Well the roof insulation is complete at last. Seems to have taken ages; in fact it has at about 5 weeks! Way over what I estimated. Still it is done now and looks really good. The rest of the Velux windows need to go in, but we will leave these until the roof tiles appear just to check the battens are right.
This photo is just before the front was finished.
Almost there with the roof insulation and the sun is out for once!
Now on to the walls………
Just came across this on the BBC Weather Site http://www.bbc.co.uk/weather/features/19810032. Explains my problems in a nutshell except I don’t really remember the dry start to September!
Oh and this http://www.bbc.co.uk/news/uk-19427139
It has not been a good year to be doing anything outside – least of all building. I’m sure we had not had a dry 24Hrs for months until last week when we managed about 3 days dry.
We have now got all the rear part of the roof insulated and ‘felted’ ready for the tiles. Brian is working round the house getting all the rafter sprockets and fascia on and then it is just the 130mm PIR insulation and the membrane. We had a slight hiccup on this front as it was not immediately available so we have waited just over a week for it. Still the tiles are not here yet so that is not a major issue and he has had plenty to get on with.
I have got the scaffolding off someone I know and Iain has helped me put it up. We have made a pretty good job of it though I say that myself!
One of the new aspects was the fitting of the Velux windows. I have gone for top spec triple glazed units with a new recessed flashing and insulated collar which significantly improves the U-Value. So Brian was working with the unknown of a new fitting system and fitting it to external insulation. The other key issue was the position of the window as the lowest open part of the window must be no higher than 1100mm for fire regs. Chris at U-Roof had done a load of work trying to get the height right but we still needed to do some adjustments on site.
In the end it was simpler that we thought. I had in my mind that we would need to do something similar to the roof edge to build a wooden frame but we have simply mounted them on the 38×50 battens with a 25mm cross piece (as the roof battens will be steel). It does remain to be seen if this work with the Nu-Lok roof but I expect it will.
Velux insulated collar sitting in the insulation before final fitting.
Velux fitted on battens
Velux from inside showing the grey insulated collar. Insulation will be cut back so the opening is horizontal to increase light.
I think we will need some sealing tape to make this airtight though.
The Velux Windows In
This is a belated entry with some photos of what has been going on.
You can see the completed Oak Frame here.
The SIP (structurally Insulated Panels) are going on.
The rear part is complete and the steel rafter panels are all in place. Note that the rafter panels and the SIPs at the gable end are at the same height.
The decision to use the rafter panels through was the right one as it made making the ridge detail and the level of the roof just work. Brian had a fair bit of ‘leveling’ to do as the Oak is not an exact construction method, but the result is very good and will not distort over time.
Would I use SIPs again – no. There are simply too many thermal bridges in this construction method to make it a good solution IMNSHO 🙂
One of the things that has slowed us down is the detailing that has had to be done. This has mostly been things that Brian Edwards has not done before so it has all had to be worked out. That and my attempts to remove as many thermal bridges as possible has added time to the build.
One of the key areas so far has been the rafter sprockets and fascia. There were discussions about how large the timber used needed to be to take both the uplift stress and the weight of the gutters etc. Firstly, we had to wait until the rafter panels were on the Oak frame so we could see where the roof line intersected so the fascia ran round level as these 2 areas are different pitches. Once that was sorted the rafter sprockets could all be cut from 89×38 timber. At the edge of the roof panels, some 38×50 was screwed to the steel and 40mm PIR insulation put between these. We are using some SOUDAL Fix & Bonds low expansion foam to help seal and fix the insulation.
The rafter sprockets are then screwed on through to the steel frame and more insulation inserted between these. Again copious amounts of expanding foam provide a well sealed detail. The gable end was done in much the same way. The SIPs were designed to come to the same height as the top surface of the steel rafter panels and the 38×50 used followed by the 89×38 both in-filled with insulation.
The next detail to be sorted out was the fascia and the over fascia protector. This is complicated by my decision to use the Nu-Lok tiling system that consists of a metal ‘Z’ batten and a clipped in tile. Partly because of this, and the fact these battens will be screwed to the counter battens rather than right through, the counter battens are 38×50.
Again the detail we have ended up with is very neat and does the job just fine.
Over Fascia Protector
The fascia itself is just 145×22 Dressed and Treated with 2 coats of Sadolins on both sides. A groove has been put on the back face to take 9mm ply for the soffit.
We also had long discussions over the use of a breathable membrane on the roof. I really fail to see why it is needed but it was an argument I was not going to win with the BCO so I reluctantly accepted this.
The other thing I should mention are the long fixings I am using. The first lot I got through ACS where I got some wall channel from (more on that another time) and they are not great. As you can see, the tips keep breaking.
I had been recommended a firm called CFT Ltd http://www.cftltd.net/stafix.html but had not used them. I have now found a local supplier Regis Roofing in Glasgow and started using them. They are far superior, Stainless Steel instead of BZP, and even cheaper for a longer screw.