Re: SB: re: metal roofing

["Huff 'n' Puff Constructions" <huffnpuff@shoal.net.au>]

G ' day balers and tin roofers


> Rob Tom mentioned that metal roofing can be attached
> directly to purlins, thereby eliminating a lot of roof
> decking while giving you something to grab on your way off
> the roof.  Sounds like a good idea to me.
>
Not a real crash hot idea.  Wet ceilings create wet gyprock
(sheet rock) and wet heads, RT, sorry to disagree old mate.

Corrugated iron roofing will create condensation even in
winter.

More important though is why have a super insulated straw
bale wall system when all the heat is escaping through the
roof?

We always insulate with anti-con sarking above the rafters
or purloins followed by a wool blanket 80% wool 20%
polyester or pure wool off the sheeps back.  This requires
some form of skill in attaching the corrugated iron
especially if the pitch is greater than 26 degrees.  We now
have to scaffold around the perimeter of the roof if the
pitch is 26 degrees or greater.  As well we are now required
to use a harness.

If the roof is raked then it is essential to insulate
between the battens, if a ceiling is in place then you can
insulate between the ceiling joists.  In every case we
always apply an anti-con layer of sarking, which is usually
aluminum foil.

Also and just as important, we like to use white or highly
reflective corrugated iron such as colourbond off white or
straight zinc-alum.  In Aus most roofing now is done by
licensed roofing plumbers.

We can achieve a rating of R2.5 with a combination of
reflective foil, wool batts or pure wool and a light roof
cladding. (Multiply by a factor of 4.6 for Murrican R rating
I think).

All for now The Straw Wolf.


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