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Old 11-04-2011, 09:16 PM   #1
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New Shingles placed over the original shingles


In order to cut down on labor cost would it be ok to have the roofing contractor not scrape off the old shingles, but nail or staple the new shingles on top of the old shingles? Does anyone know if this has been done before?

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Old 11-05-2011, 06:57 AM   #2
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New Shingles placed over the original shingles


It's been done and if done properly it works.
The problem is most roofers think all you do is nail new shingles over top the existing and walk away, which results in a high percentage failure rate.

I have lay overs I did in the 80's & 90's still intact today so I know hands on they work, but you need to make sure the roofer you hire or you yourself if this is a diy project takes the proper steps to install it properly.

You can get the basic information from the shingle manufacturers website.

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Old 11-05-2011, 09:20 PM   #3
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New Shingles placed over the original shingles


My current home had three layers of asphalt shingles on the roof when I bought it, so it is "possible." I think current codes allow for two layers, but make sure it's not going to void the manufacturers warranty..
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Old 11-06-2011, 03:33 PM   #4
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New Shingles placed over the original shingles


Make sure it is legal in your area. Here in MN it is illegal for a Contractor to install a second layer. Most of the states around us are the same.
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Old 11-06-2011, 04:20 PM   #5
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New Shingles placed over the original shingles


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Make sure it is legal in your area. Here in MN it is illegal for a Contractor to install a second layer. Most of the states around us are the same.
While we don't go over top with a second layer...MN sounds like a nightmare to work in.

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Old 11-06-2011, 06:08 PM   #6
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New Shingles placed over the original shingles


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While we don't go over top with a second layer...MN sounds like a nightmare to work in.

What do you expect? Our ideas for laws come right from IL, CA, and Wash. DC.

Ha, actually that law is in effect anywhere in the hail zone. The building officials enforce it in the current code. Some companies get around it by using a different code for their own advantage.
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Old 11-07-2011, 01:56 AM   #7
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New Shingles placed over the original shingles


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What do you expect? Our ideas for laws come right from IL, CA, and Wash. DC.

Ha, actually that law is in effect anywhere in the hail zone. The building officials enforce it in the current code. Some companies get around it by using a different code for their own advantage.
So much mis-information.....California allows up to 3 layers......this is not the Nazi state that everyone thinks it is....
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Old 11-07-2011, 06:57 AM   #8
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New Shingles placed over the original shingles


It is legal in Il to shingle over an existing roof. Mine has 2 layers. Done about 6 yrs ago. The only place nearby that does not allow 2 layers, that i know of, is a town where the houses are built with trusses 2' on center and 3/8 plywood for sheathing
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Old 11-07-2011, 08:12 AM   #9
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New Shingles placed over the original shingles


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So much mis-information.....California allows up to 3 layers......this is not the Nazi state that everyone thinks it is....
I don't think that MJW was claiming that California does not allow for a second layer.

He was being humorous about the origination of the contracting laws in Minnesota.

I don't think that anyone would argue that California is one of the more litigious states in the union.
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Old 11-07-2011, 08:54 AM   #10
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New Shingles placed over the original shingles


I think you need to consider this based on other things: For one - why are you re-shingling your roof? Has it been leaking or damaged? Will smacking a 2nd layer of roofing on top of a damaged layer REALLY fix the problem? What will you do if it doesn't - or if it even makes a problem worse?

We had serious roof/water damage a few years back from a tornado storm cell that tossed the kid's basketball goal onto the roof - they removed the original layer, and I saw the roof damage from the impact and brought it up as a concern. We were able to get that taken care of - having no singles on the roof helped them fix it more appropriately and address ALL the structural issues.

If you want to save money - scrape off the first layer yourself - or don't consider your roofing needs to be a 'save money to get it done more cheaply' project.
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Old 11-07-2011, 09:15 AM   #11
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New Shingles placed over the original shingles


This depends on if the Contractor is using the IBC or IRC for the codes.

IBC doesn't require a tear off in hail prone areas.

The IRC requires tear off in hail prone areas.


IRC section R907.3

Certain areas haven't adopted the IRC code, but instead allow the contractor to choose which code to follow. This allows the contractor to use the older IBC code which allows two layers.

The IRC 2006, 2009, and 2012 all only allow one layer in the hail prone areas.
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Old 11-07-2011, 09:36 AM   #12
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New Shingles placed over the original shingles


So, jwrob, the first thing to do is check with your local building department, to see if it is feasible in your area. The next thing that I would do is a detailed inspection of the entire roof system. Shingles are what most people see and think of when they look on top of their home, but laying shingles is only part of the trick. If water has gotten past the shingles, or looks like it has, you may have sheathing to replace. There are also valleys and flashings to consider, and there are times, depending on how the work was performed in the first place, that it is easier and better to strip everything off than it is to try to work around areas that may not be right to start with. After that, if you decide not to strip the old roof, it is a matter of the manufacturers recommendations.
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Old 11-07-2011, 10:48 AM   #13
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New Shingles placed over the original shingles


The second or third layers will not last as long or look as good as a new layer.

The manufacturers know this and secondary applications will void most warrantees.

In areas with highly variable temperature ranges and ventilated attics/roofs, lime MN, where the air temperatures can range form -20F t0 -30F in the winter to 95+ in the summer, there is a lot of movement. Everyone knows how hot a roof surface in the sun can get and many people do not realize how cold a roof surface (dark shingles on a cold winter night) that magnify the movement. It is not unusual here to have a clean roof with -20F that can get even colder because we do not always the protection of snow like people further south. Unfortunately the insulated roof is not really viable, so temperatures range.

Maybe that is why many cooler states require compete tear-offs and starting fresh with no accumulated poor details or installations.

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Old 11-11-2011, 08:15 AM   #14
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New Shingles placed over the original shingles


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Make sure it is legal in your area. Here in MN it is illegal for a Contractor to install a second layer. Most of the states around us are the same.
I think this same law prevails in michigan i see lots of roofs all over the state in the process, ALL of them get tear- offs first. They USED to always do a re-roof here, if prior roof was good and flat. bob s

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