re-roofing confusion???


Old 07-11-00, 07:09 AM
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My roof has had one leak due to a ripped shingle, we repaired this. There have been no problems since but the shingles are flimsy (look like 10-15 year shingles) so we are debating on re-shingling. All of the estimates we have gotten want to strip off the current shingles and not go over, there is only one layer. They also want to install new vents and one company wants to install 4 new turbine vents but move them all to the back of the house because it will look nicer. The house is 30years old and someone else told me I have to be careful due to the added weight of the new shingles. The roof may not support it??

I am so confused. The estimates are varying in price and what needs to be done.

The facts are: I have an 1800sq/ft roof, cottage style, nothing fancy. I live in Canada and get a good snowy winter.

Questions are:

Do I need to have the first layer of shingles removed? They are not badly damaged or curling.

Do I need all new vents? I have 4 flat vents (2 in the front, 2 in the back) and 1 turbine vent in the top middle of the house.

Do I need to be concerned about the weight of new shingles and how do I find this out???

Thanks for any help!!!
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Old 07-11-00, 07:36 PM
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If it were my house, I would strip off the existing roofing before reroofing it. Leaving the old roof in place adds about 3 to 4 lbs. per sq.ft. of weight, and since you live in an area of fairly heavy snows, that could have a significant impact on how well your roof will handle the snow. (It's called 'live load') Besides, comp. roofs (I assume that's what we're talking about here) look better and will last longer if put on over a flat surface (like the sheathing) rather than a rough surface (like your existing roof).
Old 07-12-00, 04:22 AM
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When re-roofing there is only one way to do it. Strip off the old shingles. Install 30# felt, and 250 lb asphalt shingles. If your 1800 feet is correct, the price should be around $2500. When you have the old shingles off, it is the time to upgrade any vents or move them. Vents cost about $25.00 each to install plus the vent cost.
Old 07-12-00, 05:51 AM
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Hi. I was in the same position you are. I live in Brampton Ontario, and we also get alot of snow. When I realized I needed a new roof, I gathered quite a few estimates, and of all of them, only one said that we should strip the old shingles. When I asked why, he said that the weight of two layers of shingles, with the addition of snow would be too heavy. This roofer quoted about the same price as the others for the work, except they weren't going to remove the shingles. The roofer also advised replacing the vents, his reason being, they look okay now, but as they are 25 years old, they could go at any time, and the best time to do it would be when doing the shingles.

I don't know if this helps, this is just my experience.
Old 07-12-00, 07:04 AM
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Another Canadian (from Caledon) offering his two cents.
You will find that there is no manufacturer with a presence in Canada that will offer a warranty on their product if overlayed. One good reason to strip it! Venting is imperative in order to a: meet building code, see section 9.19, b: meet the warranty specifications of the shingles. I could go on for ever about venting however I will stick to the questions asked.

You do NEED to strip it.

Stay away from the turbines. They are deffinately not a value added item. Contrary to popular belief, they do NOT pump the air out. It is the warm attic air that in fact turns them as it rushes out the hole.

Duraflo manufactures low profile vents in 50 square inches and 80. The typical turbine, that I have seen vents 86.

Don't forget to have new flashing and counter flashings, and stack vent neoprenes installed.

Good Luck
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