Rebuilding bay window and building regs

secla

We need the bay window of our 1930s semi rebuilding due to poor foundations etc. currently flat roof but want to put a pitched roof over, council are being particularly unhelpful with planning but from what I can gather I dont need planning just building regs.

being 1930s it’s of solid wall construction with suspended floor, building regs are telling me that we will need to rebuild to the same spec as a new extension with cavity wall/foundations/insulation etc to current standards. With sign off at each stage.

seems a bit overkill for a bay but is this the norm ? Or have I got my wires crossed somewhere 

grumbler

An insulated  cavity wall doesn't look like overkill to me. I think it can be a single-skin brick wall with internal insulated stud wall, but what's the point in overcomplicating things?

secla

Overkill in the sense of it’s not going to make a huge difference when the rest of the house is still solid walls. Next door neighbour had there’s done and have internally insulated with plasterboard that has 60mm of insulation on the back but they’re insisting that it has to be cavity.

Section62

secla said:

We need the bay window of our 1930s semi rebuilding due to poor foundations etc. currently flat roof but want to put a pitched roof over, council are being particularly unhelpful with planning but from what I can gather I dont need planning just building regs.

If the bay is at the front (e.g. nearest the road) then the planning department are correct about you needing planning consent.

If the bay is at the rear then it is more complicated.

secla said:

being 1930s it’s of solid wall construction with suspended floor, building regs are telling me that we will need to rebuild to the same spec as a new extension with cavity wall/foundations/insulation etc to current standards. With sign off at each stage.

seems a bit overkill for a bay but is this the norm ? Or have I got my wires crossed somewhere

Building regs relate to building work being done now, not what was done in the past.  If you are (re)building then the work needs to comply with the relevant current standards.  Having one part of the property constructed to a better standard now will help with issues such as heat less, and one day the solid walls may get improved insulation so the new work being done to a better standard now will avoid it needing to be upgraded later.

secla

Bay is on the front, so you think I will need planning or won’t ?

Section62

secla said:

Bay is on the front, so you think I will need planning or won’t ?

I think you probably will.  Formal planning consent is needed unless the work falls under one of the permitted development categories. (assuming permitted development rights exist for the property)

Raising the roof of a front bay by enough to convert it from flat to pitched wouldn't fit any of the PD categories as far as I know.

Furthermore, if you need to build the walls thicker to comply with building regs then you will end up with a smaller internal space.  By applying for planning consent you potentially have the opportunity to position the walls to maintain (or even increase) the internal space, with the bay being larger on the outside.  The internal space gain you'll possibly be allowed isn't going to be vast, but probably worth it for the cost of a householder planning application.

FreeBear

Going from a ~230mm thick wall to one of ~300mm isn't going to impact on the floor space by much. If I were doing the job, I'd also be taking the opportunity to insulate the rest of the external wall (from the inside).

Section62

FreeBear said:

Going from a ~230mm thick wall to one of ~300mm isn't going to impact on the floor space by much.

True, but I was assuming (perhaps incorrectly) it is a typical 1930's bay of about 100mm thickness.

secla

I most likely will as it’s less than 1m both sides

grumbler

Section62 said:

FreeBear said:

Going from a ~230mm thick wall to one of ~300mm isn't going to impact on the floor space by much.

True, but I was assuming (perhaps incorrectly) it is a typical 1930's bay of about 100mm thickness.

Is it really typical? Without a windowsill?

secla

I’d say it’s nearer 200mm maybe a little less and the sill on the inside has an overhang of 60mm so I wouldn’t be losing a great deal internally if a cavity is 300 total