# StrawBale Construction for Music & Theatre rooms



## Quiltzig (Jan 7, 2013)

Hi all,
As requested, I am going to try to describe my rooms (a large Music Room, and a smaller theatre room).
I got the idea for using strawbales when I visited a friend who had built one. I was struck by the lovely acoustics, even though the floors were tiled, it did not sound "busy" and there was a nice decay time & good speech intelligibility. So when the opportunity came to build a new house, it just had to be strawbale ! That was nearly 8 years ago, and it took 6 years to build, but we have been enjoying it for 2 years now.
The bales are actually Barley Straw (waste product from the brewing industry) and these bales are normal 2 string bales just like you would see on most farms. The main use for this material is animal bedding in zoos etc.
The interesting thing about building with bales is that you need to keep them dry, so you build a steel portal framed structure,and put on the roof before you stack up the bales to form the walls. The insulation values are very good. 
The bales are about half a metre thick, and are stacked up between a wooden footplate and the top plate, then pinned through with long sticks. Chicken mesh is stretched over them & stapled to the top & bottom plates, then 3 coats of plaster are applied.
I have posted some pictures of various stages of the construction. First pic shows the room as it is now. Next pic is the steel framing, then the bales arriving by truck, and one of the rear wall of the music room before it was plastered. I have to re-size a lot of the pictures, so will go do that and post some more later. Any questions are most welcome !

Now about the rooms...
I decided to use "Golden Ratios" as far as possible, especially for my Music Room. This room has a length of 10.43 metres, a width of 5.4 metres and a cathedral ceiling which starts at 4.1m high and the apex is at 6m.
For materials, I decided to try to balance the reflective and absorptive by choice of materials. The floor is 125mm thick concrete, with thick rubber underlay and very soft "Eco fib, ierre" carpet. The walls are covered with lime plaster, which although very hard, has a very even balance. The walls were left "wonky" - what we call medium wonk - ie; there are substantial irregularities, waviness, in the walls, they are not even close to flat and only plumb at the top & bottom where they meet the wall plates. This helps break up standing waves and spread room nodes. The ceiling is made from a very soft timber - Poplar sarking. This was placed onto battens that were in turn placed onto plywood with a wool insulation between, so all these materials were softer and "lossy" . whereas the walls had varying thicknesses of plaster applied to them, a little over 6 tonnes in the music room alone and 147 tonnes for the whole house !
The only treatments that I have used are two diffusors one at the front and one at the back in the centre of the walls, and a bass trap in each corner. These traps are tuned to the dominant modes, which were ar 35Hz, 72Hz and 110Hz. Overall the response is within a few dB across the entire frequency spectrum. The room is as near perfect as I can get it, and stores virtually zero energy (try turning up your voule to about 95dB, playing music for 5 minutes and then pressing the paue or mute, normally you will hear a tapering off os the sound as the reflections decay, in this room the stop is instant, with zero decay. The interesting approach os using various material to balance the sound results in a lively sound with great dynamics, no loss of bass weight and slam and no ringing or slap echoes.


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## dougc (Dec 19, 2009)

Very interesting structure. I look forward to hearing more about it, and of course, looking at more of the build photos!


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## NBPk402 (Feb 21, 2012)

Very interesting way of building a wall. :T 
Won't it smell? I would have thought it would become a fire hazard when it dries out.


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## robbo266317 (Sep 22, 2008)

This is a popular "alternative" method of construction in England and has been highlighted on such shows as Grand Designs.
Here is a good rundown http://www.vivahomes.com.au/Strawbale-Homes-Design-And-Build.aspx


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## Quiltzig (Jan 7, 2013)

ellisr63 said:


> Very interesting way of building a wall. :T
> Won't it smell? I would have thought it would become a fire hazard when it dries out.


The straw has no smell at all as it is totally dry stalks. Once the lime plaster is applied it has 5 times the fire rating of a normal stud & Sheetrock wall. Google Strawbale Fire ratings for a You Tube video of tests - it is like trying to burn a phone book !

The lime plaster is a naturally anti microbial material, it absorbs moisture which results is a very dry and healthy environment, which is why lime plastered walls have existed since .the 12th century.

Everybody who visits makes similar comments about the "feel" of the house and the organic nature.
Once you have loved in such a cool (in summer) warm (in winter) and dry ( all year round) you will understand.:T


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## B- one (Jan 13, 2013)

Very interesting,your energy bills must be very low. Thanks for sharing the pics.


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## Mike Edwards (Mar 10, 2011)

straw bale houses are INCREDIBLE for energy savings and comfort. my friend built her house that way. I wish I had the money to build a house that way instead of the one I'm in now  (leaks like a sieve energy wise)


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## Quiltzig (Jan 7, 2013)

Mike Edwards said:


> straw bale houses are INCREDIBLE for energy savings and comfort. my friend built her house that way. I wish I had the money to build a house that way instead of the one I'm in now  (leaks like a sieve energy wise)


Yes, you are quite correct, they are very cool in summer and warm in winter. Our house has 6'6" deep eaves which means that no direct sun hits the windows in summer, but in winter the low sun angle allows passive solar heating. We also have 100 solar tubes on the roof which heats our hot water and underfloor. Today it is a sunny day and we have a hot water temp of over 70 degrees C.


