workshop

[amilo]

hi been reading your forum and verey good it is to and now iam going to pester you all for some advise. my workshop is built out of 6" concreat block laid flat as its also acts as a retaining wall so it had to be strong and its 6m x 4m the roof is metal cladding there is plenty of venterlation as where the clading hangs over at the sides i have left the corogations of the cladding open to vent the roof space,
you all know whats coming nex dont you , yes thats right the roof is driping wet with condensation so i need to insulate it the roof beams are 6" deep so i could use 4" rockwool or glass and still have a 2" air gap or i could use polystyrene, but which would be best to stop the condesation and which is the best soundproof wise ( dont want to anoy the locals do we )

 

[ianmelb]

Hmm, not much experience with corrugated metal roof, but I've been told that it's best to get something like:

Roof sheeting
Air gap
Breathable membrane
Insulation
Vapour barrier

E&OE YMMV

 

[amilo]

any one got any input please

 

[Woody Alan]

Ok I'll jump in put up a thin plastic membrane under rockwool 4" if you can accomodate it, with something under that to support it. As far as I know rockwool give the best soundproofing without going into specialist materials. for handlibility you may want to use wall batts or similar which are a compressed rather than loose rockwool; but only 50mm thick. The plastic membrane can be above or below as far as I can see because the objective is to prevent the warmer moist air hitting the cold roof sheet.
Others may have more practical experience/knowledge.

Alan

 

[OLD]

There are companys that will spray foam on the under side of your roof which would be the best solution i hope you can find one that takes on small jobs.Expect a dramatic improvement.

 

[ike]

My workshop roof is also corrugated steel. The cross section is:

sheet over:
/
4" x 1" battens @ 2' centres /(effective 1" airgap) over:
/
waterproof membrane over:
/
3" x 2" truss frame infilled with glasswool batts (actually ex Concorde cabin insulation!). Batts, or even celotex are easier to put up although more care needed cutting to size to avoid cold spots, but I got my insulation secondhand and free at the time.
/
2" x 1" battening under, to fix
/
6mm MDF

Roof is warm and dry in all conditions (exluding -70C, 60,000ft at Mach 2) and well SOUNDPROOFED for those occasional evening sessions with loud tools. Don't stop up under eaves - ventilation effective as draft exits from under the ridge sheets. Note: internal panelling was fiddly cutting around ply truss plates etc, but well worth the effort. I've still to do the same on a recently extended section of the roof.

cheers,

ike

 

[amilo]

My workshop roof is also corrugated steel. The cross section is:

sheet over:
/
4" x 1" battens @ 2' centres /(effective 1" airgap) over:
/
waterproof membrane over:
/
3" x 2" truss frame infilled with glasswool batts (actually ex Concorde cabin insulation!). Batts, or even celotex are easier to put up although more care needed cutting to size to avoid cold spots, but I got my insulation secondhand and free at the time.
/
2" x 1" battening under, to fix
/
6mm MDF

Roof is warm and dry in all conditions (exluding -70C, 60,000ft at Mach 2) and well SOUNDPROOFED for those occasional evening sessions with loud tools. Don't stop up under eaves - ventilation effective as draft exits from under the ridge sheets. Note: internal panelling was fiddly cutting around ply truss plates etc, but well worth the effort. I've still to do the same on a recently extended section of the roof.

cheers,

ike

thanks you dont know where i can find a concord do you right have i got this right steel sheet sat on 4x1" rafters then plastic sheet then 3x2 frame with the insulation tucked between then your 2x1 to fasten your mdf to.
so your plastic sheet is on the cold side ie nearest to the tin roof ??
i always thought it should be on the warm side.

 

[ike]

The plastic sheet is on the cold side, yes. It needs to be as the waterproof barrier to keep the insulation dry. I have had no problems with condensation - honestly. Theoretically you should have a vapour barrier on the inner side of the insulation, and of course you can get fibreglass wool rolls with a barrier layer. Stuffing it between rafters however makes it next to impossible to seal into a contiinuous barrier, and anyway it doesn't matter in a workshop unlike the home where there is lots of sources of water vapour.

Edit: If you are really bothered about it, use breathable roof membrane. That is what was used on my house roof.

cheers,

ike

 

[amilo]

thanks everyone