Operation breathable floor began some months ago with the understanding that laying a concrete floor with modern damp proof barrier can only lead to disaster.
Far from protecting an old building, a concrete floor increases dampness. Because of the interface between walls (with little or no foundation) and floors, water trapped beneath concrete is forced directly into the walls. We need a lightweight, breathable alternative – one which allows water vapor to escape and also insulates.
Where would we be without Brian – our trusty quarry man – to ferry our building materials across hill and dale, not to mention down the terrible awkward lane way?
Our cottage floor (40 square m) takes about 18 tonnes – the layer is 8 cm deep.
Then we place another layer of membrane on top of the hardcore.
Our insulating material has traveled a long road up to Donegal – but the last mile is the trickiest of all.
A bulky cargo of LECA (Lightweight Expanded Clay Aggregate) – there are various kinds but this type is coated, which gives water-repelling and non-capillary properties. The air trapped within the fired clay balls gives it thermal insulating properties.
To stop it from rolling away out the door we butter a board with Lime to create a barrier.
Kieran has made measuring sticks which hang from the wall plate – he uses these to check the consistency of each layer at all points.
Old mortar boards serve to spread weight while walking across the leveled surface.
To date our project has used German, French and now Portuguese Lime – all slightly different hues of whitish gray – ‘Fifty Shades of Lime’ – anyone?
A pour-able ‘slurry’ is mixed to a ratio of 2:1 (sand:lime NHL5)
No wheel barrows on the LECA please – simply pass the bucket
It spreads beautifully (smooth as boxty) to form a screed, soaking into and bonding with the baubles.
The slurry layer is about a centimeter deep.
After this layer dries we shall need to add a stronger layer of limecrete – and replace our flagstones.
Almost time to brew a celebratory pot of tea!