Evening all
Following the advice last time we have reworked the plans for our extension.
This short video shows the original house in grey and the proposed extension in blue.
The proposal for the downstairs is a steel frame with glass panels down one long side (south) and large doors across the back. A block cavity wall down the other long side (north) which will be rendered. The original building is brick and I like the idea of having a distinct contrast between that and the new bit (although maybe not blue blue!).
We have a copy of next doors plans when they did their extension some 20 years ago so we have a good grasp of the groundworks that will be necessary for the block walls, but I have no knowledge of building using steels.
From what I can glean the vertical steels will need to sit on pads reinforced with mesh. Any pads will need to be joined using a shallow trench filled with a concrete and a mesh frame to prevent spreading. The glass side wall is 8m and we may add another vertical steel halfway to reduce the size of steel required. The frame can sit on studding laid during the pour, but it seems drilling after the steel is in place is preferred (avoiding any mesh is planned carefully).
Using some online calculators, steels seem relatively inexpensive but I have no idea of the cost of the glass panels. They will be static, other than the bi-folds which I plan on making. We sell the mechanisms for these at work so that should reduce the cost.
The pads will be tied into the insulated concrete floor which we plan will include underfloor heating.
The upstairs will be timber framed and tie into the original roof. The original roof will change so fundamentally as well as being converted for living that I'm guessing it might be better to replace entirely?
Do static glass walls count as windows and therefore get away with allowing a higher u vlaue? This is a semi so we will face next door out of the glass on the long side, although that is also south and they only have a single story bungalow so light should be quite free flowing.
So many questions...