Can a bungalow be turned into a regular double story house?

[Nix01]

By adding another building slab and building upwards, or are they only allowed to increase their roof pitch to allow for the attic rooms?

there is a possibility, you can do it but would depend on full engineers report. Planning is essential and part of that considers the neighbours view, light etc. You wouldnt add a slab you would use timber level.

Imagine it to be a considerable amount of money, hence why its more cost effective to turn it into a dormer bungalow with dormers, rooflights etc. Again planning, b-regs, fees etc. To convert you need a decent pitched roof as a low pitch requires more dormers as the height cant be achieved.

you aren't even allowed to up the level of your roof in some cases- all conversions on my road are up to existing roof height only (leaving 6'2 headroom in most upstairs) - only detached ones or ones where their neighbours roof is higher are able to increase the level

unlikely that you can add a floor slab, but adding lightweight walls and roof would be structurally possible. thing is that sometimes it would be easier starting from scratch as refurbs can be more risky on cost/programme than new build.

if you are serious you could ask an architect & engineer to do a quick feasibility study and/or you could speak to local planners to see how likely it would be to get planning. if the architect cant say a quantity surveyor could give you an idea of price so that you know if you can afford it before getting too far with design work

I love bungalows in a minority I know but hate dormers so personally I'd only go up if you can add a proper level.

I live in one. It had a full first floor and normal roof put on by previous owners. I think they ran out of money so there are issues with the quality of the finish, but structurally it is fine.

Depends but local planners may decide that only the current height is appropriately in keeping with others in the road so you'd only have 1.5 floors but could add dormers

My answer to that sort of question from a potential client is usually: "anything is possible, just depends upon the depth of your pocket and the local planning authority"