Confirm my suspicions - water leaking around velux

[pilsbury]

Mid loft conversion - probably more.

Insulation complete, 100mm between joists, 50mm over the top. All foamed and taped. Several velux installed with insulation around them. There was a small 1-2mm gap in places where the frame met the insulation which I foamed not particularly well leaving a couple of small gaps at the top of the frame. Thought I’d address later before plaster boarding.

Now I’ve been in the loft when it’s been hammering with rain. All seems dry as a bone. But over this last few days during this super cold snap, I’ve had drips from 2 of the windows at the top of the frame where one of these very small gaps in the foam are. Rather surprised as it’s not rained for days.

Am I right in my thinking that warm, moist air has managed to percolate in, condense on the underside of the metal velux apron flashing, likely freeze overnight then thaw during the day and find its way back in? Probably a total of 10ml of water? Just seems bloody amazing seeing the size of the gap. Thoughts?

If so I can refoam and aluminium tape the joint….. had it of rained I’d have been certain there was a leak.

 

[Mr Chibs]

I had this a couple of years ago, with a new install. I noticed it was when the frost on one side of the house thawed and I'd get an odd drip from the windows on that side of the roof, never when it rained!

It stopped and months on I forgot about it, and it's not been a problem since. Yours might sort itself out??

If the roof timbers are new (mine were) I wondered if it could have been moisture coming out of the woodwork and condensing on roof membrane.

You can fill in any areas of foam and retape where needed.

 

[pilsbury]

Possibly the same thing. Can’t be water ingress from outside in my opinion. Otherwise some downpours or sustained rain we’ve had before this cold spell would have highlighted this problem.

 

[Mr Chibs]

Bloody well jinxed mine... this morning, was washing up and felt a drip, looked up and it's dripped down from the frame... spotted I'd left it in vent position... check yours.

 

[catlad]

Velux don't recommend leaving the vent bar open in cold temperatures.
Crack pot! Did you use the installation products BDX , BFX and the BBX when you fitted your new skylights?

 

[pilsbury]

The answer to whether I fit the velux insulation collar…… no! But I was aware of this and used celotex to create my own insulation collar. I thought with 4 velux windows at £45 a pop, I’d save a wedge by doing the same thing. I also thought what do velux know about install kits for their windows

 

[pilsbury]

Not left in vent position.

 

[catlad]

Can you still fit the BBX vapour barrier or have you gone beyond that?

 

[pilsbury]

Doubt it. All fitted, tiled etc. but I can sort out the foam and foil tape the edge of the frame as plasterboard will cover. No warm air could get out then. Hope this would cure it.

 

[catlad]

So you can still fit this ?

https://www.youtube.com/results?search_query=velux+bbx+installation