Drafts under flooring

[davphi338]

Hi,

I'm trying to insulate my house to a better degree and have noticed that there are draughts under the upstairs flooring and in the dob and dab plasterboard cavity. i.e when I remove an electrical socket in the bedroom a breeze can be felt, I also had downlighters fitted in the hall recently and you could feel the wind blowing in holes cut for the downlighters.

Has anyone any suggestions on the most likely cause of the air intrusion. I've had a quick look at my waste pipes where they exit and can't see any obvious points where they are not sealed.

 

[Fluffster]

What you are describing believe it or not is good ventalation, maybe too good for your own comfort.
Air has to circulate below the floor joists to prevent rot.
Your cavity walls are possibly open to too much air flow.
You could get the cavity filled with insulation, pretty cheap these days under the gov grant scheme.

On new builds these days building control actively enforce extra ventalation in roof voids then get you to insulate with thick board.

Pete

 

[Richard C]

I had the same problem in the 60’s house we bought a couple of years ago. I eventually traced the problem to the roof void in the attached garage. Part of the hall & cloakroom extends under the garage roof void & no insulation had been installed so the ends of the joist were completely open to cold air & draughts which traveled along the joists between the ceiling & floor boards. 3 rolls of insulation from B&Q sorted it & also made a big difference to the temperature of the hall & loo!

 

[davphi338]

Thanks for the replies, the house was built in 1990 and already has cavity wall insulation. I didn't realise there was meant to be ventilation in the space between the downstairs ceilings and upstairs floor. If cold air is circulating in this area this cannot be good for insulation as the floors in the bedrooms can feel cold.

 

[Richard C]

I didn't realise there was meant to be ventilation in the space between the downstairs ceilings and upstairs floor.

Err, I'm not sure I agree with that, ventilated yes but positive draughts no! The roof space of a well insulated loft void can be very cold at night but heat up rapidly during the day, even in winter (roof tiles are not normally insulated) & you need some air circulation up there to prevent condensation forming due to internal/external temperature fluctuations.

The space within the ceiling void on a 2 story house is, however, within the main structure & certainly not short of ambient heat rising through from the ground floor. It will therefore get more than enough residual heat through the ceiling to prevent condensation.

 

[davphi338]

Richard C, that was my point I didn't think the void between the ceiling and floor upstairs was meant to be ventilated. If it is supposed to be ventilated how is the ventilation provided. i.e I've never seen air bricks half way up a wall.

 

[IJWS15]

You will have an incomplete run of "dab" adhesive along the top of the first floor allowing cold air from the lft space to enter the void behind the plasterboard and ventilate/cool the house - so much for the energy saving building regs!

Check any extractor fan ducts as well.

Went round the last house and plugged the gaps with fibreglass - made a world of difference. Have yet to do the same with this one!