[Greenbuilding] Anyone know about the Legalett Slab System

[Norbert Senf]

Dry stacked 8" concrete blocks (on their sides) can be use to make an air
core floor:

www.masonryconstruction.com/_view-object?id=00000154-2540-db06-a1fe-77488f510000

For air, using parallel ducts with a header at either end is much less
friction than a continuous (series) duct.

....................N

On Sun, Jul 16, 2017 at 10:58 PM, John Salmen <terrain at shaw.ca> wrote:

> Interesting. If a slab is to be used I am a fan of frost protected
> foundations or integrated footing in a cold climate. A lot less ground
> invasive and a lot less concrete. Not so effective here on the west coast
> as we don’t need much depth.
>
>
>
> Now ‘if a slab is to be used’ in a consistently cold place heating the
> slab makes sense if there is sufficient insulation below. The use of air
> has  a very ancient history – as does water. Air though only contains a
> tiny fraction of the energy storage potential of water. They will both
> transfer heat but what it means practically is that air will transfer heat
> quickly and water will transfer it more slowly. From here on it it gets
> more complicated looking at pumps and fans to figure out who is working
> more efficiently but strong suspicion would be that water flow would be
> drawing less energy (heated to a lower temperature, slow pumping velocity)
>
>
>
> What is generally more important to me environmentally is both minimizing
> materials and being a bit qualitative about what the material is for the
> job it needs to do. We currently waste a lot of materials on buildings.
> What seems like a good idea is often bad design.
>
>
>
> Look at the pictures on the lego slab site. A structural slab can be as
> thin as 3” and work well if reinforced properly. The buildup they have with
> what looks like 2-3” pvc pipe (or in another picture galvanized duct would
> probably require 6-8” of concrete. That is a lot of energy intensive
> material to no structural effect (simply contains pipe). Someone could try
> to make an argument about ‘mass’ but typically a well insulated drywalled
> house with a few tile floors has more than enough ‘mass’.
>
>
>
> Also a radiant water slab is typically ½” polyethylene pipe classed as
> either a type 1 or 2 plastic – a bit better on the scale than PVC which is
> a type 3 and has long been recognized as not the greatest – in comparison.
>
>
>
> The most important element is insulation and they are using plastifab
> brand type 1 expanded polystyrene. About 98.8 percent air and 1.1 percent
> of some vinyl monomer (PVC) – expanded with pentane. I don’t have issues
> with that so much as it is effective for the job it is doing and can go
> having some life as it is a solid isolatable and recyclable material (for
> some uses). Its wholesale cost is generally abound 16 cents a board foot
> and retails for about 3 times that. There are better foams and monomers out
> there but guess what PVC is cheap – so industry uses it. What can we do but
> be efficient with what industry gives us thankful people.
>
>
>
> I italicized ‘if you use a slab’ as I’ve eliminated concrete slabs in
> projects as only a footing is required for load bearing elements and have
> used the foam as the floor system with ply sheathing laminated over the
> foam supporting interior walls and finished floors. Radiant heating tubes
> are imbedded in the foam. An FPS footing can be done without an integrated
> slab. Check with your engineer.
>
>
>
> Thanks for the opportunity to comment on that.
>
>
>
> Best
> John
>
>
>
>
>
>
>
>
>
> *From:* Greenbuilding [mailto:greenbuilding-bounces@
> lists.bioenergylists.org] *On Behalf Of *Lynelle Hamilton
> *Sent:* Sunday, July 16, 2017 6:23 PM
> *To:* Green Building
> *Subject:* [Greenbuilding] Anyone know about the Legalett Slab System
>
>
>
> Has anyone had any experience with this?
>
> Many thanks!
>
> Lynelle
>
>
>
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-- 
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
www.heatkit.com
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