I've been looking at this forum all day... and the ATA forum.
In another thread I've mentioned my sloping block (only 1m fall, but still creating significant excavation costs), and how it has been suggested that I ditch the slab currently proposed, for traditional timber floor. Ground floor area is approx 90m2. However I need my floor to have thermal mass; my house will be lightweight timber construction. It is a kit, so changes such as reverse BV would make quite a difference to me.
I understand suspended slabs are $$$, so I'm looking for another way to improve thermal mass performance in the floor - which brings me to my question: Can I add a concrete screed on top of Hebel Powerfloor? What thickness of the screed would be sufficient? I'm concerned about the implications of the added weight for number of joists etc.
(I know Hebel Powerfloor+ is load bearing but as this requires a crane I'm not sure that is a good way to keep my costs down. Hebel Powerfloor is more flexible in that respect.)
I had my heart set on sealed concrete floors, so apart from the increased opportunity to increase thermal mass, aesthetics is one reason why I'm suggesting concrete screed instead of tiling.
In terms of thermal mass, Hebel specifications quotes R0.74 to R3.66 for this product (75mm), but Ecospecifyer indicates R1.6, so I'm not sure what to think.
This is what ecospecifier has to say about Hebel: http://www.ecospecifier.com.au/products/detailed-assessment.aspx?prodid=5072
So, in summary:
1. Could a concrete screed be laid directly over the Hebel Powerfloor? To what thickness?
2. I understand Hebel is insulating - cost/benefit of having polystyrene insulation under it?
3. Would Hebel plus concrete screed be that much more effective for thermal mass than just having a concrete screed over timber floor, which seems to be fairly common-place in the UK: http://www.bordersunderfloor.co.uk/underfloor_heating_photo_stclose.htm
4. Does anyone have any idea of the cost/m2 of laying concrete screed in either Hebel or timber scenarios? (Please indicate thickness of screed for quoted cost if you can)
Comfy