Very Important roofing information

jeffk · 10-11-2017, 06:10 AM

Sorry to disagree but going over a single layer of shingles with a second one is common, even encouraged in the industry. I am not a professional but there is LOTS of impartial advice available. Building codes allow "go overs". Warranties allow it. It saves money. Of course it matters that the roof under the existing shingles is in good shape and the underlayment is not badly damaged. The existing roof also needs to be prepared properly, curled up shingles cleaned up, etc. A professional can do this well.

Just because a layer of shingles over another didn't age well doesn't disqualify the practice. I had a roof with a single layer of "30 year" shingles that looked bad at 12 years and had to be replaced at 15 years. Poor quality shingles are a common industry problem, even when they are from a supposedly good manufacturer.

I think it is more important that you know the reputation of the roofer and that he has been around for a while. If such a roofer recommended a second layer, I think it would be fine.

Biggd · 10-11-2017, 09:22 AM

Quote:

Originally Posted by jeffk

Sorry to disagree but going over a single layer of shingles with a second one is common, even encouraged in the industry. I am not a professional but there is LOTS of impartial advice available. Building codes allow "go overs". Warranties allow it. It saves money. Of course it matters that the roof under the existing shingles is in good shape and the underlayment is not badly damaged. The existing roof also needs to be prepared properly, curled up shingles cleaned up, etc. A professional can do this well.

Just because a layer of shingles over another didn't age well doesn't disqualify the practice. I had a roof with a single layer of "30 year" shingles that looked bad at 12 years and had to be replaced at 15 years. Poor quality shingles are a common industry problem, even when they are from a supposedly good manufacturer.

I think it is more important that you know the reputation of the roofer and that he has been around for a while. If such a roofer recommended a second layer, I think it would be fine.

It depends on how bad the first layer is. If they are brittle and coming apart then they need to come off.

webmaster · 10-11-2017, 10:58 AM

The weight of one layer of shingles could add a couple thousand pounds to your roof. From what I've read it's about 250 lbs. per 10' X 10' area. If you don't remove the first layer when replacing it you are doubling the stress. When we have a lot of snow in the winter everyone is worrying about roof collapses and damage. Do you really want to add a few more thousand pounds in roofing on top of the existing weight?

Biggd · 10-11-2017, 11:28 AM

Quote:

Originally Posted by webmaster

The weight of one layer of shingles could add a couple thousand pounds to your roof. From what I've read it's about 250 lbs. per 10' X 10' area. If you don't remove the first layer when replacing it you are doubling the stress. When we have a lot of snow in the winter everyone is worrying about roof collapses and damage. Do you really want to add a few more thousand pounds in roofing on top of the existing weight?

There are a few factors to consider such as the pitch of your roof and the age of your home. There are many cases where roofing over an existing roof is fine. Then there are others that are questionable. It's always best to strip a roof but it's not always a must.

sky's · 10-11-2017, 02:43 PM

Quote:

Originally Posted by jeffk

Sorry to disagree but going over a single layer of shingles with a second one is common, even encouraged in the industry. I am not a professional but there is LOTS of impartial advice available. Building codes allow "go overs". Warranties allow it. It saves money. Of course it matters that the roof under the existing shingles is in good shape and the underlayment is not badly damaged. The existing roof also needs to be prepared properly, curled up shingles cleaned up, etc. A professional can do this well.

Just because a layer of shingles over another didn't age well doesn't disqualify the practice. I had a roof with a single layer of "30 year" shingles that looked bad at 12 years and had to be replaced at 15 years. Poor quality shingles are a common industry problem, even when they are from a supposedly good manufacturer.

I think it is more important that you know the reputation of the roofer and that he has been around for a while. If such a roofer recommended a second layer, I think it would be fine.

another reason why i dont post much on this site. have a good day

Biggd · 10-11-2017, 05:02 PM

Quote:

Originally Posted by sky's

Quote:

Originally Posted by jeffk

Sorry to disagree but going over a single layer of shingles with a second one is common, even encouraged in the industry. I am not a professional but there is LOTS of impartial advice available. Building codes allow "go overs". Warranties allow it. It saves money. Of course it matters that the roof under the existing shingles is in good shape and the underlayment is not badly damaged. The existing roof also needs to be prepared properly, curled up shingles cleaned up, etc. A professional can do this well.

Just because a layer of shingles over another didn't age well doesn't disqualify the practice. I had a roof with a single layer of "30 year" shingles that looked bad at 12 years and had to be replaced at 15 years. Poor quality shingles are a common industry problem, even when they are from a supposedly good manufacturer.

I think it is more important that you know the reputation of the roofer and that he has been around for a while. If such a roofer recommended a second layer, I think it would be fine.

another reason why i dont post much on this site. have a good day

Why, do you get upset when someone disagrees with you? Relax, you can't take everything you read on an internet forum as the truth, the whole truth, and nothing but the truth.

