# two layers of composite shingles



## david lange (Sep 14, 2009)

i have a 30 degree sloped house with 24 in. centers on the truss--Fox And Jacobs home--roofers here say you have to tear off old and install new--30 yrs ago many people just overlaid a lightweight 20 yr roof either directly on over new tar paper to help smooth out the lines-- i did several myself in my young days with no ill affect--fiberglass roofs are about 220 lbs per square--any comments are appreciated--main worry here is that this F and J house may collapse under 400lb per sq of weight--thanks david


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## Interloc (Apr 6, 2009)

Tear them off!!


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## glasscockroofing (Oct 23, 2009)

yeah i would tear them off. if you dont as the years go bye the roof will devleop a sag.http://www.glasscockroofing.com


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## glasscockroofing (Oct 23, 2009)

20 yr are no good. they need to stop making them. tear them off and put a good 30yr. you will happyer in the long run.http:www.glasscockroofing.com


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## kubie (Apr 26, 2009)

i just helped my brother-in-law with his roof. he purchased a 25 yr laminated shingle and they were paper thin. looked like a piece of felt with some sprinkles on top. 


like GCR said, go buy a good 30 yr shingle


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## Grumpy (Oct 29, 2008)

The roofers are right. Always tear off the old roof. I seldom ever install a 2nd layer let alone never would install a 3rd. 

It is not just a weight issue, although that is a concern (today's homes are not built as sturdy as older homes). In addition some manufacturers have limitations in their warrantys for "lay overs", meaning that 30 year shingle roof is not warranted for 30 years. Most importantly is if you do not tar off you can not correct problems with wood and underlayments.

You can do it right or youc an do it cheap. laying it over is not right, it is cheap. The shingle roof is a SYSTEM and the shingles are only a part of the system. The system is comprised of the substrate (wood), the underlayments (ice shield and felt), the primary covering (shingles), the flashings and the ventilation. If any ONE item on this list is neglected, the roof WILL fail sooner rather than later. 

Pgriz told me this, and I have used it many times since. Laying a new roof over an old roof is like going to work a full day, stopping at the gym on the way home, arriving at home and putting clean clothes on over your old clothes. You still stink underneath. 

I find that most roofers who do lay overs cut every corner possible. Quite frankly a lay over is usually nothing more than shingles over shingles. Some times, some guys, will replace the flashings and vents. However as I said most of the time it's just shignles over shingles and perhaps a little roof cement for flashing. Good stuff! (not!)


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## cavesrus (Jan 19, 2010)

We did overlays for years and year what our area called for grumpy is right most rofer dont replace vents or install new card flashings. Now most citys are taking in the new IBC 09 and depending on the area you are in you cant overlay roofs anymore.

We always stated in our contract new vents valleys flashing etc. 

Personaly i have over layed lots of my own property with no problems. i even put a 25 year 3 tab on my own home to OL it in 20 years or so. tear off = more work more mess etc etc. just my 2 cents


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## Grumpy (Oct 29, 2008)

cavesrus said:


> tear off = more work more mess etc etc. just my 2 cents


 Faster and easier does not always equal better, and I am always trying to attain the better. More work means more money means more profit and mess can be managed easily.


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## Interloc (Apr 6, 2009)

layovers SUCK!! just my 2 cents


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## cavesrus (Jan 19, 2010)

i agree with you on that grumpy. 

20 years from now im sure i prob cant do a overlay lol


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## robert (Oct 29, 2008)

Biggest waste with layover is the shingles just dont last very long in most cases,and when you have to take it off now you have twice the trash.


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## Grumpy (Oct 29, 2008)

I agree Robert, We try hard not to do layovers and I have only done one on a shingle roof in like the last 10 years. The customer made it clear they were going to buy a layover and a lay over only...


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## peter updegrove (Jan 28, 2010)

Nobody mentioned the fact that you cant find and fix rot if you dont tear off.


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## Grumpy (Oct 29, 2008)

LOl well you can sometimes find it, the major areas anyways, but fixing it is another story.


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