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Insulating around radiator pipes and electrical junction boxed

I have 1920's house with a suspended timber floor. I was thinking of adding Kingspan/Celotex 100mm insulation in between the joists. However, I have electrical junction boxes attached to the joists and also pipework going through and above the joist in a few places. What's general consensus around installing insulation around the electrical junction boxes and heating pipe in regards to fire safety. Any pointers would be hugely appreciated?

4 Answers from MyBuilder Insulation Installers

Best Answer

To start with you shouldn't be insulting a beam floor it should have air bricks either end or down the sides of the outside of the property thos is to allow air flow and prevent damp issues.
Regarding insulating around electrics allow minimum of 100mm gap around it and make sure its fire proof insulation
Thanks jon


Answered 17th Apr 2020

Celotex type boards are not good for floor insulation. Any gaps will allow air to pass through them and lessen the performance. A better material to use is rock wool, not the loft type, but the cavity batt type. This is more dense and although the u value is worse than celotex, the finished result will be better. Celotex can also be a fire hazard, where as rock wool is not. It’s easy to cut and push into place. Make sure you oversize the cuts so there’s no gaps around it.


Answered 17th Apr 2020

I would find a cheap version of Kingspan and get around 150mm thick boards of insulation. You can get a kitchen knife and slice out areas where the pipes are. The rigid boards are soft enough for you to push them onto the pipes ( small areas) eliminating the need for cutting out.
You can use the rolls of Rockwool insulation also, the rolls are split into three sections, split the roll then feed it into the voids between the joists , this method lets you fill the voids a lot better


Answered 3rd May 2020

Of course you can , room should be allowed to accommodate for boxes , that’s about it , airflow runs under floorboards , there should not be no problem To electrics provided installed properly you can always lower insulation lower on timbers , thus allowing no Contact With electrics .


Answered 9th May 2020

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