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VSS

extensions

There are five of us, currently living in a two bedroom house, and my son, nearly ten, has to sleep in the sitting room. Extension desperately needed.

Problem is that it all costs a lot of pennies.

We have kicked around various ideas and are unable to come up with a definate answer. Like the idea of building with straw bales, but this has its problems.

1) Existing house is stone built - how would you key a bale extension into the house.

2) Local planning would insist on a welsh slate roof - would the walls be able to support such a heavy roof structure?

3) Would it be feasible to put up what would effectively be a steel framed building (along the lines of an agriultural building) to support the roof and fill in the walls with bales?

4) Is there a big fire risk (i assume the straw is treated in some way) and will i be able to get it insured?

5) Life span?

If anyne has any ideas, or experience of this i would be grateful for some guidance.

www.viableselfsufficiency.co.uk
Mary-Jane

I'll put Gervase in your direction over the weekend VSS. We're out tonight - but he's around tomorrow. He should be able to give you some pointers.
Jonnyboy

From the limited amount I have read there is a method of building a wooden frame and using the bales as simply an 'infill' rather than being loadbearing themselves.

As timber framed houses suppport tiled roofs I can't see that a steel frame would be particularly necessary.
Cathryn

Try CAT site - or give them a ring (or wait for Gervase)?
dougal

Meantime, to say that if not prevented by listing, conservation area, AONB, etc, you can do some things without planning permission - its called "permitted development". http://www.selfbuildabc.co.uk/building/permitted-development.htm
And Google it for more info.
However if you DO have any of those type of local restrictions, then they are going to be the first thing to concern yourself with - even before cost, because they will affect the cost by narrowing down your possibilities. No point researching something that isn't going to be allowed.

Straw bale walls are not generally load-bearing. A frame of some sort is needed.
The straw is best smothered with (lime) plaster, inter alia restricting the air available to a fire. Other claddings can be used. Generally electric cabling would be special self-extinguishing stuff, (and armoured against rodents?)

I wonder if the simplest thing might be to create additional "living space" in a "permitted development" outbuilding or two.
Chez

Or speak to Amazonails - http://www.strawbalefutures.org.uk/ - fantastically helpful crowd.
tahir

dougal wrote:
I wonder if the simplest thing might be to create additional "living space" in a "permitted development" outbuilding or two.


Definitely worth exploring, might depend on what the planning dept defines as your curtilage.
Nick

Re: extensions

VSS wrote:

1) Existing house is stone built - how would you key a bale extension into the house.

2) Local planning would insist on a welsh slate roof - would the walls be able to support such a heavy roof structure?

3) Would it be feasible to put up what would effectively be a steel framed building (along the lines of an agriultural building) to support the roof and fill in the walls with bales?

4) Is there a big fire risk (i assume the straw is treated in some way) and will i be able to get it insured?

5) Life span?


No expert on this, but from extensive reading, rather than doing...

1. Can be done, no problem.
2. Maybe, but see 3.
3. No, no steel. Causes condensation and rotting, but a timber frame would be just fine. Think along the same lines, with straw infill, and the roof rests on the timbers, resting on the foundations.
4. None at all. Straw doesn't burn because it's packed very densely, then rendered with something, eg lime plaster or clay, depending on your locale and choice.
5. In the UK, unknown over 20 years, because it's a 'new' technology. but buildings in the States are over 100 years old.

Have a wander to aecb.com, but don't expect a rapid response. And, I'd point you at a 7 book from Amazon. Link.
derbyshiredowser

you are allowed to floor out your loft put in plasterboard walls insulation and line the roof with wickes foil insulation without planning permission put in a loft ladder and use it as a store room. I store an 18 year old boy in mine. I reckon it cost 1500 doing it myself.
judith

derbyshiredowser wrote:
I store an 18 year old boy in mine.


Laughing
MarkS

derbyshiredowser wrote:
you are allowed to floor out your loft put in plasterboard walls insulation and line the roof with wickes foil insulation without planning permission put in a loft ladder and use it as a store room. I store an 18 year old boy in mine. I reckon it cost 1500 doing it myself.


yeah but you are in breach of fire safety rules. (ignoring for the moment all the building regs and the fact that foils are crap).

Loft conversion is not always as easy as people think it is.
Jonnyboy

dougal wrote:

Straw bale walls are not generally load-bearing. A frame of some sort is needed.


Not so, the 'Nebraska' style as recommended by CAT, and which takes it's name from the earliest proponents of the technique at the turn of the last century, utilises pinned and offset bales as it's method of roof support.

Infill structures have advantages if you are going up a couple of stories or require extensive glazing. But depending upon your design, tensioned bales can be a perfectly suitable, and simpler more cost effective form of structure.
Nick

Jonnyboy wrote:
dougal wrote:

Straw bale walls are not generally load-bearing. A frame of some sort is needed.


Indeed, missed this. You can get to two stories, with a solid roof with no extra support bar the bales. You're limited on window and door sizes, but not drastically so.
MarkS

Re: extensions

VSS wrote:
There are five of us, currently living in a two bedroom house, and my son, nearly ten, has to sleep in the sitting room. Extension desperately needed.

Problem is that it all costs a lot of pennies.

We have kicked around various ideas and are unable to come up with a definate answer. Like the idea of building with straw bales, but this has its problems.

