Problems with my roof

[littlespark]

I mentioned it a couple of times on other threads, and will link to here from those....

I found this diagram on t'internet showing how my roof has been constructed... closest anyway.

In my situation, the cavity wall on the left there has been removed, with a steel beam holding it up. Modern timber frame house with external rendered brick.

Our lead flashing isnt chased into the render.... fixed with a timber beam, folded over and down onto the tiles. This is always where they think the water is getting through, and its been sealed time and time again with mastic. The water still gets through.
The lead is also secured with hangers.... 2 inch wide strips of lead that come from underneath, and folded over the edge.
There is a tiny, maybe 2mm gap either side of this hanger

I believe the water is being blown uphill on the surface of the tiles, UNDER the lead flashing... next to the hangers.... eventually over the tile, and down the surface of the wall, under the roof.
It only leaks when its very heavy rain, and strong winds..... so its only happened a handful of times since it was first done....
Its a shallow pitch.... not 45 degrees... but not flat either... maybe 20 -30 degrees?


My suggestion of a solution... is to either use wider lead... so it comes down the tile further..... or use sealent, mastic or whatever where the lead sits on the tile, filling the gap.

Both the original roofer, when the extension was built 2015, and the new roofer..... who "repaired" it in august this year, couldnt find the issue.

 

[mainline]

I mentioned it a couple of times on other threads, and will link to here from those....

I found this diagram on t'internet showing how my roof has been constructed... closest anyway.

View attachment 119013

In my situation, the cavity wall on the left there has been removed, with a steel beam holding it up. Modern timber frame house with external rendered brick.

Our lead flashing isnt chased into the render.... fixed with a timber beam, folded over and down onto the tiles. This is always where they think the water is getting through, and its been sealed time and time again with mastic. The water still gets through.
The lead is also secured with hangers.... 2 inch wide strips of lead that come from underneath, and folded over the edge.
There is a tiny, maybe 2mm gap either side of this hanger

I believe the water is being blown uphill on the surface of the tiles, UNDER the lead flashing... next to the hangers.... eventually over the tile, and down the surface of the wall, under the roof.
It only leaks when its very heavy rain, and strong winds..... so its only happened a handful of times since it was first done....
Its a shallow pitch.... not 45 degrees... but not flat either... maybe 20 -30 degrees?


My suggestion of a solution... is to either use wider lead... so it comes down the tile further..... or use sealent, mastic or whatever where the lead sits on the tile, filling the gap.

Both the original roofer, when the extension was built 2015, and the new roofer..... who "repaired" it in august this year, couldnt find the issue.

I have the same sort of problem with my conservatory where it meets the house.
Apex roof of the conservatory causing damp on the walls, been doing it for years it's been looked at by 3 different who were all of the opinion that the lead needs taking off and redoing.
Mine is chased into the render.

Can you get in the roof space to see where abouts its leaking.

 

[littlespark]

no... cant get into the roof now....

Thats what the repair was in august,.... the new roofer replaced all the lead, new tiles (as apparently a lot were broken) and new sealant right along the top of the lead.

The lead cant be chased in, as its really tight to the underside of the bedroom window sill above.... The damp patches appear either side of where the window is... so is the sill protecting the length inbetween?

We have the same issue further along the roof.... but the wall there is not on the same plane as the dining room.... so its not like the water is getting in and tracking along.... This is a different egress point.
The window here is a little higher.... not giving any protection, and theres more than one spot on the ceiling.... but they are spaced out. I would say roughly the same distance apart as the lead strip hangers.

I found a photo.

first problem is in the left hand room with the bay window. other problem is in the centre at the front porch. We dont have a problem above the garage.... which might be because there is another roof under this one from before we built the extension.

I got the blame for breaking the tiles by walking on the roof to put up those lights. but..... the roof leaked in the first year before the lights even went up.

 

[mainline]

no... cant get into the roof now....

Thats what the repair was in august,.... the new roofer replaced all the lead, new tiles (as apparently a lot were broken) and new sealant right along the top of the lead.

The lead cant be chased in, as its really tight to the underside of the bedroom window sill above.... The damp patches appear either side of where the window is... so is the sill protecting the length inbetween?

We have the same issue further along the roof.... but the wall there is not on the same plane as the dining room.... so its not like the water is getting in and tracking along.... This is a different egress point.
The window here is a little higher.... not giving any protection, and theres more than one spot on the ceiling.... but they are spaced out. I would say roughly the same distance apart as the lead strip hangers.

