Roof leak advice

[PinkPig]

Hi,

I am looking for advice - I returned home from holiday to find an area of water damage in our upstairs ceiling. It's immediately below a vent, and there also appears to be a hole in the roof membrane nearby. I'll attach some pictures.

We are in a new build and still under 2-year warranty, so we have contacted the builder and are waiting to hear from them. In the meantime, what should I make of this hole? I know nothing about roofing, but frankly it looks like the vent wasn't installed very well and they attempted to repair it with gaffer tape. How bad is it and how should it be properly repaired?

The area is hard to get to because it isn't boarded so I am not 100% sure that the water has entered this way, but it certainly looks suspicious.

Cheers
Matt

 

[DiyNutJob]

Prepare more lights and get yourself some thick boards. 28mm decking boards cut down to a little longer than the width of the joist gaps worked for me, and easy to place+manoeuvre. The boards are then given "legs" on the sides to straddle the joists. Wait for the next rain and then get up there and observe. Use the boards to move yourself around. Random guessing will not be too useful.

 

[Sonic70]

Could be coming in the vent and running down the inside of the ducting.

 

[datarebal]

Interesting arrangement , do you have a picture showing the area of exit on the outside

 

[John D v2.0]

That membrane is done wrongly, it should be draped between the rafters. Unless they have counter battened which I doubt. That would be a retile and rebatten job.
It may not be causing your issue but it's a general indicator of the work.

 

[PinkPig]

Thanks for the replies. Here's an external picture; it's the vent on the left (below the chimney).

 

[John D v2.0]

So it looks like the soil pipe used to vent out that vent tile. Then someone needed to fit an extractor fan, so they disconnected the soil pipe and put an aav on, then connected the extractor fan in its place.
At some point someone has butchered the membrane using an axe by the looks.

My guess would be the ducting is leaking a bit and convection is causing a constant flow of air, then condensation is forming on the tiles above, and it's dripping down.
There could well be humid air escaping from the soil pipe depending if the aav is connected properly.

Another option is the chimney flashing is leaking a bit and water is getting on to the membrane that way.

I'm sure there are other possibilities that others can think of.

 

[datarebal]

no easy fix for the damaged underlay here.
It'll need scaffold , a large area of slate removed , battens cut etc.
Check to see if its within regs to have the air admittance valve here? I think maybe not , but could be wrong.

Front apron flashing to the chimney is to short could be leaking there.

This will never be fixed from inside or in 5 minutes. Get them back

 

[PinkPig]

Check to see if its within regs to have the air admittance valve here? I think maybe not , but could be wrong.

Thanks for all the replies. On this point, is there a specific reg you are thinking of that would disallow this?

Is there a regulation regarding the length of the flashing?

 

[John D v2.0]

The aav, some of them are only rated for indoors due to the risk of freezing. Some are ok outside the heated part of the house
You'd have to check the spec. Either way the drain system needs to be adequately vented, which ideally means an open vent for each property.
If not you can get issues such as bubbling in the shower tray when the drains are not draining quickly enough.

 

[John D v2.0]

The aav, some of them are only rated for indoors due to the risk of freezing. Some are ok outside the heated part of the house
You'd have to check the spec. Either way the drain system needs to be adequately vented, which ideally means an open vent for each property.
If not you can get issues such as bubbling in the shower tray when the drains are not draining quickly enough.

 

[John D v2.0]

Flashing I would have thought 75mm up the chimney would be ok if there's a reasonable pitch on the roof, but others will know more.

 

[datarebal]

There is not enough lead lapping the roof covering . It's nothing to do with regs it's to do with physics.

The sav, I'm pretty sure that can not be placed just anywhere on a run.

Maybe ask on the plumbing forum .