Roofing Question

Raider Bill · May 07, 2008, 03:18:29 PM

I'm planning to put a metal roof on on the house I'm building.
My thoughts were to run 1x4 strips perpendicular [sp] with the roof line along my screwline to allow air flow up and out hoping to release some of the hot air before it got into my attic space. It would be vented on both ends.

I spoke with a roof saleman about this and he advised againest it because he said wind would get underneath and eventually wallow out my screw holes due to vibration and suggested that I run 1x4's parrellell on top of my perpenducular ones for support.

Does this make sense?

I know they can and do attach metal roofing to paralellel 1x4's.

PAnels are 3' wide so my ribs would be every 18"

Confused.............. :-\

ely · May 07, 2008, 03:31:39 PM

i think what you had in mind first would work just fine. i think what you are talking about are 1x4 lathes run across you roof to screw the tin to. this is how i do it. and i also put them about every two feet up the roof and place styrofoam ins. sheets in between the lathes. it makes a big difference in the heat that builds up in the attic.

imo opinion if you have what i call a live air space you will also have condensation under the tin roof. by putting the insulation under the tin it makes it a dead air space.=less/no condensation.

Raider Bill · May 07, 2008, 05:00:17 PM

I already have 30# felt laid and was thinking of another layer before the wood. Need to get something up there next trip to keep the felt from wind damage as I already have had to repair.

Larry · May 07, 2008, 06:03:38 PM

I'll share my thoughts and what little I know as I also plan to use metal roofing on our new home. All metal companies have written guidelines on how there roofing should be installed. There is also a universal building code. If your installation differs from either it could be reason to deny a warranty or insurance claim. For new residential construction the only method I have seen is metal on top of felt, over roof sheathing. Business and farm have different methods.

Now for the reality part...again just my thoughts. The newer screws and gaskets I think have eliminated problems with temperature expansion and contraction along with wind wallowing out the screw holes if the screws are installed correctly...forget about the stitch screws, use framing screws.

Condensation is a big problem with differing solutions. I would think your method with the strips might lead to problems.

Full disclosure time...I put a true standing seam metal roof over felt and plywood 18 years ago on a house which we sold last year. Zero problems. Think there might be a picture in my gallery. One home built shop with another shop by Morton. Terrible condensation problems...just like a rain forest. One home built shop with metal over foam, over purlins about 10 years ago which worked great. We are at present living in my shop/office that I built 6 years ago. Metal over Dow Blue-Cor, over purlins which also seems to be a winner. New house under construction. Going with metal again...think I'll go metal over felt, over plywood...course I might change my mind....especially if somebody comes up with a better idea.

ARKANSAWYER · May 07, 2008, 06:50:55 PM

DO NOT LEAVE AN AIR GAP BETWEEN THE ROOF DECK AND TIN! If air can move in then so can moisture. You will get rot and problems. If you have a roof deck and felt down then put the tin right on it.
I have done like ELY and put down nailers on a deck with foam between the 1x4's and felt over them and then the tin. That really keeps the heat out of the atic.
Here at the mill I have been puting down 1x boards and then the tin right on it. Really keeps the heat out and there is no dripping on foggy mornings.
Now if you live in a desert it would not be so bad and you would get air movement and cooling. If you get more then 8 inches of rain a year and have foggy mornings then you are going to have problems in a few years.

Don_Papenburg · May 07, 2008, 09:42:27 PM

Get some of the new roof covering underlayment. as soon as you can . It is like a tyvek type of material but waterproof. Will hold up to a lot of abuse and keep the felt frome ripping. It is pricy but very much worth the price . Plus it has a walking surface that will not rip under foot .

submarinesailor · May 08, 2008, 04:53:42 AM

Don,

Do you have a brand name of this "new roofing covering underlayment"?

Bruce

iffy · May 08, 2008, 09:44:09 AM

SS - you asked Don but I will answer too. I used Pro-Master Roof Shield UDL plus under my standing seam roof. It is manufactured by Bergerbros (bergerbros.com). It is thinner than felt, practically indestructible, and is not slippery. It actually carries a one year warranty against UV damage in case you put the underlayment down and don't get the roof on right away. A commercial remodel job here in town had it on for 6 months before they got around to putting the metal roof down. No way felt would have lasted that long in Kansas wind and sun.

Don_Papenburg · May 08, 2008, 11:47:46 PM

Rooftop Gaurd is one of the first I heard of .I bought mine at the local lumber yard. I can't remember the name but it was made in Canada. I think it is in every lumber yard and even big box stores now

ksu_chainsaw · May 09, 2008, 05:17:02 PM

Titanium UDL

http://www.interwrap.com/titanium/

I can usually get it through ABC Supply without a special order fee.

It holds up VERY well, and without many problems.

DO NOT just use staples to hold this down, as it will not work, and will slide off the roof(experience talking here)
The underlayment has markings on it to tell you how far to overlap each layer, and where to nail it down at.

I had to break down and get a cap stapler to hold it down-too many nails to put in by hand- 42 squares of roof (Home Depot had a combo kit on sale- Bostich Coil Roofing Nailer and Cap Stapler combo for the same price as a Nailer alone)

Not as cheap as tar paper, but worth it if you are going to leave the roof open for any length of time.

Charles