Velux window leak

[dapperman]

Hello both bottom corners of my velux window are leaking, not the velux window itself but getting through slates and leaking underneath the eaves, this was attempted to fix years and years ago with sealant but feel like it’s not right how it’s been sealed as seen in pictures.

I know some of the slate are cracked but not sure if this would cause it?? On the last two photos you can see it’s leaking soaking into the rafter right where the plasterboard wall meets the ceiling on the other side.

Many thanks.

 

[catlad]

There are no clear pictures of the sides, which is generally a problem area. The bits I can see look poor, if you mastic the flashings, then you are in trouble. Do you know what pitch the roof is?

 

[dapperman]

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There are no clear pictures of the sides, which is generally a problem area. The bits I can see look poor, if you mastic the flashings, then you are in trouble. Do you know what pitch the roof is?

Umm pitch of roof is about 36 degrees

 

[martygturner]

I would start with the gaskets they dry out. Its the upper grey one that fails allowing water to run down the inner one and down the back of the frame. I would suggest its the upper area on the window itself not the flashing.

 

[dapperman]

I would start with the gaskets they dry out. Its the upper grey one that fails allowing water to run down the inner one and down the back of the frame. I would suggest its the upper area on the window itself not the flashing.

Where are the gaskets located exactly? I was thinking that maybe it’s on the top and running down, as you see underneath the eaves would the torn flashing do anything by allowing it to drip?

 

[martygturner]

If you look at the window edge there are a set of flapper gaskets that meet with the frame gaskets, the actual flashing kit goes out under the tiles and you can see the bottom grey bottom skirt. If it has not been leaking for ages and after a long baking summer it does then is a rubber seal. Easiest way to test is some tracer dye around the seals and hose down. If its dark the use the florescent stuff, its about £12 on amazon.

 

[dapperman]

I’ve been trying to replicate this leak and is proving very challenging, I’ve poured water everywhere, I’ve looked down these sill valleys and it looks like near the bottom there’s a slight slit in both sides I’m not sure whether this is intentional join or what but the rest of the flashing kit overlaps properly, see photo, the overlap with the moss is correct but then there’s like a slit, but I’ve been pouring and pouring water on these and it doesn’t seem to do anything.