underground ventilation

26 Feb 2022
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United Kingdom
Hi all
I have terrible damp and fungus growth under the wood floor on the ground floor of our typical victorian terraced house. We had a new patio door put in and this has removed the air bricks. Only now do we realise the error of this. So before I go about replacing all the joists and boards, I am about to put in a vent but there is no place for an air brick at the back of the house. Kitchen floor is solid concrete and then there is the patio doors so that covers the whole width of the house. So I am going to put in a waste pipe with a vent near the patio doors, so they still open ok. The outside level is higher than the floor level inside, so I will go down a couple of feet, then try to go in through the wall/foundations. Is there any advice as I can't find much out there. Will one pipe be sufficient? I will be using 110mm soil pipe.
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So before I go about replacing all the joists and boards, I am about to put in a vent but there is no place for an air brick at the back of the house

How seriously are you considering replacing the joists and boards?

It may make more sense to replace the floor entirely, with a proper DPM, insulation and screed.
The problem would be eliminated, no need to worry about ventilation, damp, fungus, or vermin... And your house may be a bit warmer for good measure! :)
The suggestion in post #2 is a possibility but more info would help.
Is it the case that you only have the one solid floor - the kitchen floor?
And the kitchen is at the back of the house, and next to it is a wide patio doors across the back wall?
Does the rest of the house have suspended flooring?

Why not post pics of the fungal activity & damp that you can see?
Do you have any signs of damp above floor at skirting level in the living rooms?
A pic from outside showing the kitchen wall at DPC level, & the patio doors at low level the door & the ground would help?
Inside the kitchen are there any signs of damp on the floor or walls?
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putting in a solid floor??? hadn't even thought of that... the space from the floor boards to the clay is probably 450mm where I can see and may be more else where. Fortunately the whole ground floor is open plan so at least I haven't got to worry about walls getting in the way. So how would I fill this space?

so today I dug down about 600mm on the outside. I have a hatch just in front of the patio doors, so able to get to the inside of the wall. Managed to knock out a couple bricks 450mm under the door and put in a 110mm pipe. After clearing the air bricks at the front of the house, I am pleased to say I could feel air coming through them.

I couldn't get any pictures of the fungus, not a lot of room down there. The amount of water under the floor is bad... not puddles, but the wood is just dripping. We have an oak floor, on foam, on plastic sheet, as instructed. But under this is the floor boards and joists which are just soaking and knackered. There was just no where for the dampness to go. My only fear now is that this pipe won't be enough.
Its difficult to help you if you dont answer questions or post pics?

If you can see fungal growth then you can photo it - you can use selfie sticks under floors.
The layout of your floors and rooms is a mystery?
110mm is not enough to ventilate your sub-area.
In your 600mm hole do you intend to come up from the 110mm vent pipe with a 110mm riser?

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