Filling subfloor with insulation beads ?

[Steveb21]

I am planning to insulate the subfloor in my bungalow.

Lift laminate

Lift floor boards

Not sure on joist depth but I will insulate this amount with either celotex or mineral wool, leaving the void below free for air flow.

Replace/refit floorboards

Replace laminate


Obviously the main bit of work here is lifting the floor boards.


A company - www.thermabead.co.uk

Have suggested that their method will not require the floorboards removing, instead they will drill and fill with thermal beads (similar to cavity wall insulation)


My concern which I raised with them was reference the air flow. I was told that as the beads would fill the entire void then there would be no no issue with rot etc.


What are everyone’s opinions on this?

 

[foxhole]

Don’t do it .

 

[conny]

All wood contains moisture as wood is a 'living thing', (even when it's 'dead' it contains living organisms, some of which are good others not so good). Sub floors need a flow of air to dispel any moisture in the wood during warm weather. Removing the air flow will prevent the wood from 'breathing' and lead to damp issues which may remain undetected until they fail.

 

[sircerebus666]

I can't see any information on their website about sub floors....

I can't see how they could fill the void and leave a gap for air flow and provide good insulation using beads........

Seems to me they are just saying things to get you to part with your money.

Although your plan requires more work on your part it's a far better plan and cheaper too

 

[JP_]

No!

They're offering an easy fix and will not come back when things go south in a few years. Besides, unless they are totally packed in there, there will form a gap at the top surely, below the floorboards, where cold air can get in?

Do it properly with solid insulation boards or rockwool between the joists.

 

[Ian H]

How deep is the subfloor? You might be able to lift just a couple of boards and crawl around with the insulation.

 

[KenGMac]

As above, do NOT fill any void with that stuff, especially if the void is deep, what will happen is ground water will slowly percolate up via the beads and the floor boards will rot?

Back in the day, a plastic mesh was laid over and suspended between the joists, into this mesh was fitted glass wool. the result was about acceptable. Important bit was that there was no ventilation air flow chilling down the underside of the floor boards, better insulation.

Given the "development" of newer Insulation materials best way could be to [if possible, with a large crawl space] go under the floor and fit ridgid Insulation boards between the joists, leave no air gap between Insulation and underside of the floor boards! fix the insulation with any of cuts of timber nailed to the sides of the joists, or even use larger nails and drive the nails level with the underside of the Insulation ?

Fix as thick a layer of rigid insulation that you can afford

 

[Notch7]

19 x 38 tile battens set down the thickness of the insulation.

Cut celetex narrower than joist gap by say 8mm - 10mm

Get gun grade foam and a metal gun, set the gun so foam comes out slowly.

Spray down foam gaps, when set trim off.

If you want foil tape over joists with 75mm foil tape to form VCL and lay VCL on top.
Id also use a laminate underlay with vapour layer.

Id go for 100mm celetex if you can.
Set the tile battens down by about 102mm, you dont want the insulation proud of the joists, at the same time you dont want a void.....

 

[Steveb21]

Thanks all... I didn’t think filling void with beads was a clever idea!

Unfortunately I do not have a large enough crawl space so unable to do the work from the underside.
Looks like I will have to lift up the boards and either use wool or celotex.

I have the following planned

Changing windows
Cavity wall insulation
Sub floor insulation

I take it that is the best order to follow?

 

[foxhole]

Thanks all... I didn’t think filling void with beads was a clever idea!

Unfortunately I do not have a large enough crawl space so unable to do the work from the underside.
Looks like I will have to lift up the boards and either use wool or celotex.

I have the following planned

Changing windows
Cavity wall insulation
Sub floor insulation

I take it that is the best order to follow?

The first two are far more effective than the last at heat retention.

 

[endecotp]

The first two are far more effective than the last at heat retention.

...depending on what was there previously.

 

[Steveb21]

60mm never filled wall cavity
Windows - although are double glazed, have a wooden frame.

 

[foxhole]

...depending on what was there previously.

Why would anyone downgrade insulation?

 

[endecotp]

Well someone might replace windows with ones that are only slightly better than the existing ones, and that could be less effective the insulating the floor. Or not!