Nailing Tin Roof (Dumb Question)

[eastexan]

I know this is going to sound dumb to you guys who've done a lot of roofing over the years, but that's one thing I haven't done much of.

I'm going to have to replace a corrugated tin roof on a shed, and would like to know the proper way to secure it.

A guy I know said he used to work for a roofing contractor that used screws put in the valleys of the corrugated tin. I always thought the nails or screws should be placed along the ridges to avoid leaks. He said that the rubber washer on the screws seals it fine along the valleys.

When I was a kid, we had an old barn (built in the 40's-50's) that had a corrugated roof with lead-headed nails along the ridges. The lead was smashed down over nail heads making a good seal.
But the tin was so heavy you could walk across it without boards.
The tin available now at lumber yards is so flimsy that I would be reluctant to walk on it with boards. And I don't see how you could use lead-headed nails on it.

So, with the corrugated tin available these days, how is it best secured?
Ridges or valleys, using nails or screws?
And is it necessary to use corrugated filler boards between the roofing and the board it's being nailed/screwed to?

I know there's better roofing available, but the corrugated tin is all I can afford right now. Thanks for your advice.

Ronnie

 

[Big Bri]

you should use screws and put them in the valley. if you put them on the ridge you may crush it and that will cause leaks.

good luck
brian

 

[randy41]

I would use self drilling screws with the washers on the ridges. Nothing is needed between the roofing and the board underneath. Don't overdrive the screws. Just enough to slightly compress the washer.

 

[beenthere]

Check with the roofing supplier. There are recommendations from different suppliers to do it both ways. I like the ridge, as it just seems to make more common sense if there ever is some leakage around the fasteners. And I would prefer screws.

But it's not a dumb question, that is for sure.

 

[Redbug]

Good question Ronnie...I have been wondering, also.

 

[ultrarunner]

I placed them on the ridge because I bought redwood "Wiggle" Strips that matched the contour

Also makes it harder for mud daubers and other pests to get in...

 

[Bedlam]

Someone mentioned in another post about driving them at a slight angle to shed water also.

 

[Pops15]

Self drilling screws with neoprene washers on the ridges. Run the screws in deep enough that the washer slightly compresses but no farther. If you're not careful you can gain some width by over tightening as the corrugations flatten out.
Pops

 

[Big Bri]

i really surprised at all the responses that say to put on the ridge. if you look at any commercial building you will clearly see that they always screw in the valley.

 

[tallyho8]

The best way is driving screws with rubber washers on the ridges if you use 24 ga. corrugated metal or thicker. Most box stores sell corrugated that is about 32 ga. and you can not tighten a screw tight enough to compress the washer without denting the metal unless you use the corrugated filler boards under it.

This very thin metal needs more screws to hold it down, more purlins plus the corrugated strips that are not needed with 24 ga. so if you go to a metal supplier and get the 24 ga. you may wind up getting a much better roof for just a very small amount of extra cost.

Many times I have found stained 24 ga. at metal suppliers for the same price as new light gauge at the box stores.

P.S. New commercial metal buildings use R-panels that are screwed down on the flat. Different designs, different rules.