drip drip down internal cavity wall

dahamster

Hi Guys,

When it rains i have a leak dripping down on the plasterboard of the cavity wall between the kitchen and the sunroom. Got builder back ,he sealed external walls alegedly but can hear drip drip again. On the drawings none was specified by engineer, but should a cavity tray have been fitted according to building regs of four years ago? If so ( and if there is none fitted) who takes the blame builder or engineer.

Just need to have some info if I need to go to my solicitor. Builder was not homebond but i have a buliding agreement through solicitors etc. Engineer has PI.

Thanks.

Poor Uncle Tom

Is there a window in the wall above the sun room roof ?

dahamster

Yes, Small bedroom window

Poor Uncle Tom

The drip is likely to be associated with the positioning of the VDPC or the cill of the upper window and should be easy enough to stop.

Do you know what thickness of insulation is in the cavity? Is it partial fill?

The cavity tray should have been put in at the start, but it is not an option now.

dahamster

insulation is 60mm kingspan thermawall tw50. The window is ofset to the right of the drip but i suppose water will follow its own course. Shouls a tray be present according to regs? It would make sense, but i presume regs are not necessarily sensible. Is it a widow cill off job?

mickdw

Tray problem 100%. Ive seen it a hundred times. Now its not regulation as such for rendered structure but is certainly needed in exposed areas as if you think about it, the outer leaf of the wall above your sunroom roof continues down past that roof and becomes an inner wall in the sunroom. Trays cut off any possible movement of water from top to bottom. HAving said that, the window overhead can complicate this as if its too near to the line of the trays, it can make it so difficult to get the trays right.

What level of engineering supervision did you pay for?

At this stage, the solution would be to take out 2 blocks at a time at the location of trays and retro fit them..... difficult job or the other option is to completely water proof the area over the sunroom roof with a permanent seal such as bituthene membrane. This would involve removing plaster from that area, applying this tar type material, affixing a plastic mesh to this and then replaster the area.
A sealing paint is only a temporary solution but can be useful to see that it does cure the problem.
These are the type of problems that can be avoided with a good project manager on site because you will now have one trade blaming the other or if you had a builder, he will blame the drawings.

dahamster

mickdw wrote: »

Tray problem 100%. Ive seen it a hundred times. Now its not regulation as such for rendered structure but is certainly needed in exposed areas as if you think about it, the outer leaf of the wall above your sunroom roof continues down past that roof and becomes an inner wall in the sunroom. Trays cut off any possible movement of water from top to bottom. HAving said that, the window overhead can complicate this as if its too near to the line of the trays, it can make it so difficult to get the trays right.

What level of engineering supervision did you pay for? .

Paid engineer to do planning and supervision of build. Trays not speced in either drawings or building documents, so i suppose builder did as directed.
I have no building experience so did not catch this on the drawings. Altough it makes perfect sense to have them in place over what will be a doorway between rooms

mickdw wrote: »

At this stage, the solution would be to take out 2 blocks at a time at the location of trays and retro fit them..... difficult job or the other option is to completely water proof the area over the sunroom roof with a permanent seal such as bituthene membrane. This would involve removing plaster from that area, applying this tar type material, affixing a plastic mesh to this and then replaster the area.
A sealing paint is only a temporary solution but can be useful to see that it does cure the problem.
These are the type of problems that can be avoided with a good project manager on site because you will now have one trade blaming the other or if you had a builder, he will blame the drawings.

Yeah it will be fun now to get someone to take responsibility for what is either poor design on the engineers part or a lack of interest on the builders part. Retrofitting trays would be a messy business yes?

mickdw

dahamster wrote: »

Paid engineer to do planning and supervision of build. Trays not speced in either drawings or building documents, so i suppose builder did as directed.
I have no building experience so did not catch this on the drawings. Altough it makes perfect sense to have them in place over what will be a doorway between rooms




Yeah it will be fun now to get someone to take responsibility for what is either poor design on the engineers part or a lack of interest on the builders part. Retrofitting trays would be a messy business yes?

By sealing the surface of the wall outside above the sunroom roof, you are effectively cutting out the usefulness of damp tray over window, vertical damps at sides of window. You will still however need to be sure that the cill had a perfect damp proof membrane wrapping it or you would be in trouble as cill will still be exposed and going with the idea of sealing the surface, nothing can be let past the surface or its a disaster whereas using the trays etc, you are allowing the outer block leaf to be wet throughout until the stepped trays at the sunroom roof creates a break between wet wall & dry wall.

Believe it or not, many 'builders' dont understand the need for these stepped trays. The argument Ive heard more than once is..... The lead will keep it out. This makes no sense once you understand that the outer leaf is designed as a wet wall.

You should get someone in who is well clued-in in this area and work out the best way forward.

PeteHeat

Hi,

The type of construction you describe was in use long before cavity trays or building regs, while the cavity trays may have prevented the problem not everyone used them properly especially on rendered finishes as very few left out drain / weep holes at high levels.

First you need to find the source of the leak, possibly around the window frame or even tracking back under the window cill, another source could be a leak in the roof possibly at the ridge.

The problem with this type of leak is the source may not be obvious however you might be able to narrow the search by establishing which side of the cavity it is running down.

Assuming it is on the outer leaf double check the joint of the plaster to the window frame you could try using a hose however it is very hard to simulate wind driven rain.

I would think the most likely source is around the window, if a silicone sealer is being used make sure it is a good quality not just standard builders grade and ensure the top of the frame receives as much attention as the sides.

.

dahamster

mickdw wrote: »

Tray problem 100%. Ive seen it a hundred times. Now its not regulation as such for rendered structure but is certainly needed in exposed areas as if you think about it, the outer leaf of the wall above your sunroom roof continues down past that roof and becomes an inner wall in the sunroom. Trays cut off any possible movement of water from top to bottom. HAving said that, the window overhead can complicate this as if its too near to the line of the trays, it can make it so difficult to get the trays right.

What level of engineering supervision did you pay for?

At this stage, the solution would be to take out 2 blocks at a time at the location of trays and retro fit them..... difficult job or the other option is to completely water proof the area over the sunroom roof with a permanent seal such as bituthene membrane. This would involve removing plaster from that area, applying this tar type material, affixing a plastic mesh to this and then replaster the area.
A sealing paint is only a temporary solution but can be useful to see that it does cure the problem.
These are the type of problems that can be avoided with a good project manager on site because you will now have one trade blaming the other or if you had a builder, he will blame the drawings.

PeteHeat wrote: »

Hi,

The type of construction you describe was in use long before cavity trays or building regs, while the cavity trays may have prevented the problem not everyone used them properly especially on rendered finishes as very few left out drain / weep holes at high levels.

First you need to find the source of the leak, possibly around the window frame or even tracking back under the window cill, another source could be a leak in the roof possibly at the ridge.

The problem with this type of leak is the source may not be obvious however you might be able to narrow the search by establishing which side of the cavity it is running down.

Assuming it is on the outer leaf double check the joint of the plaster to the window frame you could try using a hose however it is very hard to simulate wind driven rain.

I would think the most likely source is around the window, if a silicone sealer is being used make sure it is a good quality not just standard builders grade and ensure the top of the frame receives as much attention as the sides.

.

Thanks guys i will do some investigation and come back, i just want this thing sorted with the least amount of hassle. There are no weep holes in the gable wall so either no tray or nowhere for water from tray to go. I'll be back after some investigations.