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Old 08-24-2011, 09:32 PM   #1
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replacement of shingle roof


Is it just as good to put new shingle roof over old shingle roof versus removing old shingles and putting on new roof? What are pros and cons especially for resale.

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Old 08-25-2011, 06:31 AM   #2
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replacement of shingle roof


Pro. The cost for a proper layover should be in the area of 8% too 16% less then a one layer tear off.

Con. The additional the next time around for a two layer tear off will be 25% too 40% greater then the cost of a one layer tear off.

If your existing roof meets the criteria for a layover, it can be installed in a manner that will give you the same aesthetic and mechanical quality as a tear off.

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Old 08-27-2011, 05:09 PM   #3
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replacement of shingle roof


bernicel--Another benefit of a roof-over is that it is far less messy than a tear-off.

HOWEVER...

Some shingle manufacturers won't warrant a roof-over. Ask your roofer to confirm that the manufacturer's shingle warranty would be honored if installed over your existing shingles.

In my opinion, I would never put new shingles over existing shingles. Tearing-off the existing shingles may reveal structural issues/rot that may need repair.



Hope this helps.

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Old 08-27-2011, 05:56 PM   #4
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replacement of shingle roof


Having done this job myself recently, I can honestly say I am so glad I tore off the old roof. One side had 3 layers and the other side had 2 layers. As Bl4ckhea4t said, you will expose rot/structural issues hidden under a layer of shingles. Even if it's only one layer, I say get it off of there to make sure your underlayment is sound. It will give you piece of mind and if you go to sell the house you will be confident in the most important protective structure on your home.......your roof.
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Old 08-28-2011, 07:00 AM   #5
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If there is sheathing or structural issues your roofer will see signs of the existing roof leaking during his/her inspection.
I have done roofs in which we tore off certain sections (existing system leaking) and laid over the rest.

All the shingle manufacturers I deal with (GAF, Tamko, Certainteed, Owens Corning, IKO and Atlas) have spec's for lay over installation.
You can not get their "Extra" installation warranties but you get their material warranty.
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Old 08-28-2011, 07:26 AM   #6
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Apparently, Slyfox can see through shingles and underlayment! (A friendly jab, Sly.) Interior inspection may be what Sly is referring to--and a good contractor will perform one. (Most won't.) However, insulation, limited space, poor lighting and extreme heat sometimes limit the effectiveness of an attic inspection.

He is correct, however, that the manufacturers above will honor material warranties for roof-overs, but not their 'premium protection' warranties. I should have been more clear.

This debate over roof-over vs. tear off can be found on just about ever diy/roof/handyman forum out there. Just be aware, contractors love them because it helps them under-bid their competition. Manufacturers love them because, if you make a warranty claim, in most cases they can find some problem with the old shingle, underlayment or installation that relieves them of adhering to any material warranty.

Again, in my opinion, if you can afford it, do the tear off. You'll sleep better at night.
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Old 08-28-2011, 09:00 AM   #7
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replacement of shingle roof


I was referencing the condition of the existing roof, if there is damage underneath (structure) you will see signs of deterioration in the shingles, then you will explore further by removing (core sampling) roofing/underlayments in those areas to determine if there is structural issues or not.

Major problems in the existing = not acceptable for a layover.
Minor or no problems in the existing = acceptable for a layover.

For every one layover I have done, I have done multiple dozens of tear offs, so I agree that tearing off is better, but laying over works if your experienced enough to know how.
If your ever in the Youngstown, Ohio area I can show you a dozen layovers I did in the 1980's that are still intact today.

BTW, no offense taken by the seeing through the shingles comment.
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Old 08-28-2011, 09:14 AM   #8
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(This debate over roof-over vs. tear off can be found on just about ever diy/roof/handyman forum out there. Just be aware, contractors love them because it helps them under-bid their competition. Manufacturers love them because, if you make a warranty claim, in most cases they can find some problem with the old shingle, underlayment or installation that relieves them of adhering to any material warranty.)

The debate is every where, that's for sure.

Under bidding is found every where, layover, tear off and new construction.

If the roofer installs shingles over an non-acceptable substrate it's their poor workmanship that failed, not the type of roofing system.

A good quality roofer will do a good job no matter the type of system,
A poor quality roofer won't.
Again, that's a reflection of the roofer/s workmanship,
not the method/system.
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Old 08-28-2011, 09:20 AM   #9
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Mike Holmes highly recommends the removal of old shingles before the installation of new ones.

Dave
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Old 08-28-2011, 10:16 AM   #10
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Quote:
Originally Posted by Slyfox View Post
A good quality roofer will do a good job no matter the type of system,
A poor quality roofer won't.
Again, that's a reflection of the roofer/s workmanship,
not the method/system.
Well stated Sly. Agreed.
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Old 08-28-2011, 10:34 AM   #11
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replacement of shingle roof


Quote:
Originally Posted by ddluv View Post
Mike Holmes highly recommends the removal of old shingles before the installation of new ones.

Dave

Mike who?
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Old 08-28-2011, 10:45 PM   #12
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Quote:
Originally Posted by 12penny View Post
Mike who?

You know,,,,Mike,,,,Bob Villa's old neighbors brothers, landlords nephew who is twice,,,,,,,,,,no 3 times removed.,,,,,,,,,,,Mike????? Duh!!!!
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Old 08-30-2011, 01:55 PM   #13
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Quote:
Originally Posted by Slyfox View Post
(This debate over roof-over vs. tear off can be found on just about ever diy/roof/handyman forum out there. Just be aware, contractors love them because it helps them under-bid their competition. Manufacturers love them because, if you make a warranty claim, in most cases they can find some problem with the old shingle, underlayment or installation that relieves them of adhering to any material warranty.)

The debate is every where, that's for sure.

Under bidding is found every where, layover, tear off and new construction.

If the roofer installs shingles over an non-acceptable substrate it's their poor workmanship that failed, not the type of roofing system.

A good quality roofer will do a good job no matter the type of system,
A poor quality roofer won't.
Again, that's a reflection of the roofer/s workmanship,
not the method/system.
+1

We always remove the layer. Pennywise and pound foolish in my opinion to leave it.
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Old 08-31-2011, 08:08 AM   #14
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replacement of shingle roof


Quote:
Originally Posted by ddluv View Post
Mike Holmes highly recommends the removal of old shingles before the installation of new ones.

Dave
Mike Holmes also says not to get a roof done in the winter.

Roofmaster, I do think however that mike is more knowledgeable than Bob ever was, and way more pleasurable for women to watch his show lol.
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Old 09-08-2011, 03:51 PM   #15
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replacement of shingle roof


I would never recommend new over old, this could incur other problems. Here in Texas, the heat tends to make the new shingles bend or conform around the old ones which can lead to cracking developing on the new shingles at the bend points within a few short years (usually a problem with 3 tab/20-25 yr shingles). Secondly, the bottom layer can have a tendency to retain moisture and can weaken the adhesive that is holding it together, and therefore have little to secure it to the deck in the event of high wind. Also, the old shingles can retain moisture and lead to wood rot on the decking and nail pops (nail pushes up through the shingles). If this is an insurance claim, they will pay for tear-off and disposal of the old one. If a contractor is pushing for a layover, run!!

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