Church Roof - Vent or Not?

[Denny]

Hi, I'm in Toronto Canada. I've just been appointed property manager for a small church (the fact that I know absolutely nothing about building maintenance didn't seem to faze the congregation). The building dates back to 1889, and it badly needs a new roof. I've received quotes from four roofers. Of the two I'm considering, one recommends a ridge vent while the other recommends no vent at all.

There is a flat ceiling, so there is obviously "attic" space between the ceiling and the roof ridge. There has never been any venting, so the one roofer said you've gotten along without it so far, you might introduce problems by venting it now. He didn't say what problems there might be. The other said a vent would help preserve the roof longer.

Which one is giving the better advice? Any thoughts. Many thanks in advance for your help.

Denny

[Joseph Meehan]

I would want it vented. Venting should allow your next roof to last longer and help prevent moisture damage and ice dams.

[Phisherman]

Do it right and put in a ridge vent when you get the new roof. It will help in the long term. Add more soffit vents too. You can't be criticized for adding more ventilation.

[m Ransley]

If it had no venting and was sealed tight it would not have lasted 116 years, The beams would have rotted away there would be mold on the deck and beams, there is air movement somehow, whether by the sheeting being loose or planks used for roof decking air is moving through. Will there be new sheeting, what is there now. You might change something if new sheeting is used requiring more venting. Or the construction has so many air leaks in the attic it just vents. Get more bids, a paid inspector should go over everything with you.

[tbasc]

Usually, I agree with Mr. Meehan & Phisherman. In this case, I would not be so quick to add ventilaiton. (The Canadian Home builders' Association Builders' Manual 2000 does seem to endorse venting attics in new construction.) (The Building Science Corporation web site has useful climate specific suggestions for venting.) I would at least look at the condition of the attic to see what may have happened over time. If it is in reasonably good condition, I would not change the venting arrangement. It's possible that it is unintentionally vented to the interior for instance. Perhaps you could enlist the help of a forensic architect or engineer or an architect who deals with older buildings. A church might recieve a break on the fee. They certainly do in my area. TB

[PDQ]

Dating back to 1889 the roof would most likely have been cedar shingles = over a roof strata wherein the boards/planks were not butted against = each other except at the ends. The result would be a roof that is = naturally vented via the spaces between the planks.

New roofs that use ply for the covering also do not include spacing = between the sheets. This is why venting is required on them.

If the roof is not sheeted and you are putting up cedar, you most likely = will have no need for venting. =20

If the roof is sheeted or you are putting up asphalt shingles, add = venting.

Somewhere in the church there should be a trap door for accessing the = attic. Have a look to see what you really have.

--=20 PDQ

[Goedjn]

What's the roof itself made out of? Asphalt shingles? Slate? Sheetmetal? How long did the last roof last?

(I'm inclined to agree with the first guy. If it's lasted 115 years with no venting, it can't be that much of a problem.)

[PipeDown]

115 years using labor and materials from 115 years ago. No guarantee it will last that long next time. Are you sure it never was serviced during that time? Likely, just forgotten.

Venting is SOP on almost every roof I have seen. In the summer it equalizes the attic temp so ice damming and other freeze thaw problems are reduced. In summer it lets excess heat and humidity escape helping to keep the space benieth more comfortable and extending asphalt roof lifetime.

A ridge vent is best as it has the most open area but vents in the gable ends wouldn't be too bad. Stacks would look bad on a church.

[Goedjn]

What's that got to do with anything? Of course it's going to need maintenance. All roofs require maintenance. The point is, the current arrangement does not appear to be broken in any way,

There is no evidence that ice damming or other freeze-thaw problems exist with this roof. How far past zero do you want to reduce them?

Assuming it's an asphalt roof, this may be an issue. Or, as far north as OP is, excess heat may not be a design consideration.

[Marvel]

I would confer with the manufacturer of the product you are installing and if your roofer is a top level company they will be in the manufacturers list of companys to deal with. You should get a warranty from both.