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I am needing to roof my house. Is it ok to roof over the old shingles? My present roof is the original roof of a single layer of fiber glass shingles and were stapled over a layer of felt. My plan is to just put the new shingles on over the old with a coil nailer. does any still do this?
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This has been discussed before -- check the archives. My personal feeling is that the old shingles should always be torn off. First, this allows you to identify any problems with the sheathing that may have cropped up in the original roof's twenty-odd years. Second, if the first roof needs replacing, why would it be considered a satisfactory base for new shingles? Sort of like painting over old, cracking paint. Third, most shingle warranties do not cover damage resulting from the underlayment. Old, warped or rotting shingles probably wouldn't be a satisfactory underlayment in a manufacturer's eyes. Fourth, it's been demonstrated that the new shingles will not last as long if installed over old shingles -- likely not as long as the warranty. Why do people put on successive layers of shingles? To avoid the cost of a tear off. Well, that's just temporary savings. It's a "pay me now or pay me later" situation.
*Robert - Personally, I agree with Steve. I am getting ready to start reroofing the buildings here at my place and I plan to tear off all the old fiberglass (you know you have lived too long in one place when you built all the buildings, and they need new roofs!).I will say, though, that it is common practice to go over ONE layer of composition with another, depending on the condition of the first layer. There was a cover article in a recent Journal of Light Construction about this. You might try to find a copy and read the article. - jb
*I agree with the previous posts .....more often than not, after tearing off an old roof you will find problems, popped nails, rot, in one case the CDX had just 4 nails per sheet- one in each corner.You may be lucky but there's no telling what you might find. The new roof is no better than what's under it.
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I agree with Steve and Jim. If I'm not mistaken a Sq. of Shingles weight is about 200lbs. So less is better, not as much stress on your rafters.
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Robert,
If you ignore this (good) advice and decide not to do a tear-off, at least add a new layer of felt under the new shingles. Otherwise, you may find that the roof still leaks.
*Jesus I hate it when people don't tear off the old roof!
*Robert,I've been around long enough to have actually reroofed a couple of overlays I had done in the 70's. The main thing is your existing shingles should be flat. Cupped and curled shingles make a poor base for a new roof. The new shingles should be "nested" up against the old shingles. Some shingle wrappers show this on their directions. This is critical to getting a flat appearance on your roof, and it also snugs down the old roof properly also. A second layer of roofing adds 2.4 lbs. per sq. ft. to your roof. Not much weight, thats why all the codes in my area(and all others I am aware of) allow it. Mfrs. allow it also, but as pointed out won't warrant problems caused by the underlying shingles. Thats why you don't go over rough looking roofs.Also, if there is a warranty problem with the shingles they won't pay for the cost of tearing off the underlaying roof. For some people, this is reason enough to tear off.Other factors to consider: Have there been leaks? These areas should be investigated.Are there signs of sheathing problems? If there seems to be loose or soft sheathing the roof should be torn off.Are the new or old shingles metric? You can't nest an english shingle over a metric, but you can nest a metric over an english; it will, however, take approx. 20% more shingles to do it. I would never try to talk a customer inclined to tear off a single layer into an overlay. I usually encourage a tear-off-after all, it is more money for me. But I also believe it is reasonable to overlay in some cases.John
*Robert, as the guy in the oil filter ad says, "you can pay me now or you can pay me later". If you are going to own the house for a long time, have limited funds and don't care how your roof appears, you might want to overlay. If there's any chance you may sell, do the tear-off now so you won't diminish the sales value of your home. Ask realtors, appraisors and home inspectors how they feel about overlays, and you'll find some view the second layer of shingles as an indication of the homeowner's unwillingness to spend money maintaining the residence ... kind of like buying a vehicle from someone who didn't change the oil.Regards, Steve
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My wife and I did a full tear-off and re-roof on a 25 year old house two years ago. The tear-off took about a day for 4 people, but that was two full layers, one of which was nailed down. If your are stapled down, they'll likely come up pretty easily, and your big expense will be the dumpster to haul them away.
