Insulating suspended timber floor

[kevinkellaghan]

I am insulating the ground floor of our Victorian house, have the floor up now and cleared rubble etc below to leave a nice space for ventilation below the floor joists. My question is should I cover the ground soil with anything like a layer of plastic or should I just rely on the ventilation from the air bricks and the improved space to manage this area under the floor. I am using 80mm PIR with GapoTape between the joists.

Thanks for any advice.

 

[JohnD]

Ventilation.

 

[oldbutnotdead]

If it's bare earth on the ground then yes, DPM weighted down with gravel (smashed bricks would do) will reduce the amount of water vapour coming up from the ground. You still need air bricks to ventilate the space.

 

[kevinkellaghan]

Appreciate the reply, thanks. Using Visqueen (heavy-duty plastic) so I am hoping this fits the bill.

 

[oldbutnotdead]

Appreciate the reply, thanks. Using Visqueen (heavy-duty plastic) so I am hoping this fits the bill.

Black is better than clear (plants need light and water) but under a floor with a good layer of gravel/rubble you should be ok. Keep at least 150mm between lowest timber and highest rubble.