Metal Roofing: Screws on Ridges or on Flats?

allen griggs

I am installing 36 inch wide metal roofing, green color.
Screws with rubber washers. Do you put the screws on the ridges or the flats?

320090T

I have seen it both ways and am confused as to why. Both sides have positive arguments and stick to their stories.

On the ridges - less chance to leak but harder to hold straight when putting in. Also can crunch the ridge due to over tightening.

On the flats - easier to put in straight but easier to leak. May work loose.

I'm leaning towards shingles.

dan kelly

corrugated sheet roofing is just about the most common type of roofing material over here allen, and the screws always go on the ridges,never the flats.
of course your sheeting and methods might be different there though..

babun

Always the flats.

minitruck83

Flats if using screws, ribs if using nails.
My best bet for the difference is the danger of dimpling nails, so keeping the holes high.
I'd think you could do both, using longer screws on the ribs.
But maybe that's over thinking on my part.

cranky2

When they did our roof they screwed on the ribs. I have also seen it done both ways. The contractors reason was less chance of leakage on the ribs.

Mobuck

Using flat rib(ribs every 8-12 inches) the screws go on the flats about .5" from the rib with the joint screws located to catch the underlapping lip of the previous sheet. That was the recommendation I got when we installed the new metal roofing in 2013. No screwing the ribs as it could deform them and cause leaks.

grumpygy

Would depend on what's under it. You going to be screwing to a rafter or are you using the formed pieces under the roofing. If formed on the rib, if rafter valley.

barto

I've put metal on my house, shop and 4 rentals.
ALWAYS PUT SCREWS IN THE FLATS, NEVER HAD A LEAK.(oops)
[^]barto[^]

jltrent

Ridges as those rubber washers have a pretty short life and if installed on the flats one of these short days you will have leaks.

select-fire

Flats. The screw would have to be longer to hit the wood under them on the ridges. Never seen them on the ridges

NeoBlackdog

I'm not a big fan of metal roofs but when that's what the client wants I try to talk them into a standing seam type. With standing seam most of your fasteners are covered and you minimize the possibility of leaks around screws and/or ice tearing the screws out.

mogley98

I've done it this way but I used a bead of silicone at all the joints for the full lenghtquote:Originally posted by forgemonkey
quote:Originally posted by Flying Clay Disk
quote:Originally posted by forgemonkey

Interesting,,,,,,,,

Fasteners
It is recommended that 1" or 1.5" screws with rubber/neoprene washers be used to fasten the metal panels. The general rule is to place a screw on one side of each rib in the panel, and on both sides of the overlap rib. A screw can also be used at the top of the overlapping rib.




http://www.metalroofingwholesalers.com/installation.htm


FM,

I've seen this detail before, but we didn't do it that way. Running a screw into the heel of the ridge is risky. There isn't really any need to pin the edge of the sheet below. The next screw over from the ridge would be run into a joist or roof purlin.

edit...also, there should be a 1" wide mastic sealant strip sandwiched between the overlap at the ridge.




,,,,,,read the article, the 'sealant' is there,,,,,,,,,,[:o)]

Sam06

Like said above you can screw through both.


I agree with FCD about over torquing the screws. Its very important to put them in correctly or they will leak.

Ridge to each other, flat to the roof.

That said I have only done metal roofs on barns and sheds never a house.

SCOUT5

quote:Originally posted by Flying Clay Disk
quote:Originally posted by NeoBlackdog
I'm not a big fan of metal roofs but when that's what the client wants I try to talk them into a standing seam type. With standing seam most of your fasteners are covered and you minimize the possibility of leaks around screws and/or ice tearing the screws out.



This is fact. Standing seam is by far the best way to go! Unfortunately, it is also usually the most expensive.


Standing seam is the best system for some applications, residential being one of them. Install a copper, standing seam roof properly and the home owner can live their life out in it without worrying about ever needing to roof it again. But talk about expensive!

Smitty500mag

I guess if you're building a log cabin and you want the roof to look rustic like a cabin back in the old days you wouldn't use a standing seam roof. It looks to modern to me.

moretoys

The type of fastener is as critical as location.
Most manufactures supply a 1/4" head, small shank, tight thread that fail to retain the "hold" on the wood.
The next option is a 5/16 head, heavier shank, with a taller more aggresive thread pattern that bites the wood better. Also has larger washers.

DONDALINGER

quote:Originally posted by NeoBlackdog
I'm not a big fan of metal roofs but when that's what the client wants I try to talk them into a standing seam type. With standing seam most of your fasteners are covered and you minimize the possibility of leaks around screws and/or ice tearing the screws out.


Another vote for standing seam. Much more expensive? Yes. Lasts way longer? Yes. Far superior? Yes. Most commercial/industrial buildings around here have standing seam (99% or better).[;)]

allen griggs

Thanks for all the tips and advice.
I sent an email to the manufacturer this morning, and this is the reply:

The screw placement is personal preference. Some of our guys only put it in the rib and some only put it in the flat. However, if you put it in the flat, you get a higher wind rating and there in no chance of deforming the panel. On the other hand if you have a really low pitch or a screw backs out, it would be better to put it in the rib. If you do decide to put it in the rib, be careful when tightening it down not to flatten the rib. We recommend putting the screws every 2 feet up and down and next to every rib

This roof is a 3:12 pitch, which is the most shallow pitch allowed for this type of roof.
So, I will put the screws in the ridges. It is easy to walk on this roof and we will try to be careful and not ding the metal when we set the screws.

wpage

Like the boss told me. Always wear your safety glasses and dont fall...[:o)]

jimdeere

Don't forget snow guards.

bpost

The answer depends on how long your going to live. If 25-30 years is all you need any method should be fine as long as you don't over smash the washers.

allen griggs

Explain snow guards.

jimdeere

Keeps the snow from building up and sliding off all at once, tearing your gutters off.

Tailgunner1954

Jimdeere
Those gutters are installed WAY to high.
Proper gutter installation, on any type of roof, requires that the outside edge be BELOW a line extended down from the roof surface.

On my house I went with the EDCO steel shingle. Fasteners are all concealed and it doesn't look like a typical steel roof.
http://www.edcoproducts.com/

Taken on a overcast Dec day, so the various colors don't show real well.

He Dog

Thanks for the link Tailgunner![^]