Starting from scratch...

[Greenbeast]

well it was always going to be a few years off, but it's still in the back of my mind.

I've got enough problems with my current place!!

i must admit to not frequenting the forum for a month or two

[Baz]

This has sort of turned into the straw house thread.
Are straw bales really a good idea? They are so compressed that much of the air has been squeezed out so thier insulation value reduced. Information on the web is variable but shows U values between 2 and 4 times worse than rockwool meaning the 18 inch wall may only be as good as a filled standard cavity wall. A better but still eco solution would be to make a cavity using straw board then fill it with loose thatching straw laid along the length. Still used straw but less of it and provides much more trapped air. This is the sort of thing BRE and Bath University (see other thread) should be evaluating.

Thermal mass. An ealier post mentioned a Canadian building having a high mass wall but withthe insulation on the inside. This is actually a good idea. The wall mass buffers the overnight low by taking up a mean day/night temperature so the heating does not have to work so hard. The inside has low thermal lag so quickly heats up using less energy. This suits an intermittently occupied building better than the insulation on the outside. If you think about it or do some calculations you find it uses less energy that way.

[daftlad]

This has sort of turned into the straw house thread.
Are straw bales really a good idea? They are so compressed that much of the air has been squeezed out so thier insulation value reduced. Information on the web is variable but shows U values between 2 and 4 times worse than rockwool meaning the 18 inch wall may only be as good as a filled standard cavity wall. A better but still eco solution would be to make a cavity using straw board then fill it with loose thatching straw laid along the length. Still used straw but less of it and provides much more trapped air. This is the sort of thing BRE and Bath University (see other thread) should be evaluating.

From what I have read straw has a u value of between 0.13 and 0.20 and 100 mm of celotex would have a u value of about the same (0.19). Straw can be structural and it is virtually a waste product. To build a straw cavity wall would require structural components, plasterboard, vapour barriers and some kind of external cladding, straw bales need a bit of lime plaster or earth plaster. Oh and they can be built with less skill and go up very quickly.Maybe using straw as loft insulation (once treated) could be intresting.
ta ta

[Greenbeast]

i think the ease of construction and eco credentials far out way the extra thickness of walls needed

[martin]

This is something that re-occurs throughout renewables - the inability of people schooled in "conventional" (energy intense) disciplines to get their heads round such things - they're used to going for "most efficient" as sold to them by some industry or another - as we all know, it isn't by any means as  simple as that.......... whether it be "heat per square inch" produced by solar hot water panels to "u values" - I think we should look at these things from "the other end" and cost the energy input first

[Moxi]

With regard to local planning permission would a straw bail and wood frame summer room (single storey with pitched roof) and rammed earth floor be considered as a temporary structure or permanent - would it require planning permission? or could it be considered as a conservatory?

I was thinking of two side walls (bail's in wood frame) say 3 to 4 meters out from the back of the house, south facing glazed floor to ceiling, with rammed earth floor so this threads quite interesting.

Moxi

[Greenbeast]

give the planning dept a call, you don't have to say who you are or where you live.

you can sound them out about it

[Baz]

I think the Bale proponents may be a little too wedded to the conventional - and see bales as conventional bricks. We established earlier in this thread that bales are not often used in a structural mode.
As enumerated by Daftlad a bale wall only achieves the equivalent of 100mm of Celotex whereas I think a sheave wall might be 200 - 250mm eqivalent. Surely halving your heat loss can't be ignored. Despite being a 'waste product' bales are not cheap, perhaps as expensive per m2 as celotex.

Moxi. I'm no expert but I think if detached as a summerHOUSE it would be like a garden shed - minor restrictions on height, volume, and proximity to garden fence. Being attached as a summeROOM could move it into a different category requiring safety glas, fire regs etc.

[Moxi]

Thanks Chaps,

I do seem to have got my house / room description mixed up somewhat.  Sun room is what I'm after, I'll try the planning people again but last time I called on a separate topic I was passed around the whole department (or so it seemed) with a promise to call me back (which never happened) but maybe worth trying again with more perseverance on my part.

Moxi

[biff]

hi foks,
       having spent my working life in the building trade i have to admitt that terms like rammed earth,straw and baled straw are a bit of a shock to my system.but i have learned that some of the things we believed to be perfectly good practise have,at the end of the day turned out to be nothing much more than decorative finikyness,ie,,modern brickwork,this is a terrible addmission but no matter how you look at it,it is true.
        the old yellow stocks with straw mixed through them had good insulating properties,even the soft hand made bricks are easy to live with,modern bricks tend to be rated class a or b in engineering terms,they are hard and cold,
     then there is the structural strength,i always believed that brickwork was as good as you could get but having witnessed brickwork being tested against laternal stress i was frankly horrified,it has taken all these years for this to sink in,i have ,down through the years, built my own home in different styles,in different locations.i am happy with the present house,which uses 2L2 and kingspan throughout,each room is drylined,including the solid block internal walls,and the cavity is pumped,
 if i were to move,(heavens forbid) the next house would be constructed from the large 6mtr upright hollow flooring beams,slotted into steel on top and going 8ft underground to where the bedrooms would be,above ground would be just a medium lounge small kitchen and b/r.modern insulation,and damproofing membranes such as "esso butyl" would take care of most problems.the roof would look like the normal flat tiled peaked roof but structered with steel.such a house would withstand future hurricanes and earthquakes,(well nearly )
         dream on biff,