Not only do you get the chance to check for any damage (I had a fair amount; some of the plywood in the late 60's was apparently pretty poor), you end up with a job you can be proud of.
Air nailing is definitely the way to go.
For a reference, I suggest a copy of "The Complete Guide to Home Roofing Installation and Maintenance", by John Chiles (http://www.amazon.com/exec/obidos/ASIN/1558702776/qid%3D936249305/002-0617703-3254809). All sorts of stuff is covered, and I learned enough about roofing to be able to spot a quality job (there are lot of bad roofs out there).
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Eric,
Your wrong in assuming that a stapled roof comes up easier than a nailed roof. Although staples don't hold shingles down as well as nails, they do hold tenaciously to the roof deck. One leg will pull out , but not the other, and I think you can probably imagine what a pain it is to pull these out, there is no head on a one legged staple to grab with a pry bar or hammer.
John
*Robert,There were several errors ,mistakes or at best differing opinions in the above advice.I would not be concerned with what a realtor or appraisser feels about 2nd layer installations.The fact is I have yet to meet a realtor or appraisser who can see the difference between 1 and 2 layers from the ground.Even as a professional roofing contractor I have to check a lot of roofs from the roof top to determine if it is an overlay.( a proper overlay involves cutting back the shingles on the perimeter of the roof and installing new dripedge thereby hiding the most obvious sign of a layover.)A 2nd layer installation meets the building codes in all areas I am familiar with.Although it pains me to say it, the condition of the roof will probably have little to do with the re-sale value of your home.(most in my industry will try to tell you differrent).I have a close friend who is an appraisser.He tells me that they look at the roof from the ground and if it looks ok there is no adjustment to the price. An obviously new roof does not get marked upward in value. Only an obviously BAD roof gets marked down in value. this is from a licensed appr. who owns his own successfull business and does tons of apprs.for local banks.All things being equall the BEST roof would be a tear off. this would give you a chance to install plenty of Icegaurd in leak prone areas etc.But all things aren't equal are they?COST is a big factor in your decision.Read this next part carefully........I will charge AT LEAST double for a T.O. as opposed to a layover.The work is doubled in the case of a T.O.and the cost of disposing of the debris in many cases is greater than the cost of the new materials.Also the RISK is much greater in the case of a T.O.A stapled roof is one of the toughest T.O's for the reason given by JRSI have torn off many roofs from houses that were 50-60 year old and 2 layer installations(20-30yr for first layer,20-30yr for 2nd layer).PROPERLY done a second layer can last as long as or longer than the 1st layer AND look good in the process.Installing a layer of felt between the 2 layers is a VERY BAD idea . it will prevent you from using the proper re-roof method which is the NESTING method (also called butt-up method). DO NOT,DO NOT,DO NOT...put felt between the 2 layers.Most of the roofs I do are tear-offs because most of the houses here are 60-100 years old and already have 2-3 layers.we are definitely not afraid to do T.O's but we don't let the chance of a layover pass by.A lot of guys are quick to suggest expensive solutions to your problem when THEY aren't picking up the tab.I believe in putting my money where my mouth is(you know,put up or shut up)I am planning a new roof for my own home next year.It will be a layover.My final suggestion would be.... If the shingles are laying pretty flat and you have no great concerns about the decking,do a layover.Spend some of the money you save on a T.O. and buy some really top notch shingles.(the labor is nearly the same to install cheap shingles as to install high quality shingles)Good Luck,stephen
*Stephen,I'll side with you on this one. Obviously the cost must be a factor. If it were my roof, I'd probably go for the layover. As a matter of fact I have. Your point on the felt is well taken, since a layover must be done properly or it will look bad. If done well it will look as good as a tear-off and last just as long. Then in 30 years they can tear off both layers and do a reroof.
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I am needing to roof my house. Is it ok to roof over the old shingles? My present roof is the original roof of a single layer of fiber glass shingles and were stapled over a layer of felt. My plan is to just put the new shingles on over the old with a coil nailer. does any still do this?