Category Archives: Todmorden

External cladding: Larch and lime

10 Oct 14
Michelle Gaffaney
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Now the straw walls of our eco-classroom at Castle Hill School have had their first coat of lime render, it’s time for the cladding.

We’re using Scottish-grown larch boards – a durable hardwood which will naturally mature over time to an attractive silvery grey.

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A ‘truth window’, created so that users of and visitors to the building can see the material behind the cladding.

Other parts of the building have been simply rendered using traditional lime, a material often used on straw buildings. Lime is a carbon neutral building material, created by burning limestone. When lime is applied to any surface, the carbon dioxide released during the burning process is re-absorbed as the render dries.

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Cosy cob reading nooks

09 Oct 14
Michelle Gaffaney
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One lovely feature of our straw bale eco classroom is the creation of two cosy reading nooks.

They’re made from cob, a mixture of clay, straw and aggregate (more on cob here) and are specially designed so that children can curl up inside with a good book.

They’re not yet finished, but these photos show the raw state – a simple wooden platform and cob casing.

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Arthur, our plasterer, tries it out for size.

Adding a green roof to the straw bale classroom

28 Aug 14
Michelle Gaffaney
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The walls are up, and it’s time to add the green roof to our straw bale classroom at Castle Hill School.

First the beams go on

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Then we need to edge the roof

It will be a green roof – a living ‘lawn’ of sedum on top of the classroom, so a strong ‘fence’ around the edges is needed to prevent the ground from shifting when it rains. There is also a pathway of gravel around the lawn to provide structure and drainage:

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Adding the sedum

For a project of this scale, it’s easier to buy sedum and soil in rolls, like this:

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They can be easily unrolled onto the surface of the roof:

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Dan thought he was at the park and tried to take a nap...

Once complete, the roof looks like a field – it’s hard to tell it apart from the landscape behind!

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VIDEO: The classroom so far

11 Aug 14
Michelle Gaffaney
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Take a look at our straw bale classroom in progress!

Our wonderful work experience student Autumn has put together this fab video showing the build so far at Castle Hill School. It shows the foundations being dug and built, the straw bale walls going up, and finally the timber roof going on:

Of course, there’s still plenty to do. Watch this space for further updates as we continue work on the new eco-classroom at Castle Hill School.

Straw bale compression – finishing off the walls at Castle Hill School

05 Aug 14
Michelle Gaffaney
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The walls are up at Castle Hill School, and we’re preparing to add the roof.

Missed the wall-raising? You can read about that here.

Meanwhile work has been continuing at a pace. We’ve had a mixed bag with the weather – plenty of swelteringly hot July days, but some rainy ones too, forcing us to cover up the walls with tarpaulins. Rain and straw do not mix!

straw bale walls

Here’s Rachel adding the very last straw bale:

Last-straw-bale-building

Once the walls are complete, the straw bale compression can begin. Firstly by tightening up the ratchet straps which have been placed at near intervals all around the walls:

Ratchet straps at the ready!

Emma and Rachel prepare to tighten the ratchet straps for the straw bale compression

As the straps are tightened, the straw walls compress, making a firm and solid base for the roof. There’s a real art to this process – the building designs state the precise height of the walls, so if the straw bales compress any more or less than expected, the wall height will not align with the building designs.

It turned out that our walls were the right height before compression, leaving us with a problem. But one of the wonderful things about straw is its flexibility – we were able to make up the shortfall with extra straw, so that after compression, the walls were the perfect height.

And we’re still on schedule. The walls have been compressed, the wall plate is now in place and we’ll be adding the roof this week!

Straw bale walls going up at Castle Hill School

28 Jul 14
Michelle Gaffaney
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The new straw bale classroom at Castle Hill School is progressing well!

Since the pupils broke up for the summer holidays, building on-site has been continuing at a fantastic pace, with most of the straw bale walls now in place.

Straw bale walls

Straw bale walls

We’ve had two different site managers looking after the build. Craig Taylor has managed the site up until the wall-raising, taking care of all the preliminary work, foundation-laying, service installation and much more.

Craig Taylor

Site manager Craig Taylor

Laying foundations

Laying foundations

Now the walls are going up, our straw bale expert Emma Appleton has stepped in to manage this part of the build.

Emma Appleton

Straw manager Emma Appleton

straw bale wall raising

Straw bale wall raising

Straw bales, twine and baling needles

Straw bales, twine and baling needles

We’ve been incredibly lucky with the weather – as you can imagine, naked straw and rain don’t mix. But although the walls have been covered with tarpaulins each night in case of rain, thanks to the hot, sunny spell we’ve been enjoying recently everything has stayed nice and dry. That said, our building team have had deliveries of rehydration salts and ice lollies to keep them going in the heat…

straw bale building

Thirsty work…!

Jamie gets an unofficial visit

Jamie gets an unofficial visit!

We’re hoping that the straw bale walls will be completed this week.

At this point we’ll be ready to add the ‘wall plate’, which helps to compress the bales and will provide a sturdy platform for the roof. Then it’s more carpentry as the timber-framed roof goes up, and we prepare for rendering and plastering the external and internal walls.

Emma with the pre-built wall plate

Emma with the pre-built wall plate