I spent this afternoon wielding a sledgehammer. Very satisfying. Demolishing the garage. Well we've been dismantling it for about two weeks on and off, mainly guided by R with great precision and care but today was my day to thump the walls with a blunt instrument. The photos show that there's still a way to go but it was gratifying to see the bricks falling. These three pictures were taken over a period of about 45 minutes.


Oh yes - I rule!!

Anyway, more in a day or two. We are very close to Decision Time. More photos coming too. We have two delightfully daft ducks with Tardis-like stomachs who eat everything. They don't fly so can't reach the bird table. I saw them yesterday sitting at the bottom looking hopefully up at a robin on the table eating in a very messy way - every now and then he would drop something and the ducks were ready.

Good Lord - it's 17 days since the last blog. In my defence I would like to point out that not very much has happened. We have been much exercised by wall structure. To explain the options, here is a request for information which I posted on the website of the very excellent AECB:


"Gold standard walls – the best construction

We are self-building an 11.5m x 9.5m two storey house in East Anglia. we want to build a zero heating house (woodburners for winter backup). We are currently working on a 540mm finished wall thickness. Exterior rendered. Thermal mass if possible. Reasonably tight budget. Concern about interstitial condensation.

We have looked at a number of wall systems, as follows with potential problems for each one:

1. Hemcrete – no problems except cost. Zurich will guarantee but only as an infill material so a complete structural timber frame is also needed. Double that for price of 500mm (installed) Hemcrete and add cost of erection and external render.

2. Double skin of blockwork with 300mm cavity filled with Rockwool. Dense concrete gives better thermal mass so possibly dense inner skin and aircrete outer. Ties have to be found – 450m. Zurich approve as long as ties are okay. BedZED had own ties made. Problem with large amount of embedded energy. Also difficulties around window and door reveals (no problem there with Hemcrete) and very dependent on good craftsmanship to avoid cold bridging and leakage. Construction may be slow. Rain ingress into cavity during construction. Seems a lot of bother. Why bother with external skin of blockwork at all?

3. Timber frame with 300mm studs – possibly Masonite or similar. Major problem is that we do not like the hollow sound of dry-lined walls. Would cellulose filling eliminate this? Or maybe Rockwool for weight.? How could we get to c. 0.1 u-value with rendered surface and no cavity (no point in extra skin of expensive purely decorative blockwork).

4. Clay perforated blocks with woodwool external insulation – seem like a good idea but expensive and may not achieve the u-values for a zero heating house.

5. Hybrid masonry / TF systems. We discovered these last night on this forum. How well tested is it? Which goes up first? Which is structural. The idea of building to the FF and tying it all together before going up sounds good as about one-third of our FF is in the roof so we have large gable ends.

6. Or – could we put up a thick masonry wall and insulate it externally? Window reveals would be set a long way in? How would the roof/wall connection work?

In every case – what about interstitial condensation?

Your help would be much appreciated. Otherwise going mad with too much information."


Anyway I got a private reply from their technical manager who referred us to the Passivhaus UK office. This is a standard which has been much used in Europe and is now coming to Britain, sponsored by the equally excellent Building Research Establishment. So hopefully after much floundering in the mud we are getting the advice we need.

Not too much literal floundering yet. We have four groundworkers giving us quotations for the foundations - more about that next time. We also have a muhurta or auspicious time for groundbreaking and putting in a foundation stone, which is the 28th April. That should give us time to decide what we want to build!!

In the meantime we are demolishing the garage and here are shots of both of us ruthlessly pulling off tiles. Bargain of the week was this scaffolding tower from Jewsons for £25.50 for the week. We'll need all that time. Roofs are much bigger and heavier, when you actually get up there, than you think they are going to be.

In the meantime the caravan is very spacious. cosy and convenient - The Girls came for Mother's Day and E said that we needn't bother building a house - she liked the van. A good thought and it does face due East (R chained it down).

Anyway, a few pics of the demolition. Check the cute red hat. (R did have a hardhat on for most of the time - he was sitting astride the ridge in a very dashing way for most of the day.)

An even better day today - we finally got electricity!! Also broadband. And we are considering a new and different wall system... This is perforated clay blocks, which fit together with a very thin mortar like glue, go up like babies' building blocks and have built-in insulation. Reasonably green and sold by the likes of Natural Building Technologies (as Ziegel blocks). The thing about them is that they are already used extensively on the continent, in places like south Germany so we would not be trialling a new system.

In Britain we have become obsessed with the need for cavity walls but the more I look at it the more I think this is something from the past (need to avoid driving rain getting through the old solid brick walls) and that there are a number of good non-cavity alternatives.

Again, we await the price. I expect them to be more expensive, possibly quite a lot more expensive, than concrete blocks. But the house walls could go up in a week, so we'd save on bricklayers' labour.

I promised a photo of the robin. The birdtable, outside our kitchen window, is a social centre, especially when I put bread out. What is it about birds that they much prefer white bread to good wholegrain bird food? Anyway the robin was there and I took these photos but on account of my camera packing up they were taken with my phone, so not very good quality. You can get a good view of the site though and I'll keep taking pictures from the kitchen window so you can see the progress.

Foundations - we have a bloke to do these, he comes with good recommendations. We are looking at the piles going into the ground in about six weeks. Wahey!!

I am planning a sort of bird hotel along that old brick wall to the right of the picture. The BBC has a good website http://www.bbc.co.uk/breathingplaces/nestboxes/ which tells you how to make them.


There really is a robin on this table! Honest.

ch.
Today was a great day - John came this afternoon and we set out the four corners of the house. Very precise. We now have four little posts in the ground with a nail in each and we have to tend them carefully from now until when the foundations are put in.

Also yesterday I went ot the Ecobuild Conference in Earls Court where I had a great time - beats shopping in Oxford Street any day. I spoke with, amongst others, two wall structure blokes, a solar panel bloke, a solid ground floor bloke (the ground floor not the bloke) and a guy with a scheme for bringing in outside air, taking the heat out of it, collecting all the heat together and heating your water.

Also lots of freebies, nice food, entertainment. Kate was there too in her official Southern Housing Group role. We couldn't get into the seminar we wanted, on zero carbon, it was packed out with a queue.


Anyway, here's a photo of the guys surveying - it had took a long time and it had got a bit dark by the time I took it - but we managed with the aid of an Anglepoise and two torches. The photo shows John peering through the theodolite and R holding the torch.

More news soon - I think we'll be making a lot of decisions in the next week or two.