New Extension - Roof Problems

[jamesgs]

Good afternoon,

 

I was wondering if someone might be able to shed a little light on what is going on here...

 

I had this single-story extension built recently and have been having a few issues with the roof. Initially i noticed a loud dripping onto the sill at the bottom of the doors when it rained - you can see to the left of the very right hand window the marks where water runs down, which it does when the rain slows a little. 

 

The rest of the render you can see soaks and gets water running down it, which seems to start from the very left hand side and run across as the rain continues. 

 

The front of the fascia board does not get wet, the water is dripping down from behind the fascia board all the way along. When it does rain, underneath the lead (towards the left of the photo) seems to be wet, which would seem a little counterintuitive to me, and water is running down the neighbours wall behind the gutter downpipe, and presumably running along the back of the fascia board and dripping down wherever there is a gap.

 

The builders have been back a couple of times, squirted a hose at it for 5 minutes, and either tell me there's nothing wrong or adjust a tile by half an inch and declare it fixed, but after a couple of those sessions it seems not to be any different. The bizarre thing, in fairness to them, is that when they lift tiles to look underneath, there the back of the fascia board seems to be dry, so it's difficult to determine exactly how the water is getting there.

 

So firstly, can someone just tell me I'm not being stupid, and that water should not be running down the render like that to start with? And secondly, is this a 'common' issue, with a fix that someone can describe (and I can either do myself or pass onto the builders), or am I getting into the realms of getting a roofer out to have a proper look?

 

Thanks very much!

[jamesgs]

Just a slightly better photo showing the left hand side where I think it's originating

[Dave Jones]

you need to be outside when its raining hard and film it, it appears to be dribbling down the fasica at the top ?

[SimonD]

You definitely shouldn't be experiencing water running down behind the fascia.

 

My first thought was whether the gutter is overfilling when it rains hard. We had a similar arrangement on an old house where the down pipe went into the ground but there was no soakaway, or pipework  below the ground so as it rained, the pipe filled up and eventually we got an overflowing gutter.

 

Looking at those photos, I would look closely at the flashing as it looks pretty poor, especially on the left hand side. Has it been chased into the wall properly?

 

 

[saveasteading]

First stab. Please discuss.

Water is getting behind the fascia and flowing the whole length due to a bottom seal.

Wetter at the left suggests the problem is there, and could be  a single leak.

 

If that seems a possibility then I suggest removing any seal from the bottom of the fascia, and then the source will be clearer.

 

Has the wind been driving the rain towards the left?

That flashing could be allowing water underneath.

Plus your downpipe is draining onto the flashing. I would extend it to the right to keep it away from the flashing.

That is a significant amount of leakage  and needs to be sorted.

[jamesgs]

Thanks for the replies.

 

The top of the gutter is quite a bit below the top of the fascia, so I would imagine it would overflow and just run down the fascia or run over the side, without the water being able to get up and under the last tile and behind the fascia board.

 

The fascia itself stays dry on the front, so the only way the water can be leaking is from behind. It's quite sheltered so I don't see it being the wind, but I could be wrong. There's no seal on the bottom of the fascia per se, but it only leaks out where the fascia and the rendering don't quiet meet, so essentially the same thing I guess.

 

It always starts on the left, with the first drips occurring there, then as it rains more progressing further and further right. It's that, plus the one above the third door, which seem to be a separate issue and I'm concerned water is getting below the felt somewhere up near the skylight.

 

Thanks again anyway though, I'll have to get the builders back again and see if they can do something. Again. Third time lucky. 

[PeterW]

Roof is too shallow for those tiles - what is the head lap..? That is the measurement of the tile overlap - what are the brand of tiles..??

 

I would hazard a guess that the roof is back tracking water under the tiles as they are too flat and then the water is dripping off where it touches the fascia. 

Do you have any photos of it being installed...? 
 

Oh and the builder needs a new spoon to install the rendering on that left wall ... it looks like something @pocster would do... 

[jamesgs]

It's a 9cm overlap - the builder did say they were the only tiles he could find for that pitch of roof so I assume he did look it up. The pitch is a bit greater than the photo makes it look - it drops about 1m over a 3m span, but that's only approx and I've no idea if that's good/bad/indifferent.

 

I've attached the only photos I've got of the roof from mid-build.

 

As with many things, not impressed with that concrete used to keep the lead in round the render. They weren't even going to paint it until I confronted them with a tin of matching paint and told them to get up there!

 

Edit: Sorry I neglected to answer.... no idea on the brand of tiles I'm afraid. Can't see it stamped on there anywhere

Edited May 25, 2021 by jamesgs

[jamesgs]

And the other....

[saveasteading]

There is a Marley tile that theoretically works at such a flat slope, not that it is ideal. extract below. So choice of tile might be ok.  Check out the other suggestions?

flashings, rwp.

 

Another thought. That rwp pouring down the lead and tiles will fairly splash into the gutter. Back-splash could leap to the fascia.

And another. the tiles may interlock and butt well enough for the slope, but the tiles stop short of the wall and lead is draped onto...what? There may  be gaps there.

 

The Marley Modern Tile is a fantastically well-favoured interlocking tile, which is very often one of the first choices when a roofer is looking for a good reliable, flat yet attractive tile to use at a pitch no lower than 17.5°. 

If you have a head-lap of 75mm or 100mm then using the Marley Modern will not be a problem at all 

 

I think the tiles should go full width, not just the bottom course, the the lead laps onto them, and needs to be dressed in too.

Not a roofer though, so others may know better.

[markc]

Im wondering wether the problem could be the shy lights and where they are putting water. Left had one will be taking a big hit from the down pipe.

Im struggling to see any detail on the pics to see just whats going on arounf the skylights.

[Pocster]

2 hours ago, PeterW said:

Oh and the builder needs a new spoon to install the rendering on that left wall ... it looks like something @pocster would do..

Excuse me ! . It’s not something I would do !

I’ve never used a spoon .

[SimonD]

3 hours ago, jamesgs said:

And the other....

 

It's been a good few years since I did any tiled roofing but one thing that's bugging me is I don't see any kind of soaker at the roof and wall abutment in this photo. I'm almost sure from my vague memories that you need soakers when using plain tiles and that flashing only above the tiles is unsufficient in this case. Perhaps someone with clearer, more recent memory can confirm, or maybe a google could provide the answer ..

[jamesgs]

I think that theory about soakers sounds like it might have just hit the nail on the head! There's definitely none up there, and the felt just folds back on itself under the last tile, it doesn't run up the wall at all under the lead, so there is definitely a gap between the tile and the wall where water could run down.
 

I've put a piece of MDF under the spout from the gutter running from the upper roof as well, which although won't last any more than 1 or 2 showers, with the way I've done it should spread the water flow out a bit over the roof rather than running all down the left or all at the left sky light, so that should tell whether that is part of the problem.

 

Thank you all very much indeed for your help and input, it's nice to be able to go back armed with a bit more information!

[dpmiller]

Is the black plastic over the felt and battens still there? That would create a lot of ponding if so.

[Kevin J]

Agree with earlier comment on choice of material. A metal roof at this low pitch would have been  good investment. 
ideally a metal that doesn’t need ventilation, GreenCoat PLX, Stainless steel, push the boat out-with the budget and use copper

[James Newport]

Another vote for missing soakers. Fixmyroof.co.uk has a page dedicated to it:

https://www.fixmyroof.co.uk/install-roof-flashings/step-flashing/

Edited June 1, 2021 by James Newport