Loft Insulation

[ae286]

Hi there,

I hope you are well.

I have a pretty bad condensation problem in my attic.

I think this is due to the warm air meeting the cold membrane under the roof tiles.

I currently have 100mm insulation in the floor and am planning to increase this to 270mm.

Should I also add Celotex to the roof?

I really need help on this, and any advice would be greatly appreciated.

Andrew

 

[BlueLoo]

Be careful fannying around with roof membrane. I'd get a structural engineer opinion rather than listening to us chumps on the internet.

Certainly, 200mm added insulation on the ceiling joists will be great

 

[Mike13]

Whatever you do, you need a gap between the tap paper and the celotex/kingspan so that moisture can be carried away.

 

[foxhole]

How is condensation occurring if you don’t leave the loft hatch open to allow the moist air into the roof space

 

[RandomGrinch]

Should I also add Celotex to the roof?

There will be no need to add celotex to the roof. It would be insulating an unheated space - a bit of a waste of time and money.

and am planning to increase this to 270mm

This is the way to go.
You should also check that any ventilation at the eaves isn't blocked.
Adding felt lap vents may also help.

However, for condensation to form, there must be a source of moisture.
Sometimes this is naturally in the air, but often it is coming from within the house. It can enter the roof space through spotlights, badly fitted light fittings, holes for services, badly fitting or sealed loft hatch etc.
If all those are sorted, reducing moisture within the house may also help, i.e. not drying clothes on radiators, using extractors - pretty simple stuff!

 

[ae286]

Would anyone consider using foam insulation?

 

[foxhole]

Would anyone consider using foam insulation?

Only if you never want to sell , most mortgage companies refuse to lend on foamed lofts.

 

[ae286]

Only if you never want to sell , most mortgage companies refuse to lend on foamed lofts.

Thank you, I won't be going down that route then

 

[ae286]

There will be no need to add celotex to the roof. It would be insulating an unheated space - a bit of a waste of time and money.


This is the way to go.
You should also check that any ventilation at the eaves isn't blocked.
Adding felt lap vents may also help.

However, for condensation to form, there must be a source of moisture.
Sometimes this is naturally in the air, but often it is coming from within the house. It can enter the roof space through spotlights, badly fitted light fittings, holes for services, badly fitting or sealed loft hatch etc.
If all those are sorted, reducing moisture within the house may also help, i.e. not drying clothes on radiators, using extractors - pretty simple stuff!

Thank you for this.

I went up the attic today, I was emptying it out. Some of the insulation was pushed right to the edge of the roof which seemed to be blocking airflow, so I pulled it all back a bit.

I think most of the warm air comes from the bathroom, as when ever the hot water is run, this room becomes a sauna and I don't think the exit pipe from the extractor fan is going outside (kicked off at the individual who installed that today).

Other than that I think a lot of the warm air is going through the loft hatch.

My plan is to seal the loft hatch, increase ventilation using some of those felt lap vents (I do already have air vent tiles as well).

Also seal any light fittings etc. and get the extract fan exhaust pipe sorted.

Then finally I will increase the attic insulation to 270mm

Thank you very much for your help

 

[StephenStephen]

So is the bathroom extractor venting into the loft?

 

[ae286]

So is the bathroom extractor venting into the loft?

This is a picture of the extractor exhaust. I thought it was meant to go down in to soffit?

It does seem to be doing that though, seems to just go along to the end of the roof.

 

[robinbanks]

Then finally I will increase the attic insulation to 270mm

There is no reason to delay this

seems to just go along to the end of the roof

Looks like the timber it runs towards is discoloured(damp?)..

Run it underneath the insulation, by the way; it will help prevent condensation forming inside the vent pipe when the extractor is running

Be careful fannying around with roof membrane. I'd get a structural engineer opinion rather than listening to us chumps on the internet.

Certainly, 200mm added insulation on the ceiling joists will be great

I disagree with nearly every aspect of this post (sorry)

 

[ae286]

There is no reason to delay this


Looks like the timber it runs towards is discoloured(damp?)..

Run it underneath the insulation, by the way; it will help prevent condensation forming inside the vent pipe when the extractor is running


I disagree with nearly every aspect of this post (sorry)

The timber it runs towards is a bit damp, I think I need to get the exhaust pipe down in to the soffit

 

[robinbanks]

Yes, make sure it terminates outside, and not near a path if you can; if it drips condensed water on a path in cold weather you might end up with a pad of ice where you want to walk. Fit a mesh/cowl to prevent creatures investigating it as a potential home

 

[ae286]

Yes, make sure it terminates outside, and not near a path if you can; if it drips condensed water on a path in cold weather you might end up with a pad of ice where you want to walk. Fit a mesh/cowl to prevent creatures investigating it as a potential home

Thanks Robin,

I'm order the extra insulation plus some loft stilts now, so I can have a small storage area.

Will also sort out the exhaust on the extractor fan.

Hopefully these changes will help with reducing the condensation