Full walkin basement for the 20ft wide 1.5 story Q's

[UK4X4]

Some people have done just a rear wall with some sides and a framed front wall, would there be an issue with doing just a rear wall and for example a 2ft return each side and the rest framed ?

I'm not going to be retaining anything, just wondering what rules or standards I have to follow, as the snow is deep and I have a 1-2 meter high bank blocking the view so a basement would be the best route to have the views

ie I'm not sure i want to build a 9ft high basement all out of timber and then plonk on a full house, but a full concrete basement would be expencive.

The basement would contain the garage and a workshop- kitchen area with patio doors and windows

On this pic there's an added corner just imagine that is'nt there and the concrete wall would be from the edge of the garage back across the visual front of the house with includes a 20ft by 12 wide T in the middle


so this front edge would be concrete basement level only