Possible condensation in attic?

[bb125]

Hi guys,
Recently discovered our attic insulation is slightly black and also the bitumen membrane is slightly dam in areas. Anyone every had this problem or knows what's a possible cause?

 

[harrythefurrysquid]

Too much water; not enough ventilation.

I'm guessing you probably have a leak if there's enough water to make the felt feel wet; I doubt your loft is so well sealed it would get like that just from moisture coming from inside the house.

I would try to find the leak, if there is one, and make sure you don't have any bathroom/kitchen extractors pumping vapour into the loft space. Also check that you've not covered any eaves vents with insulation, since that's the cheapest and quickest way to improve ventilation (followed by vent tiles and breathable felt I guess).

 

[bb125]

Hi thanks for reply..the bathroom extractor fan was venting directly into attic untill I noticed I've now fitted that to a roof tile.
It seems the bitumen is only wet/dam on one side right above a beam.
I've check around for proper leak but couldn't find anything.
Getting someone out Friday to check it out.

 

[harrythefurrysquid]

Moving the fan output should help massively.

I expect the roofer will have more specific advice. Hopefully it's more "fit eaves vents and vent tiles" than "reroof with breathable membrane".

Might be worth putting down some bin bags underneath the damp patch so you can see if you're getting water dripping onto the insulation.

 

[bb125]

Yeah hopefully he's going to get to the bottom of it. Hopefully doesn't cost to much either. That's a really good idea will definitely do that.

 

[datarebal]

Ventilate. Make sure you are insulated properly including loft hatch. Ventilate some more

 

[bb125]

That's one thing I have noticed the loft ladder hatch doesn't have insulation around it.

 

[ShowerWoe]

The more insulation on the floor of the loft, the more likely water vapour will condense on the wood above etc due to the temperature drop as less heat from the house is able to get through.
The more the insulation, the more important the loft space is ventilated.

 

[JohnD]

CONDENSATION IN LOFT (ANSWERS)

This seems to be the time of year for condensation in lofts, so instead of replying to lots of queries I though I would write this "one-size-fits-all" post. Please also see //www.diynot.com/wiki/Building%3ACondensation-in-Houses Condensation in lofts occurs when the amount of water...

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