Can I block up this Victorian basement coal chute?

[Peterd1987]

Long story/awkward explanation, sorry.

We have a converted/tanked basement in a Victorian property that sits below our living room connected by a pretty open staircase. It looks like it has two skins of brick wall which helps with the damp/waterproofing. The living room has a larger footprint as the ground floor is a single brick wall.

Unfortunately it has an old coal chute (see pics) which is not tanked from beyond the inner wall and is a single skin of brick in contact with the ground outside. There's a modern window on top. It also has a 100mm duct/vent which I think is helpful for some fresh air. I've tried extractor fans here but that actually seemed less effective than leaving it open to let fresh air in as it's an awkward cold/damp space. The living room floor above extends to the outer wall and there's a wooden board over the roof of the chute separating the floor from the basement.

Originally it was rendered with the same stuff as the exterior of our house, but it was a bit damp (not terrible) and then developed a bit of a leak, so we tried to get someone in to tank it properly. Unfortunately they turned out to be cowboys that did a low quality job with cement and waterproofing additive who disappeared (fortunately without payment). It's an awkward space and basement companies around us only seem to be interested in full conversions or if I let them retank an entire wall plus this for thousands.

It's more damp and leaking again and I'm trying to find someone else to tank it.

But I also wondered if I could strip off all the outer wall in the chute, repair/repoint it, then brick the chute up at the external wall of my house and tank this new single skin somehow to prevent damp and stick an extractor fan in this wall instead? The fan would blow into the 20cm void and find its way out the 100mm duct higher up. I'd also unseal the window above so it's more of a cover and ?render the inside of the hole.

Is that a terrible idea? Would the new wall just get damp? Would the hole outside my house be a weird void? Should I duct the fan up to the 100mm vent rather than just let it blow into the 20cm space and find its way out (then install another airbrick for the void)? I'm wary of creating new problems but considering it because tanking the space seems to be really awkward and it'll always be a bit of a cold/damp space. The window lets in a bit of light, we'd lose, but I'm pretty sick of this random hole and it's issues.

Maybe I'm overthinking it. I'd love to find someone reliable and experienced to sort it. Open to any suggestions. Thanks for your help.

 

[blup]

The basement wall can’t breathe in the way an above ground wall does, so the damp has to be tanked out. Chop out the plaster on the chute where in contact with the earth and apply multiple coats of bitumen paint/slurry. Review how effective that is in due course. Ventilation helps but wont remove the source of the damp.

Blup

 

[Peterd1987]

The basement wall can’t breathe in the way an above ground wall does, so the damp has to be tanked out. Chop out the plaster on the chute where in contact with the earth and apply multiple coats of bitumen paint/slurry. Review how effective that is in due course. Ventilation helps but wont remove the source of the damp.

Blup

Thanks. I think I've been put off by the first attempt at getting it tanked but probably just need to find a decent tradesman to give it a go. It's an awkward space but maybe if they took the window above off temporarily that could make it easier. I guess they would need to tank all the way up to the top of the chute?

If I were to close it up with a brick wall (with a vent) I guess it'd be the same principle?

 

[blup]

Yes and yes.

Blup