You knew there was a use for cork except for sealing wine bottles…

Description
Cork is a natural and effective insulator. One disadvantage for the UK builder is the need to import cork from countries with the climate to grow it such as Portugal and other Mediterranean countries (China and India are now getting in on the act). Cork is fire-retardant, resists mold and is non-toxic.

Features

• Biodegradable.
• Renewable.
• Low embodied energy.
• Excellent acoustic insulation.
• Low impact production – few chemical additives.
• Self-supporting. Cork boards do not slump and therefore maintain their structure and insulating properties over time.

Performance
Cork boards at 120 kgs/m2 have a thermal conductivity or K value of 0.04 W/m.K.
(Watts per meter Kelvin ~ a lower value is a better result)

Cost
As production is still relatively small scale, cost is relatively high – I guess! I’m currently unable to get UK prices for Cork insulation – anyone able to advise?

…if only we could collect our wine bottle corks and make our own…

Progress in August was … sporadic. A case of tidying up and finishing off. Plaster boarding continued, the ‘missing’ kitchen window was ‘found’.

The one major piece of progress was the installation of the new gutters and downpipes – aluminium and moulded on-site so that they consist of a single piece for each section (no joints). Very neat they look too.

It’s amazing how quickly time passes, how quickly the weeks go by.

Sorry for such a dull month – I’m expecting (and currently seeing) great things in September!

I’m judging that we are something over half-way through the conversion, not in terms of time or money, but change – it’s no longer a barn and not yet a house.

This is one best left to the pictures, so no more words…

Before…

Before (picture taken October 2007)

During…

During (picture taken August 2008)

Keep checking back for after…

To those yet to be introduced to the wonders of hemp, this type of insulation can seem like a hippies dream, however a simple Google search will soon lead you to the world beyond students bed-sits and Pink Floyd soundtracks to textiles, biodegradable plastics and fuel.

However, we’re interested in insulating properties of hemp, so back on track…

Description
Usually produced in batts (a precut, presized, blanket of insulation). Inorganic, non-toxic natural salts and thermoplastic binder are used to improve structure, durability, moisture, rodent & insect protection. Grown in many climates C02 is ‘locked-in’ during growth.

Features

• Non-toxic & non-irritating.
• Biodegradable.
• Renewable.
• Locks in carbon.
• Low embodied energy. Relatively little energy is consumed in its production.
• Self-supporting. In comparison to most other light-weight fibre insulations, hemp batts do not slump and therefore maintain their structure and insulating properties over time better than other comparable products.
• Note for UK readers: Hemp insulation is often grown and / or processed outside of the UK. You may want to take that into account when considering the overall ‘green’ credentials of this product.

Performance
Hemp Batts have a thermal conductivity or K value of 0.04 W/m.K.
(Watts per meter Kelvin ~ a lower value is a better result)

Cost
As production is still relatively small scale, cost is high…

Representative cost:
A 75mm x 575mm x 1200mm roll of batts costs approximately £50 (rounded) including VAT and covers 5.5 m2 therefore approximate cost per square metre at 75mm depth is £9.

Other Information
An impressive statistic quoted often in information sources about hemp insulation is that for each kilogram of hemp insulation used instead of mineral wool, 1.4Kg of CO2 is saved.

References:

http://www.natural-building.co.uk/hemp_natural_insulation.htm

Whilst not wanting to become a lime-pointing-bore (I bet there aren’t too many of those in the world) I feel another update is in order.

The tools that I ordered to help in raking out the mortar joints have disappointingly not arrived yet but the repointing tools have. I managed to break the mortar hawk as soon as I took it out of the box so it didn’t score highly for resilience, but it’s nothing a drilled hole and suitably sized bolt can’t fix. More on the pointing gun below…

I’ve tried some innovations to my repointing technique with good and bad outcomes…

Good
Whilst despised by many as water wasting and noisy, I found using a pressure washer to clean out the joints and dislodge loose mortar before hacking out, then tidying up again with the pressure washer saves time and leaves clean, well-prepared joints ready for re-mortaring. (Sorry about the noise and wasted water).

Bad
Don’t use a cement mixer to mix lime putty and sand – it doesn’t work, you just get blobs of putty encased in sand rumbling round-and-round in the mixer. I know everyone who knows anything about lime mortar knows this one – I just had to prove it for myself.

A mix of 3-1 sand to lime putty doesn’t work in a pointing gun (an over-sized version of the sealants guns that we all know) it just compresses the mortar and squeezes out the water. I think the problem is a combination of not using a plasticiser and / or the ‘wrong type’ of sand – I just used standard building sand. As the plasticiser supplied was not to be used with lime and the instructions for the gun say not to use sharp sand I’ve hit a bit of a (stone) wall with this one. I might try messing around with the mix (less sand or a finer one). Anyone know if there is a plasticiser suitable for use with lime?

The saga continues…