Which order is best (insulation / rewiring)?

4 Jan 2012
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United Kingdom
Hi Guys,

Brand new homeowner here who has extremely limited DIY experience so please be gentle!

My house needs to be rewired (including the installation of a new consumer unit), have loft insulation redone (the last guy laid it across the joists and then haphazardly boarded it - so its way under 100mm at the moment) and I have a suspended timber floor and really want to put in some underfloor insulation as it is freezing.

My question is - what order would be best? Should I do the underfloor insulation first (as it is a messy job) and then rewire or will rewiring involve some floorboard lifting? Can I do the loft insulation before rewiring or will they have to pull it all up?

Apologies if it is a newbie question - but I have literally only visited B&Q for the first time two weeks ago.


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I take it you are referring to a suspended ( wooden boards ) ground floor ref. the insulation? Do you intend to insulate the !st floor? The loft insulation must be lifted for re-wiring, and the loft wiring protected from excessive insulation heat build-up.

There are various ways of mixing different kinds of insulation in the joist bays and combined with re-wiring and ceiling roses and downlights it can be quite complicated for a newcomer.

Perhaps if you ask on the sparkies forum and do a lot of research you will come out ahead of the game.

Heating pipework, various cables, and carefully numbering, lifting and replacing T&G boards are to be considered - dont let some speed chancer hack your floors to badly fitting off-cuts.

First research, then come back here
and there are far better people on here to answer questions on insulation than me.
Ground floor.

Any wiring for power-circuits should be in conduit and attached to underside of joist to allow for heat dispersal. Insulation can then be suspended between joists by netting ( fibre-wool ) or jammed/held by nails or fixed with expanding-foam( insulation boards).


Easier - and therefore cheaper - for sparky to work without lots of insulation around. Decide the depth you are going to have, tell him you want all cabling clear of insulation and ask what runs he suggests,

Will cost some tens of pounds more ( if normal-sized house/electrical systeml ) for extra cabling.

If you want to board loft after fitting insulation which rises above height of existing joists, search on forum, many posts.
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Thanks guys - it was underfloor insulation on the ground floor but I would like to eventually insulate the first floor as well, noise reasons more than heating. I have got a sparky coming round tomorrow to give me a quote for rewiring - might get him to do the wiring in the loft if I can't do it myself and insulate before saving up for the major rewiring (definitely out of my league).

Finding it difficult to look online for builders with underfloor insulation experience (and like you mentioned I don't want a cowboy to muck it up and leave everything to rot), if its doable I'm happy to give it a try! Will do some more research before attempting anything ;)

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