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.

 

[Big Bri]

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.

oh, learned some thing new. thanks

 

[tallyho8]

My metal supplier recommends screwing their 26 ga. corrugated in the valley but I believe that this is because it is too thin to screw it tight on the ridges. I still would screw down 24 ga. on the ridges though this involves using longer screws.

 

[studor]

I have used a fair amount of metal roofing made by Ideal. In their instruction sheet the screws go on the ridges where the two sheets overlap .. so you are going through two layers of metal and therefore harder to compress (and harder to put the screw in ) Screws go in the valley if you are using it as siding (cause the valley is where the two pieces overlap) and the valley is the same as the ridge for roofing but reversed Putting screws in the valley on roofing seems counter intuitive somehow but maybe I just haven't seen the material where it would make sense. On long runs you can run a bead of caulking down the ridge on the bottom piece, then when you lay the next piece on top you have a raised waterproof seam -- JMHO

 

[studor]

My metal supplier recommends screwing their 26 ga. corrugated in the valley

It looks like that stuff does not even completely overlap even once on the ridge --most of the stuff I have ever used completely overlaps at the ridge and some designs are meant to create two overlapping ridges -- whose stuff is that? -- Is it an "inexpensive" brand?

 

[Lineman North Florida]

I built a 32x60 barn and screwed all the tin in the flat, have not had a leak yet, hope my luck holds out, around here about 90% of tin roofs are screwed in the flat, must be a regional thing, my roof is about 4 years old seems like if screwing in the flat did'nt work well I would have already had a problem.

 

[Tig]

I've done a few steel buildings and roofs in my day. Manufacturer's instruction has always been screw the ridge on the roof. This allows the screw to give a bit with the metal expansion as the temperature changes. Otherwise the metal will work the screw hole larger as the metal shrinks and expands.
The ridge also keeps the screw head high and dry.
Check with your supplier.

 

[tallyho8]

It looks like that stuff does not even completely overlap even once on the ridge --most of the stuff I have ever used completely overlaps at the ridge and some designs are meant to create two overlapping ridges -- whose stuff is that? -- Is it an "inexpensive" brand?

If you read their instructions on "Lapping" you will see that they recommend lapping 2 corrogations on roofing and one corrogation when it is used for siding. I have never seen any corrogated metal with different instructions.

If you expand the jpg after you open it you can read it much better.

 

[studor]

Sorry Tallyho -- I was just looking at the screw diagram showing overlap not the lapping instructions -- course if you have to overlap it too much, as you said buy the thicker stuff and only overlap it once with caulking in the overlap Still not sure of the logic of putting a hole in the part that most of the water flow is on .

 

[Big Bri]

My metal supplier recommends screwing their 26 ga. corrugated in the valley but I believe that this is because it is too thin to screw it tight on the ridges. I still would screw down 24 ga. on the ridges though this involves using longer screws.

that jpeg showes in the valley on ribbed roofing. i really thought that was the way to do it. i think if you do it in the ridge you will dent the ridge, and not only will it look bad but it will also make it more prone to leak. the only time i have ever put a screw in the ridge was on the lap and that screw did not go into the wood. speaking of wood you do know not to use treated wood where it will touch the metal.

 

[SuperDuty335]

Nailing or screwing through the flat works just fine until the washer disintegrates and every screw hole leaks. I have a building that was built by someone else with the exact problem. I always attach through the ridge.