Can anyone help me with this damp problem? (Photos Attached)

[brooky_agb]

Hi Folks,

We have a solid brick house (1849) which has some minor damp problems. Please see attached photos of the inside and outside of the wall where damp is. Can anyone tell me what kind of damp it is and what we might be able to do to fix it? The patch on the outside of the wall is where some blown plaster was repaired.

Inside: http://imgur.com/Z4R60.jpg
Outside: http://imgur.com/NcvEp.jpg

 

[joe-90]

I bet it's the flippin' dog.


It could be rubble in the cavity.

 

[brooky_agb]

More likely me after a few beers as we don't have a dog. There's the solution... cut down on the beers...

There is no cavity. Solid victorian brick (it was an old school). Anyone have any other ideas?

 

[NickB_99]

There is no cavity. Solid victorian brick (it was an old school). Anyone have any other ideas?

Any pipework chased into the plaster and covered ? e.g. radiator.
Clutching at straws a bit

 

[brooky_agb]

None around that area. Thanks for the ideas.

Some of the outside plaster is blown. The morons we hired to fix it just did the worst patches and didn't redo the whole lot.

 

[Richard C]

It’ll be render on the outside not plaster. Are you sure it’s actually damp & not something else leaching out of the bricks? Was it re-plastered on the inside? what type of base/finishing plaster was used? Was any type of damp membrane or water proofer used in the mix? Was the outside render stripped back & repaired & then the inside stripped back & left “open” (for some weeks) to allow moisture trapped within the brickwork to escape? If you’ve other “blown” areas of render on the outside they could act as water reservoirs feeding the damp patch, in which case you’ll never get rid of it until you stop water permeating through.

 

[JohnD]

look for a dripping gutter or pipe above.

What is the thickness of the wall?

 

[brooky_agb]

Thanks for the helpful info. The wall is about a foot thick roughly.

I don't think the gutter is dripping down but I'll have another look when it rains next.

 

[RedHerring2]

The pointing on that highest visible course of bricks is not good. Where's the dpc in relation to that course?

 

[brooky_agb]

You are right the pointing is not great in places. We had a damp company come to look some time ago and they seem to think it has had DPC's three times already. I didn't want to spend money doing something again that probably hasn't worked great.

I think the DPC is under the top angled brick ... I'll check..

 

[brooky_agb]

There seems to be tarmac butted up to the brick. Do you think it would help to dig some of that away? Saying that the damp on the inside is higher than the tarmac. The floor inside is about the same height as outside.

 

[brooky_agb]

What do you think we should do? Dig away the ground at the base of the wall to see if that helps? If not re-render? And if that doesn't work dry line/plastic cover the inside of the wall?

 

[JohnD]

lowering the ground so it is at least 250mm below the DPC will help reduce wall dampness generally. If you dig out the soil against the wall and fill it with pebbles (look up french drain) this will reduce water getting to it. Allow it to dry out by ventilating the subfloor or cellar.

However you appear to have a localised wet patch. If you can't find a cause, I would be inclined to hack off the plaster and render and see what you can find. I would doubt hydroscopic salts, but it might be. Or there could be a piece of iron or even an old pipe. Looking under the floor may give some clues.

you can test to see if it is condensation by taping a piece of clear plastic tightly to the wall.

how thick is the wall? Thick victorian walls sometimes have a gap that water can drip down, or bridge on a snot of mortar. Or there might be a crack that water is tracking down.

 

[brooky_agb]

Thanks John, really helpful. There could be a bad tile above the wall as its about a foor thick. I'll get up and have a look. There was indeed an old boiler near there once so I'll look into the possibility too and try the condensation idea. Wonderful thanks.

 

[RedHerring2]

I think the DPC is under the top angled brick ... I'll check..

That could be one possible cause then. The poor pointing is allowing water into the wall at that point and spreading.

There seems to be tarmac butted up to the brick. Do you think it would help to dig some of that away? Saying that the damp on the inside is higher than the tarmac. The floor inside is about the same height as outside.

As John has mentioned this could be another culprit.
Normall the dpc could be between 50mm to 200mm below internal ffl, depending on type of floor, and then you want external ground level at least 150mm below dpc.