Insulating under block and beam floor with perlite

[Iceverge]

I wonder is this a factor also. I don't think they would perform well where wind-tightness isn't done well.

 

 

 

[Radian]

I had begun to contemplate how to measure air movement inside a cavity to evaluate efforts to improve airtightness. My current thinking is to build a small solid-state anemometer probe inside the end of a small diameter copper tube. This would then push into a hole drilled through the inner or outer leaf and sealed up afterwards.

[S2D2]

The airflow through reasonably well packed beads will be vastly reduced relative to outside air due to viscous drag etc. So I would neither rely on it for ventilation (though indeed it is not airtight) nor worry about it for insulation. I don't have any figures for you but it would be not too much effort to model.

[callamart]

Hi, I’m looking into possibilities for insulating the void below a suspended block and beam ground floor to improve insulation before installing wet ufh on 25mm eps tile direct boards with a ceramic tile floor above.

I like the idea of pearlite beads from an ease of installation perspective but am concerned about airflow diminishing the limited insulation properties.

Any thoughts on pearlite beads versus blown loose eps versus polyurethane foam injection would be greatly appreciated.

[MikeGrahamT21]

Just found this as an approved retrofit application: https://source.thenbs.com/product/energystore-under-beam-block-insulation-system/bhJN6zXr5iSRNwvFAYrW9G/bSUUubuFs5fkWDGuLZbRzW

[ADLIan]

Only for new build. Not sure how you’d retrofit a dpm under an existing b&b floor?? Under existing Appr Docs and British Standards adding the insulation layer under b&b floor makes it a ‘solid’ floor which requires a dpm.

[Radian]

30 minutes ago, MikeGrahamT21 said:

Just found this as an approved retrofit application: https://source.thenbs.com/product/energystore-under-beam-block-insulation-system/bhJN6zXr5iSRNwvFAYrW9G/bSUUubuFs5fkWDGuLZbRzW

• Level ground and build up external wall. With Superbead there’s no need for vents.

 

That's very interesting. The gut feeling I had might be right after all.

 

16 minutes ago, ADLIan said:

Only for new build. Not sure how you’d retrofit a dpm under an existing b&b floor?? Under existing Appr Docs and British Standards adding the insulation layer under b&b floor makes it a ‘solid’ floor which requires a dpm.

 

Desperate times... 😅

[S2D2]

15 hours ago, ADLIan said:

Only for new build. Not sure how you’d retrofit a dpm under an existing b&b floor?? Under existing Appr Docs and British Standards adding the insulation layer under b&b floor makes it a ‘solid’ floor which requires a dpm.

 

Yes, still no luck for retrofitting unfortunately, from the technical docs:

 

[MikeGrahamT21]

It looks like using blocks in block and beam is a bit outdated these days, i found several systems where high strength EPS blocks are used for the infil, which are designed for no thermal bridges, it wraps under the beam.

 

What is the issue with just sticking some PIR on top of the slab, and then float a chipboard floor on top of that? Appreciate you'd lose a bit of height, but surely worth it?

[S2D2]

1 minute ago, MikeGrahamT21 said:

What is the issue with just sticking some PIR on top of the slab, and then float a chipboard floor on top of that? Appreciate you'd lose a bit of height, but surely worth it?

From what I've seen this issue mostly applies to 90's houses where the common build up is block and beam, 50mm EPS, floating chipboard floor. Worse, like mine, big gaps are often left in the EPS to run ground floor heating pipes... So the insulation is okay (read: better than nothing), but there's a bunch of space under the beam and block that won't be on show that it feels like there should be a solution to add a boatload of insulation to. The lack of a DPM is a key limitation though as ground gases can't be ignored.

[Andehh]

4 hours ago, MikeGrahamT21 said:

It looks like using blocks in block and beam is a bit outdated these days, i found several systems where high strength EPS blocks are used for the infil, which are designed for no thermal bridges, it wraps under the beam.

 

What is the issue with just sticking some PIR on top of the slab, and then float a chipboard floor on top of that? Appreciate you'd lose a bit of height, but surely worth it?

It's great, but does require greater depth to be dug out from under the block and beam.... This comes at a cost. 

 

We chose not to go down this route as the cost of muck away was going to be too much for our site... Then ended up needing to dig it out anyway after orders had gone in and commitments made!! DOH. Fortunately we got 160mm PIR in at a reasonable cost to compensate.