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Roofs can’t dress in layers any more

Posted on April 24th, 2008 – 9:34 AM
By James Shiffer

From our Fixit columnist, Karen Youso:

Roofers at work in Shoreview, 1998 (Marlin Levison/Star Tribune)Piling new shingles on old was a way to save money in your re-roofing project. But a change in the state building code makes that practice a no-no in southern Minnesota.

The common practice of laying new shingles over existing shingles, up to three layers, is no longer allowed under Minnesota’s Building Codes and Standards. The state, designated a moderate to severe hail exposure state, now limits the number of shingle layers depending on where you live.

In most of the northern half of the state, only one layer of shingles can be covered with a new layer. In other words, roofs can carry no more than two layers of shingles.

In roughly the southern half of the state, including the metro area, new shingles cannot go over an existing layer of shingles at all. The shingles must be torn off and the roof cleared to bare wood with every installation.

Click here to learn what is allowed in your area, go to or contact your local building official.

But even when the practice of laying new over old was allowed, it wasn’t a good idea, according to Bill O’Meara, an instructor with Community Action, a non-profit organization in Hopkins. New shingles laid on old just don’t last as long as they do when installed on the roof deck, he said. And, in many cases, laying new over old will void the manufacturer’s warranty.

This entry was posted on Thursday, April 24th, 2008 at 9:34 am and is filed under Home improvement. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

8 Responses to “Roofs can’t dress in layers any more”

  1. Bonnie Says:
    April 24th, 2008 at 10:37 am

    An older home I used to own had three layers of shingles. The last I knew those shingles were over 30 years old and we never had a problem with our roof. The people who owned it before us would not have had the money to have the best shingles. The last time I heard that there could only be 1 layer was supposed to be because the newer construction was not strong enough to carry 3 layers. I can’t help but wonder what the REAL reason behind this law is.

  2. Greg Lang Says:
    April 24th, 2008 at 10:50 am

    I have a 25 years old double layer of shingles on my 45 degree pitch roof on my http://searshouse.com I have good insulation and a couple of decades back did a “house doctor” sealing of infiltration. Most roofers I know tell me the roof can go another five to ten years.

  3. icare Says:
    April 26th, 2008 at 6:39 am

    Reading this particular subject makes me wonder how this is going to be enforced.

    Are building officials going to be going up on rooftops now and making sure that roof jobs are being done according to the new building code?

    When a roofing job is being done, are building officials going to be driving around town to see how the work is being done?

    What prompted this to pass as a requirement now? If homeowners haven’t been having a problem with it, then I have to conclude that this will just put more money into someone’s pockets.

  4. John Says:
    April 29th, 2008 at 12:31 pm

    Well I hope they have to inspect each roof. My house is 11yrs old now and I had to tear off the shingles lastyear and found NO frost protection, starter strip and areas where they didnt even put down felt. I wont name the builder but it seems they dont have to be inspected by I had to have it done when I reroofed it. Wonderful Sherburne County inspectors….. Oh and since it wasnt found in the first 2yrs I couldnt use the builders warrenty.

  5. Harry Says:
    April 29th, 2008 at 3:38 pm

    I am a building inspector and I can assure you, I inspect the reroof during and after completion. If I can not be there during, the contractor is required to take pictures and have them available for the final inspection. If no pictures, I require the contractor to show me that all shingles were removed and that Ice and water shield was applied. I have witnessed first hand that new shingles do not last as long when they are installed over another layer. Furthermore, without removing the shingles, you can not inspect the roof boards.

  6. bucbandit Says:
    May 4th, 2008 at 8:31 pm

    Pictures for a building inspection, that is a good one.

    Here is an idea; actually do your job. If you are understaffed quit approving large developments and hundreds of permits.

  7. icare Says:
    May 5th, 2008 at 11:13 am

    I think pictures are a very good idea.

    My question is how do you know that the pictures you’re looking at are actually for the house that the roofer is working on?

    They could easily take pictures of a roof board to show they stripped all the old shingling off. Also, have pictures of various stages of the shingling job. But, do you know the pictures you’re seeing are for that specific house?

    I know I’m being picky, but it seems that nowadays, people will try to get around the rules any way they can.

  8. Mike S Says:
    January 6th, 2009 at 6:35 pm

    it’s my understanding the insurance industry pushed for the change in code. Roofs with more than one layer of shingles incur more damage in a hail storm than a single layer. The multilayered roofs absorb the impact of the hail which damages the exterior shingle. With one layer of shingles, the roof deck (the plywood under the shingle) absorbs the impact. However, large hail will damage a shingled roof no matter how many layers of shingles are in place. For example, 1/2 inch hail will damage a multilayered roof but will most likely not damage a single layered roof.

    Please note, the hail size referenced above is an example. Your results may vary :-)

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