[GSBN] Straw Bale Insulated Ceiling

Tue Feb 4 20:14:35 UTC 2014

Hi!

I have had really good experiences with sheep's wool- Here, it is dirt  
cheap if you buy it unwashed (assuming that cost is an issue).  
Unwashed wool is definitely for owner-builders since it is time  
consuming, but easy.

Both washed or unwashed should be treated with borax.

The good thing about wool, is that humidity, and even water has a hard  
time damaging it and it does not burn easily.

It is best to wash the wool without soap (or the minimum possible) so  
that the straw retains the maximum amounts of Lanolin, which helps to  
protect it. If you need to wash it, you can put it in a woven bag (the  
kind onions or potatoes often come in). An leave the bag in a stream  
for a day or two; let nature do the work!

Another good way to find cheap Washed wool is to buy old, wool  
mattresses in second hand shops, if that is possible in your country.  
Here in Spain they are still fairly easy to find.

I have never tried them, but I bet old wool blankets piled up would  
work good too.

take care,

Rikki Jennifer Nitzkin

rikkinitzkin at gmail.com
www.rikkinitzkin.wordpress.com
0034 657 33 51 62
Aulás, Lleida

“Cualquier cosa que puede ser pensada, puede también transformarse en  
realidad.” Albert Einstein

On 04/02/2014, at 11:35, Feile Butler wrote:

> Thanks to all of you for your replies
>
> Danny and Jorge - you both mention the difficulty in packing the  
> gaps between bales effectively. I suspected that might be a problem  
> - so good to get your practical experience in the field.
>
> You both also say that sealing with plaster is the best way to  
> achieve fire rating. Bohdan mentioned a fire test from Germany -  
> does anyone know who the author is so that I could look it up? Or  
> does anyone have information on thicknesses of plaster required to  
> achieve various fire ratings?
>
> Bohdan - I understand why you are questioning why they don't just  
> use a natural fibre batt. I think a big part of the reason is ethos.  
> The clients have access to plenty of locallly produced straw bales -  
> which are as close to an unprocessed but effective insulation  
> product as they can get. I suppose another option would be to look  
> at accessing and cleaning a load of sheep fleeces. But if that is  
> not an option - then they need to buy a manufactured product. Only  
> sheep's wool is produced in Ireland (which would be a good option),  
> but it is manufactured in the exact opposite corner of the country.  
> Anything else (wood fibre, hemp) would have to be imported from  
> Europe.
>
> But, as you say, if we end up using an excessive amount of timber to  
> support the bales, then that is not a truly sustainable solution  
> either. It's always a balancing act! As I said in the previous email  
> - we're just exploring the option at the moment.
>
> Jorge - I thought that was interesting that you used the LECA with  
> the lime - I presume you did it to have achieve the maximum  
> insulation values. But with an entire bale doing the job for you, do  
> you think that was an excessive detail? Or was there another reason  
> I missed?
>
> I also have to say I LOVED the look of the house when it was  
> entirely enclosed with bales - great to see bale walls AND roof.
>
> And as an aside - I love the colour of the floor too, particularly  
> the yellow. Was that an earth floor? Did you have very pale earth on  
> the site and pigment it up with ochre? It's a really beautiful finish.
>
> Cheers
>
> Feile
>
>
>
>
> ----- Original Message -----
> From: Van Krieken
> To: Global Straw Building Network
> Sent: Monday, February 03, 2014 10:44 PM
> Subject: Re: [GSBN] Straw Bale Insulated Ceiling
>
> I used strawbales in the roof, with a special atention to fill the  
> voids between the bales (its quite time consuming). We sealed the  
> bales with a hidrated (or aerial) natural lime mixed with expanded  
> clay aggregate.
> You may see some pictures here: http://strawhouses.carbonmade.com
>
> All the best
>
> Jorge Van Krieken
> Portugal
>
>
> On Mon, Feb 3, 2014 at 4:09 PM, Danny Buck <dannycbuck at msn.com> wrote:
> Our experience here in New Mexico was that the roof structure gave  
> us a lot of voids between bales that were very challenging to pack.  
> If it is a true attic with a flat open surface to work off of, that  
> would be different.
>
> The surface of the bale that is accessible to air (oxygen) is best  
> sealed with a plaster.
>
> Danny Buck
> Daniel Buck Construction, Inc.
> ----- Original Message -----
> From: Feile Butler
> To: Global Straw Building Network
> Sent: Monday, February 03, 2014 2:57 AM
> Subject: [GSBN] Straw Bale Insulated Ceiling
>
> Hi All
>
> I have clients who are considering insulating above the ceiling with  
> straw bales. They have a large attic which could easily accommodate  
> the bales and plenty of outbuildings, so they don't need the attic  
> for storage.
>
> I have never detailed a straw bale ceiling before, but would like to  
> explore the idea.
>
> One of my main concerns is fire. Is it enough to encapsulate the  
> bales within plasterboard/clayboard on both sides (top and bottom)?  
> If we want to deck out the floor above the bales, would it be enough  
> to coat them in a lime or earth plaster before building up the floor  
> above them? Is there any data out there about the behaviour of straw  
> bales in ceilings that I can show the building control officer,  
> particularly with regard to fire?
>
> Any advice on or experience of straw bale insulated ceilings would  
> be very welcome.
>
>
> Thanks
>
>
> Féile Butler
> MRIAI B.Arch Dip. Arch Conservation Grade III
> Mud and Wood
> Grange Beg, Skreen, Co. Sligo, Ireland
>
> T:  +353 (0) 71 930 0488
> M: +353 (0) 86 806 8382
> E : feile at mudandwood.com
> W:www.mudandwood.com
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