Attempting a straw bale, off-grid passive house in Somerset

[Smallholder]

Hi Folks!

 

Having used BuildHub as a learning resource for a little while, I've pulled my finger out and got a sign-in.

 

After a year of getting our ducks in line, we are about to apply for planning for a home on our smallholding in Somerset.

It may be on the optimistic side, but we are aiming for an off-grid build, to passive house standards (intending to get certified), primarily from sustainable materials.

 

The design is very close to complete now, and the next stage for us is to put our plans in front of a design review panel. Part of the reason for this, is that our planning application will be made under paragraph 80e (previously paragraph 79, before that paragraph 55).

(A national planning policy, first established in 1997, which sets out various circumstances which can enable the erection of new isolated dwellings in the open countryside.)

I understand that getting a good report from the design panel is a significant step towards success with this planning route.

 

The fundamental plan is to try and build:

• A 4 bed detached home
• Concrete-free foundations
• Using load-bearing straw bale construction technique
• To achieve an overall carbon negative construction
• Off-grid
  • A large PV array
  • Several large lithium batteries for storage
  • Bore hole for water
  • WETs system to process grey/black water
• Achieving passive house certification 

 

We still have a lot to figure out, but I'm learning more every day. Thanks for everyone on here for contributing to BuildHub as an information resource.

[gc100]

Good luck. Admirable.

[Smallholder]

Thanks!

 

The easy bit is having grand ideas. The next part will be harder.

[Gordo]

You are brave. Strongly advise you find someone with first hand experience to discuss the issue they had and how to avoid them. Don’t reinvent a wheel

[ToughButterCup]

First, welcome. Next, lay in a good supply of cider. I think you'll need it.  Network, network, network.

Good luck 

Ian

[Smallholder]

15 minutes ago, Gordo said:

You are brave. Strongly advise you find someone with first hand experience to discuss the issue they had and how to avoid them. Don’t reinvent a wheel

 

Something about a thin line between bravery and being a total eejit!?

 

I've found some local self-builders that have used straw bales, and they seem to have got on well. But not yet found much in terms of fully off-grid.
There's a cool place on the Mendips that has a large WETs system, and I went there recently for a presentation by the chap that designed and built it. That was very interesting.

But good advice, I'll try to network and learn from other peoples projects

[Smallholder]

17 minutes ago, ToughButterCup said:

First, welcome. Next, lay in a good supply of cider. I think you'll need it.  Network, network, network.

Good luck 

Ian

 

We've been planting an acre of cider apple trees, but I hope that's more of a long term investment than this planning application will be!

 

I'll heed that advice, and make a point of networking.

I'd be interested to see how many vaguely similar projects there are in the local area

[Gordo]

2 minutes ago, Smallholder said:

 

Something about a thin line between bravery and being a total eejit!?

 

I've found some local self-builders that have used straw bales, and they seem to have got on well. But not yet found much in terms of fully off-grid.
There's a cool place on the Mendips that has a large WETs system, and I went there recently for a presentation by the chap that designed and built it. That was very interesting.

But good advice, I'll try to network and learn from other peoples projects

That’s encouraging. I’m sure you will make it work

[Alfie]

Best of luck @Smallholder

 

We had our first Design Review Panel last month, we've got a bit more work to do before finally submitting proper. Sounds like you're a bit ahead of us. Fingers crossed that they fully endorse the design

[Smallholder]

17 minutes ago, Alfie said:

Best of luck @Smallholder

 

We had our first Design Review Panel last month, we've got a bit more work to do before finally submitting proper. Sounds like you're a bit ahead of us. Fingers crossed that they fully endorse the design

 

Sounds like you're ahead.

I'd be very interested to hear about your experiences, and what feedback you got.

 

Have you written about it anywhere?

[Conor]

Do you have a source for the straw bales? Had some friends who wanted to build a straw bale house. The plot sale eventually fell through, but they were never able to find a source of the right spec of straw bale. All the modern bailers make them far too big.

[Smallholder]

2 minutes ago, Conor said:

Do you have a source for the straw bales? Had some friends who wanted to build a straw bale house. The plot sale eventually fell through, but they were never able to find a source of the right spec of straw bale. All the modern bailers make them far too big.

 

As far as I'm aware, there are 2 main bale sizes that we use in the UK. Small bales are about a metre long (by 460mm wide & 365mm high), and big ones are 2.4m long (x1.2m x0.7m).

You can build with either, but nearly all residential builds use the smaller ones. 

 

Small bales can be moved by hand, give a sensible wall thickness and great U value.

Big bales are quicker to build with, and give better insulation. But need a telehandler to move them, and you end up with very thick walls.

Small bales seem to be very easy to source, and only cost a couple of quid each.

 

I wonder what problems your friend had finding them? I'm confused 

[Cpd]

Sounds like a great  project, I looked briefly at buying a straw bale house in australia when I lived there, I absolutely loved  the look of it but the location was wrong for me.

Have you been on the green building forum ? I think you might find some leads there. Best of luck. 

