Damp Area - Downstairs Toilet

[Georgie73]

Hi

We have a new home and noticed the downstairs toilet - external wall felt damp to the touch. I put a small dehumidifier crystal box (supermarket thingy!) on the window ledge. Over a couple of weeks it was full of water.

There isn't a radiator on this wall but I am planning on having one fitted.

We have hacked off all the plaster back to the bare brick. I've taken some pictures of the outside wall - I think the white is salt?

Can anyone recommend a solution?

I was thinking of using a tanking slurry then replaster and add a radiator to the external wall.

 

[vinn]

You have a solid floor but an airbrick can be seen which suggests that the floor was previously suspended - unless the air brick is ventilating a next room floor?
My point is: do you have/can you see a membrane at the edge of the solid floor?
Is your wall a cavity wall?
Can you do a more detailed photo of your external window cill? It looks odd.
Could you also do a photo of the larger elevation?

Dont use a tanking slurry or gypsum plaster - a 3:1 sand & NH lime mix of render is needed - stopping 40mm short of the floor.
Plastic angle beads are also required, not metal.

 

[Georgie73]

I will take more pics and post them.

The air brick is on the outside of the toilet - not the next room. I can see the membrane - it is about 1 inch above the concrete floor. I believe it is a cavity wall as the front and sides of the house have had cavity wall insulation as I can see the filled in holes.

On closer inspection, I can see that the back of the house including the downstairs toilet has been cavity insulated. The holes are about 6 courses above the airbrick.

Will post pics shortly.

 

[vinn]

Why not remove a few bricks from the inside wall and check the cavity for blockages or sodden insulation (the render might be covering insulation injection holes)?
Counting brick courses, your DPC seems to be pretty low on the inside skin. Can you ID it on both skins?

 

[Georgie73]

Yes - I can see the DPM internally and externally. Externally it is sitting on top of the airbrick. I can see the membrane further along the wall.

 

[chris1982]

Below that (overflow?) pipe, where the bricks are discoloured, does that correspond to the damp patch inside?

 

[Georgie73]

The damp patch is immediately beneath the window. The area that is discoloured is towards the rear of the downstairs loo - parallel to the cistern.

 

[chris1982]

Hm, to me those bricks look like they have suffered from some water, leaving behind some salt.

I am sure you checked whether the toilet is leaking, but now that you mentioned the cistern, I am wondering where the water goes that probably condenses on the cold cistern; does that drip onto the wall? (the condensed water itself obviously would not carry any salts)

 

[vinn]

Thanks for the photos - but if you add information please dont back edit - put the new info in a new box.
Presumably you have a WC in place in the compartment? Can you photo that back wall with the WC?
As above, you should knock out a few bricks to examine in the cavity - but be cautious after the first brick that bead insulation doesn't come tumbling out.

You could pour a little water on the cill and tile creasing and watch how it runs off - hopefully without pooling or backtracking on to the brickwork.

Some of the pointing is excellent and some looks to be rough.

Modern fill & flush valves dont require an overflow pipe - it can be eliminated.

 

[Georgie73]

Yes, I will take a photo of the toilet. We have taken out the old one and in process of having a new one installed.

I have a horrible feeling this house should never have been cavity insulated. It is in Devon at the top of a hill and at times the wind really batters the house.

We have come across several areas on the ground floor which are damp around the skirting boards and made them rot.

 

[Georgie73]

Hm, to me those bricks look like they have suffered from some water, leaving behind some salt.

I am sure you checked whether the toilet is leaking, but now that you mentioned the cistern, I am wondering where the water goes that probably condenses on the cold cistern; does that drip onto the wall? (the condensed water itself obviously would not carry any salts)

I wonder if there is salt in the air as we are near the estuary.

 

[Georgie73]

 

[vinn]

Hopefully, the new WC isn't a Back to Wall type - why? because you need the least amount of boxing-in possible in that damp compartment.
What is the reddish tint in the photo's - red Devon clay/soil effect?
The floor seems dry .
There's no obvious changes in the exposed brickwork.

Penetrating damp seems to be the no 1. suspect - bridging the cavity through the insulation. Followed by condensation (it can piggy back on the penetrating damp).
But remove some bricks and confirm or whatever?

Plan on installing an extractor - elec forum will help with up to the minute details.
Dont plan on tiling the outside walls.

 

[Georgie73]

I guess it is back to the wall. It's in a housing unit. I'm hoping to remedy the damp.

The floor is bone dry. The walls seem to be dry now too (since hacking off plaster!). The red is coming from the bricks and the mortar. I am new to the area so I'm not familiar with red Devon clay.

I can't seem to find a 'thank you' button on here. Thank you for your input it is appreciated.