I found a photo.

View attachment 119014

first problem is in the left hand room with the bay window. other problem is in the centre at the front porch. We dont have a problem above the garage.... which might be because there is another roof under this one from before we built the extension.

I got the blame for breaking the tiles by walking on the roof to put up those lights. but..... the roof leaked in the first year before the lights even went up.

Can't you moan to the roofer and get him to come back.

 

[brianmoooore]

Your plan doesn't go quite high enough, but there's no sign of a cavity tray in that plan. As it is, you will get damp patches exactly where you have them, following driving rain.

 

[littlespark]

Can't you moan to the roofer and get him to come back.

hes coming tomorrow morning.

The issue is, we have had water leaks in the past. We spent a lot of money to him to fix the water leaks.... the exact same leaks are there. he hasnt fixed anything.
Shall i just ask for my money back? (optimistic badge ready)

Your plan doesn't go quite high enough, but there's no sign of a cavity tray in that plan. As it is, you will get damp patches exactly where you have them, following driving rain.

Thats not my plan.... just an example of how the roof has been put together.
The wall is original from when the house was built in 2007.... We just made a big hole in it and made it into a room.

 

[brianmoooore]

This is what's missing in the plan, and if missing in your build would result in the damp patches you have: Bespoke Type E Cavity Tray - 500mm Length | Roofing Superstore® - https://www.roofingsuperstore.co.uk/product/bespoke-type-e-cavity-tray-500mm-length.html
Water penetrates the outer leaf of a cavity wall, especially in driving rain, and runs down the inside of that leaf to the foundations, where it soaks away. If you block the cavity horizontally, this water cannot escape, so cavity trays are required above the lead flashing to collect this water. It either escapes through weeps fitted between every few bricks, or for a reasonably narrow opening, a steeped tray can be fitted, moving the water sideways to where the wall becomes outside again.
Edit: Looks like the trays I have linked to have their own integrated weeps.

 

[littlespark]

I would have thought the render would protect moisture from getting through the brick and mortar?

If that was missed, I’ll have to go right back to the builder who did the extension, or the architect for not specifying it in the first place.


Will see what the roofer says when he comes

 

[littlespark]

And….. he phoned to say he had a hospital appointment and wouldn’t get to us until after 12.
Just had to reorganise my mornings work back in after cancelling…

 

[Dan]

Ahh now I can help. Render is pourus like the cement so the airflow in cavity is meant to keep the two apart.

People have been spraying foam in the cavity around here and it's caused damp to come inside the houses! A government scheme that wasn't well thought out.

So a tray thing is needed?

 

[littlespark]

I’d it is, I wonder why it hasn’t been mentioned by anyone that’s been on site….
Is it a new thing that maybe wasn’t thought about when the extension was first done

 

[Dan]

So the extension has a cavity for sure?

This may just be down to one or two tiles broke with the wind to be fair mate. Just all works down the same route to the living space once its inside.

Round here I know some roofers there are two companies local that drank in the same pubs as me a decade or so ago, and I'd have been able to pinch one for half hour and bring them to you (something I've done for family before now).

They'd spot something fairly quick or at least give you 3 things to check. But only a roofer will work it out mate I think.

A roofer or @brianmoooore ha

 

[Dan]

Hang on I've just found your picture and explanation mate I can see that roof is a bit if a monster!

Can you see any broken tiles or anything when you put the lights up mate?

 

[Dan]

P.s. the cavity trays will be a tool in a roofers options.

Like with these end caps. You can use these or cement them up or cement and lead. Or a bit of all 3 over the whole roof.

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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.

So it'll be lead they're likely to fix anything with as its going on the outside and doesn't want to upset existing lead fixes etc

Roofers hate a flat roof (although easy money usually) but they hate lots of rooves joining each other more over time.

 

[littlespark]

The picture with the lights is a few years old now.
He said there was broken tiles, and we paid to have them replaced along with the water leak supposedly fixed.
I think we were kinda scammed on the broken tiles… I mean, I’m not that heavy, and I wasn’t jumping up and down. Gingerly climbed out the bedroom window and edged along the top putting up the high gutter lights.
I think his guys were rough handed… they managed to break more new tiles and blamed a bad batch from Doves.

I’ve not been out there since the new roof was put on… only his guys.


There must be a specialist service maybe from the council that can come out and tell us how it’s supposed to have been done.

 

[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….

 

[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.