Straw bale construction

[Mike Halmarack]

That's very reassuring. Straw kinda grows on ya dunnit?

I'll delay putting that one to the test for as long as possible.:)

-- Regards, Mike Halmarack

Drop the EGG to email me.

[Anna Kettle]

No, they could be available by now but weren't a couple of years ago when a loadbearing bale house was built in ... um Devon I think. I expect that a building control officer with experience and confidence is a prerequisite and I think the Devon house was "experimental" so if it failed the buck didn't stop with the BCO. Of course it didn't fail.

Round here (Suffolk) I suspect a strategic first move would be to get Ralph Carpenter on board. He is the architect who has won awards for a batch of eco-starter homes in Haverhill.

I shan't rise to that bait :)

Anna

~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

01359 230642

[John Rumm]

Looking back at that grand design's house, he just used waney edged weather boards... simple and effective no doubt.

[BigWallop]

The more I'm reading about this type of build, the more I like it. The basic types seem to be, really, just a timber frame with the straw wrapped round it and rendered over. Very simple. Very effective. And very energy efficient according to all the info' I've dug up. One owner in the USofA says they have saved the cost of building the house in what they would have paid in fuel bills over last twelve years. They also say that the build, in their climate (temperate I think), is expected to last in excess of 120 years with only minor maintenance works.

Looking good for the strawbale housing market, me thinks. :-)

[biff]

An article on straw building appeared in Permaculture Magazine and is available online here:

[bigcat]

AIUI the basic problem with straw bale is that when render deteriorates, or something allows water onto the straw, repairs must be made rapidly else things deteriorate fast. And yer average jo isnt nearly quick enough with repairs. So ideal for someone wililng to inpsect it regularly and repair themselves promptly, but that just doesnt describe most people.

NT

[Owain]

Hold in with long wooden staves driven into the bales.

Blue plastic held down with baler twine.

Owain

[The Natural Philosopher]

Andrew Firebarce are giooid on structural calcs. The BCO will take their word for it.

Well you know Anna, there are two ways to do things: let the damp in and arrange for it to get out outwards, or not let it in at all barely, and let it migrate inwards and have a bit of internal heating and ventilation.

Your way is number one, but I see no problem with modern ways to insulate/heat/ventilate and put a waterproof skin outside- you need that anyway to get rid of the water that humans give off.

[The Natural Philosopher]

I think it could be incredibly effective. With 3ft thick walls at the sort of ciondictivity lebvels of maybe high densiy polystyrene, there would be almost no heatloss through the straw at all. Only the doors windows ventilation and floor and roof would need actual attention paid.

It really is a hugely fast and energy efficient way to build IMHO.

[The Natural Philosopher]

Its the same for timber.

[The Natural Philosopher]

You know, SWMBO wants a summerhouse thing...I wonder if our farmer will have some bales...

[bigcat]

But with quite a different time scale. Wet timber lasts a few years, wet straw lasts what, a few weeks?

NT

[The Natural Philosopher]

Dunno. About 15 years for straw thatch, and up to 60 for reed?

That's fully exposed - but not dug-in-the-ground straw...

You have to look at what will decompose it.

Sodden straw in the ground is actually EATEN by things like nematodes.

Wod is attacked by fungi and wood biring insects etc.

Once in structure and even marginally drier than the ground, these things don't happen.

Thatched rooves 'wear' more from constant pounding of water droplets for example. Then build up of dust and dirt allows damp soil areas to appeaar, and grass and other weeds and moss takes root...and the other life then follows.

I would see the lifetime of a straw vbale wall doine decently as being similar to timber - a couople of hundred years.

Maintenace would be a cinch. cut a hole, take our rotten, and stuff with new straw and make good..

[Owain]

You've got me humming "follow the yellow brick road" now...

Owain

[Asher Hoskins]

That's next on my list of things to investigate! Am I right in assuming that a coat of lime mortar on the outside of the wall would need to be balanced by a similarly breathable covering+paint on the inside of the wall? Or given a typically dry, heated interior and a wet British winter outside would this just allow water to migrate the wrong way, inwards?

There's a good guide (78 page PDF) to strawbale construction on her website:

Buildings with a structural timber framework and straw infill are

Building regs were the main reason for thinking about a wood framed house, although wood framing does mean that you can put a roof cover on before stacking the bales - a very useful thing in the UK climate.

Asher.

[Asher Hoskins]

Is this the "British Board of Agrement"

I shall contact them. Googling reveals several large conventional buildings using straw bale insulation so presumably some official specs must exist.

I also found a note on one document saying that strawbale insulation is treated with sodium borate to prevent rodent damage.

Asher.

[Mike]

I think you've hit on a problem. Under Prescott's latest planning laws 3 ft walls leaves you about 2 ft for the living space between them :-(

[Mike]

Yes. Give them a phone and let us all know as this is obviously a topic a lot of people are interested in. I was intending to build a stone barn myself next summer but now wondering if straw might be easier.

[Anna Kettle]

Don't know them but will squirrel the name away for future reference. Where are they based?

You got me thinking about the differences between the two building methods and I came up with

Traditional: Breatheable Slightly flexible Eco friendly ... man

Modern: Impermeable Rigid High embodied energy

Straw bales sit firmly in the traditional zone on the ecofriendly front, being bio and degradable. On reflection I can't see a problem using them under an impermeable skin so maybe there is potential for crossover there, but the design would have to be thought through with care if they are to be loadbearing cos they will definitely not be rigid and impermeable is only any good if it stays that way

Anna

~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

01359 230642

[Anna Kettle]

Baler twine aint what it used to be. I remember when it only came in orange but the last bale I bought was blue

Disgusted of Pakenham on Sea

Oh good! It would make an excellent summerhouse and if you tell us all about it I will be able to build a strawbale house by proxy

Anna

~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

01359 230642