[Strawbale] Fwd: Repair work on danish strawbale house

Dave Howorth dave at howorth....uk
Wed Oct 5 22:00:07 CEST 2011

On Wed, 2011-10-05 at 01:02 +0200, Michael M. Jørgensen wrote:

>  Have you seen the way the aussie Emerald SB-House was repaired using
>  polystyrene EPS blocks to replace the damaged bales in the bottom of
>  the walls. 

I wasn't aware of it but I've now found some mentions of it.

>  This is not an option for me, as the walls in general are
>  coming down. The timber frame pillars are inside the house giving the
>  actual bale wall nothing to support is if the bottom doesn´t bear it..
>  BUT, their solution of EPS could be used in my case too, as I could
>  use this to elevate the strawbales from the ground. Simply build the
>  first 50 cm in EPS and then continue with bales. The other alternative
>  would provide a much heavier wall which according to our ingenieur
>  requires a different foundation with steel beams and a lot of extra
>  costs. 

Am I correct to think that your walls are not load-bearing? If so, I
can't think of any problems with your plan; it sounds a very good plan.
If the walls are load-bearing, I suspect it should still be possible,
but you would need your engineer to check all the factors. It has the
great merit of simplicity.

Your structural engineer will be able to confirm the correct grade of
EPS to use for strength and stability; there shouldn't be any problem
about the insulation value. Are you aware that EPS doesn't keep water
out as much as XPS does? I haven't really thought about which would be
better for your application.

I expect you will need some reeds or mesh over the EPS if you plan to
use the same render as for the bales. You might also need some primer
coating; I'm sure the external insulation specialists could advise (EWI,
ETICS etc). You can easily cut some sloping drainage channels in the top
to allow your bales to drain outward.

>  I know it does not sound especially eco to use EPS, but on the other
>  hand, if the alternative is to use a lot of galvanized steel and on
>  top of that some manufactured "bricks".

There are many different opinions about what is eco but my personal view
is that this would be a sensible choice in your circumstances.
Polystyrene is one of the more innocuous plastics and as you imply,
other alternatives also embody a lot of energy.

> But what do you say - can you think of other materials to do the trick
>  of elevating the bales, keep the walls light and even remain eco?

I suppose it might be possible to make some form of timber box structure
that could be filled with a porous mineral insulation but that would
need careful design to avoid the possibility of rot if it flooded again.

> VH Michael
> Michael M. Jørgensen

Apologies for misspelling your name in my first reply :(

Cheers, Dave

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