16 September 2014

On Technology

Dimitri writes. This is not an article about the technology that will become part of the house. There is remarkably little of that in the sense of gadgetry and gizmos; of course, the materials involved are all technology of one sort or another, as are things like windows, doors, lighting and heating, but it's all fairly conventional stuff. The only thing in that department that stands out is the MVHR unit which ventilates the house while retaining the house's heat.

We decided not to go for the clich├ęd self build tech such as

28 August 2014

Sneaky Peak

We are preparing to leave our current home and shed all the superfluous stuff we have accumulated over the last 3.5yrs.  I love the feeling of relief and lightness I get when I drop off huge bags to the charity shop or recycling.  We have no choice as our new house is smaller than our current one.  We've also had to shed a lot of furniture as it won't fit/isn't needed.  But I am not sad about this, in fact I'm really looking forward to having fewer things and keeping on top of it all, more space often just means more dumping and clutter...

At the same time work is non-stop at the house as we try to get as much done before we move in.  We are moving before it is ready or finished, a couple more weeks would have made things a lot easier for the work schedule.  But needs must.  We promised we would leave our current house by the end of the summer and the children are starting at their new school.  Enough already.

As I really can't prioritise the blog at this critical time, I thought I'd share a few photos to preview everything that I will detail soon.  It has been very exciting to finally get to this moment... I can't believe that we are actually going to be living there.

23 August 2014

Kitchen progression

The chaps at Sustainable Kitchens have been busy and I popped into their workshop to get some previews!

This beautiful Dinesen box is going to house my extractor fan.  It looks amazing!

The carcass is constructed from birch ply and is rock solid.  Even without the fronts it looks fantastic.

I can't tell you how beautiful these drawers are.  They are dovetail jointed at the corners and they feel like they will last forever.

I got to open the box and have a first look at my sink, Kohler Vault Offset Double.  It was chosen over the internet as I couldn't find anywhere locally to look at it in person, but I'm not disappointed. This was one of the first things I chose for the kitchen, and you know what i'm like about sinks and taps!  The decision for the countertop material was one of the last choices.  I was very nervous about having a sink and countertop in the same material, I was worried that the sink would lose it's impact.  Also I prefer inset sinks to under-mounting and I worried about how the edge would look. Below I was looking at how the a wobble-sanded stainless steel finish would look.  This way of finishing the steel has many advantages as it shows less smearing and fingerprints and also allows you to sand out any scratches yourself relatively easily.

And finally my moveable island.  WOW!

21 August 2014

So, so, behind with updates

Hello, I am still here!  I am so sorry for the lack of updates.  I thought that my deadline of the build finishing sometime during the Summer Holidays was really clever.  After all, instead of the normal Xmas deadline with the focus all leading towards one day, this time there were 6 whole weeks.  However the sheer craziness of the 2nd fix, with so many decisions to be made and items to be ordered, coinciding with school holidays and trying to find time to enjoy with my three children has been HECTIC! I'm exhausted, mentally and physically. There is NO spare time, and I don't have time to write about it all now.  But I will and soon - before I forget it all!  

3 August 2014

The Dinesen arrives!

The day arrived for the Dinesen Douglas delivery from Denmark.  The boards arrived on huge pallets, which would have taken hours to unload by hand.  Ali was quickly sent off to get a tele-lifter to get the crates out of the truck.

We unwrapped them straight off the truck.  So full of character.  Beautiful.

Within an hour and a half of arriving on site the floor was already being laid.  Andrew reported that it was the best floor that he had ever put down.  The planks were perfect and went down very quickly.

We had a four day hiatus before it was sanded in preparation for finishing. 

I had convinced Andrew that he and I would be able to do the finishing ourselves.  He would do the sanding and I would do the applying of products and polishing of the floor.  I had spent hours pouring over the Dinesen post installation booklet and watching the Dinesen videos.  First job was to apply the lye solution.  This lightens the planks and prevents the colour deepening over time.  Using the provided roller, I applied the lye solution and already we were in unknown territory as it didn't behave like in the video.  We were finishing the floor on a hot summer evening, and who knows what difference that made.  The lye was absorbed by the planks very quickly.  I was left wondering whether I should go over it all again...

