Asphalt shingle reroof over exhisting
I plan on having a new ashalt shingle roof put on my house in Phoenix, Arizona. One roofing contractor told me that if they left the exhisting asphalt shingle roof and roofed over it the old shingles would wick the moisture out of the new ones. Is there any truth to this? Are Tamco asphalt shingles any good?
Thanks,
Steve
Replies
They're likely to want to sell you a bridge as well.
>>>>>>>>>>>One roofing contractor told me that if they left the exhisting asphalt shingle roof and roofed over it the old shingles would wick the moisture out of the new ones. Is there any truth to this?
No. There are other reasons I don't like to do layovers. Make sure the flashings are all replaced. Tamko is a good company.
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A new roof over the old will not last as long (or look as nice) for several reasons, but the reason given is not one of them.
I refuse to do roofovers. I think it looks bad and I get very concerned about the weight. I have never heard of the wicking moisture out story.
I do not like Tamko shingles because they are not consistently the same size. At least the ones we get in Alabama are not the same. They will vary up to 3/8 inche on the length and height. The quality is good but I do not like the varying size.
James
I just replaced a couple damaged shingles on a friend's house (tree rubbed against the rake) and found out it was the second layer--what a mess! Everything is squishy and nails popping through. I'd never put a second layer on my house. Strip the old ones off and that way you know what's going on with the sheathing and the flashing. Like you say, that extra dead weight isn't good either.
>>>>>>>>>>I do not like Tamko shingles because they are not consistently the same size. At least the ones we get in Alabama are not the same. They will vary up to 3/8 inche on the length and height.That's weird. The one's we get in KY are fine. We have that problem with GAFs here.http://grantlogan.net/
I don't know what it is about the tamko shingle. When you chalk your lines, some of the shingles will be downhill 1/4 to 3/8 because of the difference. Makes the roof look bad. Our favorite is Owens Corning. We don't care for Georgia Pacific either.
If a customer has already bought tamko shingles we will put them on but we really have to watch the bottoms and make sure they stay in line.
James
Just do it like wood -- nail a strip of wood down and set the bottom ends of the shingles against it. ;)
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I think the major problem you'll have with a lay over is heat. In the north, I think you can get away with it more although it is not good practice. In Arizona, with the direct sun and heat you get, I would never even consider it.
If you are looking to save money by doing the lay over, then strip it yourself. You do not get much rain in Az, and I know most house are lower pitches and one or two floors. One person should be able to strip it in a day and a dumpster won't cost much.
There are a few reasons that contractors may like to do double layers:1) They're lazy2) Saves on tar paper3) They don't have to snap lines -- just shove the new shingle against the old (see #1)4) Saves on disposal fees (significant in some parts of the country)Of these only #4 is really significant, cost-wise, but it's penny-wise and pound foolish for the consumer since he (or the next buyer of the property) will end up paying even more down the line to dispose of two layers.The one situation I can see doing a shingle-over is when the original roof is hail-damaged or something similar -- no significant curling, but not water-tight -- and you need the job done quickly and for minimum money.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
tamkos are fine.
Your part of the country is a region where it is vary commonplace and acceptable top do a roof-over, if he knows how to deal with flashings. Quiz him about how he handles that detail to be sure it is sealed.
Also be aware that manufactureres do not warrant their shingles for roof-overs so you want to ask him how he handles warrantee problems - then check his references.
The roofing trade is full of shingle layers who call themselves roofers and are uninsured and offer only a tail light warrantee - the roof won't leak until you see his tail lights disappear, so find out how lond he has been doing this
The line about wicking makes absolutely no sense to me whatsoever. Are you sure you understood him right? Is he sure he understood himself right?
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Thanks for all the info. Of the 4 roofing contractors I had out to the house all but 1 wanted to leave the exhisting shingles and reroof over them. The guy I chose will be tearing the old ones off and laying down new Tamko Heritage (Arhitectural shingles). He's also the one who told me about the moisture being "wicked" out.
I also asked him if he was going to use the neoprene style roof jack collars. he said that they crystalize in the heat and he uses the metal style. Do the neoprene breakdown over time?
I know that attic heat can be particullary brutal to asphalt shingles here in Phoenix. It gets really hot in my attic during the summer and I want to get rid of as much heat as possible. I was planing on elliminating the 4 roof dormer vents that are currently there and puting 2 Power cool plus 1170 CFM attic vent fans in their place. Does anyone have any experience with these units, do they work well? The home is an older 50's ranch home with a hip stlye roof. I also want to create more vents under the soffit. The previous owner simply removed a number of the wood pieced between the rafters (forgot their technical names).
Steve
"Do the neoprene breakdown over time?"Yes, the UV rays and heat will rob rubbers of their volatile oils that keep them pliable. The metal stack flashing is better there.If adding power vents, you need to be sure that your soffit make up flow is equivalent to the flow produced at the fan vent, or you will be sucking conditioned air out of the house.Bird blocks is the high tech name for the blocking.
;)
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>>>>>>>>Do the neoprene breakdown over time?We probably replace 50-100 a year.http://grantlogan.net/