[Conor]

1 hour ago, Smallholder said:

 

As far as I'm aware, there are 2 main bale sizes that we use in the UK. Small bales are about a metre long (by 460mm wide & 365mm high), and big ones are 2.4m long (x1.2m x0.7m).

You can build with either, but nearly all residential builds use the smaller ones. 

 

Small bales can be moved by hand, give a sensible wall thickness and great U value.

Big bales are quicker to build with, and give better insulation. But need a telehandler to move them, and you end up with very thick walls.

Small bales seem to be very easy to source, and only cost a couple of quid each.

 

I wonder what problems your friend had finding them? I'm confused 

Probably a regional thing then.

[Gordo]

6 minutes ago, Conor said:

Probably a regional thing then.

Most farmers have moved towards those huge round bales of hay in our area. Only hobby farmers seem to use traditional rectangular bales 

[Smallholder]

54 minutes ago, Cpd said:

Sounds like a great  project, I looked briefly at buying a straw bale house in australia when I lived there, I absolutely loved  the look of it but the location was wrong for me.

Have you been on the green building forum ? I think you might find some leads there. Best of luck. 

 

As a building technique, it has so much going for it. The list is just so long!

 

Thanks for the green building tip, I'll check it out.

[Roundtuit]

30 minutes ago, Gordo said:

Most farmers have moved towards those huge round bales of hay in our area. Only hobby farmers seem to use traditional rectangular bales 

Best not to confuse hay and straw, but I think you're correct that small bales are now a bit of a niche market.  It might pay to get straw baled specially to order, particularly if you can get it locally.

[PeterW]

2 minutes ago, Roundtuit said:

Best not to confuse hay and straw, but I think you're correct that small bales are now a bit of a niche market.  It might pay to get straw baled specially to order, particularly if you can get it locally.

+1 to this
 

@Smallholder This is the issue - it’s only normally hay that gets baled small. You also need to decide if you want wheat straw or barley straw, and the compression rates etc. You’ll need to find an Ag contractor to do this and a farmer who will be happy for you to bale probably only part of a field in this way. 

[SteamyTea]

Welcome.

You are very brave.

How are you going to comply with all the Passivhaus parts like the MVHR and whites goods they insist you have?

[ProDave]

I have only worked on one straw bale house.  I seem to recall part of the issue sourcing bales, apart from the size issue, was moisture content which seemed a lot more important for something that will be stacked up and kept for many 10s of years than normal bales that will usually be used within a year.

 

It was a case of needing perfect weather conditions leading up to harvest and then between harvest and baling.

[Smallholder]

2 hours ago, PeterW said:

+1 to this
 

@Smallholder This is the issue - it’s only normally hay that gets baled small. You also need to decide if you want wheat straw or barley straw, and the compression rates etc. You’ll need to find an Ag contractor to do this and a farmer who will be happy for you to bale probably only part of a field in this way. 

 

We have bought small straw bales over the last few years, and have never had problems sourcing them. Though for these, we never had a spec to try and meet.

They can be wheat or barley for construction, it makes little difference. What is important is that they are as dry as possible, and are baled at the maximum compression possible. 

 

We have built up lots of farming contacts locally over the years, and a neighbour has offered for us to use his straw. This grows 100m from where we hope to site the house.

It may be a bit of a faff for him in terms of the exact spec we are looking to achieve with the bales, but even if we paid double the market rate for the finished bales, it would add less than a grand to the build cost.

 

We've not even applied for planning yet, and I'm well aware that the odds are stacked against us.

But we'll fight as hard as we can to get it, and have a lot of support locally. Including all the local residents. 

We can but try.

[Smallholder]

2 hours ago, SteamyTea said:

Welcome.

You are very brave.

How are you going to comply with all the Passivhaus parts like the MVHR and whites goods they insist you have?

 

I'm not quite clear on how this might be a complication?

We're looking at an array of at least 54 PV panels (20kW), which should provide adequate power. Was it the electrical power requirement you had in mind?

[Smallholder]

1 hour ago, ProDave said:

I have only worked on one straw bale house.  I seem to recall part of the issue sourcing bales, apart from the size issue, was moisture content which seemed a lot more important for something that will be stacked up and kept for many 10s of years than normal bales that will usually be used within a year.

 

It was a case of needing perfect weather conditions leading up to harvest and then between harvest and baling.

 

This is certainly food for thought. 

It's not an issue I've heard much about before, but you've probably had more experience than me!

[SteamyTea]

7 hours ago, Smallholder said:

 

I'm not quite clear on how this might be a complication?

We're looking at an array of at least 54 PV panels (20kW), which should provide adequate power. Was it the electrical power requirement you had in mind?

No.

Part of the Passivhaus standard, if you want to get a certificate, is that they specify all sorts of things, like washing machines, that meet their criteria. (Ecolabel)  This is why many people do not bother with certification.

There is also the airtightness, which may prove difficult to achieve with a structural straw bail build, it is hard enough to achieve with cast concrete.

[PeterW]

@Smallholder why not aim for EnerPhit rather than full Passiv..? As @SteamyTea said, you will struggle with air tightness on straw with lime plasters etc, so will end up with internal membranes such as Intello so you’ll start to lose some of the ethos of why use bales IMHO.