UNDERFLOOR INSULATION

[cabot]

I am planning to insulate under the floor of my detached 1930 bungalow.Its freezin cold underfoot and i WON'T be blocking up any airbricks of which there are 4 on the front and 3 on the rear.I was hoping to pack in between the joists some rockwool type material as access is a slight problem.Should i forget it or choose something else.I am open to suggestions but polystyrene slabs are ruled out because of access .I will be fitting some 80 square metres

 

[jm2000]

No its a good idea, you can buy the loft insulation type stuff, and pack it in. Its just keeping it in place mate, slate batons may do the job, but then your going to need to be underthe floor to screw them to the bottom of the joists and by the sound of it a bit at a time.

Is it drafts, or just a cold floor thats the problem.

 

[noseall]

You need some nylon netting to secure the insulation. This is fixed to the TOP of the joists and simply looped down between each joist gap.

 

[cabot]

its a cold floor right thru the ground floor of the house.what happens if i pack it in tight.would i get away with it or in time is it likely to drop out

 

[XrayDave]

Hi

Most likely drop out over time. Best suggestion was the netting from noseall as you don't have to be a contortionist to secure battens from beneath the joist. Picture shows you exactly what to do. You can secure the netting simply by using staples from a stapler (or a staple gun)! Wear a facemask and gloves when handling the Rockwool.

Personally, I'd also screw the floorboards back down after fitting the insulation.

Make sure when cutting the floorboards in order to lift them that you don't go through a central heating pipe or mains electrical cable.

What I have found best is to use a circular saw where the depth is set to as close as possible to the thickness of the floorboards.

Make sure that when you slice ACROSS the floorbord, you do so where the middle of a joist is - that way you will have some support for the floorboard either side of the cut.

I also run the circular saw along the gap between adjacent floorboards (if there are gaps) in order to remove the "tongue". Otherwise, you risk splitting the floorboard when you prise it up.

Finally, when re-laying the floorboards, mark the position of cables & c/htg pipes ON TOP of the floorboard for future reference!

I have just done this in my son's bedroom (which is over an unheated garage, has 2 outside walls and is North-facing). Has made a tremendous difference. Only difference here is that beneath his floorboards was the plasterboard of the garage ceiling, so no netting required.

Hope this helps

Dave

 

[suts89]

I,d be climbing under the floor if it was me.

Unless however the house was empty of furniture with no carpets down.

 

[alittlerespect]

Follow 'noseall's' advice and you will stay out of trouble - use around an 80mm thickness of PIR insulation depending on the overall U value that you wish to obtain - 80mm thickness PIR would give a U value of around 0.25W/m2K.

I would also recommend including a vapour barrier over the top of the joists before relaying the flooring.

Others may have differing opinions?

Regards