Water ingress on bay

JuzaMum

The bay in my child's bedroom (upstairs) has started to leak. The window was replaced as few years back, and the house has also been re-rendered, again a few years back. The bay was also repaired - rotting wood removed and replaced. We haven't had any issues until this year. I do realise we have had a lot of rain, but it should not be coming in. I can't see anything obviously wrong on the outside. What should I look for and how can I remedy this? tia

bjorn_toby_wilde

Is the top picture under the windowsill?

JuzaMum

https://forums.moneysavingexpert.com/discussion/comment/81924256#Comment_81924256

yes

stuart45

Do you know if it's timber frame walls between the bays? It often is because of the problem of supporting the weight.

Bigphil1474

What's the condensation like on a morning? We used to get mould, but not as bad as yours, around the lower bay in our old house and it was all down to condensation - we had the old plaster hacked off, insulation fitted and re plastered and problem solved.

bjorn_toby_wilde

https://forums.moneysavingexpert.com/discussion/comment/81924426#Comment_81924426

It does look more like condensation than penetrating damp. Hard to tell from photos though.

JuzaMum

https://forums.moneysavingexpert.com/discussion/comment/81924426#Comment_81924426

It's north facing and the window is often wet on winter mornings. The bay has been insulated.

JuzaMum

We also have some mould above the window, but no sign of water ingress there.

JuzaMum

https://forums.moneysavingexpert.com/discussion/comment/81924416#Comment_81924416

Yes, timber framing

WIAWSNB

Could we see the other bay corner too, please?

And the above-window mould.

ComicGeek

With it being north facing, the bell mouth bottom of the external render might be staying too wet - greenish algae is normally a sign of high moisture levels. Algae needs killing and repainting.

But the detailing of the bay just doesn't look right to me. There's no real drip bead at the bottom of the render, it looks like the water would just soak into the adjacent boards to the windows - the paint is all flaked away on the boards, so obviously getting too wet. The timber frame provides a route for moisture to travel up, so could be a combination of external water ingress and internal condensation on windows.

The flashing to the underside of the first floor window also looks strange to me, not sure what that's doing - so could be an additional route for wind driven rain where the internal mould is showing.

If no insulation between the timber frame, then internal mould and damp could be condensation - as that corner below the window sill is going to be the coldest surface in the room.