Having completed the roof, just the walls to do! We had a major design issue with the walls and getting a solution acceptable to Building Control to meet the Scottish regulation relating to fire propagation in a cavity. The BCO decided the cavity was everything including insulation through to the steel frame so we came up with a solution using Promat SupaLux. As ever this added to the cost but it cannot be helped as that is what they want. What I fail to understand is why there is not a standard detail for this. A Light Steel Frame is not that new a system. It is in the NHBC Handbook!
So to the detail;
There has to be a vertical and a horizontal break. The vertical is fixed to the inside of a stud; the horizontal is fixed to a piece of right angle bar originally supplied for the roof.
In the last picture you can also see the insulation fixed to the ends of the steel rafter panels. This fitted in quite nicely but as the overhang is not huge, the depth of this is limited to 90mm. Will be interesting to see if it is a hotspot if I ever get an TI camera on the place.
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 🙂