Shingles over a tin roof


#1

I have an old tin roof - the thin embossed type that is like long shingles - not the standing seam type. I want to put down 30 lb felt and install regular fiberglass shinges over top. I think that all the nail holes thru the tin will provide some air and condensation relief for anything under the tin. I could put extra holes in the tin as well if need be. Really don’t want strip the tin off. I am in Northern Virgina - and the roof is very steep - 10:12. There is about a 3 feet separation between the roof and ceiling - with cross attic ventelation.

Does anybody have any experience or knowledge about this - pls let me know -

tom@bashampc.com

thanks


#2

I would not suggest doing that for a few reasons. Mainly the shingles would really have nothing to hold them to the roof. There would be a major blow off problem. Second you would have zero warranty on the shingles themselves.


#3

The shingles would be nailed thru the tin just like they would on any roof. There is 1 x 6 solid planking under the tin - so I am not worried about blow-off. As for warranties - not sure what they are worth - just would like to know if there are technical reasons or experiences people have had. Thanks for your response.


#4

never heard of such thing… I vote to remove the tin.

I am not even sure if this has ever been done …holes in the tin wont work for ventilation you need actual exaust vents and intake vents… condensation will get trapped under shingles… I wouldnt do it.


#5

Reguardless of wood being there or not. You must remove the first roof for many reasons. Shingles laying flat, sealing of shingle and so on. Why do the job half way.


#6

You should get you a harness and some roof cleats, by the time you felt over the tin you can get you a cordless drill and take off that metal install your new felt and shingles. As long as you have fall protection 10/12 pitch is a piece of cake.


#7

Are you saying you have the type of tin roof that looks like fake cedar shakes? If that is the case, then you certainly won’t have sufficient substrate to mechically fasten the shingles onto. Regardless, I agree with the other guys, this is not something you want to do, so bite the bullet and tear-off the tin roof.

BTW, where in NoVa are you from? I was born and raised in Fairfax and Oakton.


#8

First I would reconsider tearing off the old tin.

Good old tin shingles will last a long time if maintained. If the tin has been neglected and there is a lot of deterioration, I would suggest tearing it off, as there may be rotten wood.
If there is not much deterioration of the tin, you might want to call a professional who specializes in old roofs to get a second opinion.

Can you post some pictures?


#9

if you insist on recoverin the metal shingles and they are layin flat enough,
then dont bother with felting over the metal. just nail them rite to the metal.
extra nails to vent the shingles underneath? no.
no.
dont know how old you are,
but if your gonna live in said house for another 20 years or so,
i think your screwin up.
tear metal roof off and put a new galvalume metal roof on.
itll be the last time you mess with it.

gweedo.


#10

I dont agree with the whole thing or the no felt over the tin. A job like this i would not touch for a million dollars. With no felt under the shingles you will do 2 things, 1. condensation will build under the shingles in the hot summer and cold winter with the heat on. 2. You will superheat the shingle to the point of very early failure, basically burn the back side of the shingle.

Best advise hire a pro tear it all off and be worry free.

A 10/12 is no place for someone that is not a pro. 1 fall and your broken up.


#11

if never seen a shingle burned up from the backside.
and alot of houses in the southeastern u.s. dont even see felt paper.
shingles are nail rite to bare plywood.
so i guess all those roofers and contractor are just doin it wrong.

gweedo.


#12

So felt is not code in florida? The tin will overheat the back of the shingle. Heat transer.


#13

i was tryin to be nice and not single out any one state.
lets just say its a country thing.
tampa bay florida is not country.

i use felt here in tampa bay , and titanium when i can afford it.
but when ya get down to it, its just an underlayment not the roof.
it will not stop a leak only slow it down.

i have torn off many 15 plus year roofs with no felt, the wood fine, everything normal.

so it can be done.
just not by me.

gweedo.


#14

I agree with you on that point. I have torn off many without also. Sorry misunderstood.


#15

My 100+ year old house in Rhode Island has a hip roof with no ventilation whatsoever. The original roof layer was 9x12" interlocking tin shingles, then 2 subsequent layers of asphalt shingles. Anyway, our chimney started leaking from bad mortar and introduced lots of moisture into the attic without letting me know. For a month during this past winter the inside of the house, especially the second floor, seemed very “humid”. I finally went up into the attic, and whoa… it was wet. Damp. Water drops forming from condensation on the inside of the cold metal shingles.

I ended up putting a big dehumidifier up there to at least try to dry it out. This summer we’ve had the whole roof stripped, new plywood where necessary (actually all the decking on the 3’ wide soffit on all 4 sides needed to be replaced because the soffit was stuffed with blown in insulation with no ventilation), and beautiful new architectural shingles. Actally the last shingles went on tonight!

Your situation sounds a lot like mine, except you are in the position our house was in 5 or 6 owners ago… think of the next guy. :slight_smile: Anyway I highly recommend ditching the tin completely. Good luck!


#16

Hi,

Why would there be condensation?

If there is none with the tin roof. There will be none with shingles over tin.


#17

in a nut shell,
ya want deckin wood and underlayment between your attic space and roof.

and remember water forms when cold meets hot.

gweedo


#18

Hi,

So there is no cold meeting hot on a tin roof?