Glass foam loose fill under floor

[trimattrdg]

I’m getting suspended floor insulated next week and will have access under floor . We do get occasional water under there (clay) but it tends to soakaway fairly quickly the clay seems mostly wet to touch after all the heavy rain .

Would it be worth laying some geocell glass foam down there to a certain level to help manage the moisture and have less damp clay exposed ?, I have about 45cm in depth to play with and looking to do something practical to help. The airbricks are fairly high so these would not be blocked.

I can see it being used with limeCrete floors but unsure if it’s worth it when just a loose fill.

 

[trimattrdg]

 

[fernicarry]

Isn't the point about glass foam that its vapour permeable? So whatever water currently evaporates from the surface of the clay will not be prevented from doing so. So long as the sub-floor is well ventilated it shouldn't be a problem. The floor timbers appear from the pictures to be dry so that suggests its all working just fine as it is.

If its quite wet I'd get those electrical cables fixed to the underside of the joists. T&E isn't guaranteed water proof although it generally handles a bit of damp just fine. The feed to my utility room did however fail due to water ingress and it was a right faff to get it back out because it was under a section of floor that I can't get under.

What sort of build up will you be using for the insulation?

 

[trimattrdg]

Thanks , yes that would make sense so probably not worth it then. Good point on the cables I will certainly take those of the ground. After much debate I settled for 100mm rock wool for insulation which will be applied from above in a breathable hammock. I have monitored the humidity down there and in the past few weeks it has been around 85% RH , which for winter I think is about expected and there is certainly some air movement down there since I unblocked the air bricks

 

[Mikeyboy7]

View attachment 12581

View attachment 12582

What I did with my suspended floors , I mixed up sharp sand with some 6mm stone and quicklime
3 aggregate & 1 quicklime mixed dry , and add to your oversite , this will manage any dampness greatly

 

[trimattrdg]

What I did with my suspended floors , I mixed up sharp sand with some 6mm stone and quicklime
3 aggregate & 1 quicklime mixed dry , and add to your oversite , this will manage any dampness greatly

Thanks is this just a case of mixing it in a cement mixer and laying it in and I assume when you are mixing and laying it it fizzles with the moisture and you just need to ensure plenty ventilation? What kind of quantities did you use as we would have about 25sqm to cover and will have the floor up for a day or 2 and would be asking contractor sorting floor to do this . The contractor had suggested some concrete and ballast but I wasn't keen on this so wondering if your option could be a good alternative.

 

[Mikeyboy7]

Thanks is this just a case of mixing it in a cement mixer and laying it in and I assume when you are mixing and laying it it fizzles with the moisture and you just need to ensure plenty ventilation? What kind of quantities did you use as we would have about 25sqm to cover and will have the floor up for a day or 2 and would be asking contractor sorting floor to do this . The contractor had suggested some concrete and ballast but I wasn't keen on this so wondering if your option could be a good alternative.

So, 25sqm x50mm that’s 2.5ton of sand , yes dry mix it in the cement mixer will do and just level it out over your floor , so when it’s gets wet or damp it will turn to a sort of limecrete floor , so if it gets wet it will dry out over time again

 

[Mikeyboy7]

Thanks is this just a case of mixing it in a cement mixer and laying it in and I assume when you are mixing and laying it it fizzles with the moisture and you just need to ensure plenty ventilation? What kind of quantities did you use as we would have about 25sqm to cover and will have the floor up for a day or 2 and would be asking contractor sorting floor to do this . The contractor had suggested some concrete and ballast but I wasn't keen on this so wondering if your option could be a good alternative.

So , mix 2 ton of aggregate A gritty sand 4mm with quicklime , mixed dry in a cement mixer , leveled to 50mm ! Any dampness will turn your mix into a sort of limecrete floor , oh and I would definitely use sheeps wool and membrane

 

[fernicarry]

which will be applied from above in a breathable hammock.

Why installing from above when you have access from below? Are you using a contractor or doing it yourself? Admittedly it'll be easier from above but its nigh on impossible to lift boards without damage.

As I've said in another thread you need to ensure there isn't an air gap above the insulation so make sure the membrane is kept quite taught so you have a rectangular cross section to fill.

 

[trimattrdg]

Why installing from above when you have access from below? Are you using a contractor or doing it yourself? Admittedly it'll be easier from above but its nigh on impossible to lift boards without damage.

As I've said in another thread you need to ensure there isn't an air gap above the insulation so make sure the membrane is kept quite taught so you have a rectangular cross section to fill.

Thanks, This will be contractor who plan on doing a partial board removal and doing the membrane as you suggest

 

[Lime]

If you get ponding under the floor, it might be worth thinking about a sump and pump to keep the water level down.
It would reduce the dampness.