Shed insulation mistake...

[danbr]

Hi All,

I think I made a big mistake when finishing off part of my shed.

I insulated a partitionof the shed whish is kept at around 30 degrees.

I have 9mm OSB, 100mm glass wool, 18mm OSB, breathable membrane and then corrugated roof sheets.

Above the insulation is soaking, I guess it's because I should have put a vapour barrier after the 9mm OSB.

I'm getting the same issue in the walls.

Is there anything I can do to resolve the issue? Is there a paint I could put on the inside of OSB?

Thanks in advance

 

[jacko555]

I insulated a partitionof the shed whish is kept at around 30 degrees

Why so hot?

 

[danbr]

I have fish tanks in there which keep the room at around 29-30

 

[big-all]

how big is the air gap and does it vent anywhere[hopefully through air flow]

 

[catlad]

Wow! are they metal sheets?

 

[kingandy2nd]

Fish room - it's condensation from the tanks. Need a extractor fan, a big one.

 

[danbr]

how big is the air gap and does it vent anywhere[hopefully through air flow]

There is no air gap if I didn't have an airgap would a vapour barrier have solved the problem?

Wow! are they metal sheets?

Coraline bitumen sheets

Fish room - it's condensation from the tanks. Need a extractor fan, a big one.

Thank you, the tanks have lids so any condensation from them should remain in the tank. Or atleast wouldn't it condensate on the OSB inside?

 

[catlad]

Hmm.. Everytime I go to buy fish food for the pond I notice how humid it is in there with all those heated tanks!

 

[kingandy2nd]

There is no air gap if I didn't have an airgap would a vapour barrier have solved the problem?



Coraline bitumen sheets



Thank you, the tanks have lids so any condensation from them should remain in the tank. Or atleast wouldn't it condensate on the OSB inside?

Honestly mate, unless your lids are sealed and air-tight, this is the source of your problems. I have fish tanks (marine ones) myself - like @catlad says, fish shops are dripping wet unless they have decent ventilation (by way of extractor fans).

 

[danbr]

Honestly mate, unless your lids are sealed and air-tight, this is the source of your problems. I have fish tanks (marine ones) myself - like @catlad says, fish shops are dripping wet unless they have decent ventilation (by way of extractor fans).

Okay thank you, so putting visqueen under the OSB won't make any difference? Extractor fans aren't ideal as I'm heating the space and not the water

 

[big-all]

membrane encourages vapour to pass through and stop water getting back througheasilly so a very very good thing
now what you need is the escaping water a route to evaporate usually a 20-25mm air gap with an open vent that can cope with perhaps 2 or3% damp escaping over time for the odd leak
or through ventilation to clear maybe 5 or6% as quite a hostile situation as the damp should be far less if insulation properly fitted and sealed to keep damp air below it

 

[danbr]

membrane encourages vapour to pass through and stop water getting back througheasilly so a very very good thing
now what you need is the escaping water a route to evaporate usually a 20-25mm air gap with an open vent that can cope with perhaps 2 or3% damp escaping over time for the odd leak
or through ventilation to clear maybe 5 or6% as quite a hostile situation as the damp should be far less if insulation properly fitted and sealed to keep damp air below it

I thought a visqueen vapour barrier was to stop the moisture from being able to get from inside to the insulation cold side? Meaning no condensation. Have I got it wrong?

 

[raykf]

Dehumidifier?

 

[mattylad]

Grow some weed in there - perfect temperature

 

[regsmyth]

Yes any form of vapour barrier will stop the moisture getting through. Yes you should have put up the vapour barrier before your 9mm OSB. Stapling polythene to the inside would work, but it wouldn't look pretty.
The insulation above should start to dry out, but won't be very effective until it does.