Buried air vent?

[Cynan]

After doing some gardening over this weekend we made a discovery under 5” of soil below our front dining room window.

I’m thinking this is an air vent, though seems unusual being in the ground as water would run in so perhaps it’s an old drain?

Either way the front suspended floor is rotten and no other vents in sight. All other walls are surrounded by concreate floors courtesy of the previous owners. Sigh.

 

[MikeG]

Have you dug along the rest of that wall down to the same depth?

 

[Cynan]

Hi,

We have dug the same depth all along th front of the dining room -approx 2.8m, same depth as the photo. After the dining room it’s stone flags across the entrance and the living room wall (which I believe was once the kitchen as there is a big open fireplace with signs that an old stove was once there.

 

[88v8]

So the external level is above where the vents would need to be?

See this
https://www.castironairbricks.co.uk/product/cellar-soil-waste-vent/
it attaches to the wall and is piped down underground with 4" iron pipe - straight, bend, straight - that goes through the wall and creates a vent.
Bit of a hassle to retrofit, and of course you'll need a good few of them on all sides of the house to ventilate thoroughly but that's how to vent your underfloor.

Ivor

 

[Cynan]

Yeah the external floor is the same height as the internal floor. One side of the room leads to next door, the other to an internal stairwell, and then the concrete floored living room. The rear kitchen has been concreted too with stone flags placed on top.

The living room used to be a suspended timber floor, but that’s been concreted, the walls seem to have been injection DPMd along with concrete render. The kitchen at the back seems to be the same. All by the previous owners in the recommendation of a damp company.

As I see it there is now no longer any way to provide sufficient air flow to the dining room sub floor and given its rotting (a screwdriver goes through some of the joists ends and the floor is quite bouncy in places)... so without ripping up all the floors, taking down all the plaster, and turning the house into a building site (wife says no!) I’m a bit stuck!

I need to get the floor up I think and investigate how damp it gets damp there.

 

[88v8]

Yeah the external floor is the same height as the internal floor. One side of the room leads to next door, the other to an internal stairwell, and then the concrete floored living room. The rear kitchen has been concreted too with stone flags placed on top.

The living room used to be a suspended timber floor, but that’s been concreted, the walls seem to have been injection DPMd along with concrete render. The kitchen at the back seems to be the same. All by the previous owners in the recommendation of a damp company.

As I see it there is now no longer any way to provide sufficient air flow to the dining room sub floor and given its rotting (a screwdriver goes through some of the joists ends and the floor is quite bouncy in places)... so without ripping up all the floors, taking down all the plaster, and turning the house into a building site (wife says no!) I’m a bit stuck!

Oh dear. And that looks like cement pointing on the outside wall. Still, fixing all that will keep you out of mischief!

Ivor

 

[Kearn]

The living room used to be a suspended timber floor, but that’s been concreted, the walls seem to have been injection DPMd along with concrete render. The kitchen at the back seems to be the same. All by the previous owners in the recommendation of a damp company.

As I see it there is now no longer any way to provide sufficient air flow to the dining room sub floor and given its rotting (a screwdriver goes through some of the joists ends and the floor is quite bouncy in places)... so without ripping up all the floors, taking down all the plaster, and turning the house into a building site (wife says no!) I’m a bit stuck!

Sounds like you've identified most of your culprits - concrete floors, concrete/gypsum render, cement pointing, incorrect levels, no airflow, impermeability. And also the solution - rip off all of the foreign materials, and let the place breath for a year or so to dry out. Then replace with correct materials to keep the place standing for a good while longer.

A few quick searches on here and you'll get all the insight you need and more on sorting these things out. Unfortunately, all very common and potentially fatal issues if not reversed...

Good luck!

 

[Abi Cott]

(wife says no!)

Is she happy with the status quo? Is paint peeling off and stuff going black ok?

If she would like a permanent fix the method you've described is the correct option. If she would be satisfied with a reduction in the current issues there are options.

We would all love a dry house just by slapping a coat of specialist goo on the walls, but that isn't the reality. She can have 'damp but slightly less unsightly' she can have 'reasonably dry longterm' but if she wants no work and perfectly dry she needs a different house.

 

[88v8]

..... if she wants no work and perfectly dry she needs a different house.

With some elderly houses that is indeed the reality.

A quote from the details of an NT holiday cottage we've just booked:

'...was built .... long before the days of damp proof courses and cavity walls etc. Without the benefit of these, or inappropriate modern waterproofing techniques, some of which would change its appearance, it is impossible to avoid flaking/erupting paint and damp patches on the inside and outside walls.

This is why ventilation is so important in the older house, and the temptation to eliminate all 'draughts' should be resisted!!

Ivor

 

[Cynan]

As usual, thanks everyone. Your thoughts and advice are much appreciated.

After looking round the neighbour and not seeing any air vents on any house, and seeing another thread with a photo of the stone flagged living room, it occurs to me that originally perhaps my floor was flagged throughout and it had been changed to a suspended timber floor at a later date... I think that’s going to be the answer. Restore it to a stone floor on a bed of lime as I’ve been reading on here.