How to vent a sub floor - advice please

[Sherlock121]

Looking for some advice please, be gentle this is my first post

I am in the process of renovating a 1902 terraced house

In my infinite wisdom i decided to have the window in the second reception room removed and replaced with some nice UPVC french doors that was the easy part. However under the window was the air brick for ventilating the sub floor, with the window gone there is no ventilation. Due to some doggy building work in the past i have had all the floors up in this room and in reception 1 there are 2 gaps in the dividing wall which allow air to travel back and forward and room 1 has 2 outside vents

My question is this sufficient to ventilate room 2? i would add an air brick to room 2 but there isn't room to do so, on the outside (see photo - excuse the mess) it appears there is plenty of room to the right however what you can't see on the inside is this is actually a slab of concrete in that corner, plus the wall is about 2ft thick the only other source of air i can think of is the old chimney could i use that to get air to the sub floor, its bricked up with just a vent in at the moment

any advice would be welcome

 

[JohnD]

when you dig out that broken drain, you can take up the paving and reduce the ground level against the house walls. This should allow you room to improve the ventilation. You can use a periscope vent if necessary, it is Z-shaped so it can he higher on the outside.

Try and find the original DPC, and where the ground level used to be when the house was built.

 

[Sherlock121]

thanks for the tip, there is no drain in that corner its part of the old cast iron soil pipe that the builder (who i think is a relative of lord lucan or shergar) left when he put the new one up. but i do agree about lowering the paving at that end as i think its too high. as its about level with the floor inside. the only related issue to that, is just out of shot of that picture is an new inspection chamber building inspector told me to have installed, the builder did so but left it about 1 - 2" above the paving slabs so i think i need to build a step to lower the end by the french doors but to add height to the rest of the paving to get it level with the inspection chamber.

 

[Mr Chibs]

Can't see the inspection chamber, if it's new, I presume it might be circular black plastic, if so it might have a riser on it already, this could be removed and chopped down to meet the ground level.

If you can't pull up the other end near your french door to reduce the level (which would be best) perhaps you can cut a 150mm trench around the wall and fill with large pebbles, this would be effect against damp bridging your DPC. I did the same a year or two ago.

 

[^woody^]

How was that airbrick at that height, ventilating the floor void?

 

[Sherlock121]

there was a cavity in the bit under the window (dont know if there was a door there originally) which lead to 2 outlets under the floor or gaps in the bricks to be more precise

 

[^woody^]

I'd be inclined to take up the paving and install an airbrick (150 x 225mm) below the cill and then install (and adapt) an ACCO drain channel at paving level which will allow the air in to the airbrick and still give a surface to walk on.

 

[Sherlock121]

thanks will give it a go

 

[Nige F]

the only other source of air i can think of is the old chimney could i use that to get air to the sub floor, its bricked up with just a vent in at the moment

any advice would be welcome

You could get air from the sub floor out via a chimney. I have done it in my house.

 

[^woody^]

You could get air from the sub floor out via a chimney. I have done it in my house.

Yes, but that won't give crossflow ventilation across the void or in the corners.

I'll be on standby with a 25 litre tub of boron if ever the floor feels a bit bouncy.