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## Quiltzig (Jan 7, 2013)

Here is a picture of the front wall of the music room being plastered.
The first coat is 10mm thick & is applied over the chicken mesh.
The second coat is also 10mm thick and has a fibreglass mesh pressed into it as it is being applied.
The final coat is applied with plastic trowels (can't use steel as the lime reacts with it leaving black marks) and is hand burnished to a lovely marbled finish that is almost as smooth as glass.
3 tradesmen spent 2.5 years fulltime in plastering this house inside and out !


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## NBPk402 (Feb 21, 2012)

How is it for soundproofing a room? How do you run electrical wires in bales?


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## Quiltzig (Jan 7, 2013)

ellisr63 said:


> How is it for soundproofing a room? How do you run electrical wires in bales?


The soundproofing is incredibly good, but the room does not trap the sound inside as would be the case with use of soundproof sheetrock, or multiple layers of it.
The thickness of the walls and the tubular nature of the straw tends to trap and absorb sound over a wide frequency range. The solid nature of the plaster gives solid bass and the waviness of the walls deters standing waves and gives good dispersion,

The electrical wires can be done in two ways. We just ran ours between the bales and spray painted lines onto the walls to show where they were so that nobody damaged them with staples etc during the bale work. Others have run plastic conduits for them, but we only did this between floors and between areas where we wanted to "future-proof" ourselves. In these cases we ran 100mm pipes between the bales and packed loose straw around to fill the gap. These have been quite handy in adding extra cables for things that we overlooked ! I have managed to get wires through the walls after they were plastered by simple drilling a hole in the plaster & then using a long rod with a hole in the end (sorta looks like a very large sewing needle) to thread it through the wall & into the ceiling - this worked a treat for adding a PIR for the alarm in a location that we had not expected to need one.


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## ALMFamily (Oct 19, 2011)

What a neat idea - I have never actually heard of building this way before. Subscribed!


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## Quiltzig (Jan 7, 2013)

Here is a picture of one of the outside garden walls showing half of it with 3 coats (the left side) and the other side with 2 coats - the first is called the scratch coat as it has large grooves in it to allow the second coat to stick. The last finishing coat is just 5mm thick


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## alfa-74 (Aug 31, 2013)

Quiltzig said:


> http://www.hometheatershack.com/gallery/file.php?n=13816
> Here is a picture of one of the outside garden walls showing half of it with 3 coats (the left side) and the other side with 2 coats - the first is called the scratch coat as it has large grooves in it to allow the second coat to stick. The last finishing coat is just 5mm thick


This is very interesting!!!!!

Can i ask what is the cost per m2 when compared vs regular construction method?


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## Quiltzig (Jan 7, 2013)

alfa-74 said:


> This is very interesting!!!!!
> 
> Can i ask what is the cost per m2 when compared vs regular construction method?


We employed contractors (the most expensive way to go about it) and it worked out around the same as other building methods. Here in NZ the costs are around NZ $2000 - $2500 per square metre for a high quality of fixtures & finish - our building ended up at $2265 - so about average. Now that we know what we learned during the build we could & would do a lot of the straw work ourselves, and that would save a lot of labour costs.


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## ALMFamily (Oct 19, 2011)

One question my wife asked when I pointed this process out to get - what do you do about insects in the straw?


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## alfa-74 (Aug 31, 2013)

Quiltzig said:


> We employed contractors (the most expensive way to go about it) and it worked out around the same as other building methods. Here in NZ the costs are around NZ $2000 - $2500 per square metre for a high quality of fixtures & finish - our building ended up at $2265 - so about average. Now that we know what we learned during the build we could & would do a lot of the straw work ourselves, and that would save a lot of labour costs.


Thanks!!! That´s good to know, cost is good and you have lots of benefits


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## Quiltzig (Jan 7, 2013)

During construction we did not notice any insects in the straw. My theory on this is that as the straw is dry stalky material, there is no nutritional value in it, and it is not decomposing (as it is perfectly dry) so there is nothing for them to eat or get interested in. Once it is covered in plaster there is no way they can get in, so again no problem.


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## ALMFamily (Oct 19, 2011)

Quiltzig said:


> During construction we did not notice any insects in the straw. My theory on this is that as the straw is dry stalky material, there is no nutritional value in it, and it is not decomposing (as it is perfectly dry) so there is nothing for them to eat or get interested in. Once it is covered in plaster there is no way they can get in, so again no problem.


Thanks for the description - I figured once the plaster was on there would be no issues, but I had a hard time explaining to her why the insects would not be there in the first place...


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