In the morning we could see that the planks had been lightened by the lye.  The instructions said that we needed to lightly sand the planks before applying the oil.  We were really unsure how much to sand as there was a cloudy white layer on the top of the planks and we could either leave it mostly there or sand a bit more and let the grain come up.  It was our bad luck that the morning we were doing this the Dinesen office was closed for annual holiday (they had been brilliant about talking me through the process the previous week), so we had to just decide for ourselves.  We were applying a white oil next so we were worried that if we left too much pigment on the boards then the floor would be really white and the grain obscured.  

Then came the white oil application, saturating the floor with the oil twice in quick succession and then polishing the excess oil away.

No photos of this part of the job as it was extremely time pressured and busy.  Applying the fluids was simple but we quickly realised that I was not strong enough to operate the floor polishing machine- an enormous brute that had a mind of it's own.  With the oil on the floor it was like a skating rink and even Andrew struggled to control it.  But eventually he wrestled it into submission and I became a builders mate, constantly changing the floor cloths.  If you decide to do a similar thing my tip is buy a LOT of floor cloths.  I bought 50, thinking it would loads more than I would need and I'd be using them for the next 5 years.  I could have got 100. An hour or so later we were admiring the floor.  The grain was now being fully expressed and it was a gorgeously rich colour.  The oil seemed to have dissolved any lye pigment and had brought out the colour of the floor.  In retrospect we wondered whether we should have not sanded as much after the lye coat, but seeing as we have nothing to compare it too we're none the wiser!

After 48 hours we applied the second, single, coat of white oil and that has given the floor a subtly lightened effect.


I love it!  And I loved being involved with finishing it!  It feels like it's ours now and I know it's story.  Things have been incredibly stressful recently (it's money/mortgage related - I haven't been able to write about it as it's been too much like an open wound, there will be a post soon) so this process of getting closer to the final finishes and creating our family home has been so positive and energising.

It really is a beautiful floor!

31 July 2014

The Airtightness Test

We set out to achieve a low energy house with the principles of "super-insulate, build tight and ventilate right".  This means that the building needs to be pretty airtight. This ensures that the air that you heat can't just escape through gaps in the building, it is directed through the MVHR to heat/cool the incoming air - minimising additional energy input.  The other thing to worry about when air leaks is that the internal air will be warm and moist, when this moves through a gap in the fabric it can cause interstitial condensation - damp and mold!  No good!

To conduct the test the building is sealed and a calibrated fan is mounted in a doorway.  It sucks air out of the building to depressurise it.  Then they can test the pressure differences between outside and inside and watch what happens as they test at different pressures.  A number of different data points are collected and graphed, creating a final averaged figure.  We have tested twice now and will have one final test when the building is finished.  So the first two tests have been used as aides to discover where in the building the airtightness needs to be improved.  As the inside is depressurised it pulls in air from outside (actually air from outside pushes in and tries to fill the space) and you feel with the back of your hand where air is moving through the building envelope. 

Searching for leaks

Two figures are calculated in the test; air permeability and air changes per hour.  The two figures are very similar and to be honest i'm yet to really understand the difference! (Dimitri says "One is flux and the other is just a measurement that builders and architects can understand"!) However it is the Air Changes per hour that we are really interested in.  Air permeability is measured in cubic metes per hour per square metre of the dwelling envelope area when the building is subjected to a differential pressure of 50 Pascals (m3/(h.m2)@50Pa). Air changes per hour is the number of times all of the air in the house is replaced in an hour at the same pressure difference as above(without MVHR obviously).

Building Regulations state a maximum figure of 10 air changes per hour, although 3 is the minimum standard for AECB (Association Environmentally Conscious Buildings) Silver Standard for environmental building.  Passive Houses have to achieve 0.6. Getting a score of 10 down to 5 is relatively easy, however from 1 to 0.6 is very challenging...

