shingling
 

Is it safe, and usual to reshingle a roof (to repair) by nailing shingles over top the old ones?
A contractor told us this.

Hello
I have been a roofer for about 6 years now. Applying new shingles over old shingles is a very common practice. It saves you money now, but if you ever get it reshingled again, you will have to pay more to get both layers removed.
Besides that, its fine.
Matt

It's not necessarily fine. You haven't given us all the info we need to properly answer the question. The most important question is, how many layers of shingles are on the house at the moment. If it is more than one, than you do not want to place any more on top. The load would probably be greater than the allowable amount for your roof.

If it's just one, then go ahead.

Before applying a second layer of shingles, I walk the roof-checking for spongy spots, and follow that with an inspection from the attic side. If poor detailing or flashing has allowed deterioration of the sheathing, that must be corrected prior to installing the new layer of roofing. Also, I won't install a second layer if the existing shingles are curled at the corners and are highly brittle. In that scenario, you end up with a broken mess in between the roof sheathing and the new shingle layer. Finally, if the existing shingles were stapled on, they must come off. I won't risk my reputation by topping a bad installation.

If you plan to be in the house for quite a few more years. Do it right, remove the old shingles first, remove any tarpaper if used, walk the roof checking for soft spots, THEN reshingle. Its the best way.

Get a licensed contractor. Find one by getting references from friends and neighbors. Don't just go with the cheapest one. A bad roof can cause major damage if not repaired right. Its not worth cutting corners.

Local code allows up to three layers.

Nice. Find a reputable contractor that will do it. I won't.

i have roofed in MI In MO IL and KY and have seen u 5 layers first one ceader usually i hate to " lay over " if you use a good shingle usually not what you buy at lowes it could be ok but all cheap shingles life are cut in at laest half when you lay over. if you go more than 2 layers its not good on roof or house. it was actully my moms house that 5 on it and the nihgt i tore them all off the house poped and cracked all night siging that fianlly the load was off.. if you have a very unsteep pitch ( less that 6) i would not recomend layover a couple said it was more expensive to do the next time when you tear off but its also more expensive now to tear off... my rule is this if your only gonna be there 5 years do it.. if not tear off now and do it right..

My code allows three layers also.

Tear offs are a bitch and thus costly no matter how many layers (Had our house done this year) It's amazing how people become less tolerant of heights as we age.

Did my garage myself. Watch the heat and pay attention to your courses, what looks good while your in the middle of it may look shitty from the ground.

When my wife and I moved into our new home, our first home, about 4 years ago, we had to make a lot of choices, and do a lot of work. It was a handy man's special to say the least!

One of the first things we did was rip off, resheath and reshingle our roof. Pro roofers have told me that we did a great job, with a good eye towards detail and just doing it all right.

Here is what I can tell you, and a few things I would do if I had it to do over again:
1) For the tear off I would pay a wrecking crew to do it
2) I would pay the money to have all, and I do mean all the materials loaded and distributed on the roof by the delivery people.
3) ....well, there is no three!

What no one has said here is that shingle warrantees are typically voided by doing a second layer on top of an existing one. In addition, the second layer, or third layer tends to cause the new roof to loose its longevity, cutting its life span significantly, meaning that you may be back up there in 5-7 years doing it all over again.

In Every town I work in in Northern New Jersey you may only re-roof once...After two layers you must rip it all off and start over again...Also, according to GAF, a re-roof only will last about half the time as a new roof.

5 layers! haha, that's nothing. I looked at a house that had 3 layers of shingles. Did I forget to mention that on top of the 3 layers, they put another 1/2" of plywood and then two more layers of shingles?

I was scared to stand on it.

i've had a couple years experience roofing...

if the new layer is only the second one and the bottom one doesn't have significant portions of soft/brittle shingles... then i would usually say it was ok to just lay over top.

try to walk the roof with the contractor beforehand and point out any worrisome areas. it's worth it to patch the old layer up a bit if there is serious danger of the old stuff coming loose underneath.

it's common practice though, for most cases i wouldn't give it much worry.