New Roof Leaking Water

[Devonish]

We are in the process of building a single storey extension. The roof is on and the lead flashing has been fitted.

However yesterday we had steady rain and I noticed two dribbles of water coming through the wall and slowly making their way to the ground.
I wire brushed off the paint around the area and the wall beneath the paint was wet up to the timber work. I can't see how the water is getting through.

Has anyone got any thoughts?

The builder is now off site and I do not intend to get him back, I need to get this sorted myself before floors go down and plasterboard is put up.

Thanks for any suggestions.

 

[HERTS P&D]

Are those the correct tiles for that pitch of roof?

Andy

 

[John D v2.0]

It's possible it's coming down the cavity and there's no tray to bring the water out, but I guess it's right below the overlap so it's tracking through.
Search the sheet lead association and they have a load of recommended details including how much overlap in this situation. I've a feeling they recommend Two lengths, one chased into the wall and one angle with hooks under it with offset joints.

 

[vinn]

The very top batten should be a doubled batten with a course of Top's Tiles. The Tops are missing.

The flashing appears to have been merely siliconed to the wall - it should be chase into a 22mm slot.

Were cavity trays installed?

There are cracks in the render above and below the flashing line.

 

[Devonish]

Are those the correct tiles for that pitch of roof?

Andy

Yes they were what Redlands recommended.

 

[Devonish]

The very top batten should be a doubled batten with a course of Top's Tiles. The Tops are missing.

The flashing appears to have been merely siliconed to the wall - it should be chase into a 22mm slot.

Were cavity trays installed?

There are cracks in the render above and below the flashing line.

Ok I know there is no double batten, so is that the problem?

I don't understand how cavity trays can be installed. The main wall is the wall of the existing house.

There was a cut made in the wall I saw the builder cutting it with a grinder so I guess the lead had been inserted, unless it has become crimped or buckled whilst fitting and has not gone into the slot enough.


There a crack in the render below but above, the crack is in the paint. This wall takes the weather and the paint tends to bubble up

 

[Devonish]

I have just measured the overlap, every 1.5 m length overlaps at 100mm.

 

[HERTS P&D]

Spray a hose pipe from the window onto the lead and tiles and see if it leaks. If not then it is a problem higher up.

Andy

 

[Devonish]

Surely if the lead was inserted deep enough into the wall, then water running down would hit the lead and be diverted across the tiles. The builder liked taking short cuts and I wonder if he has barely cut through the render and only just lipped the lead into the cut. Also the lead sealant is very cracked.

I am wondering if I should cut in another piece of lead above the flashing. Ensure that it goes deeply into the wall and then hangs down over the existing lead like an apron.

 

[John D v2.0]

As I mentioned there's information here on your situation,I had a bit of time so here's a direct link
http://www.leadsheetassociation.org.uk/apron-flashings

 

[Doggit]

Herts makes a good suggestion, but do it in two stages. Looking at the lead flashing, the overlap isn't tied down. If the rains blowing across the roof, it could get blown under that section.

Where about is the water coming in, in relation to the roof, as this is the section that needs checking.

 

[^woody^]

You've got flashing only chased into render. That's a no no. The render should be cut off and the flashing chased into the wall.

There is also a crack in that render above the flashing, which could allow water in.

In addition, there is clearly water under that flashing on top of the tiles that should be looked at to see if that's a route in.

 

[Devonish]

You've got flashing only chased into render. That's a no no. The render should be cut off and the flashing chased into the wall.

There is also a crack in that render above the flashing, which could allow water in.

In addition, there is clearly water under that flashing on top of the tiles that should be looked at to see if that's a route in.

Thanks Woody, That makes sense. I think when he formed the lead the chase was about 15-20mm in depth. The render depth at various places is 15mm.

So to remedy, should I remove all the flashing and start again? Or could I chase in another deeper flashing above, that drops down the face of the wall?

 

[Doggit]

Whilst Woody is right about the depth, and it ought to be done at some stage, I doubt it's where the current problem lies. Do the water test, and then get back to us.

 

[Devonish]

I will get up there with a hosepipe tomorrow.