Straw-bale building: introduction

What is straw-bale building?

It’s a building technique that uses straw bales (or even hay bales – although it’s best to use hay for animal feed) for walls – which can be load-bearing, or used to infill a timber frame. It was pioneered in the US mid-west in the 19th century by farmers whose only building material was the waste from their wheat crop. The buildings were intended to be temporary until conventional building materials were delivered. However, they found them to be solid, warm and comfortable, and many continued to live in them in preference to traditional houses.

straw-bale-sheep-shed

Redfield Community’s straw-bale sheep shed before and after lime rendering.

Walls can be rendered with earth or lime – breathable materials to protect them from the elements (see image).

Three common misconceptions are that they are a fire risk, they can house vermin, and they are not durable. None of these is true.

US tests have found that even unrendered straw-bale walls are less of a fire risk than timber walls (rendered walls are no more flammable than bricks).

Mice and rats are not attracted to straw as it is not a food source. They are attracted to holes though, but as long as walls are rendered, they won’t house vermin.

straw-bale-lilac

Homes at LILAC cohousing project in Leeds are made of straw bales and timber.

As for durability, there are 100-year-old straw-bale houses in the States. The wetter climate of the UK presents more of a challenge, but weatherproof rendering and a good moisture barrier means that there will be no problem, whatever the wall material.

In theory, there is no reason why a well-built and rendered straw-bale building with a solid roof shouldn’t last for at least 100 years and possibly a lot more. Furthermore, any problems can be rectified very easily.

straw-bale-needle

Baling needle: this home-made tool allows you to cut and re-bind bales to any size necessary to fit a gap or a corner.

What are the benefits of straw-bale building?

Environmental benefits

  • Straw bales don’t need to be fired like bricks, and don’t need cement, both of which use a lot of energy and cause pollution and greenhouse gas emissions.
  • They don’t need (often) environmentally-damaging insulation materials either, as straw has a much higher insulation value than brick or concrete.
  • This means lower heating bills / reduced CO2 emissions.
straw-bale-lime-plaster

Internal lime plaster on straw-bale walls.

  • Straw is biodegradable.
  • It’s also a way of capturing carbon and sequestering it in buildings.
  • Straw is a natural material, can be locally sourced, and if used in combination with other natural materials like timber, earth, slate and lime, means no toxins or ‘sick building syndrome’.
straw-bale-persuader

A ‘persuader’: another home-made tool, this time for gently persuading bales into the position you want.

Other benefits

  • Cheap (bales usually cost around £3 each).
  • Easy and quick to build by non-experts.
  • Good soundproofing.
  • They look good (like a cottage but at a fraction of the price).
  • Easy to modify.
  • You can easily build curved walls and add alcoves etc.
  • Each building is unique – no ‘little boxes’ with straw bales.
straw-bale-walls

A circular straw-bale building going up on a ‘wall-raising’ weekend. Note the gaps for door and window frames.

What can I do?

If you’re building a garden office, extension or storage shed etc., why not have a go at building it with straw bales? A small, single-storey building could be a good thing to practice on. Then who knows – you might graduate to building a straw-bale home.

First, do some reading, attend a course, and/or sign up for our online course.

straw-bale-office

Straw-bale garden office with living roof.

If you intend to live in your straw-bale building, the first thing is to talk to your local planning officer. Getting planning permission depends on the local authority, the planning officer, and where you want to build, and not so much what you intend to build it from. There is nothing specific to straw-bale construction in the Building Regulations, but they certainly conform to criteria concerning health and safety, fire resistance and energy efficiency. Problems may arise either with neighbours or planning officials who are averse to anything new in their area. On the plus side, your ideas may fit in with the local sustainability agenda, especially regarding insulation levels and the use of natural materials.

When it comes to designing and building, there are many options for every part of the house. Foundations can be concrete, flint and lime, brick or timber pillars, or car tyres with rammed earth (foundations don’t need to be as deep as for brick houses). Roofs can be slate, tile, corrugated metal or bitumen, shingle or thatch. Floors can be concrete, earth or floorboards on joists.

However, we don’t recommend using cement / concrete on a natural build – see here.

Introduction to our straw-bale building online course with Barbara Jones.

Bales are laid with each course offset, like bricks, with hazel stakes pinning the bales together. Smaller bales can be made using a baling needle (see image). Recycled materials can be used, including timber, doors and windows. Frames can be inserted during the wall-building process, and doors and windows fitted later.

If your build is timber-frame with a straw-bale infill, build your roof first, to keep your straw-bales dry. Otherwise, make sure you have lots of tarpaulin to hand to cover the bales and keep them dry until the roof is on.

straw-bale-rendering

Lime rendering a straw-bale kids’ play house by hand.

You can self-build entirely, in which case you could invite lots of friends round for a ‘wall-raising’ weekend, or a lime rendering / earth plastering event. People will love it – just lay on lots of food and drink. Alternatively, you could employ a natural builder, or get professional help with plumbing, carpentry or electrics.

Thanks to Barbara Jones of Straw Works for information.

 


The specialist(s) below will respond to queries on this topic. Please comment in the box at the bottom of the page.

Phil Christopher is an environmentalist, builder and trainer and he believes in making a low-impact lifestyle an attractive possibility for everyone.  Phil runs Huff and Puff Construction, specialising in straw bale and sustainable building, training and design.  He’s a passionate advocate of earthen and lime plasters, stating “It’s the part everyone loves doing, even if they didn’t think they would!”


We'd love to hear your comments, tips and advice on this topic, and if you post a query, we'll try to get a specialist in our network to answer it for you.