# Should I shingle over?



## jampg (Jan 27, 2007)

Our 20 year old unheated detached garage at our cabin needs shingles. There's currently the one original layer. Should I tear off or shingle over the original shingles. Their not cupped at all but looking tired. No leaks yet...
Thanks


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## Luv2hunteup (Mar 22, 2003)

Tear off. The next time you do it you will be older and it will be a lot more work.


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## multibeard (Mar 3, 2002)

Strip the old off!!!!


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## JUSTCATCHINUM (Feb 19, 2004)

Tear it off. Using a shingle shovel is not bad. Start from the top and work your way down. I think cleaning up the old shingles is more work that the tear off.


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## JPK (Aug 11, 2014)

First off, How long are you planning on being there? Second. If you have a standard three tab shingle on there now. And they are not cupping. Ask your roofer about it and ask him for a price on a butt and run. (that is to roof over what is there now) So you only need to purchase the shingles and ridge cap. And maybe some new drip edge. And you will easily get another 20 yrs. plus. But it's up to you.


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## Fishsmith85 (Mar 4, 2015)

Guessing that the garage is not huge, the labor will take a few more hours and the cost will be a fraction more. Seems to me like a small price to pay for total reassurance that your not putting new shingles over something that won't last. Something else to think about is that Plywood is also damaged by ants a lot of times, not just water.


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## -Axiom- (Jul 24, 2010)

For an unheated garage it doesn't really matter too much,* if the existing roof is installed correctly and in somewhat decent condition.*

The biggest issue here is the additional work later in removing 2 layers, I'd wager that if you used a Certainteed Landmark Pro you would get 20-25 yrs out of it with no issues.

The life of the shingle gets cut short (when shingling over) because 2 layer roofs retain heat longer than 1 layer does, heat breaks down asphalt.
This is the same reason thicker shingles tend to get brittle faster than thinner shingles.

In an unheated structure heat build-up & retention isn't an issue.

You will always get a better result by tearing off existing roofing before installing new.


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## hawgeye (Mar 3, 2011)

Steel over the shingles, done.


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## kozal01 (Oct 11, 2010)

hawgeye said:


> Steel over the shingles, done.


This X2. Just did that on my garage this spring


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## JPK (Aug 11, 2014)

Metal roofing over existing shingles? I don't know about that.The metal roofing has a painted top side finish. The under side of the panel is only primed if not just bare metal. When you install metal roofing directly over existing shingles. here's what can tend to happen. The existing roof does have moisture, Installing metal over that can and could most likely lead to rusting of the panel from the underside, but not to say all of the time. Then up and through to the top.Just something to think about. That's why proper venting is so important. But I know it is only a garage. So go for it.


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## Josh R (Dec 4, 2010)

JPK said:


> Metal roofing over existing shingles? I don't know about that.The metal roofing has a painted top side finish. The under side of the panel is only primed if not just bare metal. When you install metal roofing directly over existing shingles. here's what can tend to happen. The existing roof does have moisture, Installing metal over that can and could most likely lead to rusting of the panel from the underside, but not to say all of the time. Then up and through to the top.Just something to think about. That's why proper venting is so important. But I know it is only a garage. So go for it.


Yeah and they aren't usually as smooth of a finish, every install I've seen you can see mini ridges from the layers. Not saying that every install looks like that but the ones I have seen did. Especially when they screw right next to the single ridge, it'll leave a cease when screwed to tight


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## grapestomper (Jan 9, 2012)

rip it off and either shingle or metal. Not worth the pains you could get from the shortcut.


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## shoelessjoe (Dec 13, 2012)

The steel over the old layer is an excellent idea. This of course depends on your budget and future plans for the property. As far as Im concerned, shingling over the old, as long as the old are intact (not crumbling, or full of moisture, mold, and rot0 is just fine if cost and effort would present a problem for you. Discarding the old dumpster, dump location, availability of help with the labor, condition of the deck and rafters etc. All of these items considered, nothing wrong with it, it has been dome for years prior to the new wave.

Do your due diligence with your workmanships quality, and you should not have a problem. If labor and waste issues and not a problem, tear it off or sheet it with metal. Just my opinion. Should you tear it off yes, do you have to enjoy 20 years out of it, no. But as I said quality, no short cuts on a re-skin.


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## jancoe (Jan 24, 2010)

Metal over old asphalt shingles is a leak waiting to happen. I'm my opinion.


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## -Axiom- (Jul 24, 2010)

jancoe said:


> Metal over old asphalt shingles is a leak waiting to happen. I'm my opinion.



Exposed fastener metal systems over heated structures is less than ideal but it is done pretty frequently.

IMO it's better than shingling over the old roof fwiw, "better" being relative here.


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## 2508speed (Jan 6, 2011)

jancoe said:


> Metal over old asphalt shingles is a leak waiting to happen. I'm my opinion.


And IMO I've never seen a nice looking metal roof.


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## multibeard (Mar 3, 2002)

-Axiom- said:


> In an unheated structure heat build-up & retention isn't an issue.
> 
> You will always get a better result by tearing off existing roofing before installing new.


I beg to differ on that statement. If the unheated garage is not vented correctly the area will become an oven from the sun and fry the shingles at the peak area.

In one instance we had to put vents in at the peak of a detached single car garage because the top three or four foot of the shingle had curled from the heat build up. A few year later the elderly woman died before she had the garage roof redone. The new owner asked my why the roof was that way. I told him about the garage not being vented until only a years or so before.

Strip the old shingles off no mater what new roof you decide to put on. Do the job right rather than taking a short cut that might bite you in the butt down the road.


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## shoelessjoe (Dec 13, 2012)

jancoe said:


> Metal over old asphalt shingles is a leak waiting to happen. I'm my opinion.


Any move is a leak waiting to happen if not done correctly.


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## 2508speed (Jan 6, 2011)

shoelessjoe said:


> Any move is a leak waiting to happen if not done correctly.


At your age, you are correct!


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## shoelessjoe (Dec 13, 2012)

2508speed said:


> At your age, you are correct!


Huh?


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