Sticking wood fibre insulation to metal roof

[Ouch77]

I've got a metal roof on a prefab garage that suffers some pretty serious condensation problems. I can't really afford to replace either the garage or its roof right now, but I've got some wood pulp underfloor insulation panels which I reckon could help insulate the roof a bit.

Question is, which glue would be best for sticking the panels up there (and making sure they stay put- I originally thought a spray glue (for speed), but then figured I'd be high as a kite after fixing the first panel, never mind a whole 5x3m garage.

Some sort of grab adhesive perhaps? The insulation panels aren't heavy, approx 450x600 in size, and less than half a kilo per panel (very rough guess).

 

[ntb]

Not sure I'd reccomend this course of action. Wood pulp is going to be permeable to water vapour. The condensation will still form behind the panels unless you install an effective vapor barrier. I suspect given time you would end up with wet mouldy insulation and corrosion problems.

 

[Ouch77]

You're probably right, but I'm kinda stuck as to how to fix this without massive effort (I'm supposed to be landscaping the garden, and don't have time for other project). The garage is half empty, so I figured I'd try to blitz the problem in between getting muddy.

Don't suppose you've got any suggestions as to how I can sort this?

 

[ntb]

No real easy 'proper' solutions. A bodge that may work is to stick the insulation on the outside and then cover with roofing felt.

 

[Ouch77]

how about if I stuck the fibre insulation on the inside, and then underneath it some of that foil-y bubble insulation stuff - with foil tape on the joints? Hopefully that'll be enough of a vapour barrier to keep the fibre relatively dry..?

 

[ntb]

May be worth a try if it's not going to cost much. It will depend on how well you are able to do it. You will also need to check for air paths from the outside and seal them depending on the construction.

Quick setting expanding foam is available that may work for sticking the boards.