2nd Layer of Shingles...Any Real Reason Not To?


Old 09-06-13, 08:51 AM
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2nd Layer of Shingles...Any Real Reason Not To?

The web is full of advice about not putting additional layers of shingles on your roof. Mostly because it will not give you a chance to inspect/replace damaged sheathing.

Okay...but what if your roof is in good physical shape and you have no leaks or reasons to be concerned of damage?

My roof is nearing the end of its lifespan. It is still flat and in perfect shape, but it is not pretty....it is light grey and has faded over time. I just installed vinyl siding and the roof looks hideous now. I figure now would be a good time to replace it instead of a few years from now when a leak pops up.

Soooooo....any reason not to save some money and go with a second layer?

I understand a second layer lessens the lifespan of the roof but I plan to be out of the house long before then.

Oh...and yes....up to two layers is allowed per building code in my area. Thanks!
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Old 09-06-13, 09:54 AM
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2 layers of shingles is allowed most everywhere. The 2nd layer of shingles might not lay as flat as they would over a clean roof ..... and while I'm not fond of going over shingles it is an accepted practice.
Old 09-06-13, 10:25 AM
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That's what I was gathering. The web is so full of info about good reasons not to do it.

Now I just have to find a contractor willing to do it!
Old 09-06-13, 10:30 AM
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When you find your shirt a bit dirty do you change it or just put another one over the first?

Adding a new roof over the old IS often allowed but it is poor practice and false economy. In addition it adds TONS of weight to the roof structure. Pretty much any saving that results from not tearing off the old roof will will be negated when it is time to redo the roof properly. Also, a second layer of roofing will rarely last as long as a properly laid single layer.

I personally would use the fact of a second layer to lower my bid for buying a house because I KNOW that it will need to be torn off sooner than it should.
Old 09-06-13, 11:11 AM
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I think it mostly depends on your own personal financial situation.
When I was still working and bid a roof job, I charged a set fee per square to put them down, depending on roof design and pitch.
I charged an equivalent set fee per square, per layer, to remove old shingles, and a fee for haul off and disposal. All clean up was included in those fees.
Exactly how much can you afford to put in the job that will not seriously affect your financial ability.
A bundle of shingles weigh approximately 80 lbs, there are 3 bundles in a square, equals 2.4 lbs of additional weight per square foot on the roof.
So if you have a 3,000 square foot roof area, you end up with an additional 2 and half tons on the supporting walls.
A reasonably well constructed house could generally handle that additional weight, but the additional weight is also directed to your foundation, so you might to want to consider whether the foundation blocks, piers, or slab might be affected by the additional weight.
Additional weight "could" cause a corner pier to sink, while not affecting any others.
Or cause a slab to crack.
Just some thoughts on the matter.

It's down to which alternative you would be more comfortable with.
Old 09-06-13, 08:18 PM
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Keep in mind that your trying to save a few hundred bucks by installing new shingles over old may come back to bite you (big-time) when it comes time to unload the place. You did mention you don't plan to hang around long, right?

I "negotiated" a $6000 price reduction, with significant help from our mortgage lender, on the last place we bought that had squirrelly-looking shingles (not lying flat and sealed), simply because the seller thought he could save some money by installing a cheap grade of 3-tabs on the existing, curling and almost rotten 3-tabs. The wind had already picked up and carried off some of the new layer, because of improper sealing. Self-sealing shingles only work if their sealing strips are in complete contact with the underlying layer of material. And no, you don't have to remove the cellophane first.

I would never buy the cheapest grade of shingles for a new roof. I like the look and performance of 40- or even 50-year architectural grade products. Most of roof replacement money is in prep and installation labor, so why cheat yourself on shingle quality?
Old 09-08-13, 05:37 AM
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Save part of the cost of a roof replacement now and expect to give a significant discount because of it when you sell, or do it right now so you can get a higher price later. If you take the cheap way I don't think you'll win on both the front and back end.
Old 09-08-13, 08:16 PM
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There are many reasons to due a tear off and new roof. If you only want to re -roof, for what ever reason, there is a right way and many wrong ways to do a roof over. Make sure your roofer knows the right way, installs new flashing where there is flashing and new plumbing boots, not just caulking.
Old 09-09-13, 06:15 AM
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All good points everyone! To be honest....the existing roof is older but in good shape, so it doesn't have to be done today. The main driving factor is that it is an eye sore compared to the new siding.

We could afford a new layer now...but it sounds like we will be better off saving up for a complete tear off.

I calculated about 19.5 squares. 13 squares of it is on a 10/12 roof with a single dormer and two chimneys, on a 1.5 story colonial. 6ish squares is on a low slope wrap-around farmers porch, and 6ish squares is on a small 8/12 pitch single story add-on room.

I got a quote last year with a highly reputable company that only does tear offs with 40 or 50 year architectural shingles. I was given a quote for $8,500.

Just for curiosity sake I'm wondering how much I would actually save just having a second layer put on. $1,500, $2,000, $2,500??? Probably not as much as I thought I would.
Old 09-10-13, 12:51 PM
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Just by shopping around, you should be able to save 2000-2500 on the full roof price. This should get you lifetime shingles, the better underlayment (not tar paper), ice and water protection as needed, ridge vents, new drip edge, flashing
and pipe collars. The whole works !!!!
A roof over should run about 4500 at the most.

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