"Thermal Bead Screed"...anyone used or heard of it?

[JohnW]

Hi

We have been asked if we would consider using "Thermal Bead Screed" on the ground floor, it's an Italian product, real name Politerm Blu 110. It appears to be a lightweight screed with insulation beads used as aggregate.

 

My original ground floor build-up gives me a respectable U-Value of 0.14 and is as follows;

 

1. 100mm Sand & cement screed with UFH pipes embedded
2. 3mm Polythene
3. 125mm Thermafloor TF70 insulation boards with hot & cold water pipes embedded
4. 3mm Raydon barrier
5. 150mm dense concrete sub-floor

 

The key to reaching the U-Value of 0.14 is that the boards are installed correctly without gaps or voids.

 

The "Thermal Bead Screed" approach appears to remove the risk of gaps & voids and the floor build-up is as follows;

1. 50mm Liquid Hemihydrate screed with UFH pipes embedded
2. 3mm Polythene
3. 175mm "Thermal Bead Screed" with hot & cold water pipes embedded
4. 3mm Raydon barrier
5. 150mm dense concrete sub-floor

 

This won't give me as good a U-Value, I've been told 0.16 by the company selling it to me and 0.18 by an independent energy assessor.

 

Have any of you used "Thermal Bead Screed" or know anything about it?

Edited November 16, 2018 by JohnW

[ADLIan]

Your energy assessor looks to have the correct U-value (comparing the 125mm PUR). To get the same U-value would require twice the thickness of the insulated screed product (0.022 W/mK vs 0.043 W/mK).

[Dudda]

I don't see the point. The thermafloor is easy to put down and by putting a polythene sheet above the insulation your stopping the screed flowing between the joints in the insulation (if any exist) which would create a thermal bridge. It would want to be incredibly poor workmanship or a very complex shape with an uneven sub floor to justify the thermal bead screed I think.

What you could do is increase the thermafloor insulation to 150mm and use a 75mm concrete screed. This would give you an even better u-value while still providing a decent 75mm thick slab for the underfloor heating pipes.

[Declan52]

Why would you want another layer of concrete.  The hot and cold pipes will sit on the subfloor and will be covered over with a 50mm thick insulation.  You can then overboard with your next layer whatever that depth is.  

Mine was  75mm sand cement screed

Dirt cheap near enough cling film polythene 

100mm pir

50mm pir to cut upto any pipes for sinks, baths etc.  I mixed a very weak screed 7:1 and infilled over so the top sheet sat flush. 

Radon barrier 

Sub floor. 

The thing I didn't like about the liquid screeds is that although they heat up quick they also cool down quick.  

[scottishjohn]

speaking from experience of UFH routed into chipboard flooring+tile floors --(20years ago) and living with the quick heat change it gives you

It is bit of a 2 edged sword --our climate here is so changable --cold one day hot next  -so house never overheats but can  do big change in 1 hour or so-every room zoned.

fine if you found some way to make people shut doors every time 

 

 a wife that  always wants windows open every day for a while  no matter outside temp 

as the temp changes fast  It can be good .cos you dont, loose that much heat when  windows open+heating off and  thenshe shuts them quicker .

then it heats back up pretty quick .

can only see a good reason for VERY thick thermal mass if you got MVHR and  cheap off peak electric +ASHP to charge it up at right time

she is still fighting me on MVHR  for new build -a fight she,s  maybe going to loose --

 

Edited November 22, 2018 by scottishjohn