Friday, February 29, 2008

Storms & membranes

Once again, now the joiners have finished the roughings (plasterboard etc) inside the house and are ready to move on with the larch cladding outside, we’re getting battered by gales and rain. Nevertheless, despite getting a soaking in their first ten minutes outside yesterday Craig and David did one wall of the three to be larch clad and we’re delighted with the results. Ironic really, as the larch which the kit company sent was completely the wrong profile to what we specified, but we actually quite liked it and went with it!
The profile specified was ‘bevelsiding, which is wedge shaped in cross section and simply overlaps the board underneath. But we were sent a more robust tongue and groove profile which interlocks with adjacent boards, a detail which I feel adds a more robust line of defence against the weather.

Talking of which, my mind has been considerably exercised recently as to whether we really needed a layer of breather membrane on the outside of the woodfibre board cladding, something I really need to get off my chest on the blog and hopefully solicit comment. As a reminder to construction detail geeks who are still with me, from inside to out our wall build up is as follows:

Battens to form 25mm service void
Polyethylene airtightness/vapour control membrane (VCL)
OSB3 (‘stirlingboard’) racking board
140mm structural frame
60mm Pavatherm Plus woodfibre board
Vapour open breather membrane
50mm Cavity
Brick / larch cladding (this outer layer often referred to as ‘rainscreen’)

The problem with the breather membrane is that it has a tendency to be blown off in high winds when exposed, as the staples don’t get a good fix into the Pavatherm boards. Once the bricks are up however, it is properly fixed back with large plastic washers which are clipped onto the wall ties, and of course it is fixed in place in the timber areas by vertical battens. Inspecting the cavities from unfinished window reveals shows this solution to be just fine (looks rather like a quilt!).

On the minus side there is the cost of material and about a day of labour to fix it on, plus a fair degree of effort in marking out where the studs are so the brickies know where to bang in the wall ties. On the plus side however it does add that extra line of defence against the outside world, and at the very least has provided a good degree of protection to the structure during construction prior to the rainscreen being built up.

Breather membrane is a ‘must do’ detail in standard timber frame construction which has the following build up:

VCL (or this and the above are replaced with foil backed plasterboard)
140mm or 89mm structural timber frame
OSB racking board
Breather membrane

The conundrum is that the suppliers of Pavatherm advise that the breather membrane is not required as the outer layer of this board is water resistant, but also say its not a problem if a membrane is used!? So has it been worth the effort to add this extra layer? On balance yes, but only on the basis that we are building on a very exposed site.

Friday, February 22, 2008


I must admit to being a little tardy with my blogs of late, not least down to the fact that our cosy holiday let has no broadband so onlin leasure time is restricted. But, after a solid week in the office I'm ready to knock off early for the wekend so here's a pictorial tour...!

Kitchen area; dining to take place where larch cladding and frames currently being machined (covered in plastic)

Entrance hall on entering front door and looking up; stairs to be against wall on left (to replace ladder!!!). Next photo shows view into utility room from kitchen - heat pump on right hand side with electrics/TV/SAT/DAB/Cat5e wiring all terminating on board on end wall (must work out what magic boxes to buy to distribute signals!)

Room with a view - our bedroom to be precise, and this is the ever changing picture that we will wake up to... Next photo is the hallway looking down.

Tuesday, February 19, 2008

8.30am long view towards the farm from behind our local hill, The Dumpling

Tiles 'R' Us

We've now sourced, and agreed on, tiles for all three bathrooms. My able assistant is showing the accent tile for the ensuite shower. For those of you who know the Hillington industrial estate in Glasgow you will appreciate the number of tile showrooms there are available and the angst of then getting the man of the house to approve selections. I bought the tiles for the ensuite and family bathroom this morning and just need to go back with accurate measurements for the downstairs bathroom as the dimensions of that have altered recently. The tiler is booked for next week so we'll see big changes inside. The white goods for the bathrooms are all in place now. I also swapped the shower tray for the downstairs room because of last minute adjustments there ensuring the door width complys with disabled access regs. The change made the shower tray larger than plan.

Back to the office for 11am so did the day job too.

We've found the camera so here's a few pics from the holiday lodge we're renting. For the past 10 days we've had cold, dry and mainly sunny conditions which has been marvellous. It has been very cold at night so we're glad to be out of the caravan for the time being. The lodge has 3 bedrooms so we've got plenty of space to play with and its generally very pleasant to be in a real house again. The lodge is set in woodland at the end of a long track and there is plenty of wildlife around, particularly deer and pheasant but we also have owls and woodpeckers both of which make plenty of noise at different times of day.

Friday, February 15, 2008


Our camera has gone awol so unfortunately there are no photos again today. Its looking good though on another sunny chilly day! It seems fairly quiet on site today (only 2 white vans!), the joiners have plasterboarded the kitchen and dining room today and the electrician is tidying up/routing the masses of wiring to the consumer unit in the utility room. It looks like mission control in there. The BT cable is being fed into the house before the external render is started which is due to happen from Monday.

We had a visit from Ordnance Survey the other day. Amazingly in this era of satellite and other mapping technologies there are still people driving round in cars checking on changes to the landscape, apparently its a whole lot cheaper too. In order to accurately update the OS the surveyor is going to return in April to plot the buildings etc.

A lady also called by as she has traced her family history to the area and in particular to a joiner who lived here in 1871. I've promised to send a photo of the house which stood here, parts of which date from that time.

