We'd like to build a small extension under permitted development on a brick and block cavity wall Bungalow on a thick concrete raft. We hope to clad the whole building with weatherboard so was hoping I could DIY the extension in timber. I'm no builder but a good diy'er with good wood skills as I used to repair wooden boats. I'm just not versed in the details of building construction. The extension would be about 2.7 by 4,.5 metres wide with a pitch roof. Any advice - dont do it, get on with it etc. I guess I need to speak to building control to see what floor they will accept, i.e. More concrete slab (its very thick) or foundations and joists. Its not a very warm bungalow despite the cavity being filled, we may put some thin insulation in when cladding (which apparently I do need permission for). How do i match and hopefully improve the thermal in the timber frame and avoid cold bridging through the timber frame please?
There are a lot timber frame firms, who offer timber frame extensions kits, either supply only- self build or supply and erect, that bolt on to a exsisting house. https://www.planningportal.co.uk/info/200130/common_projects/17/extensions http://easytimberframe.co.uk/technical-information/building-timber-frame-house/ http://www.ukhouseextensions.com/
Also look at SIPS, Structural Insulated Panels, used in extension & many area's of construction. A quick way of construction, there are firm who do extensions using them. https://www.homebuilding.co.uk/introduction-to-structural-insulated-panels/ https://www.sips.org/about/what-are-sips https://www.sipbuildingsystems.co.uk/ http://www.sips.uk.com/ http://sipsecopanels.co.uk/
Thanks again Kiab, we were also looking at a garden room in Sips. Its quite surprising though how the price jumps up from a basic finish yourself Sips box to a supplied completed room (windows, cladding, roofing, elecs etc). What are my options for house extension foundation please. We currently have a very thick concrete raft, for a timber frame extension would it be likely I would need such substantial foundations? I know it depends on the local building control but I wonder if trench foundation would be OK.