Underlayment for metal roof
Printed From: Unofficial Allis
Category: Other Topics
Forum Name: Shops, Barns, Varmints, and Trucks
Forum Description: anything you want to talk about except politics
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=160619
Printed Date: 05 Aug 2025 at 4:57pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Underlayment for metal roof
Posted By: JohnCO
Subject: Underlayment for metal roof
Date Posted: 03 May 2019 at 12:31pm
|
My rental house roof is leaking and I've decided to remove the asphalt shingles and replace them with pro panel steel. I have to replace some of the plywood under the roof as it has started to rot. Wondering what you all think I should use for underlayment. Seems like tar paper isn't in favor anymore as it doesn't seal to the wood well. TIA ------------- "If at first you don't succeed, get a bigger hammer" Allis Express participant |
Replies:
Posted By: jaybmiller
Date Posted: 03 May 2019 at 12:54pm
|
The Hy-Grade steel roof on my house has been on 12-14 years ? Install consists of strapping 2by3 vertically over existing roof( it was slid), then strapping 1x4 horizontally, then the steel shingles go on that. It provides a solid WELL ventilated underside for the steel. LOTS of air flow is necessary. In your case, Once the mess is removed and repaird , I'd cover 100% of the roof with 'ice and water shield' or whatever it's called south of the 49th. The low pitch(3-12) addition was 100% covered then we put 3-4 layers of it at the 'valleys',each one bigger than the last by 2-4 inches.Not one drop has ever come into my house since then. I don't know what 'pro panel steel' recommends for air gap, but I'd suggest 2by4 vertically instead of 1x3s. Cost is not much more and 2by4 are better boards. Buy 16' one, better grade, at least up here, so less waste. Jay ------------- 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: Dakota Dave
Date Posted: 03 May 2019 at 12:54pm
| Up here we use ice shield on top of the decking and steel directly on top of that. that is current code for new residential construction. |
Posted By: DMiller
Date Posted: 03 May 2019 at 3:49pm
| What the installer was told here(no code) was 3/4" underlayment for steel or furring strips 1x3 or 1x4 at no greater than 32" intervals, Use a decent top cover on the plywood prior to the furring strip install. We have a sheet material called titanium paper under our roof. |
Posted By: Thad in AR.
Date Posted: 03 May 2019 at 5:05pm
Titanium paper and similar is what they put under everything around here. I like it because if it gets rained on it doesn’t wrinkle up. |
DMiller wrote:Posted By: Stan IL&TN
Date Posted: 03 May 2019 at 7:44pm
|
On my 2/12 pitch I have ice and water shield on top of deck then the steel on top of that. Been on maybe 15 years and no leaks. ------------- 1957 WD45 dad's first AC 1968 one-seventy 1956 F40 Ferguson |
Posted By: shameless dude
Date Posted: 03 May 2019 at 9:31pm
| hot tar it! lol |
Posted By: Dakota Dave
Date Posted: 03 May 2019 at 10:53pm
| If you put the ice shield on the deck and steel directly on it youll have a very quiet roof.with a continous ridge vent you wont have condensation problems. |