So good news: Our old house/new roof installation gets installed as planned. We take a lame-o and withering 3-tab shingle roof and upgrade to a 50 year warranty Bellaforte Slate roof. The 130 year old house gets a roof consistent with the neighborhood and its Georgian pedigree. We also have premium underlayments from Grace, notably Tri-Flex Xtreme and Ice and Water Shield.
We even beat out the rainiest month ever recorded in our area to get the house dried in. Toward the end of the project I was happy that the house already had gable venting (several 24×24 inch gable windows) that kept the attic moisture in check for over a century. And to hedge my bets I not only improved the chimney flashing, I added counter-flashing. A little extra work now saves lots of extra work later.
Or so I thought.
Homeowner: My attic is soaked.
Mark: But that can’t be.
Homeowner: My attic is soaked and there is mold. Lots of mold.
I did a few more “that can’t be’s” (and other words; I’ll tell you later) then got on the phone to some experts. Had I done something wrong? Was there a product failure? All the bases had to be covered. The attic was dry when I got there and wet when I left. It HAD to be my fault. Right?
Actually, not at all. But I was on the hook—and felt obligated to the homeowner—because it was the roof that delivered the “before and after shock.” Or so it seemed.
The reality is that the roof project was the last domino in a series of improvements and lifestyle changes in the house beneath that resulted in massive amounts of unanticipated moisture getting trapped in the attic.
First, the most water on the interior side of the roof deck seemed to be in the valleys, so to make sure it wasn’t an installation error—and to rule that out as a possible cause—we took them apart. Good news: they were dry as a bone. (Associated bad news, they had to be re-assembled…for free…good times…) However, this was the evidence needed to pinpoint that all the moisture was coming from the inside of the house—and lots of it. But how?
Even though there was 15 pound felt and two courses of asphalt shingles before—a stuck-together system I would hardly describe as permeable—I checked with Grace to make sure I used the right product. Tri-Flex Xtreme is the right stuff.
Next, I checked with a ventilation expert SunRise Solar. SunRise Solar further helped me diagnose that there was heat escaping into the attic (what’s more, they continued to help me once they realized that there product probably wasn’t the best solution—can’t make up that kind of class) by asking me the right series of questions.
Bottom line for this up-top room was the entire house—not just the roof system—changed. The homeowner had replacement windows installed the winter prior to the roof installation. Also, he kept the heat down in his dwelling and the rental unit in the home was not occupied after the window install. Fast forward to this year: Homeowner has new roof system, new windows keep more heat in house and restrict make-up air. The heat-load is increased in the main dwelling and the rental unit is occupied and heated. All that adds up to more heat being generated and escaping through the ceiling joists (which have R-21 insulation at best) into the attic space where there is now not enough cross-ventilation to evacuate it.
BOOM. There’s the moisture, there’s your mold. Where warm air meets cold air, water happens.
The solution turns out to be the installation of Vent Air’s ShingleVent II continuous ridge vent. Vent Air’s air foil and high-quality design make it not only effective in this (and other) situations, but it is low profile making it attractive and like it was always part of the house, which was the main intent of installing the Bellaforte roof system in the first place: Classic looks for a newly modern home.
Note: one more thing…it’s always one more thing with old houses. The complete solution to this problem is to increase the insulation. But that’s a project for another day.