The first airtightness test was conducted once the windows and roof had been installed.  Where the concrete blockwork meets windows and doors and the roof, we have used a lot of very expensive airtightness tapes. We've been told these tapes will last for 50yrs, but to be honest no one has had them in use for that long so nobody really knows as lab conditions are never quite the same thing as reality.

Paul Jennings, the airtightness guru, arrived with all his gear and got to work. We achieved a result of 4 in the first test, we were all disappointed! Leaks were searched for around junctions of the walls and windows and roof and sealed with more tape.  This got the figure down to 3.6.  Not the start we were hoping for.  

Unusually for a passive-style house, we have used traditional concrete blockwork.  Blockwork can vary a lot in air permeability and the more environmentally friendly blocks composed of fuel ash can make the blocks even more porous and very leaky.  So the blockwork could not be relied upon to give us the airtightness.  The redeeming feature of blockwork is that it is a great thermal store, absorbing heat and very slowly releasing it.  It will take a lot of energy to change the temperature of the mass.  At this point in construction we had used blackjack, a paintable bitumen, as a seal when perforating the blocks, so we guess that this had not been as effective as we had hoped either.  

Once our internal render had been completed we conducted our 2nd test.  This time the first score was 0.9 - hooray!  We were under 1, which was the figure we were aiming for when we first began this journey.  A huge accomplishment.  We always said that the aim was to do the best we could without throwing huge amounts of money at it. The costs can increase exponentially as you get down to the final 0.1s.  Just goes to show what a difference a layer of render can do.

But Andrew and Charlie were really hoping they could make it to 0.6. It's boys- they see a target and they want to hit it, goal driven! With more rushing around with smoke pens and backs of hands against junctions they found some more air movement and used an airtightness sealant and mastic to fill the voids.  Apparently this stuff is the business and doesn't fully harden and leak at a later date.  A lot of our issues were around the electrical switch boxes and the wire perforations through the render.

There was a lot of nervous tension as we waited for the final series of tests to be performed.

We managed to get a result of 0.72!  I think that is amazingly good! The photo below shows a result if 0.62, however each result has to be plotted on a graph and it is the average which determines the final score.

I am so delighted.  0.6 would be great but to be honest the difference of 0.12 is nothing that we will notice, our house is going to be super low energy and that is what we wanted.  It remains to be seen whether we'll improve the score by the 3rd test.  Andrew is planning to use some of the mastic inside the switch boxes in an attempt to improve the score.  We've also completed the plaster layer now which may have an impact.  However it has been known for scores to increase in the final test, as during the final finish more perforations are made in the airtight skin when you hang shelves and so on.

(I have to confess that I failed to write down the scores at the time, believing that they would be indelibly etched into my memory, however that has turned out not to be so!  Paul may correct me if I've got any of these numbers wrong.)

10 July 2014

Render and Plaster

Those experienced in the building trade know the difference between render and plaster.

The render, sand based cement with waterproofing additives, went off really quickly.  We think it must be the thermal mass releasing the heat from the last couple of weeks of good weather. It's this layer of render together with the plaster which forms the majority of our airtightness layer.  The plastering was started a couple of days earlier than expected. 

In order to keep things simple visually we have chosen a shadow gap detail on the door.  The stop bead itself is not expensive, but it was the fact that they only sell them in boxes of 50 which put the costs up.  So we now have about 30 pieces unused in each box, as we needed two different sizes of bead - anyone interested in buying them?  I'm becoming a supplier now!

There was a break in the work after all exterior walls had been rendered but not yet plastered, when we performed the critical air-tightness test (next post).  

WOW!  Mike and his team, R. Churchill Plastering, have done a fantastic job.  A local firm who were able to fit us in on pretty short notice.  It's a beautiful trade to watch - it's like ballet!  It's really looking like a proper house now.