Do you like a metal roof??

[JRR]

If there is an vented air-gap between the tar paper and the metal roofing, it could become quite a torch in the right situation.  An air gap because of wooden purlins and furring would be very risky.  However: if the roof metal style is a flat type, not corrugated, and sits directly on the paper there would probably not be much risk .... but the fire code is probably too rigid to allow even this.

[Dave Sparks]

Thanks JRR for your input. I can see your point of the airspace being a problem and the code being too rigid in other cases where a flat metal roof is on tar paper on sheathing.

[grover2044]

I have read a lot about metal roofing on here, and I think its really the only way to go... But I am a bit confused... My local building store, begins with a H and ends in a T (2 words) told me that I should NOT put any tar paper down on the roof and then the metal. They said to just put some strapping on and attach the roof right to that... Any one care to shed some light?

[MountainDon]

Thanks JRR for your input. I can see your point of the airspace being a problem and the code being too rigid in other cases where a flat metal roof is on tar paper on sheathing.

FWIW, our insurance company gave us a discounted premium. Their only requirements were that the old roofing material be removed before the metal was installed. No mention at all about what was required for underlayment.

[glenn kangiser]

I have read a lot about metal roofing on here, and I think its really the only way to go... But I am a bit confused... My local building store, begins with a H and ends in a T (2 words) told me that I should NOT put any tar paper down on the roof and then the metal. They said to just put some strapping on and attach the roof right to that... Any one care to shed some light?

That will work in a barn , but a house or barn with damp materials such as vegetables stored will need the barrier or insulation.  The metal cools fast and the warm moist air inside will condense enough water out to rain inside - it will run down and drip from the purlins or strapping. 

One member here had to spray foam insulation after the tarpaper was left out by her builder, in order to pass inspection - or tear the roof off and put it in.

I built a farm building for a customer who stored sweet potatoes in it.  The rain from the potato moisture was falling on them and wetting them causing mold.  He had to insulate to get away from it.

The HD guy only knew a little of what he was talking about but was wrong for a house.

[grover2044]

Thanks for the reply Glenn.... So the proper house method would be sheathing, tar paper and then roof? Or is there still a need for the strapping as well...

[MountainDon]

From what I see here, if the roof is sheathed, then has underlayment (tar paper or synthetic) then the metal roofing is installed right flat on top of that. No strapping or furring. That's what I would do (did) unless the metal roofing manufacturer said otherwise.

[Don_P]

For residential the preferred method is over a solid deck. If wood purlins are acid producing, like oak, they require tarpaper or other to make a barrier between the purlin and metal. I can't think of a reason not to use tarpaper. I'm not a real fan of metal.

[JRR]

.... I'm not a real fan of metal....

Not even Metallica? ... how 'bout Led Zep?

...(Sorry, the Devil made me do it!)

[Don_P]

It takes a real class act to make it to a ripe old age