Tuesday, February 12, 2008

Hello again after another week has passed in a flurry of activity. The weather has changed significantly for the better and it has been dry for nearly a week which is quite remarkable after at least a month of driving storms. We spent a lot of time outside at the weekend, I was planting bulbs and Steve was building the climbing frame. With the advent of fine weather after such a long spell of hibernation it seemed that many of our local friends were out for walks and cycle rides so popped by for a viewing and it was a real pleasure to have so much progress to show people.
The big event of last Thursday was the switch on of the heating system and by Friday the builders were over warm and had all the windows open. We were mightily relieved and feel quite chuffed that it is already performing so well - partly because some observers are unsure of our reliance on renewable energy so its good to have an early positive response and mainly because we're desperately looking forward to living in the house. The system is being commissioned tomorrow. It will be interesting over the course of the first full year in the house to see how the comfort levels change and what running costs we encounter.
We need to have paint colours decided and bathroom tiles purchased by the end of this week for the upper floor so feel slightly under pressure. The bath and washbasin are fixed in the family bathroom and most of the other goods are in our en-suite if not actually plumbed in. I'm collecting an alternative shower tray tomorrow whilst on the way to order the kitchen and utility room cabinets.
Externally the brickwork is complete and I think the rendering commences next week. There appears to have been a change from the early days when Steve and I thought we were getting a smooth white render and the current drawings specify wet dash. I think this is being resolved but to be honest I can't remember where we're at with this..........just about sums things up as we juggle house building needs with the business and family. Plenty of evenings of work for us and lots of scraps of paper and lists here and there.

Tuesday, February 5, 2008

Getting there....

The final window in the house has been fitted and is this triangular piece to the south west corner of the master bedroom window. This is one of those architectural details which just adds something a little more to the overall scheme. Originally it was to be 50% larger and would have been the better for it but it is still a refreshing detail. One of the balances in self-build is to order goods in sufficient time to avoid delays so we had ordered (and now own) the original 50% larger window. Unfortunately it transpired that the architect's plans did not concur with the timber frame manufacturer's and...the client picks up the tab, hmm. We have thought to use the spare window in one of the holiday lets but its not a great idea to design a whole building around one window just 'cos it happens to be spare...but we'll see if it fits somewhere.

We're keen to make progress on the holiday let plans but the architect hasn't moved forward with these since our meeting before Christmas which is a bit disappointing.

We've measured the areas for wall tiling in the two upstairs bathrooms as the plumbing work there is well on the way and the plasterboard is due to be taped at the end of this week. It brings to focus the need to have some idea of final finishes upstairs. The painting will commence in 2 weeks so colours for the bedrooms are no longer a distant thought. After so long on the detail of the build its quite a prospect. In certain areas we've got very clear ideas and aspirations, in others the blank canvas seems daunting! Last week I went up to Perthshire and sourced the midnight black slate which will cover most of the ground floor. The tiler is coming this Thursday to help me (and 3year old Finlay) measure the area.

The master bedroom has two areas for wardrobes/cupboards etc which will probably need some made to measure kit. We spent a couple of hours last evening working out what could go where - we know how to spend an evening in!

The final picture today is of the holiday let we're enjoying. We managed to have a children's party here on Sunday to celebrate Molly's 5th birthday. Aside from the usual birthday stuff it was just very pleasant to have friends 'round, something that isn't easy in the caravan

Saturday, February 2, 2008

Heat pump installation

Work started on installing our heat pump last week. We have specified a Nibe 1240-5kW - the smallest capacity they make - with integral 'tank-in-tank' hot water cylinder. It 's a very neat unit, being the same size as a 1.9m tall fridge freezer. The pipework next to it will be ultimately enclosed in a cupboard which will still have some storage space at the front, whilst allowing access to the pipes at the back if need be.

Specifying a heat pump uses the opposite logic to specifiying a combustion boiler, as it must be just undersized to operate at its most efficient when taking into account the building's heat loss and anticipated peak heat requirement. The reason for this is that heat pumps dislike being 'cycled' - switched on and off - and actually benefit from running for longer periods at a time than conventional boilers. In extreme circumstances where, say, there is significant heat and hot water demand (eg. Christmas with visitors!) then the heat pump employs an electrical element to supplement itself, but the trick is to set things up so this hardly needs to be used at all, electricity being a relatively high-carbon form of energy.

The unit is being installed in our utility room where all the pipes from the ground loop, hot and cold water, underfloor heating and 1st floor radiators/towel radiators terminate. The guys are making a neat job of connecting this spaghetti together and hopefully by late next week we should be in good shape to switch on and get some heat into the 40 tonnes or so of concrete which forms the floor slab.

As it happens one of the founders of the heat pump supply company - Ecoliving - popped round yesterday to look at our windows (he's building an extension to his own house!) and he told me that the heat pump even had a setting to dry the floor slab out over a four day cycle, this will be important before we fit engineered board flooring.

Anderson Floor Warming of Glasgow are doing all of the plumbing in the house using a German plastic/aluminium pipe system. Hot and cold feeds are fed to manifolds from which each tap is fed, thus reducing pipe runs. Also the hot water feed is circulated from and back to the hot water tank at peak use periods (controlled by a timer) such that when a hot tap is switched on, hot water appears almost instantly.

Apart from the plumbers, the rest of the guys on site have never built a house with a heat pump in it and we are all waiting in anticipation for switch on!