Putting a new metal roof on got i got questions

aokss · 06-04-2006, 08:30 PM

hello...
im building a new garage i have a 4/12 pitch truess 2x4 on ends 2' apart the metal is 12'8" long with 1/2" styrofoam under it. question is hows the best way to put the screws in? getting on the roof it self? its way slick. i guess im asking hows the best way of doing it. and also
is it best to put the screws in the flat part or on the rib?
Todd.:confused:

**joasis** · 06-04-2006, 08:56 PM

Well...I wouldn't put the styrofoam under the metal...but that is your choice...depending on the metal profile (R panel, classic, low rib, ect.) we always screw on the ribs, except for the eaven which we double screw (each side of the rib) on the flats...wind screws. Metal roofs will never fail if they do not come loose at the eave or gable..so bear this in mind. Screw rows 2 feet apart is overkill, but since your purlin spacing is set, there you are. You should have no problem walking 4/12 pitch with metal, but try shoes without a slick sole, and try stick-um...lightly....if you really are not sure. A safety rope from the opposite side may not be a bad idea. Check out my other post in metal roofs to see a 12/12 we did last winter. Good luck

aokss · 06-04-2006, 09:10 PM

Quote:

Originally Posted by joasis

Well...I wouldn't put the styrofoam under the metal...but that is your choice...depending on the metal profile (R panel, classic, low rib, ect.) we always screw on the ribs, except for the eaven which we double screw (each side of the rib) on the flats...wind screws. Metal roofs will never fail if they do not come loose at the eave or gable..so bear this in mind. Screw rows 2 feet apart is overkill, but since your purlin spacing is set, there you are. You should have no problem walking 4/12 pitch with metal, but try shoes without a slick sole, and try stick-um...lightly....if you really are not sure. A safety rope from the opposite side may not be a bad idea. Check out my other post in metal roofs to see a 12/12 we did last winter. Good luck

thanks for ur input :-) i think screwing into thr rib would be better and less likly to leak myself to. i just don't understand why they say use nails in the rib and screws in the flat part.
you won't use styrofoam?? why not and what should ive gotten?

**joasis** · 06-04-2006, 10:19 PM

Styrofoam degrades badly when used directly under metal sheets on a roof exposure. We use "double bubble" foil back insulation...less expensive, and it provides a heat and vapor block. In this day and age, I can't imagine anyone telling you to nail a metal roof panel...I don't think I have seen tin nails in years for that matter. Use woodgrip style screws...2-1/2 inches in length..and 1-1/2 inch screws for the windscrews...you can get them from dynamic fasteners if the place you purchased your metal from does not carry them...and whatever you do, do not overdrive the screws.

Bonus · 06-05-2006, 12:01 AM

Just to confuse the issue a little, around here the steel is always attached on the flat, not the rib. It's actually easier to do as there is no question of crushing the profile by overdriving and you don't get nervous about that and underdrive so the neoprene washer doesn't get compressed. Perhaps these are regional diffs, we also put 15# felt under the steel. Any way you do it, you should be able to walk in runners on a 4/12 on a dry day, it always helps to have a rope as you get near the edge, but be careful, if you step on the rope you will very quickly come to understand the scientific principle behind roller bearings!

AaronB · 06-05-2006, 12:22 AM

I think you need to be able to put the screws in the ribs properly to be able to install the roof.

Also, metal roofs do fail, which is why I make such a good living coating them with waterproofing systems.

**joasis** · 06-05-2006, 07:47 AM

Failure of the metal roofs we install will be due to extreme winds, tree falling on the house, ect. Any roof system can develope a leak, but I haven't seen a metal roof we install need to be coated.

AaronB · 06-05-2006, 01:11 PM

Yeah, probably not for about 20 years or so. Usually due to fastener backout, when the screws loosen up and have to be retightened and sealed, the neoprene washers rot away, the caulk tapes will eventually dry out and crack, Air condiotner units, flashing transitions, original sealants fail, a whole number of age related issues.

aokss · 06-09-2006, 10:46 PM

if i screw into the flat, do they need to be next to the rib or in the middle between the ribs? and what about skipping a run as in diagram below (don't laught at it)

^_l_^__^_l_^__^_l_^

also my sheets are 12'8" long and got my purlin 7 in all 2'oc would it be ok to skip(not screw into) the 3rd and 5th one plus do as above?

i wanna thank you all for your help so far!!

**joasis** · 06-10-2006, 01:06 AM

Yes, and yes.