Thread: Missing ventilation?

Would an open bean ceiling that has been closed up with faced fiberglass batt insulation and drywall need some sort or ventilation? Owner states there is no air gap whatsoever. Will it have future condensation problems?

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Good question. Either way you call it, it could be wrong. Too many variables to know what is going on in a space you don't have access to, unless there are visible signs.

Factors include, insulation levels, ventilation, occupant load, vapour barrier, air changes.

Sounds like a job for an infrared camera analysis.

Originally Posted by Mike Jacquez

Would an open bean ceiling that has been closed up with faced fiberglass batt insulation and drywall need some sort or ventilation? Owner states there is no air gap whatsoever. Will it have future condensation problems?

It looks like the insulation is pressed up on the underside of the roof sheathing with no vapor barrier or air circulation due to the drywall installed within 3 inches of the underside of sheathing.

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Originally Posted by Mike Jacquez

Would an open bean ceiling that has been closed up with faced fiberglass batt insulation and drywall need some sort or ventilation? Owner states there is no air gap whatsoever. Will it have future condensation problems?

It looks like the insulation is pressed up on the underside of the roof sheathing with no vapor barrier or air circulation due to the drywall installed within 3 inches of the underside of sheathing.

Could there be those hard foam baffles between the insulation and the roof sheathing?

Well, there should be ventilation, but the amount of ventilation needed can depend on the roofing material. If there are composition shingles, then more ventilation is needed. The recommendation these days seems to be adding a ridge or peak vent and continuous soffit vents to promote as much ventilation as possible.

Cooking composition shingles is probably a bigger concern than condensation.

Originally Posted by Mike Jacquez

It looks like the insulation is pressed up on the underside of the roof sheathing with no vapor barrier or air circulation due to the drywall installed within 3 inches of the underside of sheathing.

There may be some impact on shingle warranty.. I know some will reduce or limit warranty.

Here is an example of one manufacturer. Again this is only one example, and each may vary.

18. Any damages or failure in performance of Shingles installed over insulated roof deck panels, except as outlined below under thesection “REDUCED WARRANTY COVERAGE FOR INSTALLATION OF SHINGLES ON INSULATED ROOF DECKS”;

REDUCED WARRANTY COVERAGE FOR INSTALLATION OF SHINGLES ON INSULATED ROOF DECKSThe coverage under this Limited Warranty is reduced for any Shingles which are applied to any of the following:
a) roof deck assemblies (of slopes greater than 2 in 12) where foam insulation is prefabricated into the roof deck system(commonly known as “nail board insulation”), or
b) where insulation is installed immediately beneath an acceptable roof deck system

In the event that such Shingles are installed on insulated or unventilated decks the Warranty Period available to the Owner is reducedto 10 (ten) years with no Iron Clad Protection coverage. The annual reduction figure in this case shall be 10% per year.

In my area ventilation is critical. I looked at a home yesterday which had a new roof put on in June. Contractor's website references how they verify ventilation as part of the job. Vaulted ceilings are blocked, soffit vents are blocked and the entire attic and vaulted ceilings are soaking wet. Tannin staining is present on the siding, at windows and interior ceilings. This is going to involve the removal of the new shingles, plywood sheathing and all insulation. Contractor is going to get seriously hosed on this one and it could have been prevented had he paid attention to what his website says. Oddly enough my client for that home is the contractor - he isn't going to like what I write. The village signed off on the permit - now they have cited the homeowner for the tarp on the roof.

Originally Posted by Robin Wells

Here is an example of one manufacturer. Again this is only one example, and each may vary.

REDUCED WARRANTY COVERAGE FOR INSTALLATION OF SHINGLES ON INSULATED ROOF DECKSThe coverage under this Limited Warranty is reduced for any Shingles which are applied to any of the following:
a) roof deck assemblies (of slopes greater than 2 in 12) where foam insulation is prefabricated into the roof deck system(commonly known as “nail board insulation”), or
b) where insulation is installed immediately beneath an acceptable roof deck system

What manufacturer is this?