Small damp corner of carpet

Smithy99

Hello,

I wondered if anyone might have any ideas about the cause of this small damp area of carpet. There's a bit of a hole in the corner and we had slugs coming through last year, although i haven't seen any since i chucked some salt down and didn't find the carpet damp then. We've just moved the bookcase that's usually in front of it and the carpet was definitely damp but it's literally just that one corner bit.

I've also noticed the paint peeling off the central heating pipe there although it's not damp on that area of carpet (just dirty and dusty!).  

FreeBear

Copper pipes going in to concrete ?

Looks like there is a hint of green at the base of one of those pipes - I'd suspect that one of the pipes has corroded under the floor. If the boiler is loosing pressure, that would add weight to the suspicion.

It is going to be an expensive & messy repair I'm afraid.

Jeepers_Creepers

Is it a concrete floor?

As FB asks, does your boiler have a pressure gauge? If so, what's it been sayin'?

It's 50:50 at the moment - yes there's green around the pipes, but that could be from external damp too, I guess?

Smithy99

I noticed that too Freebear, it is a concrete floor yes. I lifted the carpet along the wall, up to and around the pipe, but it gets drier towards the pipe and is definitely damper in the corner. 

The wall the pipes go through is an internal wall (it's the bit that juts in slightly when an extension was added) but the wall to the right where the corner is damp is external.

The boiler doesn't have a pressure gage (or at least not showing on the outside) so how would I tell? 

I have trace and access cover will that cover some of it? How expensive are we talking?  This is the extension side of the house so the pipes this side should be newer.  I'm pretty sure my plumbers about to disown me as we have endless plumbing issues in this house! 

theoretica

If you have a hole that goes through and slugs could get through that implies the hole goes all the way to the outside.  What is on the outside of the hole?  Any reason water couldn't have got through where the slug did?  Tracing that hole would be my first investigation, followed by blocking it to slugs and water.

FreeBear

It may be possible that the builders left a pile of debris in the cavity when adding the extension - If it has bridged the cavity and/or DPC, that could be part of the problem. A fairly easy task to investigate if you have an endoscope or bore camera (you can get cheap USB cameras that are about 8mm diameter from Amazon or ebay). Drill a hole through a mortar joint just above the DPC and poke a camera in to see what is happening. If it is crud in the cavity, a few bricks will need to be removed which shouldn't cost the earth.

As for the boiler, if you tell us the make & model, someone will be able to advise on how to check the pressure (assuming it is a fairly modern one).

Smithy99

We have an endoscope. We also have cavity wall insulation. Will we still be able to see? 

I think it's a Potterton Suprima HE. Unvented system if that makes any difference. I just googled the manual but still none the wiser to where the pressure gage actually is in my house 🙈

Smithy99

Actually I'm not sure there's cavity wall insulation in the extension, One company said the extension was unsuitable for some reason so refused to do any of the house because they said you had to do a certain % of the house to qualify for the free grant but then British Gas agreed to do it and incan't remember what happened re the extension bit.

FreeBear

Smithy99 said: We have an endoscope. We also have cavity wall insulation. Will we still be able to see?

Only one way to find out...

While you are out there, make sure you don't have any leaking gutters or downpipes in that area and the ground level is well below the DPC.

Smithy99

This is the outside. In the first pic you can just about see where the extension joins. The pipe to the right is a saniflo discharge pipe. It sits next the older part of the house and is about a metre away from the extension damp we've found. The pipe discharges into a drain under the paving. 

The 2nd pic is to the right of the discharge pipe. One part of older part of the house has a lot of moss, i posted about it before but was told it was okay because its under the dpc?

We had a drain survey done when we bought the house but it came back clear.

Had a look at the french drain this morning and it seems to be a layer of gravel with earth under. Is it supposed to be all gravel?

Smithy99

Sorry the pics have reversed. The first is the older section of house, the second is the extension