strange patch on wall in utility room

mw96472 · 16 Sep 2013

Hi - in our utility room there has been a strange patch on the wall since we moved in. It hasn't really changed over time and I showed it a builder and he wasn't too concerned about it. Some of the plaster is missing and the wall, especially on the corner where the door to the kitchen is feels crumbly:

utility room

mw96472
16 Sep 2013
1

utility room

mw96472
16 Sep 2013
1

What could it be? Is this damp or some form of rot?

This wall used to be an external wall, i.e. it's a cavity wall. The previous owner added the utility room which has a flat roof.

Any ideas?

Cheers
Michael

rjm2k · 16 Sep 2013

What's on the other side? Are those rusty nails in the skirting underneath it?

mw96472 · 16 Sep 2013

Hi rjm2k - on the other side of the wall where the patch is there is the kitchen. On the other side of the room is the garage.

Here is rough layout if the rooms:

Untitled

mw96472
16 Sep 2013
1

The patch is where the arrow is pointing to. The brown areas are where the flat roof is.

All nails in the skirting boards of the utility room are rusty like the one in the picture and have been like these when we moved it. I can only assume that the room in general must have been very damp at some point and condensation must have been so high that the nails rusted. I know the previous owner had a tumble dryer in the utility room and there is no radiator. So this is the coldest room in the house.

dann09 · 16 Sep 2013

That looks to be rising damp - there's no condensation spotting and the plaster is bubbling and disintegrating.

If you remove the nail rusted skirting and examine the back, you will probably find that its fungal damaged.

The other side of the wall will most likely show similar indications ( unless its been treated or properly rendered).

I notice that there's a step-down from the kitchen - that might be significant.

If you want to be taken thro "what to do next" then come back here with some pics of the utility room and kit wall (if accessible).

mw96472 · 16 Sep 2013

Thanks damn09 - I found a picture when we did up the kitchen in 2007 which shows entrance into the utility room:

kitchen

mw96472
16 Sep 2013
1

The patch in the utility room existed then and hasn't changed since and is on the other side of the wall where I drew the arrow in the picture. There was nothing visible on the kitchen side. The wall is now behind units.

joe-90 · 16 Sep 2013

You've got a leak mate. You won't get rust staining like that from a bit of damp.

dann09 · 16 Sep 2013

Thanks for the pic.

I cant see any indications on the kit side but the pic detail is none too clear.

Perhaps , move any items and appliances away in the utility room and examine the wall and the return (exterior) wall for damp. Post a pic of the cleared area.

Solid floors should have membranes coming up behind the skirting, and walls should have a DPC at near the floor height.

Given that the plaster (& skirting is damaged), then take it off back to brick at the pic damaged area. Then look for a membrane or a DPC.

mw96472 · 16 Sep 2013

I haven't taken the skirting board off but it looks and sounds (when tapping it) solid; I did take the skirting board off from another wall in this room which also had the rusty nails and a similar patch; the skirting was not mouldy at all.

I know there are a lot of pipes in that wall including the mains. If it is a leak then it must be a very small leak as the patch doesn't grow; maybe it's the flat roof that has a leak or maybe the flashing...

I'll take some more pictures tomorrow evening...

mw96472 · 16 Sep 2013

dann09 said:
I cant see any indications on the kit side but the pic detail is none too clear.

Do you mean you can't see any signs of damp or the arrow?

tony1851 · 16 Sep 2013

If the mains pipe is attached to or within the wall, you will get a lot of condensation on it, particularly with it being a utility room.
This might explain the localized dampness.

dann09 · 16 Sep 2013

I didn't see any damp signs.

The above ref the rising main is a sound suggestion.

I dont understand why you haven't taken the skirting off - it will eventually have to come off to make good the, hopefully, render?

mw96472 · 17 Sep 2013

dann09 said:
I dont understand why you haven't taken the skirting off - it will eventually have to come off to make good the, hopefully, render?

I didn't have time last night. BTW, when I said in my previous post that I had taken the skirting board off from a different wall I should have mentioned that I did this many years ago

mw96472 · 17 Sep 2013

I've uploaded some more pictures to show the 2nd patch and its location in relation to the strange patch I reported initially. As I said, both have been there for years and not changed:

utility room

mw96472
17 Sep 2013
1

2nd strange patch

utility room

mw96472
17 Sep 2013
1

both strange patches

BTW, the skirting board under the 2nd patch doesn't show the rust mark anymore as I had cleaned it when I took it off a few years ago.

dann09 · 19 Sep 2013

Your ground floor layout, and the common flat roof to the utilty rooms and garage would suggest, perhaps, that part of the concrete floor might have been the original garage and hard standing floor.

Consequently, it might not have had a membrane.

Notice that the utility room floor is lower than the connecting rooms, perhaps rising damp in the walls is choosing the easiest option?

At some stage you will have to remove skirting & plaster, & render with a remedial mix.
Any rusty corner bead will have to be replaced.

mw96472 · 25 Sep 2013

Thanks dann09 - you might be right. I know that a previous owner extended the utility room by moving the wall separating the utility room and garage to make the garage more narrow and the utility room wider. By doing so they probably needed to lower the floor in the utility room to bring it inline with the garage floor. By doing this they may have removed the DPC which I know in my house has only been painted on - see the blue layer in this image from a different room:

living room

mw96472
15 Sep 2013
2

blue layer and DPC

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strange patch on wall in utility room

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