TheTimeTraveler · 10-11-2017, 05:48 PM

After reading this thread I can see why more and more folks are making the expensive switch to lifetime metal roofing.

Far better than asphalt shingles and never needs replacement; snow and ice easily slides off.

.

ITD · 10-11-2017, 05:56 PM

Sky did work for me, did a great job and is a nice guy. For what it's worth, I agree with what he says and always have the old roof removed. Last roof I had done, the original builder of my house did not install the ice dam material he was supposed to install.

Slickcraft · 10-11-2017, 06:05 PM

Well I do agree with the OP. When it comes to major house or camp maintenance projects I don't kick the can down the road. Do it right and live in peace for a long time. Off with the old, new ice guard and paper, new flashing and new shingles. Sleep well and dry for a long time.

Shingle over the old? That is a substantial weight subtracting from snow load margin. And what if that 30 year new roof only lasts 12? Now you really get to pay the piper.

BTW, my wife and I did the roof on our Welch Island cottage 15 years ago and we did it the right way. Extra work but done right, done once.

Just my 2 cents.

SAB1 · 10-11-2017, 07:48 PM

I'd always strip it so I know what the condition of the wood under the shingles looks like. I don't know any roofers in my area that don't strip the roof. Gotta be a reason(s) why.....

10-11-2017, 05:48 PM	#7
TheTimeTraveler Senior Member Join Date: Aug 2015 Posts: 880 Thanks: 278 Thanked 285 Times in 176 Posts	Roofing Alternatives After reading this thread I can see why more and more folks are making the expensive switch to lifetime metal roofing. Far better than asphalt shingles and never needs replacement; snow and ice easily slides off. .

10-11-2017, 06:10 AM	#1
jeffk Senior Member Join Date: Feb 2004 Location: Center Harbor Posts: 1,170 Thanks: 205 Thanked 434 Times in 251 Posts	Sorry to disagree but going over a single layer of shingles with a second one is common, even encouraged in the industry. I am not a professional but there is LOTS of impartial advice available. Building codes allow "go overs". Warranties allow it. It saves money. Of course it matters that the roof under the existing shingles is in good shape and the underlayment is not badly damaged. The existing roof also needs to be prepared properly, curled up shingles cleaned up, etc. A professional can do this well. Just because a layer of shingles over another didn't age well doesn't disqualify the practice. I had a roof with a single layer of "30 year" shingles that looked bad at 12 years and had to be replaced at 15 years. Poor quality shingles are a common industry problem, even when they are from a supposedly good manufacturer. I think it is more important that you know the reputation of the roofer and that he has been around for a while. If such a roofer recommended a second layer, I think it would be fine.

10-11-2017, 10:58 AM	#3
webmaster Moderator Join Date: Jun 2002 Posts: 2,453 Blog Entries: 1 Thanks: 457 Thanked 3,819 Times in 839 Posts	The weight of one layer of shingles could add a couple thousand pounds to your roof. From what I've read it's about 250 lbs. per 10' X 10' area. If you don't remove the first layer when replacing it you are doubling the stress. When we have a lot of snow in the winter everyone is worrying about roof collapses and damage. Do you really want to add a few more thousand pounds in roofing on top of the existing weight?

10-11-2017, 05:56 PM	#8
ITD Senior Member Join Date: Apr 2004 Location: Moultonboro, NH Posts: 2,927 Thanks: 476 Thanked 691 Times in 387 Posts	Sky did work for me, did a great job and is a nice guy. For what it's worth, I agree with what he says and always have the old roof removed. Last roof I had done, the original builder of my house did not install the ice dam material he was supposed to install.

10-11-2017, 06:05 PM	#9
Slickcraft Senior Member Join Date: Mar 2008 Location: Welch Island and The Taylor Community Posts: 3,301 Thanks: 1,222 Thanked 2,088 Times in 955 Posts	Well I do agree with the OP. When it comes to major house or camp maintenance projects I don't kick the can down the road. Do it right and live in peace for a long time. Off with the old, new ice guard and paper, new flashing and new shingles. Sleep well and dry for a long time. Shingle over the old? That is a substantial weight subtracting from snow load margin. And what if that 30 year new roof only lasts 12? Now you really get to pay the piper. BTW, my wife and I did the roof on our Welch Island cottage 15 years ago and we did it the right way. Extra work but done right, done once. Just my 2 cents.

10-11-2017, 07:48 PM	#10
SAB1 Senior Member Join Date: Feb 2012 Location: Tuftonboro Posts: 1,230 Thanks: 190 Thanked 320 Times in 235 Posts	I'd always strip it so I know what the condition of the wood under the shingles looks like. I don't know any roofers in my area that don't strip the roof. Gotta be a reason(s) why.....