Bay damp at floor level - possible causes?

[dormermike]

Hi

Just wondering what to make of the following please - the skirtings in the front two bays of my bungalow are rotten, the house is circa 1930's.

This dirt has been removed from behind the skirtings, and even though it hasn't rained for a few days (maybe a bit but nothing heavy) this material is damp to touch and smells damp too.

The big grey bits are concrete that was put in to block the gap up between the parquet floor and the bottom of the skirting, where the floor slab has settled away from the wall (Surveyor said this is longstanding).

The parquet is mounted to the floor on bitumen, and the DPC (bituminastic) is approx 2.5 inches above the concrete floor or at approximately the height of the top of the parquet bricks.

Pointing on the outside of the bays has been done about 6 weeks ago. The ground level (block) is 6" beneath the exterior DPC.

I'm clearing out the dirt to let it breath and dry up, before moving forwards and replacing the skirtings.

In the meantime i just wondered if anyone had any thougthts on what could cause this.

Thanks
Mike

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• dormermike
• 14 Apr 2011
• 1

Untitled

• dormermike
• 14 Apr 2011
• 1

 

[dormermike]

i'm thinking/hoping that the compacted dirt material has been wicking / absorbing moisture from the exposed face of the brick which is below DPC, and as there is no ventilation, this is rotting the skirting and does not evaporate away.

Does this sound plausible?

 

[HERTS P&D]

Post a picture of the outside of your property.
one major cause is faulty guttering/down pipes and the soil on the exterior wall being too high.

Andy

 

[Nige F]

very plausible , the dirt being the remains of the original cork expansion joint round the edge of the parquet some form of damp treatment needs applying before skirtings go back- strange the DPC is too high , usually a good decade for housebuilding- anyways there will be other replies from more experienced guys

 

[dormermike]

Post a picture of the outside of your property.
one major cause is faulty guttering/down pipes and the soil on the exterior wall being too high.

Andy

Here you go - this is the outside of the corner pic shown above. The bay wall is a cavity wall btw.

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• dormermike
• 15 Apr 2011
• 1

You can't really see it in this exterior shot, but the bituminastic DPC was either the top level of the vent or the bottom level - I think it was the bottom level. When the repointing was done, they removed part of that DPC so you cant see it now.

BTW I was told these exterior bricks are of the engineering variety and so shouldn't be absorbing moisture..

 

[dormermike]

very plausible , the dirt being the remains of the original cork expansion joint round the edge of the parquet some form of damp treatment needs applying before skirtings go back- strange the DPC is too high , usually a good decade for housebuilding- anyways there will be other replies from more experienced guys

Yeah the interior wall DPC is higher than the floor level. This house had extensive renovations back in 1994, and a damp company was brough in to inject chemical course at that point (in these two original front rooms only). I have since had a damp company out, and they said there is nothing that can be done - presumably because the injection has already been done.

Just to be clear, there is no damp above the DPC, so the DPC is working..

The "damp expert" chap said the floor just needs ventilation along the lower edge behind the skirting, and was essentially behaving as expected.

I must admit at this point, this is the second of two bays, and I cleared out the first bay several months ago and it is a lot better - however this bay is much, much damper in the material that came out.

Also I hadn't considered that this could be cork remnants, makes senses and I did wonder what it was... however it wont be original (as in 1930s) as when the renovations were done, the two front bay parquet floors were not touched, but the roof and other interior walls were removed - the floor and two front bays were essentially all that was standing for several months (so i've been told). The material feels more like damp earth than cork though.

So, the damp problem has been very longstanding in these two bays. I guess it could be elevated ground level outside, though I suspect the cavity is also full of crud - unsure how to inspect that.

 

[dormermike]

Any ideas please? Its been scorching here for a few days and the concrete floor is drying out, but only in places...

 

[wavetrain]

Yes, take the skirtings off and lift anything away that is damp until you uncover the root cause of the damp.

I assume you have a sold flloor that the parquet is stuck to? The tanking/dpm must be continuous and lap upto the DPC.

 

[dormermike]

Yes, take the skirtings off and lift anything away that is damp until you uncover the root cause of the damp.

I assume you have a sold flloor that the parquet is stuck to? The tanking/dpm must be continuous and lap upto the DPC.

Thank you

The parquet floor is stuck to the concrete (or cement?) floor with bitumen, which i've been told is effectively the DPM. This does not meet the DPC which is slightly (2inch ish) above the level of the concrete floor.

What you say makes sense, in that the DPM should meet the DPC.

But it doesn't... so effectively, what i'm seeing is expected, really? I need therefore to apply some sort of DPM and bring it up to the DPC.

 

[wavetrain]

If a brush-on bitumen compund will stick, and stay stuck to the wall between floor DPM and DPC, then your problem should, in theory, hopefully be solved.

 

[foxhole]

Do the windows have a lot on condensation.?What level is the vent internally?

 

[Nige F]

as said above - also you have a tall skirting to work with ( but some untidy pipes ) so consider cutting back plster behind skirting then apply Synthapruf to bricks - then get some plastic trim/ sheet. etc. as packing - and stainless steel screws - then pack the back of the skirting away from the treated wall/floor ( after having painted it on back and cut joints ) stick it with a gripfill type glue to the plastic packing - then fill the small gap @ the top with painters acrylic . Lot of messing about - but it is DIY and your time is free and you`re keeping the skirting away from the potentially damp area

 

[dormermike]

Do the windows have a lot on condensation.?What level is the vent internally?

No condensation internally no - the bathroom is next to this room, and the bays are the only cavity walls in the property that are not insulated - I did consider that the moisture at the bottom of the wall could be condensation but the amount of crud impacted behind skirtings would act as an insulator and moisture, if any, would condense elsewhere (window).

We are also very careful to keep the moisture in the bathroom and the extractor is always on when someone in there, and window open etc. Plus there are two doors seperating the bathrooom from front bay room.

Interesting that you ask about the vent - the external vents do not extend internally.. AFAIK they are cavity vents.

 

[dormermike]

Do the windows have a lot on condensation.?What level is the vent internally?

So should the vents extend internally?

 

[dormermike]

Nobody know if vents should always extend internally or if such a thing as cavity only vents exist?