Problems with my roof

[brianmoooore]

So it's not to say they've missed or forgot them as such. Might be wishing if you wanted to add them now I can't see how it could be done properly other than from inside the roof which you can't get to.

They should have been there from the start. Cowboy operators aren't only a problem for the electrical industry.
The trays I linked to are intended for retrofitting, and only require the removal of two adjacent bricks at a time, before sliding in the tray, refitting the two bricks, then moving on to the next two. They fit immediately above the lead flashing, so still accessible.
These particular trays are fairly expensive, as they are designed for easy retro fixing. When building from scratch, the much cheaper trays, that are shown at the bottom of the link, are used.
In 2012, following the death of my parents, I inherited a farm yard, with buildings all around it. I already lived in one of the 'barns', and set about converting four of the other buildings into living accomodation, including their design, so I had to get fully up to speed on all the building regs and building techniques. I scaled back my electrical and plumbing business a little to find the time, and then, come 2020, was forced by Covid to stop all external work, and was able to devote my time solely to on of the projects during lock down, including building sections of cavity walls at first floor level, and a few hundred square metres of re roofing in welsh slate. It was at the base of these cavity walls that I had to learn all about cavity trays.
By the end of the lock downs, I was well past normal retirement age, so I never went back to external work, having got three of the projects up and running as holiday cottages.

 

[Mike Johnson]

According to your diagram and script there is not mention of "Soakers" behind the flashing on the existing wall onto the under-cloaking membrane. No too clear if you do have cavity insulation, but that could be the whole problem if the cavity is filled.

 

[brianmoooore]

Soakers are only used at the side of a sloping roof, where it joins a vertical wall.

 

[Mike Johnson]

That is generally so, but if they or a secondary flashing was installed under the top batten it would direct any driven rain onto the under cloak and down to the gutter.

It's indicative that the damp is on either side of the window above so the window cill is protecting that part of the flashing/roof, perhaps a good look at the high level guttering is needed.

 

[littlespark]

Like I said, the diagram is simply an example of how the roof is fitted.
I believe my wall is rendered block on the outside, then however a timber frame is constructed with air gap, membrane, OSB, Kingspan insulation, plasterboard etc on the inside.

The roofer, after having a look is now thinking the water is getting in beside the stonework around the left and centre windows, and as suggested, is creeping down behind the render.

He is proposing sealant around those two windows, and windowsills on the outside where the stone meets the render… to try and stop anything getting past.
The right hand side bedroom window doesn’t have this stonework. The render is up against the pvc window.

So nothing to do with the roof, or the extension at all.

It may just be enough to stop it happening

I still think I need some form of expert to have a site visit and explain how it can happen….
A proper building surveyor.


We’re satisfied that it’s not a great deal of water… only enough to stain the paintwork inside. It’s not like it’s actually enough to cause drips, or anything more serious.
If it were to be a mass puddle of water sitting above the dining room, I’d be very worried.

Likewise, if it was a lot of water caught behind the render, that would be cracking off by now.



The trouble is, we can’t know for sure how the water is getting in, and we can’t know for sure if any repair is successful UNTIL we have the heavy rain and winds again… which could be months away again.

 

[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….