Metal roof myths video

I support the use of metal roofing, this Youtube vision deals with some of the myths
myths about metal rooves

Interesting! I'm thinking about roofing a lot lately. Is there a metal roofing type or installation method that can be used on an almost flat roof, and can be walked on? Maybe a plywood roof over beams, and then metal laid flat on the plywood?

My house has a flat roof (well, just enough slope for the rare precipitation to run off) as all houses do here, and I need to be able to walk around on it. I use it for drying vegetables, storing stuff, access to the solar water heater, etc. It's mostly earthen, with a layer of asphalt inside for waterproofing, and a layer of "straw clay under that for insulation, but I want to add several inches of something much more insulating. Putting insulation under the roof, inside the ceiling, would have issues.

Would it be possible to put a wood frame on top of the existing roof, several inches of insulation, and then a surface that will be possible to walk on and be waterproof?

YES.
Just about any metal roof can be walked on.
The roof structure will have joists, battens at 1M intervals and then the metal.
Insulation etc can be installed within the framework the roof can sit at fairly low angles, check local supplies.
I walk over my skillion roof probally once a week.

I'm not sure you would want to dry anything on a metal roof, they get red hot in the sun. We have both brand new black coloured plastic coated pannels, and older red painted zinc coated pannels both get very hot, to hot to touch even in the weak sun we get. The old pannels can be walked on the new ones cannot, they are thinner and you dent them if you step on them.

My roof in Bendigo Australia gets to 76 C on the surface.

If you cannot walk on the roof without damaging it, the battens are either too far apart or the roofing in too thin or the wrong profile [ shape ] for a roof.
In Australia it is used extensively and damage in very rare.

Unfortunately in some other countries the roofing metal is of far lesser quality than what you're used to in Australia, John.
I'm far from a lightweight, and I could walk on my old corrugated iron roof on Australia with no worries. But the roofing metal they sell here in the UK? Some isn't much thicker than aluminium foil. Okay, slight exaggeration! But quite a bit of what's for sale is flimsy lightweight stuff that doesn't compare well at all.

Whoa, I suppose it reflects the popularity or otherwise of the metal roofing.
A lot of ours is high tensile strength as well. so it may be thin but it can take it.
What a pity.
Here are the specs for Australian roofing iron;
"Revolution Roofing only use 100% BlueScope Steel products.
ZINCALUME® steel aluminium/zinc alloy-coated steel complying with AS1397-2001 G550, AZ150 (550 MPa minimum yield stress, 150g/m2  minimum coating mass); or
Stainless Steel standard grade designation is AISI/ASTM Type
430; UNS No. S43000.
COLORBOND® steel metal thickness is 0.35, 0.42 or 0.48mm. G550, AZ150 (550 MPa minimum yield stress, 150g/m2 minimum coating mass).
COLORBOND® Ultra base metal thickness is 0.42 or 0.48mm. G550, AZ200 (550 MPa minimum yield stress, 200g/m2 minimum coating mass).
COLORBOND® steel .60 Blue Orb G300, AZ150 (300 Mpa minimum yield stress, 150g/m2  minimum coating mass).
COLORBOND® Metallic steel base metal thickness is 0.48mm. G550, AZ150 (550 Mpa minimum yield stress, 150g/ m2  minimum yield stress, 150g/m2  minimum coating mass)."

Allowable span
800mm up to 1300mm depending on thickness and location IE end, single or middle span.

That doesn't sound much different than what I install on a regular basis. The metal here is usually 26 or 29 gauge, 26 being the thicker of the two. I usually install on a 2 foot span, but the manufacturer determines the span of their product and currently the manufacturer I use will allow a span of up to 3 feet.

I usually tell people to step in the flats and not on the ridges, but it will support person of lighter weight on the ridges between the furring. I can (and have) dented the ridges while wearing tools, probably around 270 pounds tools and all. So I tend to walk on the screw line where the furring is and only then in the flats.

The metal I install has a 40 year warranty on the paint coat, and who knows how long the metal would last. I like it.

Ben, what does this mean please?

where the furring is

Aso, we dont use gauge as a measure of thickness much nowadays, do you know the mm size?

Found it!!
25g = .531 mm
26g = .455 mm
29g = .343 mm

John C Daley wrote:Ben, what does this mean please?

where the furring is

Aso, we dont use gauge as a measure of thickness much nowadays, do you know the mm size?

Found it!!
25g = .531 mm
26g = .455 mm
29g = .343 mm

I prefer to install metal onto 2"x4" (1.5"x3.5") furring, that is fastened either to the rafters, or on top of sheathing if the client so chooses. I find that installing metal directly onto sheathing (OSB or plywood), does not hold good. The screws will tend to back out of the thin sheeting easier than a 2x4. I have had to re-screw roofs that were fastened only into OSB.

Also it goes without saying that a vapor barrier is needed to help with the metal sweating, and that is even with the insulation in the attic!

Ben House wrote:

Also it goes without saying that a vapor barrier is needed to help with the metal sweating, and that is even with the insulation in the attic!

For our old house we bought sheeting with a felt backing already applied it worked and was of course very easy to put up.. as it was already attached! The only thing we had to do was if we cut a sheet and that backing came out from inside the house onto the overhang was varnish it so it couldn't pull water back up inside.