Loft Insulation under floor boards

[tsomo2000]

Hi All

This may sound a daft question but can i use loft insulation to insulate inbetween my ground and first floor?

I am currently rennovating my 1970's semi and am taking the floor boards up in each room to run cable etc, so i thought it would be practical to put some insulation in there whilst i do it.

As long as i miss out putting insulation on top of pipes and wires will it be ok?

Thanks

Alex

 

[Chri5]

You can insulate between floors with rock wool, but:-

* Electric cables MUST not be enclosed in insulation (it increases the operating temp of the cable, which in turn means a cable load capacity could be reduced by 60% !)

* You can insulate the pipes, might even help keep the bills down

* Make sure you don't over stuff the void, try to get 200mm thick in to a 150mm void will cause stress on the ceiling below.


If you get some PVC trunking (over size such as 40mm x 20mm) you could enclose the cable in that, and then insulate everywhere because there will be air apace around the cable. Although adding in groups of cable to trunking then have a derating due to grouping, but that is far, far less a problem than cable direct in insulation.

Hope that helps

 

[freddiemercurystwin]

between my ground and first floor?

Whys that then? Tis somewhat unconventional.

 

[Chukka63]

every property ive worked on has "rockwool over/around cables .new houses have insulation between the joists these days.just do it

 

[Chri5]

every property ive worked on has "rockwool over/around cables .

And that makes it right ?

Giving out advice based on bad practice is stupid and dangerous.

Lighting cable have a lot of headway- often fused at 6a and 1.5mm TE will take 15a, so a 60% derating due to running hot in insulation is still in the ball park of the cable capacity.

It is a big issue when insulating radial circuits such as electric showers, cooker points and electric heating. The cable might have only 20% headway and installation in insulation will cause over heating.

Ring main cabling 2.5mm TE can cope with odd areas in insulation since the cable will cope with some derating, but do it belt and braces (keep insulation away from cable or contain the cable) is still the best thing.

If all else fails have the cable laying on insulation rather than in it. The issue is then that the cables will be directly under the boards, a mere 20-25mm from surface.
This goes against the 17th edition 50mm below surface rule, unless all circuits less than 50mm from surface are protected via an RCD or RCBO.

What is the normal result of over heating ?

Ignore Chukka63's advice please

 

[freddiemercurystwin]

between my ground and first floor?

Whys that then? Tis somewhat unconventional.