Best thermal insulation under bamboo flooring.

[TheMitchells]

We are planning to lay bamboo flooring to our ground floor, using the Uniclic system.  But I am quite confused re the thermal properties of their recommended underlay.

My preference is for their 5.5mm Fibreboard https://www.bambooflooringcompany.com/fibreboard.html

which has a thermal conductivity of 0.050W/mK.  their other products are Silver Bam with a 0.9 tog and CushNWood with a tog rating of 1. 

 

Which of these gives the best thermal insulation?  What does 1 tog relate to?? It would help if they used the same measurements.  

 

Any help with this will be appreciated. 

 

[Ferdinand]

Can't use the same measurements, as then people would understand it!

Edited December 15, 2017 by Ferdinand

[RichS]

A tog is 0.1 m²K/W. In other words, the thermal resistance in togs is equal to ten times the temperature difference (in °C) between the two surfaces of a material, when the flow of heat is equal to one watt per square metre.

Edited December 15, 2017 by RichS

[TheMitchells]

1 hour ago, RichS said:

A tog is 0.1 m²K/W. In other words, the thermal resistance in togs is equal to ten times the temperature difference (in °C) between the two surfaces of a material, when the flow of heat is equal to one watt per square metre.

 

thank you - but can you translate that for me? 

 

Is 0.050W/mK better than 0.1W/mK??   Sorry for being thick but I need help here...........

[Ferdinand]

I rest my case .

[TheMitchells]

I need @JSHarris! 

[pdf27]

Ummm... what are you trying to achieve? If you're using underfloor heating you want minimum insulation (and how much is a problem depends on how well insulated the rest of the house is), if you aren't then more insulation is better

[A_L]

2 hours ago, TheMitchells said:

 

Is 0.050W/mK better than 0.1W/mK??   Sorry for being thick but I need help here...........

 

For the same thickness of material 0.05 is twice as insulating as 0.1. as pdf27 says for UFH you do not want the floorcovering to be too insulating because you have to have the floor at a higher temperature to achieve the same output.

 

On the TOG scale your 5.5mm Fibreboard is TOG = 1.1, so is slightly more insulating than the others. However the effect appears to be quite small, see page 11 here -

 

http://www.johnguest.com/wp-content/uploads/2014/07/UFH-Tech-Doc-Z2105-387-0914WEB.pdf

[TheMitchells]

thank you - it is not for any underfloor heating - I just want to insulate the ground floor from the cold coming up from the cellar.  it used to have rockwool pushed between the joists in the cellar ceiling but they got damp and was slowly rotting the joists.  We dont want that happening with the new joists so I plan to only insulate anove the chipboard floor before laying the bamboo floor. 

 

Thankyou - now I just need the Bamboo flooring company to have a sale!  Were waiting till after Christmas in the hope they do.....

[Nickfromwales]

Is there any natural ventilation to the basement? If you can't use rockwool, can you not use polystyrene EPS instead ?

Rockwool and foil backed plasterboard may work tbh, but it'll be a cold floor with such a small ( poor ) insulating layer otherwise. 

Even better would be to rockwool again, and then put full 8'x4' sheets of 30mm foil faced cellotex / king span OVER the joists, not in-between, and cover all the joins with 4" foil tape. If you aren't bothered about looks just leave it as is, or gets some long PB screws and PB it. 

[A_L]

4 hours ago, TheMitchells said:

thank you - it is not for any underfloor heating - I just want to insulate the ground floor from the cold coming up from the cellar.  it used to have rockwool pushed between the joists in the cellar ceiling but they got damp and was slowly rotting the joists.  We dont want that happening with the new joists so I plan to only insulate anove the chipboard floor before laying the bamboo floor. 

 

You have moisture condensing on the joists and insulation? The question has to be, where is it coming from? There are two possible answers 1) the warm room above, or 2) from the cellar below, either through external air entering through air-bricks or because the cellar is inherently damp.

 

If case 1) then a vapour control layer  (VCL) is required to prevent water vapour reaching and condensing on the cold joists. This could be foil faced and taped Celotex. You can then insulate between joists as normal.

 

If case 2) then insulation below the floor joist is required to keep them warm and prevent condensation and an air barrier, to prevent bulk movement of air to the joists would be useful. This is a very complex area.

 

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14655&page=1

 

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14655&page=1

[TheMitchells]

Sounds very complex!  The floor of the cellar is damp when it rains but only in one corner, which is the corner where we replaced the joists.  we have added a second airbrick there  and sat all the joists on dpm and that seems to have worked well.  the beams are certainly not damp now.  but I do want to give some insulation to the lounge.  Please bear in mind this is a renovation to sell so if the new owners want to add insulation under the floor, they can but we will not be doing that.  The dining area to the back of the cellar has the old rockwool between the joists and this seems fine as that area does not get damp like the front part.   It is an old Victorian terrace house and the cellar has bare earth floors. 

 

I shall go for the fibreboard and I have taped up the gaps between the floorboards and the wall in the lounge with some airtight tape.  There are plenty of other draughts for the fire but at least it means less from the cellar. 

 

We have spent some time in the house, now it is nearly finished and on the coldest night of the year, it was okay, not cold at all.  so the radiators are all working well.  just need to get the floor done then it will be nearly ready to sell.