New roof over old?

Hello, and thanks in advance for any help you can offer. Our roof is in pretty decent shape, but it’s getting older and so are we. We want to replace it BEFORE it starts to leak, or we get too old to do the job ourselves. It would save an enormous amount of work if we could put the new shingles over the old. Someone told us the newer shingles are mildew (?) or algae (?) resistent (I forget which), and cannot be put on top of older shingles because of this. Is this true? Would putting tarpaper between the two layers make a difference? The old roof is probably between 10-20 years old (put on by previous owners.) It is standard asphalt shingles. The new shingles would also be standard asphalt, but with a slightly different “cut” to them. Thanks for your help!

I never recommend installing new shingles over old shingles, as this will usually reduce the life of the new shingles.

Personally, I don’t do a “layover” of shingles on top of an existing layer. The cost in removing the first layer isn’t quite as high as you would probably think.

I have also not heard of an AR (algae resistant) shingle being a cause for not doing a layover. Not ALL shingles have this & it is more difficult to find on a 3Tab (flat, smooth shingles with the 3 ‘fingers’ or tabs that you see on a roof).

Not knowing your situation (size, shape, steep-ness of house, etc). I suggest you get @ least two or three estimates & in the event someone is charging a LOT to remove the first layer ask them what this figure is based on.

If you use the search function, you will come across this same discussion; it is asked here about once a month at least.

Other reasons for NOT doing a layover are added weight which can cause damage to the wooden roof deck & if you were to sell the house, it might make it a bit more difficult to get the price you want if a buyer isn’t interested in the added expense of removing two layers.

It also makes a roof keep heat a bit longer & won’t dissipate the heat quite as fast a single layer roof (especially if the new layer is a dark color).

just nail em on.
use a hammer , perferably.
dont need no tar paper in between.
its how we roll in the burg.


As long as there are no issues with the decking(leaks, structure, ventilation) you should have NO problem going over top of one layer. Never heard of AR(Algae Resistant) shingles going over non-AR causing a problem. Make sure roofer follows manufacturer instructions for roof over applications. Yes almost ALL manufacturers allow and warrant a roof over application. Make sure roofer uses all new flashings and you should have NO problems. all that talk about never going over one layer is HOGWASH. :smiley:

BS! Show me a warrantee from a manufacturer other than Certainteed that warrants a layover? There are none, so don’t come on here and make crap up.

[quote=“Severance & Gallant R”]

BS! Show me a warrantee from a manufacturer other than Certainteed that warrants a layover? There are none, so don’t come on here and make crap up.[/quote]

GAF warranties 2nd layer. I registered 4 warranties last year for 2nd layers.

Whoo Hooo another arguement

I’d rather walk on a possible recover than do the job. Too many problems can come up with a recover. In the last 5 years I have done 2 recovers and both were houses that we did in the spring and the house was sold in the fall and the new homeowners wanted a different color. I won’t do em unless situations like this are present.
Recover = Problems in my book especially when you are going over an organic shingle.

You might get a manufactures warrany for a recover but you won’t get one from meeeeeeeeeeeeeeeeeeeeeeeeeeeee!

in the new york state market…shingle overs are very popular with homeowners (always have been) i try to sell against it…but if thats what they want…thats what they get. if i dont do them, i might as well close shop, because all of my competitors will. i did a bid today for a tear off of 4 layers over cedar (the 2nd most extreme i have ever seen). its just what people here are used to. if code allows it (2 layers max) thats what they want.

You will find a problem when putting laminate shingles over standard three tab shingles. Every few rows you will see a few rows that look higher than the rest. Standard shingles have a 5in exposure and most laminates have a 5 5/8in exposure. If you have to roof over try to find a 30 year laminate shingle with a 5in exposure, only way it will work and look ok.

The correct way to lay a second layer over an existing layer is to first cut off all the overhang and install either new drip edge and or replace the old. Next you have to run your bleeder and put your first shingle up under the second course. You will have to cut off the bottoms but this way you run every shingle up under the next bottom. Tear off the ridge shingles and replace all vents. If there are any missing tabs fill them in prior to going over. No ice and water shield or felt is needed when roofing over.

If your shingles are curling a roof over is not recommended. Certainteed puts a 10 year I wanna say warranty on roof overs and no Star Warranty is offered when roofing over. Certainteed does not recommend putting metric Landmarks over standard 3 tab roofs.

I did a roof over last year and the homeowners warranty was 1/6’th my normal warranty.

Whatever you decide to do, good luck!!!

if the shingles show any signs of curling we bust out the hook blade and de-tab the entire roof.

might as well rip it then… don’t ya think? :?

takes 5 minutes to de-tab a roof, im not defending 2nd layers…just telling ya what we do to stay in competition.

95% of roofs done here are done by tear off. I try and stay away from the ones that want recovers. But im picky, i look for customers like they look for roofers. The word callback just makes me shiver. As far as redabing a roof. Well you would never catch me doing that. Tear it off would be my answer. Not like it wiull last very long i would think.

if you got someone that is established and well recomended tellin you
your roof is a good canidate for a recover ie: good slope, no leaks or bad
wood, just a few flashings to seal around, customer needin only a few more years cause they’re old as hell, then he/she is rite an probably
capable of doin just that. take your family out and have a good time with the money youll save.

another roofin pro. i will have to remember that name.

and tar monkey, you aint the shingle monkey in discize are ya?
i like that dag gum monkey.


[quote=“Severance & Gallant R”]

BS! Show me a warrantee from a manufacturer other than Certainteed that warrants a layover? There are none, so don’t come on here and make crap up.[/quote]

Well Mr. Severance I have checked so far with Tamko, GAF, Certainteed, and Owens Corning and they ALL, ALL, allow for reroofing over 1 layer provided you follow the application instructions so it seems that I am not coming over here and making up crap, sounds like maybe You are!!!

reroofing is a terrible mistake.You cant check for any deck damage you cant re-flash.And if you have thin decking 3/8" decking your really cruzin for a brusin.