawl spaces) is the latest and greatest debate in the building sciences. A building with no roof overhangs by default will have no eave vents, but it isn't necessarily more prone to a hot or moldy attic. And this is true of older homes in general as they have less ventilation and are less likely to have eave vents. Yet the roof right next door, with full ridge, eave and gable vents, might be a mold factory and surprisingly hot in the summer.
Too much venting, we find, can actually pull moisture up into the attic in some cases. And venting from multiple angles can reduce convective airflows. We are finding that the shape and orientation of the roof to the sun, moisture leakage from the living space into the attic, insulation levels, roof type and color have as much to do with keeping an attic in good shape as the venting. Venting is not the panacea as was thought just a few months and years ago, contrary to code and normal good practice.
So, yes, we're all confused, and the information seems contradictory to what has been preached. In the past, we were taught that venting helps increase roof life by keeping it cool. Muddling previous assumptions further, I paraphrase one scientist who deals with these issues daily: "Venting the underside of a sunbather does not prevent sunburn."
So to answer the first questioner, 20 years should tell you a little something about the proclivity of this attic to accumulate mold. If the plywood roof sheathing is not molding up, and the shingles did not prematurely buckle from heat stress (at 20 years, you either have a new roof or need one), then don't mess with success.
As for the second questioner, I would be more concerned about areas at closed cathedral ceilings, less so at common attics and areas with scissor trusses. In your case, when changing roofing from cedar to composition, venting is more of a potential issue since the cedar tends to breathe, whereas the composition will hold moisture and more easily condense moisture on the inside.
Q: Our home (built 1996) has EIFS siding on the front of the first and second floors. We are preparing to sell and would like to understand what sort of liability we face so we can get it addressed before we get into a sale situation. Should we get it inspected and repaired if problems are found?
A: This is a long and complicated issue, but in most cases it is better not to be proactive when selling your home — this absolutely does not mean covering anything up, but don't go out of your way to find and repair problems. Disclose? Heck, yeah, disclose that it has EIFS, inform them that it can be problematic, inform them that there may be insurability issues and let the buyer take it from there. You have a duty to disclose everything you know, but no duty to go out of your way to hire professionals to find problems. Going out of your way to find problems might even increase your liability. What if the person you hired was wrong?
Darrell Hay answers readers' questions. Call 206-464-8514 to record your question |
