How do i fix this damp issue in my under stairs pantry?

[G J]

Good morning everyone,

My house is a semi detached house and the pantry is joining the neighbours house.

I decided to decorate my pantry (last thing left to do in my house, it's under my stairs in the front of my house, when I went to clear it out (only been living here 6 months) everything I put in the pantry had a layer of mould on and when I looked deeper, there was damp plaster in the corner. There is no ventilation and a gutter in front of the wall as can be seen in the picture. So I removed all the damp plaster in the corner and added an air brick. From my research I need to tank the wall below the dpc level (which is a layer of slates) and tank the floor, but would I need to actually tank the entire level including my neighbours wall? And would I need to tank with something like KA slurry then sand and cement ontop and then skim the room? Under the old vinyl on the floor are old red tiles but these where very wet so I've let them dry and my plan is to use the KA tanking slurry on them and then use self leveling compound ontop?

 

[JohnD]

What makes you think you need to tank?

Where is the water coming from?

Is there a plumbing leak, from a drain? Or a pipe under the floor? Or a bathroom or kitchen?

Is there rainwater from a gutter or downpipe, or defective render?

Since there is a gulley and downpipes next to the damp, examine these first for blockages and leaks. If you have a clay gulley built before 1945 it is almost certain to be broken and leaking. There are signs that earlier attempts have been made to block or hide a leak or overspill.

Dig away the soil from the wall and photograph the DPC.

BTW, in your third pic, I think I can see where the original airbrick was blocked up.

 

[G J]

From what I can see it's either damp because there was no ventilation prior, or because of the neighbours porch drain infront of the wall( can see in drain in the bottom left of pocture) or the water level because of soil

 

[JohnD]

It's the gulley and downpipes.

 

[G J]

So if I clear this gutter/ dig out the soil, and it fixes the leak, do I just sand and cement the wall and plaster ontop or should I paint the outside wall with something like stormdry cream to stop ingress of water from the outside? Also if the gutter itself is broken shall I just point it/ build a new concrete frame inside

 

[JohnD]

You probably have a broken gulley. Dig round to expose it. A garden trowel will do. Look for blockages as well.

If the ground is wet and sunken, and if the gulley has tilted and sunk, or has been patched up with slates, tiles and concrete in previous futile attempts to hide or repair it, it is broken. This is normal. You may find red worms in the ground.

If you are very lucky it will just be blocked. It is much more likely to be broken.

You cannot repair it. You remove the broken one and fit new.

If you are handy and energetic, it is not a complicated or difficult job to fit a new one. It will become clearer when you start digging.

A new plastic gulley and trap are quite light and easy to handle.

You do not need chemical damp treatments or tanking or slates.

You may need to chip off the render near the ground once you have found the DPC

you may need to repoint the brickwork with mortar if it has been eroded by 50 years of leaking water.

It will become clearer once you start digging.

 

[JohnD]

Some examples

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www.drainageshop.co.uk

 

[G J]

Brilliant, thank you so much!