Advise on damp problem

gsxr1

I have been called back to a clients house. They are having a really bad condensation problem. This has been ongoing but due to the conditions has got out of control.
this is a small 2 bed apartment under a duplex .

The main issue is the french doors in the back bedroom . Under the patio of duplex above.

Water seems to be leeching from concrete around the doors . 12" beyond is affected.
I have lifted the filling from outside and used 12" DPC as a barrier from back fill/ground to the outer leaf. It has had no affect.

drainage from patio above seems to be fine.

I believe it to be a cold bridging problem. But I am welcome to your ideas on it. It is very very wet. I have worked on all the apartments in the street and this is twice as bad as the rest.

Should there be kingspan under the door where it was backed up with sand/cement?
There is some water dripping from french door but the most seems to becoming from under.

This is starting to get the better of me and constant arguments with the owners are testing.

there is 3 adults and one baby living there with the cloths drying on rads.
It is like a sauna . I tried to explain condensation and cold walls but it seems to be falling on death ears.

delly

moved from DIY at OP's request

DublinWriter

I'm no expert, but a lot of recently built apartment blocks were built on re-designated flood planes. Have you any information regarding the topography of the original site?

gsxr1

DublinWriter wrote: »

I'm no expert, but a lot of recently built apartment blocks were built on re-designated flood planes. Have you any information regarding the topography of the original site?

its across the road from the waterways in sallins. But the the our site was unaffected by the floods. I dont think its ground water as we built them a good few feet above the original ground level, which was always dry

Poor Uncle Tom

Getting rid of condensation is a balancing act of management of heating and ventilation. I know that you know that, so I wont go any further there.

Something to consider. The cavity in every build (where one exists) will always have a low point and a door threshold will always fill/block the cavity which could lead to a 'pond' on on side of the blockage within the cavity only to soak into the surrounding blockwork.

gsxr1

Poor Uncle Tom wrote: »

Getting rid of condensation is a balancing act of management of heating and ventilation. I know that you know that, so I wont go any further there.

Something to consider. The cavity in every build (where one exists) will always have a low point and a door threshold will always fill/block the cavity which could lead to a 'pond' on on side of the blockage within the cavity only to soak into the surrounding blockwork.

Yes. thats what I was thinking. I think the cavity is flooded. I repaired a juction above the gully . With out explaining the whole gully system I will just say that the water from above was pouring into the cavity . But was fixed 6 weeks ago.

Could it still be wet down there.? how does one dry out a cavity .

Poor Uncle Tom

gsxr1 wrote: »

Could it still be wet down there.? how does one dry out a cavity .

Yes it more than likely is still very wet there, believe it or not it takes a full season cycle to dry out a cavity, so the end of next summer.

But, if you have fixed the problem then the symptoms will fade away until then. Provided it's fixed properly the problem shouldn't return again.

gsxr1

Im going to dig out the concrete around the inside of the door this week.

Such a mess but i need to know there is a DPM there .
I suspect a barrow full of concrete was just tipped in around the door with no membrane or insulation installed. It will give me an idea of the source of the moisture.

Kango hammers and consaws. Perfect environment for a family:(

gsxr1

Right. Here is a rough Photoshop alteration of a cross section pic I found.

It is near the exact same construction of the offending wall in the apartment.

Except the external surfaces have Monocouche plaster on them. And the outer leaf is a solid on edge and not facing brick

the foundation is missing. Just imagine it.

There is no ventilation at all in the cavity . It is sealed at the top in the duplex upstairs with the capping .

I added a 4" vent on the pic to show you my thoughts on creating a draft that may help keep the cavity below dry.

What do yas think. Bad idea?

The Helpful Engineer

If its as wet as you say it is its unlikely to be condensation. I'd say its a leak in the waterproofing, but its hard to say without seeing it. I have experienced this problem before in that type of construction. In that case there was a hole in the water proofing membrane protecting the concrete, it was complicated by a slow draining outlet.

You could have that problem as well as the water could be getting in through a leak remote from the French doors and flowing along between the underside of the membrane and the top of the concrete to a weak point in the concrete close to the doors.

What about the coping, was the DPC installed under the coping stone. If it wasn't or it was installed poorly that is a route for rainwater to bypass the waterproofing and enter the property. That might flood the cavity as well.


Eitherway, I don't like a patio over a separate dwelling, with our climate its asking for trouble in my opinion.

gsxr1

The Helpful Engineer wrote: »

If its as wet as you say it is its unlikely to be condensation. I'd say its a leak in the waterproofing, but its hard to say without seeing it. I have experienced this problem before in that type of construction. In that case there was a hole in the water proofing membrane protecting the concrete, it was complicated by a slow draining outlet.

You could have that problem as well as the water could be getting in through a leak remote from the French doors and flowing along between the underside of the membrane and the top of the concrete to a weak point in the concrete close to the doors.

What about the coping, was the DPC installed under the coping stone. If it wasn't or it was installed poorly that is a route for rainwater to bypass the waterproofing and enter the property. That might flood the cavity as well.


Eitherway, I don't like a patio over a separate dwelling, with our climate its asking for trouble in my opinion.

Thanks.
Its a terrible design TBH.
The thing is. Because everything is wet above and wet everywhere, im finding it next to impossible to locate the source . Its very frustrating for all concerned. Upstairs was torched when I believe it should have been tanked with fiberglass. There has been other areas on other buildings where the fools for block layers(cheapest) did not install any DPC under the capping.
Compounded by the distrust I have with the laborer who filled under the new doors with concrete . I know him and also know he has no idea about the importance of an intact membrane.

Its a big mess that I have to fix with minimal cost.