Costs of an attic extension

yobr

I’m looking for some advice on the potential costs involved of converting my attic. It’s an L-shaped room of approximately 720 sq. ft. and the house is a bungalow. I currently have a stira, which gives me access to it, and I can stand in it, as it is around 7ft high. It is also floored in all parts of it.

In terms of what I want, I was thinking about a home office, in the smaller part of the L-shape, which is approximately 13 ft. x 10, and have two rooms and possibly a bathroom elsewhere. I've set out below what I think are the major elements of the work and am happy for comments.

Electricity: There is electricity in it with some plug points and lights but I’ll need more.

Stairs: What would the cost be to construct and fit a stairs? Ceiling down stairs is about 8.5 ft.

Heating: There is no heating so I’ll need to extend the oil central heating. Could I have an underfloor option?

Flooring: There is flooring but will I need any loading bearing support or steel?

Insulation: There is insulation on the floor of the attic but none directly on the underside of the roof. Would regular insulation or spray on be a better option? Does the type of insulation matter depending on what the attic is used for?

Bathroom: Just wondering on cost of a bathroom might be.

Thanks

Pink11

I'd also be interested in hearing rough costs of converting an attic by anyone who has any experience?

Calvin001

Its a question that would benefit from a drawing or sketch.
You say you have 7ft, is that in the middle?
Do you have a A-frame roof (ie. does the standing height reduced at both sides?)
You talk about 3 rooms and possibly a bathroom up there? how do you get from stairs to the last room - is there head space for a corridor from the stair location down to the office or back to the last bedroom? (ensuit / bathroom could be off the bedroom)

Are you thinking of building a dormer into the attic?

Calahonda52

If you don't have7 by 2 or so as floor joists then you will need to upgrade the floor, either with steel or timber, which may reduce your head room.
IMO, no spray foam.

Use ventilation baffles at the eaves