The Holy Grail

[geraldthehamster]

Sigh. Having sanded and varnished most of my downstairs floors (suspended over a space too small to access), fitted new skirtings, a hearth and a fireplace (which seemed like quite enough work at the time), I'm now wishing that I'd really bitten the bullet, taken up the floorboards and insulated underneath. Even if I'd demolished most of the tongues in the process, I could have ripped them into straight- edged boards.

I have one room to go, and might go the whole hog there (ironically it's a spare room). But for the rest of the ground floor, the idea of pulling off all the skirtings (how else to remove the T&G boards whose ends go under them, and are fixed with brads an inch from the wall?), and doing the floors again, is heartbreaking, though I might just bite the bullet when I've completed all the other jobs. Or I'll content myself with lots of rugs.

Which leaves the Holy Grail, discussed on here before - how to insulate under a suspended timber floor, with no access from underneath, without removing the floor.

Cheers Richard

[Owain]

Could you cut an access through an external wall?

Or squirty foam.

Owain

[geraldthehamster]

Even if I did cut such an access, there's not enough room for anyone other than an unskilled very small child, and the dwarf walls that support the joists at intervals would necessitate many such holes.

Helium-based squirty foam,that would rise and stick to the underside of the floorboards?

;-)

Oh come on, there must be a way we haven't thought of.

Cheers Richard

[Martin Bonner]

*LOTS* of squirty foam to entirely fill the underfloor void?

Ventilation for your joists? Why would you want ventilation?

[Spamlet]

Rats; mice; and wasps seem to be pretty good at filling up under floors with insulation.

Otherwise: foam through the knotholes. The cavity wall insulation people very quickly filled up the walls in my old house. Sure they could quote for floors if you asked.

S

[Phil L]

Filling the entire void is not an option, unless you want your joists to rot away within a few short years.

You can't get access under the floor and you don't want to take the entire floor up? - then it cannot be insulated, end of story.

You could insulate above the existing floor, with 75mm celotex or similar, then put a floating floor above that, but then you'd lose about 90mm of room height (and your internal doors would be 90mm shorter too) plus you'd have to put new skirtings all the way around

[geraldthehamster]

These have been my conclusions, every time I've thought about it :-(

I can only see two ways to make the floor warmer, short of a detested fitted carpet, with its propensity to collect dust, and stains from coffee, wine and mouse blood. Or ripping the lot out and replacing with concrete, which would be stupid and unnecessary ;-)

One is to remove my skirtings, prise up the floorboards, insulate, tidy up the boards on a table saw, refit, fit new skirtings and decorate. In three rooms and a hallway.

The other is to continue to collect relatively inexpensive Persian rugs, and attach Tri-Iso insulation to the backs of them. That way much of the heat loss would be eliminated.

Hence my reference to the Holy Grail - don't bring me common sense, bring me solutions ;-)

Cheers Richard

[Phil]

Surely only one or two long boards removed would provide access to blow insulation under? Even if you wanted to remove ALL the boards, sawing through the tongue on one with would release them all (once skirtings off).

[Adam Aglionby]

Do wonder about insulating under floor voids, roof voids have air and draughts deliberately introduced to stop rot, concerned that creating static air under floor timbers might introduce a rot encouraging enviroment?

Cheers Adam

[The Natural Philosopher]

Bite the bullet Richard, and lift the floor.

Then wedge 60-100mm celotex between the joists, tape over with the approved tape. seal any edges with expanding foam till its completely airtight, and re-lay the floor.

[The Natural Philosopher]

That's why you should use the same system as for rooves. Celotex and leave the air circulation alone.

[Adrian C]

One of the issues I have procrastinating about doing a DIY job is overestimating the effort and potential problems I may encounter. Sometimes it turns out easier than I first thought, but getting started is hard.

The OP has the training run-up available to do the undecorated room first. Press on!!

Now, reading these posts is making me wish that we'd done the same for the floors as well as the external walls (which we did Celotex) prior to our recent whole house replastering. But that would be messy now, take effort, I'd have to clean up, price of fish could rise...

See ;-)

[geraldthehamster]

Absolutely - it's important not to interfere with the ventilation, which is why you can't simply fill the void through a hole.

cheers Richard

[Jules Richardson]

How much space are we talking about? It's surprising how small a space a human can fit into. Insulating probably doesn't need a lot of clearance, either - no messing with power tools, no need to swing a hammer etc.

cheers

Jules

[robgraham]

Don't tell me about it !! Mine is an 18th Century stone cottage - in the 1920's it was upgraded and the original earth /stone slab? floor (where did the slabs go?) was replaced by a well ventilated suspended wood floor throughout, plus the white-washed stone walls were covered over with lath and plaster. Our first winters were awful (but we were young and in love!!) as the underfloor winds funnelled up between the plasterwork and the 3 ft thick stone walls into the roof space - we huddled round a small coal fire with a massive heatsink all round us.

The walls were all dealt with - stripped off, insulated and re- boarded, but I didn't do the floors. Wish I had but really too old now !

Rob

[geraldthehamster]

I think perhaps when the memory of having just *finished* the rooms in question has faded (after a couple of years, perhaps), and when I've done all the other, not inconsiderable jobs (like building an extension), I must just be able to come to terms with ripping this out and doing it. I know how to do it, technically, but thanks for all the advice.

I admit to being slightly disappointed that nobody seems to be better at thinking outside the box than I am ;-)

Cheers Richard

[The Natural Philosopher]

When the box has no holes, its not worth thinking outside it if you cant get to the outside to do the work..;-)

I am perpetually surprised how much LESS works it is to do a strip down ad rebuild than to tinker..

Watdching American Hot Rod last night..no oil pressure. Manager says 'engine out, strip, sort' and they find that in fact, the oil pickup is jammed against the sump. Nothing less than a total strip to get to that anyway.

I had a bit of architrave to make. Curved moulding. I sent three weeks agonising, and acquiring router table and bits, half an hour jigsawing and hand sanding curve, and 15 seconds machining the moulding with the help of SWMBO.

Use to spend all day bashing at break drums on MGBS in the mud. One day, brainwave. Remove rear axle complete, in vice with blowlamp and angle grinder, replace all corroded bits in warm, refit axle, bleed brakes. 3 hours.

It probably takes less than a day to rip up a floor, fit Celotex and put it back down.

[geraldthehamster]

I agree with you in principle, though my experience with floors leads me to question your timescale ;-) The last floor I laid took several evenings just to get the floorboards down, though admittedly that involved a lot of measuring and cutting that wouldn't be needed if you were re-laying boards in their original position. Subject to the condition you managed to pull them up in, and any remedial work on a table saw, given that they're already sanded and varnished... And you're not allowing for cutting, fixing, caulking and decorating new skirting ...

Thicker socks, there's another.

Cheers Richard

[<me9]

Flat panel insulation needs a big hole in the floor to fit if there is no depth, particularly if thick. Flexible insulation is generally an irritant, I don't like getting too close.

I'm toying with pulling through spaceblanket (mineral wool (or is it recycled bottles) wrapped in a plastic film, much less irritating than bare stuff.--

[jgharston]

There's this invention that's been around for, ooo, only about 150 years, called a va-cuum clean-er.

JGH

-- People who want decking should be.