TOPIC: I Have An Existing Metal Roof and Have A Question
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.032 Aluminum Gulf Coast Supply "Gulf Loc" Standing Seam Profile with Polyglass MTS self adhered metal underlayment to the decking, with eave drip, valley hip and ridge, wall flashings and closures to match and 50 l.f. of cobra ridge vent under ridge caps were installed on coastal southwest florida house 2/2020. 1234 S.F. (living space) wood frame house was built in 1984 and had 2 shingle roofs which needed to be removed first. Wood replacement in several spots of roof decking were also made. As temps/humidity began to climb in late 2/2020 we began noticing a horrible stale air smell coming down through the A/C Vents. All HVAC components - air handler, duct work, drops for supply and return vents - are all located in the attic. We contacted the salesman at the roofing company a couple times via phone and emails complaining of increased heat/humidity in the attic. We questioned whether the correct Vented Ridge System was actually installed (as an incorrect type was initially sent and exchanged for the correct one) and whether we needed additional insulation (loose, blown-in fiberglass already up there) to address the problem. He responded with, R-38 @ 14" as to what's recommended, the name of an insulation company to contact and provided numerous pictures which were taken during the roof installation showing work-in-progress. There are two gable vents with screening at the east and north sides of the house. One (small) vent on top of the south side roof that looks like an upside-down "J".
After doing some initial research (beginning in 6/2020) about improper attic ventilation and talking with our local Building Department Superintendent, at his recommendation, we replaced the existing soffit vents (which had been painted over several times) with a plastic-type material 14" wide, dotted with tiny holes, in the hopes of increasing airflow into the attic. The smell got worse over time as the outside temps/humidity increased. Next, we had an Indoor Air Quality Engineer test for Mold inside the house and in the attic. Nothing found outside of normal limits. Then, a new HVAC System with all new ducting, drops, etc., with a 5" Media Filter at the unit and an APCO-X UV Light and central dehumidifier were all installed. We're on top of changing the (horsehair type) filters in each of the Returns monthly and have semi-annual maintenance of all of the HVAC/Dehumidifier equipment. While the dehumidifier has helped reduce the intensity of the smell, it's still there and we're still coughing as the heat/humidity of the day progresses. The smell is also evident at the cans surrounding ceiling lighting and at electrical outlets. If you suspect it is improper attic ventilation, could you please provide a possible route for us to pursue in resolution. Thank you!
Building codes in most areas require at least 1 square foot of NFA (Net Free Airflow) ventilation, sploit evenly between intake and exhaust per 300 square feet of attic floor space. Have you been able to determine if this is what you have? Also, I would strongly suggest using spray foam to seal any air leaks from the living space into the attic. Are there any things like bathroom or laundry vents just venting into the attic?
Todd: Thanks for getting back to us. Don't actually know whether we have the appropriate NFA. How/who would we go to, to confirm this and determine if it meets the building codes you outlined? Understand about using spray foam to seal air leaks into living space. We've considered this. We'd need to hire someone. As far as anything venting into Attic, both bathroom exhaust fan vents were replaced and redirected to vent outside the soffit area 8 years ago, but when new soffit vents were installed in 2020, not sure whether installers made sure those vents were redirected to actually vent outside. Hubby thinks they're just now laying on top of the openings of the of the soffit vents. Clothes dryer vents directly to the outside of the lower part of the house.
The ridge and soffit vents should have NFA ratings showing the amount of ventilation per linear foot. www.airvent.com can be a good source of information on ventilation. Robin, also on this panel, reminded me that, if exhaust vents go out through the soffit, the moisture and accompanying smell is likely being drawn up into the attic through the adjacent soffit vents. Such vents really need to go through the roof not the soffits.
Thanks, Todd. Have actually researched airvent.com's site previously. Will check there, again. Understand about venting bath exhaust out through roof. When house was built in 1984, those exhausts were just venting into Attic. We didn't know that wasn't good until 8 years ago when Electrician explained to us & we had him redirect to outside via soffit. (House belonged to Mom before she passed away.) Would our local building department have on record from when house was built, what the ridge-to-soffit ventilation per linear
foot was? Of note, we've consulted with a few Contractors, each of whom have their own idea how to address. Two have suggested spray foam insulation for entire attic (except floor) and another suggested we have more of those upside-down-J-looking vents added to roof in several spots. Am reluctant to cut holes in roof to allow for these (as it may not work and cause water leaking, etc.) and reluctant to spray foam entire attic b/c have read it doesn't always work on a retrofit for an older house.
We keep coming back to thinking Roofer (who has excellent reputation in SW FL and did shingle roof on house in 2002) should have addressed potential attic ventilation issue with us before we decided on metal roof. Any thoughts? Also, what have you come across regarding trying to retrofit older house with spray foam insulation after metal roof put on?
Todd: Emailed COO of Roofing Company outlining situation and steps taken to try to remedy. Fortunately, he seemed very open-minded to what's going on here. He's coming for a site eval. Meantime, he's recommending either Passive (add'l "J" type Vents) vs. Active (Solar Powered Attic Exhaust Fans), but will know better once he's actually seen everything. We'll see.
Todd: thought I'd submitted these add'l questions a few days ago, but perhaps not. 1) Would our local building department have information from when the house was built ('84) as to whether attic ventilation calculations were made at that time and when a shingle reroof was done in 2002? Have you come across any information regarding the drawbacks of adding hard, spray foam insulation to the entire attic space (except floor) after a Metal Roof goes on?
I apologize for the delay. I do not think that anyone will have that information on file. Usually it has to be calculated in each situation. As far as foam ... closed cell foam can be very helpful. Have you ruled out that smell / moisture is just rising back into the attic from the things vented through the soffit? Happy to talk things through if you wish to call me. 1-800-543-8938 ext 201
Hi Todd: thanks for getting back to me and offer of your # to discuss further. Would like too very much.
Thank you so much!
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