# Insulating a basement



## Student (26 Jan 2019)

This isn’t so much about a workshop build as a question about modifying my existing space.

My house is built on a slope so we have two storeys at the front but three at the back. Some 30 years’ ago, the area under our dining room was excavated and the floor lowered. Prior to that, the room in the basement varied in height from 6 ft. at the bottom side to 3 ft. at the top side. The work was all signed off by building control including having to underpin the wall at the back. However, at the time, nothing was ever done about the ceiling. There’s about 6 ft. 3 ins. headroom and there are just the joists and floorboards from the dining room above, all painted black some 50 years ago before we moved in. What I would like to do, after all these years, is put Celotex or similar between the joists before boarding between the joists with either plasterboard or MDF. I can’t afford to attach anything to the bottom of the joists in view of the restricted headroom.

The question is, does this sort of insulation work require building consent?


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## MikeG. (26 Jan 2019)

Student":2lj6tyzh said:


> This isn’t so much about a workshop build as a question about modifying my existing space.
> 
> My house is built on a slope so we have two storeys at the front but three at the back. Some 30 years’ ago, the area under our dining room was excavated and the floor lowered. Prior to that, the room in the basement varied in height from 6 ft. at the bottom side to 3 ft. at the top side. The work was all signed off by building control including having to underpin the wall at the back. However, at the time, nothing was ever done about the ceiling. There’s about 6 ft. 3 ins. headroom and there are just the joists and floorboards from the dining room above, all painted black some 50 years ago before we moved in. What I would like to do, after all these years, is put Celotex or similar between the joists before boarding between the joists with either plasterboard or MDF. I can’t afford to attach anything to the bottom of the joists in view of the restricted headroom.
> 
> The question is, does this sort of insulation work require building consent?



What country are you in?


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## Rorschach (26 Jan 2019)

No, but why do you want to insulate it?


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## MikeG. (26 Jan 2019)

Rorschach":12gibb3a said:


> No, but why do you want to insulate it?



No in England and Wales. I'd be cautious of saying the same thing about Scotland or Ireland.......hence my question.

Presumably the desire to insulate the floor is for the sake of the room above, not so much the room below.


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## Rorschach (26 Jan 2019)

MikeG.":ic7dbjjz said:


> Rorschach":ic7dbjjz said:
> 
> 
> > No, but why do you want to insulate it?
> ...



Why does he need consent to insulate? It's not changing the structure.


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## MikeG. (26 Jan 2019)

I'm agreeing with you. In England and Wales the answer is no, permission isn't needed. Scotland has its own system, and although I've done a couple of jobs there, I can't claim familiarity with it. Ireland......I know nothing. Hence asking where the job is.


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## Student (26 Jan 2019)

Mike

As shown in my profile, I live in Bristol (home of AndyT, EtV and Rafezetter amongst others).

Perhaps mentioning insulation was a red herring. The main thing is that the boiler is in my workshop and all the heat disappears into the space within the rafters. Not only that, but the fact that the joists and underneath of the floorboards are painted black means that it’s quite dark in there.


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## MikeG. (26 Jan 2019)

(Joists, not rafters ).

That heat isn't disappearing. It is warming your house. Cut that off and you'll possibly need to run the boiler for longer (if the amount of heat from the boiler isn't exceeded by the heat losses through the floor into the basement). So, you're allowed to do it without permission, but whether it is wise or not is much more difficult to answer.


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## Rorschach (26 Jan 2019)

MikeG.":fg86d3ml said:


> I'm agreeing with you. In England and Wales the answer is no, permission isn't needed. Scotland has its own system, and although I've done a couple of jobs there, I can't claim familiarity with it. Ireland......I know nothing. Hence asking where the job is.



My apologies, misread that.


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## Student (28 Jan 2019)

Whoops; joists not rafters! I got it right in my OP.

In fact, insulation is probably unnecessary. There is no radiator in the workshop, the only heat comes from the boiler casing and one or two unlagged pipes. By boarding between the joists, I would hope that what heat there is stays lower down and not rise into the gaps between the joists.

The other main issue is the darkness of the room with black painted joists and floorboards. By infilling with MDF panels between the joists, and painting the infill white, will make the whole room brighter.


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