Be Constructive!

Friends, I am very excited.

Yesterday I signed and returned the contract to have external wall insulation applied to my house. The work will start in mid-September in time for what I hope will be a really cold winter!

My calculations suggest this should reduce direct heat loss through the 133 square metres of walls on my house by a factor which might be as large as 5 – WOW!

There are still many uncertainties. For example:

• I don’t know the extent of heat loss to the Earth through the ground floor.
• And I am unsure about the significance of air flow in losing heat.

But by continuing my measurements through this summer and next winter I hope to gain insight that should help me plan the next steps.

Be Constructive

The company I have engaged to do this are charmingly called Be Constructive and they seemed very professional in their assessment of the work.

The work itself is conceptually easy to understand. But it has many time-consuming steps that are required in order to get a finish which will last for many years. The video below shows some of the basics of the process.

When the work is being done I will add more details but here are some of the decisions I have made.

I want the house to look visually similar before and after…

The reason for this is that I want to show that this can be done by ‘normal people’ – and not just measurement obsessives such as myself. Consequently:

• I have resisted my son’s request to paint the whole house bright yellow.
• I have restricted insulation to a thickness of 100 mm. I think this is thin enough that the insulation will not be immediately visually obvious.  
• To get the best thermal performance from this thickness, I have reluctantly used a proprietary insulator – Kingspan K5. I would have preferred ‘Rock wool’ but the Be Constructive surveyor thought the thermal performance would not satisfy me! 
• The lower part of the house – and the neighbouring houses – has exposed brickwork. This will be matched as closely as possible using ‘brick slips’ – thin ‘faux bricks’ – on top of the render. This looks incredibly tedious and I am glad not to be doing it myself!

This work is expensive. The whole job will cost around £20,000 or about £150 per square metre, rather more than the guide price (link) of £90 square metre. This increased cost per square metre is due to the improved insulation, the use of brick slips, and one or two ‘fiddly bits’. My guess is that about 40% of the cost is associated with the rendering rather than the insulation. 

But in terms of heat loss, the work is considerably more cost effective than the triple-glazing I had done previously, and should represent a big step towards making the house carbon-neutral. 

The return on investment – in terms of reduced bills – will probably be around 2%. But my rationale is moral rather than financial.

I see wasting heat and putting carbon dioxide in the atmosphere as being in the same category as leaving a sewer to spill onto the street. Given that I have the wherewithal to do something about this, I feel it would be shameful not to act.

..but I do have a large empty wall…

..and my son did want the house pained yellow… Perhaps I should get a mural like this fantastic painting of William Morris?