Damp under suspended floor - and where's the airbrick?!

[Jonesy127]

I have been under the timber suspended ground floor of our 60s detached house, insulating the floor from underneath (via a crawl space) using Knauf Ekoroll.

Whilst down there, I noticed the ground was slightly damp around where the soil pipe from the upstairs bathroom goes from the ground floor through to the outside (see first photo).

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• Jonesy127
• 28 Nov 2014
• 1

The damp is only in that corner. I cannot feel or see any damp on the pipe itself. So my first thought is inadequate airflow has meant a build up of condensation (it was surprisingly warm down in the space, and of course the pipe is going to be comparably cold).

So I thought: check the airbricks. There are 2 outside; one on the front of the house, one on the side. From the crawl space (in the dark!) it’s clear the side airbrick was completely clear, but I couldn’t see any daylight through the one on the front of the house.

Here's the side one:

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• Jonesy127
• 28 Nov 2014
• 1

So I checked outside, and it’s now I start to feel a bit foolish. The reason I couldn’t even get a bent wire coathanger through this ‘blocked’ airbrick: it’s bricked up!

Er, here's the front one!:

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• Jonesy127
• 28 Nov 2014
• 1

What is confusing for me is that, from the inside of the house (in the crawl space) it looks like it’s always been bricked up, as if it was never actually a functioning airbrick. The bricks and mortar where this airbrick would be look the same age as the rest to me (see picture 2. Note: the pipe in this photo is a different soil pipe from the downstairs cloakroom). I can’t believe a builder or previous owner would decide to brick up the airbrick, and be really careful to match old with new??

So my questions are:

Is a build up of condensation a likely cause for a slightly damp ground below a house?

Is it common for a house to have an airbrick on the outside, that was never actually installed, as it were?

 

[Nige F]

Is a build up of condensation a likely cause for a slightly damp ground below a house?

Is it common for a house to have an airbrick on the outside, that was never actually installed, as it were?

In a 60`s house anything is possible . Your underfloor looks like mine - rubbish everywhere - is that a piece of rotting wood in photo 1 ? If the soil pipes are the same ( salt glazed drain pipes) then it`s likely the damp patch is coming from a cracked pipe

 

[ree]

As above,

so remove all lengths and off-cuts of timber from the oversite - they will attract fungii.

Clear away all the debris from the damp oversite area and rub down the sand and cement (?) joint in the salt glaze pipe hub with clean tissues. Give it a few days & go back and examine the area for damp.

Damp might be penetrating where the soil pipe pierces the foundation - is that greenish stuff surrounding the pipe polystyrene?

I dont think condensation is an issue, so perhaps, leave the venting as it is - its survived 50 years so far.

 

[Guitar_man]

Looks like a water leak to me. I would open up the airbrick, it was clearly in the design, perhaps it was a friday and the brickie had been to the pub for lunch?