Shops, Barns, Varmints, and Trucks - steel roofing question

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steel roofing question

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Forum Name: Shops, Barns, Varmints, and Trucks
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=210594
Printed Date: 01 Apr 2026 at 1:20pm
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Topic: steel roofing question

Posted By: jaybmiller
Subject: steel roofing question
Date Posted: 01 Apr 2026 at 6:46am

Curious...

Is it 'normal practice' to install steel roofing DIRECTLY on to shingled roofs ?

Amish(?) crew doing my old shop, left the shingles on, strapped the north side, installed tin, south side NO strapping, went direct onto the shingles.

FWIW Job costing $12K, I'm thinking $4500 in tin and 1x4x16 boards, 3 day+-.

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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water

Replies:

Posted By: DMiller
Date Posted: 01 Apr 2026 at 7:02am

Not ever seen Tin installed on Nailers over Shingles. EVER. Most here will strip a roof add a Roofing Sheathing Cover(Ours has Titanium paper) then Purlins and finally Tin. On a strip off Complete Rebuild to afford for better Snow Load, ours has 3/4" T&G Sheathing then the paper and Tin directly screwed to Sheathing.

Posted By: jaybmiller
Date Posted: 01 Apr 2026 at 7:33am

the roof has ,from top layer to bottom layer...

new steel tin

3 tab shingles(south side 10 years old,on top of say 30 year old , north 30 year old)

5/8" t+g plywood

original aluminum roofing on 3x4 purlins(girts ?), trusses 12' on center .

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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water

Posted By: Dave in PA
Date Posted: 01 Apr 2026 at 7:38am

My thoughts on this. The shingles are bad, get them gone, remove! As for tin directly on the shingles, you can answer this yourself. Is it a good idea, to lay a painted metal sheet, screwed down, when it is going to expand and contract due to the change in temp. directly on a coarse grit shingle acting exactly like a piece of sandpaper?? Not in my opinion.

dave

Posted By: DMiller
Date Posted: 01 Apr 2026 at 8:35am

Shingles needed Offed. Plain and Simple. Girts Wrap a Building Purlins top a Roof. Per a Builder here.

https://strucalc.com/blog/industry/girts-vs-purlins/" rel="nofollow - Girts vs. Purlins: Unraveling the Key Differences | StruCalc

Posted By: DanWi
Date Posted: 01 Apr 2026 at 9:00am

Strip it with 2x4 over shingles. They will have a little control over getting those 2x4 nailed or screwed solid. Then the screws in the tin will have less chance of ever coming loose. Taking the old shingles off probably doubles the price of the job.

Posted By: jaybmiller
Date Posted: 01 Apr 2026 at 9:40am

Nice to see we ALL think alike !

'contractor' is cheap....

I'd have got rid of all the shingles( easy 4/12 pitch),strapped, tinned but sadly no longer MY shop.

-------------
3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water