I'd earlier posted a question about venting the ridge cap on an insulated 70' x 100' open machine shed. I was advised that venting was not necessary, and tried, but wasn't successful in adding the following comments: The insulation for the walls and roof of the building is a foil covered fiberglass blanket style, laid on top of the purlins and building support structure of the building, but under the steel roof sheeting panels. Pieces of the ridge cap sealing foam had been blown out by high winds, winds which also prevented an up close inspection. Before I posted the first question I'd been getting conflicting advice about venting the ridge cap, some saying that you MUST have a vented ridge cap to prevent condensation, other contractors (those selling an exterior coating process) were recommending to just cover the entire ridge cap as well as 6" on each side of the ridge cap. Today I was able to recover some of the foam material that Cuckler had used 30 yrs. ago and you cannot blow air through the foam that was used in the original construction. Therefore I'm considering using some cans of expanding foam ("Great Stuff", "Max Fill", etc.) to solve the wind & snow from entering through the gaps with out having to remove and reinstall the ridge cap....and the possible nightmare of screw alignment and/ or over sized replacement screws. But I realize if the expanding foam is used and that turns out to be a mistake, then it's all but impossible to remove that expanded foam once it has dried . Comments appreciated.
Todd Miller
Isaiah Industries, Inc.
Is this a heated and air conditioned building? I assume not. You also say that it is "open" ... does that mean that air continually flows through it? This is sounding like a structure that would not need ventilation. You may wish to contact the Metal Building Manufacturers Association and pose these questions.

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