Category Archives: Castle Hill School

Castle Hill School

 

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.

Straw bale classroom: Lime render and clay plaster

02 Sep 14
Michelle Gaffaney
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Our straw bale classroom at Castle Hill School is really starting to take shape now!

The walls are up, the roof is on, and it’s time to start covering the walls.

The naked straw walls, before rendering.

Externally, we’re using a lime render to protect the building from the elements.

Lime is often used on straw bale and cob buildings and is a traditional building material. It is particularly suited to our harsh Yorkshire weather, as it has a sponge-lique quality, absorbing rainwater in bad weather, then releasing it, rather than allowing it to soak into the inner wall.

Here’s Arthur, our plasterer, tackling the first coat:

Lime render

Arthur lime rendering

The difference is astounding, and it’s so exciting seeing the classroom start to look more like a ‘real building’!

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Internally, we’re using clay – the oldest and simplest building material of all.

Clay is applied to the wall much like regular plaster, except that more coats will be needed. We start with layers of rough clay plaster, mixed with coarse sand to grip tight to the straw walls. Once this has built up, we apply a final layer of fine clay plaster (made using a finer sand) to give a nice smooth finish.

clay plaster