Condensation in loft. 11 December 2022 at 5:03PM in In my home (includes DIY) MoneySaving 87 replies 6.4K views

stuart45

One important point with insulation, is that it helps prevent ice dams, and icicles hanging off the eaves.

ashe

Just been up into the loft and there is good news and bad news. 

The good news is I can only see a couple of beads of condensation which feels quite positive. 

The bad news is I knocked one of the loft lids I installed on the GU10's with the hatch and knocked it over, and noticed that the inside has condensation inside it. Right now these are just situated on top of each spotlight while I wait for the sealant to arrive (collected it today and not had a chance to do it yet) and I understand you usually create a seal around the edge and the cable entry points. 

Is this condensation likely to just be from the loft air due to it not being sealed? I'm a little concerned now that if air can get up into the GU10 hence needing the hoods in the first place, that air once sealed will have nowhere else to go?

grumbler

This condensation is likely to be from the air leaking to the loft through the light fitting.

ashe

grumbler said:

This condensation is likely to be from the air leaking to the loft through the light fitting.

Yes, makes sense. In which case if I have a loft lid on top of each gu10 fitting and seal it with sealant  wouldn't it end up with this moisture trapped inside? 

Co1umbofan

My loft felt was also dripping last week similar to the other pictures,  seems to be much improved last couple of days with some warmer weather and bit of wind,  really worrying though just wondering how others were doing now

gutovicky

Hello All,
Yes, this has become a very popular thread...

My question is...   does it look like I've done irreversible damage to my roof rafters??

I'll briefly describe what's happened.    

I live in a fairly poorly-insulated bungalow, built 1970.
When the really cold weather started (10-12 days ago?), I have to say I panicked and decided that I should have my CH on low (13degs C) CONTINUOUSLY - not just to keep the house vaguely comfortable, but TO REDUCE THE RISK OF PIPES FREEZING & LEAKING IN THE LOFT......

You guessed it, after going up into the loft at some point last week, I realised I had a HUGE amount of condensation - on the surface of the floor insulation, on the roof felt and on the timber rafters.   
Most frightening of all was the extent to which the rafters were/are damp - WET actually....

Of course, now the weather is once again crazy mild (and breezy thank goodness), the CH is OFF, and..
..I can see there is now NO condensation on the roof felt... 
..the dampness on the surface of the floor insulation will take a few days to dry out I reckon...
...but the timber rafters are going to take a while to 'recover'...  and frankly, I am worried that a few may be permanently damaged.

I am going to try to attach some photos to this message to illustrate:





Those are 2 of the worst affected rafters in the loft (not all are this bad).
Is this all as bad as it looks?
Please can you offer me any advice on how to save those rafters? 

Thanking you, Vicky 

grumbler

I don't think that there was any irreversible damage. They will dry.

But you have to think seriously about sources of humidity in your loft - a lot of condensation is a result of hight humidity, not just low temperature.

And is the loft ventilated well enough through the eaves?

grumbler

ashe said:

grumbler said:

This condensation is likely to be from the air leaking to the loft through the light fitting.

Yes, makes sense. In which case if I have a loft lid on top of each gu10 fitting and seal it with sealant  wouldn't it end up with this moisture trapped inside? 

Without flow there would be no moisture supply and only small amount can be 'trapped' - no more than the amount of moisture in the same volume of air in the room. However, with all the wires you have to improvise to seal everything reliably.

My recessed lights with integrated LEDs are sealed by foam washers between the lights and the ceiling, but for GU10 fittings the design can be different and air can possibly pass through them.

Co1umbofan

With the amount of people suffering here in hoping it was a kind of rare perfect storm with constant sub zero temps and no wind. 

If ths is the case I would imagine your rafters will soon dry without long term damage. 

In my case parts of the insulation got quite damp,  does anyone know whether this will just dry again and be OK? 

Norman_Castle

gutovicky said:

Those are 2 of the worst affected rafters in the loft (not all are this bad).
Is this all as bad as it looks?
Please can you offer me any advice on how to save those rafters? 

Thanking you, Vicky 

They should dry quite quickly and be fine. Wood is damaged by water if it remains wet for an extended period and rot sets in. Its possible they got wetter when the house was being constructed. The felt and timbers in my loft are wet and have dripped onto the loft floor. I opened the windows and the loft hatch for a few hours today to speed up drying it out.

Really annoyingly, in the loft above my recently decorated bedroom condensation has dripped onto items then pooled on the ceiling leaving brown water stains.

After a valley leak about 10 years ago part of my roofs underfelt was replaced with breathable membrane. One side is bitumenised felt, the other breathable membrane. The two sides are east and west facing so have equal amount of sun but the breathable side is dry while the bitumen side is wet with condensation.