Week 26: plaster boarding, MVHR ducting and cladding...

This week we have had four guys on site for much of the week which is double what we have had for some time so its been great to see the progress.

The cladding is looking really nice. Picture below from this morning. The East, North and West (pictured below) walls are probably about 60-70% complete and we hope the will be finished next week to allow Tommy and Zac to move onto the South (front) of the building and balcony area.

The apparent vertical ladder of missing (cutout) bits toward the front of the building below are the method we are using to obscure the unglazed windows in either end of the balcony.

Then two new faces have been on site.

John (above) and Steve (below) have been inside cracking on with the plaster boarding, installing the MVHR ducting and ports, door linings, shadow gaps etc and crack on they have. With some pretty huge days they hope to have completed approximately 80 - 90% of the plaster boarding by the end of this weekend as well as the door linings, and all the MVHR ducts.  

Much of the upstairs is now mostly boarded.

The downstairs is also coming on rapidly. With the boards on the walls it really helps develop a sense of the spaces which is very exciting. The big exposed oak posts are also looking really good too as they have been covered up for protection for a long time. 

Week 25: insulation, airtest and cladding...

Monday of Week 25 started with the Insulation guys turning up. This job is absolutely crucial to the thermal performance of the building and along side the airtightness of the building envelope makes up a crucial element in achieving passivhaus performance.

The job of these two guys was to fill the fairly enormous cavities in the timber frame walls and roof  with Knauf Supafil 34 (read all about it here http://www.knaufinsulation.co.uk/en-gb/more/supafil-34.aspx) which is basically processed recycled glass that is formed into a silicon coated glass wool or fluff. So the way it works is that they bring 'bales' of compressed Supafil in two large transit vans all the way from Southampton.

They then load a bale at a time into a big machine in the back of the van which breaks and fluffs up the insulation into a much greater volume and blows it down the pipes to a jet that the installer uses to fill the cavities. 

This is what it looks like, very similar in appearance to cotton wool or candy floss. 

Here one of the installers fills a wall cavity. There is a cavity between each frame of the house (approx 400 or 500mm apart) so many many cavities per wall per floor. Each cavities has a depth of about 300mm so some fairly massive volumes of insulation. 

The walls took most of the first day. Then on the second day the guys brought two more van loads of insulation and completed the upstairs walls and the roof. The roof is even deeper at 400mm so again a huge volume of material. Below filling the roof cavities. 

Later on in week 25 Jonathan arranged the first airtightness test. Basically shut all the windows and doors, seal up any traps and drains and attach a pump to the house to apply 50 Pascals pressure (suck and blow I think) and monitor how much air leaks out. The idea is this give you a way of determining how leaky your building is. Obviously as low as possible is good. That way you don't have unmanaged heat loss, instead you control air circulation efficiently via the MVHR.

Airtightness testing kit. Pump and monitoring equipment installed in a window opening.

Passivhaus standard requires no more than 0.6 air changes (the volume of the house blown in or sucked out) per hour at a pressure of 50 Pascals. Which is approximately the equivalent of less than 1m3/m2/h @50 Pascals. Interesting to note that current UK Buildings regs are approx 10 times this amount. So how did we do? We got a result of 0.57 air changes per hour. So we were just inside. This was a bit disappointing for us and Jonathan as I think we had all thought and hoped for a figure of more like half of this. However the problem was identified as a number of doors that had not yet been adjusted. The tester through that once this was done approximately 0.2 reduction would be further archived. This is not the final test though as the Certification company will do an independent test at point of certification when we hope to get a better result after the doors are adjusted. Crucially it was not bad enough to hold fire on other work for remedial work to be done. Put another way it allows the plaster boarding and ultimately plastering to continue.  

While all this was going on Zac and Tommy were getting stuck into the cedar cladding on the North, East and West 1st floor walls. Its great to see his go on as it really starts to give and idea of how the finished building will look. The detailing of the 8mm gaps between planks and mitre joints is a very time consuming detail compared with a normal tongue and groove style cladding but its looking really good and we are very pleased. It should also much aid air circulation around the cedar increasing its lifespan. 

week 24: roof on and cladding started...Pt2

The other progress since the last entry has been some work on the cladding (or cladding prepraration on the first floor). Zac and Tommy have covered the wood fibreboard in the black waterproof membrane and then covered in a series of battens to attach the cedar cladding to.

They also mocked up a sample detail:

This confirmed suspicions that the battening needed to be stained black so it could not be seen between the relatively large gaps in the cladding (8-9mm). A number of people have raised concern about these "big gaps" but we think they look good and will really help movement all around the cedar to keep it dry and prevent static moisture. So I painted the battens black last weekend.

Jonathan suggested doing away with the cedar and white rendering the gaps between the black timbers for a Tudor look! In fact is it too late to make it look a bit more like...

In other news...

The pressure testing is booking in for Thursday..


Then the Knauf Superfil 34 blown in insulation is coming on Monday - lets hope its more like this:




and less like these geezers:

week 24: roof on and cladding started...

Its been a bit more than two weeks since the last update. In terms of what's been going on.

Roof. Jonathan had appointed B&C Roofing from Plymouth. The job turned out to take a good deal longer than expected. Firstly they had concerns about the scaffolding location so left the site to return the following day with a guardrail which they erected on the opposite side of the roof to where they were working (which seemed a bit odd but doubtless health and safely). So a day and a bit down. Then we lost a series of days through bad weather which obviously cant be helped and some "discussion" about quality of workmanship, appropriateness of detailing etc which resulting in B&C understandably halting work till the matter was resolved. There was a good deal of discussion with various parties including distributors, manufacturers and others and one thing that is clear is that the manufacturers and distributors guidelines are far from consistent which makes evaluating work a tricky business.  

However the rubber roof (think single layer of bicycle inner tube style rubber stuck and jointed) was finally completed on Tuesday 8th. Interestingly Jonathan plans to do the remaining sections of EPDM roofing (on the balcony, canopy over the front door etc) with his own team.

Some of the areas of concern below (admittedly when the job was still in progress)

 Detailing of EPDM laid over a drain pipe connector that passes through the parapet wall.

On completion: