Lifting floorboards - replace with chipboard? - also insulation

[David WE Roberts]

[First, a GNAH! for Pan - there isn't an 'undo' function in the edit menu. I just wiped out my text, presumably by hitting CNTRL+A instead of SHIFT+A and then typing on.]

Anyway, starting again using Notepad!

I will be lifting floorboards in three rooms - two upstairs and one down - to insulate under the floors. All rooms will be carpeted afterwards.

I am wondering about the advantages/disadvantages of replacing the boards with chipboard.

So far

Advantages:

Smoother surface. Less creaks. Less draughts.

Disadvantages:

More fiddly to lay around odd shaped bits such as bay windows and CH pipes. Harder to lift a small part to gain access to pipes and wires.

I suppose there is also the issue of which insulation is used.

Downstairs I will be using Celotex or similar, so will probably have to lift most or all floorboards, which favours replacement.

Upstairs I could use fibreglass roll and only lift a few runs of boards if I can pull the roll through. I have wondered about using vermiculite upstairs - easy to install with the minimum of board lifting but it does find any cracks, and can be a pain when changing light fittings or fettling lighting wiring.

Suggestions, advice, experience all welcome.

Cheers

Dave R

[geraldthehamster]

Why do you want to insulate in the first floor? Fire resistance and sound deadening might be reasons, but there is little point from an energy conservation point of view, assuming you have your upstairs ceiling or roof insulated.

I certainly wouldn't put vermiculite in there.

Is cost an issue? You would need to buy chipboard, but you already own the floorboards.

Do you have a method in mind to lift the boards? It can be fun ;-)

Chipboard can suffer badly if it gets damp or very wet. I expect someone will suggest ply as an alternative.

Personally I'd just put the floorboards back, especially if access is going to be an issue. Though fitting chipboard would be quicker, and you could always have cut-out sections where access was needed.

I lifted all my downstairs floorboards and insulated with Celotex. Simplest way is to cut to a loose fit between joists, support temporarily (with nails, or propped up with offcuts), and stick to the sides of the joists with expanding foam.

Cheers Richard

[meow2222]

boards shouldnt be an issue under underlay

lay tarpaper etc first

the boards are all cut to fit already

Putting the boards back is cheaper, they don't get water damaged, they look great when finished properly and retain the historic character of the house. I struggle to see any reason to replace them with chip

Thermal insulation between floors is generally not desirable. If you want sound deadening, you could add plaster, pressed papercrete, or a /small/ amount of stone, small hardcore or sand. You could also fit noggings.

NT

[David.WE.Roberts]

I would like to keep the heat for downstairs, downstairs. We have one north facing room which is always cold so insulating below and above seems a good way to retain more warmth. I see no reason to heat a bedroom (perhaps not in use) at the expense of a living room.

I wondered about this, but if you can use it above a first floor ceiling as loft insulation, I'm not sure why you couldn't use it above the ground floor (as you might in a bungalow).

Thankfully, cost is not a major issue.

I have an Aldi multi-tool which can cut a very fine notch through a floorboard along a joist which makes lifting and refitting relatively easy. The main problem is the flat iron nails holding the original boards down and the tongue/groove between the boards (where they haven't been lifted previously). However I have a flat bar which lifts boards quite well.

AFAIK nearly all builds in the last 20 years (probably quite a bit more) have used flooring grade chipboard including for bathrooms and toilets.

So I'm not convinced that possibly greater water resistance in the event of a major disaster is enough reason to use floor boards.

Celotex and foam are the plan for downstairs.

Upstairs is still open to debate.

Cheers

Dave R

[harry]

Chipboard is good. Almost no waste. Make little trapdoors over key points, e g over light fittings in the room below. I put a floorboard over my cable runs so they can be accessed. You can get water resistant grade chipboard BTW. Be sure to glue the joints (PVA)

If your insulation in there should ever get wet, it will never dry out. There may be interstitial condensation issues. So I wouldn't do that.

[Nightjar]

On 10/04/2013 12:21, geraldthehamster wrote: ...

These days, all flooring quality chipboard is water resistant - the stuff that used to be coloured green and was intended for use in bathrooms etc. I have had a piece of it outdoors, covering a broken window in the garage, for a couple of years now without it suffering any ill effect.

Colin Bignell

[Roger Mills]

I wouldn't take bets on chipboard creaking less than boards. The stuff we've got is *far* worse!

[ARW]

The cables for the sockets will not be up to regs if surrounded in insulation.

[meow2222]

cable is normally under or over the insulation, which is fine. PB, board and chip are all thermally conductive enough for regs compliance.

NT

[ARW]

I was under the impression that the OP was going to fill the void between the floorboards and the plasterboard with insulation by ramming/pulling the insulation in. The cables are already in place and will almost certainly not be above or below the insulation when he has installed the insulation using such a method of installing the insulation.

[meow2222]

The cable surely ends up under the insulation.

Even if it doesnt:

1mm^2 clipped direct is rated 16A 1mm^2 buried in insulation is rated 8A All fully compliant.

NT

[ARW]

Not fully compliant at all. I said the cables for the SOCKETS

[geraldthehamster]

My neighbour suggested a method to me for lifting floorboards, which worked well and quickly - remove two runs of board using "delicate" methods (sawing out tongues and prying up), then do the rest with stout 3x2 or 4x2 - rest a length across two joists in the exposed bit, as a fulcrum, then use another as a lever to wang the floorboards up off the joists. Work your way along the boards, lifting 2 or 3 runs at a time. The brads pull out of the joists pretty swiftly under that kind of onslaught.

Obvously this will only work where you have sufficient void under the floorboards, so on the ground floor but possibly not the first ...

Cheers Richard

[meow2222]

Right. Method 100 -> 21A continuous cable rating, method 101 -> 17A continuous rating.

NT

[ARW]

It's more than just that. I have no idea of the OPs electrical layout. It could be that there is an electric shower cable that runs under the floorboards.

I always try to keep insulation away from cables (apart from upstairs lighting).

Imagine the OPs cables passing through the joists and then insulation is added. The insulation may end up above the cables (remember that the insulation was going to be poked/pulled in and not laid on the plasterboard. The insulation would soon completely surround the cables due to gravity (the same can happen if the cable is laid ontop of fibreglass insulation if they run in the same direction as the joists).

Apart from lighting circuits then the best advice is never to let insuation come into contact with cables - and that's not just my opinion - it's in the regs.

Cheers