Problems with my roof

[brianmoooore]

There are bodges that can help alleviate the problem, but if the trays are missing, bodges they will remain. The inside of the outer leaf of a cavity wall is not designed or intended to remain dry. If it was, you wouldn't need a cavity. The outer leaf is to shield the inner leaf, so that does remain dry
I often see similar on car forums I frequent, where members are concerned with water getting past the outer seals of doors and sunroofs or into the sills. None of these are designed to keep all water out, just to minimise the amount, so that the built in drains can deal with it. The real problem in these cases isn't that water is getting in, but the drains are blocked, stopping it getting out.

 

[littlespark]

So for your idea, Brian, is that a full fix would involve taking blocks out the wall, inserting the trays and making sure they divert water away… filling the hole and repairing the render that was removed? It’s not something that can be done from inside?
We’re going to be painting anyway, and the plasterboard might need replaced/ reskimmed.
Could go through from inside under the bedroom window.
I will be wetwalling the en-suite (centre window) at some point in the future, so will have the plasterboard off in there.

If that should have been done, when the extension was built, then maybe some recourse through NHBC?

Where’s that “optimistic” badge again?

 

[brianmoooore]

Can't realistically be done from the inside, since the base of the tray goes right through the outer leaf, or at least to substantially overlap the lead it sits on.
Should have been done from the start, but any complaint will just result in builder, architect and LBC all blaming each other.
IMO, the blame lies with the LBC for signing it off. In your case, and in many more high profile ones, such as allowing what are very tall chimney like structures to be lined with Celotex.
First thing to do is to establish whether the trays are missing or not, but I know where I'll place my money.

 

[Mike Johnson]

Have you inspected the joint between the window and the brickwork at the cill level on either side? if not done correctly this would cause a bridge across the cavity and allow damp onto the inside leaf of the cavity wall.

 

[DPG]

Interesting. I've got a very similar extension at the rear of my house. Was built around 10 years ago, and signed off by the council, but like yours it is built onto a cavity wall and has no cavity tray.

We've never had any water/damp issues at all. It does have the lead flashing cut into the wall right the way across though (which sits 1 brick below window cill level).

My neighbour's house (semi detatched) had the exact same extension and also has no damp issues.

 

[littlespark]

Have you inspected the joint between the window and the brickwork at the cill level on either side? if not done correctly this would cause a bridge across the cavity and allow damp onto the inside leaf of the cavity wall.

Those upstairs windows are the original build from ‘07. We only really got problems after the extension.
If water was getting in from day 1, and just draining away into founds… we never knew.

Thinking about it, our bedroom window steams up more now after the extension was built, and started with black mould that we didn’t have before….. suggesting it’s damp below the window itself???


Now the big question….
If I don’t jump around, should this sloped tile roof take my 16 stone walking across it?
My house feels naked this year without the high gutters all lit up.
It needs Christmasticated a little more!

 

[Mike Johnson]

Water does not drain down to the foundations, it drains onto a stepped cavity tray and drains out of the weep holes in the stretcher course of the brickwork, that is why it is important not to raise the level of flower beds around the outside of your hose, it will possibly compromise the bottom of the cavity tray and or DPC above it.

Spread the load on the tiles with a board or ladder laid horizontally.

Mould and condensation are caused by lack of ventilation, have you draft proofed that room recently?

 

[littlespark]

Spread the load on the tiles with a board or ladder laid horizontally.

Mould and condensation are caused by lack of ventilation, have you draft proofed that room recently?

Horizontally..... on a sloped roof.....
i think ill just hang lights on the inside of the windows



no draughtproofing.

There are vents built into the windows, that are always open... and we open the windows when its not too cold.
The ensuite has an extractor, which is always used, and we open the window for a shower, whatever the weather.
The radiator for the bedroom is on that outside wall, not quite under the window, to the side..... but that has never been moved.

 

[Mike Johnson]

You have already said it's a small slope and it will in all probability take a ladder horizontally with the addition of a few soft supports at each end and perhaps the middle, use a bit of imagination.

Where does the en-suite extract too? endless connotations of what can cause condensation and mould, I just gave you a few suggestions to show that it could be a simple problem and not involve taking a wall down, I have tried to help, but now suggest you get a qualified Building Surveyor to have a look.

 

[littlespark]

I appreciate all help, so thanks to all who have contributed.

Before the extension, there was no trouble with damp, or mould…. So the existing windows, fans, vents must have been working ok.

As mentioned, there may have been water getting into the wall, but draining away adaquately so it wasn’t noticed. That drain is maybe now blocked and it’s finding a new exit route. - through the ceiling.


Next years project, once I get the funds back up, is to strip out the en-suite. Redo the drain pipes from the shower as it backs up…. Plumb in a towel rail in place of the radiator, electric uhf, a big mirror/ cabinet/ light…. Wet wall right around….

 

[brianmoooore]

Redo the drain pipes from the shower as it backs up…

If the joist layout permits it, take the 4" right up to near the shower, if possible, dropping the basin waste into it as well. I've just put in a new ensuite over the summer, with about 400mm of 40mm between the shower trap and the 4" drain. Unlikely to ever block, but dead easy to rod if it does.