1) Existing house is stone built - how would you key a bale extension into the house.

can be done. Bales can be load bearing or as said used as primarily for insulation in a steel or wood frame. careful about condensation if steel frame.
VSS wrote:

2) Local planning would insist on a welsh slate roof - would the walls be able to support such a heavy roof structure?

slates are lighter than many alternatives. But yes bales can support a roof. wallplates spread the load
VSS wrote:

3) Would it be feasible to put up what would effectively be a steel framed building (along the lines of an agriultural building) to support the roof and fill in the walls with bales?

yes, but see comments about condensation
VSS wrote:

4) Is there a big fire risk (i assume the straw is treated in some way) and will i be able to get it insured?

No big risk, the bales are very tightly packed and rendered in and out. they dont easily burn. insurance may be variable - might have to find a company that is intelligent.
VSS wrote:

5) Life span?

hundred years enough?
dougal

I'd still hold to my opinion that straw bale walls are generally not used as load bearing - at least here in Europe. Not saying it can't be done, or shouldn't be done, just that it would seem relatively rare (or relatively unpublicised), other than for small, simple and relatively temporary structures.

Regarding insurance there are folk like these that might be worth a call http://www.naturesave.co.uk/

And the Ecological Building Society is known to be very open to the idea of providing mortgage finance for 'unconventional' building - and straw bale construction specifically. http://www.ecology.co.uk/
VSS

Thanks for all those ideas - i hadn't thought about timber framing -daft really.

I think the biggest difficulty will be financing the project and i expect we will have to do the majority of the work ourselves (with help from family and friends i hope) to make it a possiblity.

The problem with diy we are so busy that the Iestyn (10) will probably have left and got married by the time we have done.

Having said that i get the idea that timber frame and straw bales would be pretty quick - an i right?

www.viableselfsufficiency.co.uk
Jonnyboy

VSS wrote:

Having said that i get the idea that timber frame and straw bales would be pretty quick - an i right?



In terms of labour it is fairly straight forward. You do have slack times, such has having to leave the bales to settle for several weeks after tensioning. And there is something about leaving lime for a few weeks that gervase will be able to advise on.

But a single story building should be perfectly achievable. And we very well insulated.
dougal

VSS wrote:
... - i hadn't thought about timber framing - ...

Take a look here!
http://www.strawbalebuildingassociation.org.uk/contacts.html
Nick

dougal wrote:
I'd still hold to my opinion that straw bale walls are generally not used as load bearing - at least here in Europe.


Based on the fact that straw isn't generally used, you're correct. However, within straw build structures, either method is quite acceptable. There are plenty of buildings that use them structurally.

For an FAQ that talks about many of the original questions, and many more, look here.
http://www.strawbalefutures.org.uk/FAQ.html

It even gives you some cost guidelines.
VSS

[/quote]

But a single story building should be perfectly achievable. And we very well insulated.[/quote]

Two storeys? A dining room would be nice as well as the boy's bedroom - or am i pushing my luck?

www.viableselfsufficiency.co.uk
Nick

Two should be fine. Think sloping roof, with low walls at the edges, raising to full normal height elsewhere.

Have a look at Amazon nails' site. Tons of buildings on there.
Jonnyboy

Nick Howe wrote:
Two should be fine. Think sloping roof, with low walls at the edges, raising to full normal height elsewhere.

Have a look at Amazon nails' site. Tons of buildings on there.


Like a 1 1/2 story? that's an excellent idea. If you wanted to spend a little more to create dormer windows you could have quite a lovely looking structure.
wellington womble

MarkS wrote:
derbyshiredowser wrote:
you are allowed to floor out your loft put in plasterboard walls insulation and line the roof with wickes foil insulation without planning permission put in a loft ladder and use it as a store room. I store an 18 year old boy in mine. I reckon it cost 1500 doing it myself.


yeah but you are in breach of fire safety rules. (ignoring for the moment all the building regs and the fact that foils are crap).


Only if you call it living space. For storage, building regs are not required! You can even use it - so you can call it, say, a studio or home office, you just can't call it a bedroom.

We sold our last house with an ensuite 'studio'! (The stairs were too steep to meet current bulding regs)
RichardW

Jonnyboy wrote:

In terms of labour it is fairly straight forward. You do have slack times, such has having to leave the bales to settle for several weeks after tensioning. And there is something about leaving lime for a few weeks that gervase will be able to advise on.

But a single story building should be perfectly achievable. And we very well insulated.


You only tension a structural straw wall to help reduce settlment. Its not needed in a framed wall. If you wait for all the settling to be done it will be a very long time (years). Thats why when building with straw you leave settlement gaps over doors & windows.

Justme
Jonnyboy

Justme wrote:


You only tension a structural straw wall to help reduce settlment. Its not needed in a framed wall.



3 weeks is recommended to help eliminate cracking in the lime plaster, according to my book.
RichardW

Jonnyboy wrote:
Justme wrote:


You only tension a structural straw wall to help reduce settlment. Its not needed in a framed wall.



3 weeks is recommended to help eliminate cracking in the lime plaster, according to my book.



I bow to your book lol. I only read a PDF about straw builds so have no real experiance either.

Justme
MarkS

Jonnyboy wrote:
Justme wrote:


You only tension a structural straw wall to help reduce settlment. Its not needed in a framed wall.



3 weeks is recommended to help eliminate cracking in the lime plaster, according to my book.


which book is that then ?


Interesting articles in Green Building Mag. Earthships, cob and strawbale.
Nick

Re: extensions

Nick Howe wrote:

This one.Link.
MarkS

Good is it? Given that I presume you all have a copy ?
Nick

Well, I have a copy, and it explains everything very simply and very well. I've not built anything from it, so it might all be lies and hogwash, but...
MarkS

fair enough. Ta.
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