Metal roof installation advice

[EddieWalker]

7/16 OSB is probably the most commonly used sheething material used. Plywood used to be pretty common, but it's rare to see anything but OSB in new construction. It holds nails very nicely and doesn't sag like some plywoods have over the years.

If you are installing shingles, be sure to look at the architectual ones. Price isn't too much more, but the look is ALLOT nicer. Be sure to use 30lb felt. I think this is what leads to more issues then anything else. The thin stuff just isn't very good and doesn't last as long.

If the nails go all the way through the sheeting, then they will not come out. I don't know what or how a rood cold be nailed so the nails come out, unless they were too short, or the sheething wasn't attached securily and is flexing. Is there any water damage? What pound felt was used?

When something fails, it's rarely the fault of the component that failed, but something else entirely. If a screw comes out, it's not the screws fault, bu either the instalation of it, the wrong screw was used, or it didn't have a solid point of attachment. The same is true with nails.

Eddie

 

[rvaitor]

I used 26ga 5V for an outbuilding roof 20 yrs ago; nails with washers on the peaks, no leaks!

In a recent adventure I put down 29ga 5V with no nails or screws, just lots of 50yr urethane to the solid sheathing underneath. It's not going to go anywhere. If you don't believe it, get some good quality 50 yr urethane caulk and glue anything together, let it set for a week, then try to take it apart!

It also works great for glueing windshield antennas to glass, but it takes days to set.

Mike

Well,

I'm a believer in poli-urethane calk as well, but hadn't considered this application. I am thinking of re-roofing(replacing) 5v roof on my sheds, barn and like this idea - do you think there would be enough area to secure it on the cross slats? Maybe a combination.

 

[tallyho8]

In a recent adventure I put down 29ga 5V with no nails or screws, just lots of 50yr urethane to the solid sheathing underneath. It's not going to go anywhere. If you don't believe it, get some good quality 50 yr urethane caulk and glue anything together, let it set for a week, then try to take it apart!
Mike

The only thing I don't like about this idea is that there is no underlayment between the panels and decking which may lead to problems.

 

[mrutkaus]

That's true about the underlayment...for what it's worth I've been under many farm building roofs looking up at bare metal roofing.

IMHO urethane would do fine on anything that nails/screws would do. I'm trying to imagine the forces involved and I would think a 3" strip of caulking would equal a screw or nail.

I'd be sure the metal is cleaned of any oil if its new, or weathered, and the wood dry.

Mike

 

[meball]

Ok - I said I would post some images of where I am at with my pole barn so here they are : ) 2 walls up and the roof done. Adding more gravel to the floor tonight after work - doing the rest of the walls this week. Pouring a 4 inch floor the following week. Then I have to decide on what to use for the siding - something economical...

Cheers,

Mitch

 

[patrick_g]

Nice building. I hope to be so lucky as to have mine turn out that nice.

Note to folks considering compositon shingles AND insulation in a building: If the insulation is close or in contact with the nail deck then there is not proper ventilation and the shingles will overheat and degrade.

I have 50 year guarantee shingles and among the requirements to: 1. Get the guarantee and 2. Get the insurance discount, I had to ensure there was ventilation on the underside of the nail deck.

The shingles heat up in the sun and the heat is trapped by the insulation but the nail deck and the shingles get a whole lot hotter and it shortens their life.

Pat

 

[db2]

I put a metal roof on my house (newly "reconsturcted" century farmhouse) in 1983. Used a low rib contour. Nailed 1X4 strapping to the trusses/rafters then the metal went on. Screwed the metal down to the 1X4 with srews on top of the raised rib and just very slightly compressed the metal capped rubber washer. The pitch is 12/12. Screws on 2 foot centers. No problems to date. I'm on a hill totally exposed. We get lots of storms but no Katrina's

You may want to confirm the installation procedure with the people who make and supply your metal. Might affect any warranty.

My barn has had metal roof since the 30's. Nailed down.

Just my 2 cents

 

[EddieWalker]

The only thing I don't like about this idea is that there is no underlayment between the panels and decking which may lead to problems.

Tally,

You lost me here. What type of underlayment are you refering to? Metal roofs don't use felt or any waterproofing underlayment, and in my experience, they are not supposed to be used.

Eddie

 

[tallyho8]

Tally,You lost me here. What type of underlayment are you refering to? Metal roofs don't use felt or any waterproofing underlayment, and in my experience, they are not supposed to be used.
Eddie

A typical metal roof attached to purlins with no decking does not use underlayment but if you place metal flat down right on top of plywood or osb decking, then you should have an underlayment such as felt paper, inbetween. Please see the link to Ideal Roofing in post # 41 for details.

 

[shvl73]

If installed over solid decking rather than on purlins, I would suggest 30lb felt as a condensation barrier. This detail is in the installation manual for standing seam roofing that is designed for such installations. The same detail isn't in the Max-Rib manual I linked for the face screwed panel, which is more commonly installed over purlin but, I would still recommend it when installed on sheathing.
As far as the 7/16" osb, I can only relate to the New England area that I have experience with but, in general, it is not considered to be a quality product. It is widely used for sidewall sheathing and if the siding is nailed through to the stud, (ie: wood clapboards or cement plank siding) I'd use it. For any roof application, I would not.
The higher quality osb's are extremely popular such as, Advantech by Huber or StabilEdge by Norboard and others.
For shingled roof application, most will use 5/8", if using osb or 1/2" or 5/8" if using plywood (depending on rafter O.C.).
SYP ply was popular in the late 80's and early 90's but it delaminates easliy and doesn't seem to be used nearly as much in this region any more. Fir ply is more stable and stronger and still the choice for many, 5 ply more than 4 ply, though the premium osb's are gaining popularity quickly.