Extension guesstimates...

Gurgle

I'm planning to get things moving on an extension in the next few months, still deciding on whether to go single-storey or 2-storey.

Its a 3-bed semi, ~9 meters back to front and we want to extend out 4m to the side.

Thats 36m2 / 385 square feet.

The plumbing will be just a couple of rads, electrical is just a few lights & sockets.

Plans, fittings, fixtures, internal doors, painting and decorating, electrical and plumbing will be DIY / nixers for my mates.

Sooo....
Guesstimates....

Cost of building for foundations, walls (dry-dashed back and side red-brick cladding at front), windows (1 bay window @ front, 1 small utility room window @ rear), patio doors and a tiled hipped roof?

How much extra if I go to a second storey?

An extra bay window at the front, an extra window at the back, more bricks and another rectangular hole cut in the side wall of the existing house. (2 more rads, 2 more light fittings, 4 more sockets - more beer for the lads).

seclachi

Its a tough one to estimate, especially with all the foxers. Probably best to get a spec made up and see what builders come back with.

RKQ

Gurgle wrote: »

Its a 3-bed semi, ~9 meters back to front and we want to extend out 4m to the side.

You will need planning permission for this side extension.
It will be much easier price once you have a full set of drawings and have finalised the design - single or two storey.

It will be possible for you to work out lengths of foundation trenches - giving you cubic concrete volumn. Floor area will allow you to work out tonnage of stone hardcore, tonnage of sand, sqm of radon barrier and floor insulation, cubic conc. volumn of floor slab.

Trench lenght with give wall lenght x height (each block course).
It will be easier to compare prices once you know linear length, sqm area or cubic volumn.

Gurgle

2-storey vs 1-storey
The difference will be approx 800 blocks + 2 bedroom windows, plus the extra labour of building those blocks....
I've seen estimates for brickies at 50c per block to lay them, would that be way out ?

seclachi

Gurgle wrote: »

2-storey vs 1-storey
The difference will be approx 800 blocks + 2 bedroom windows, plus the extra labour of building those blocks....
I've seen estimates for brickies at 50c per block to lay them, would that be way out ?

What about plaster, insulation, roof insulation ? Theres always the little things (well maybe not those examples :rolleyes:) in a building job and they`ll be the killers when it comes to a budget.

Gurgle

More details...
After annoying everyone all day, I've got this bom:

Extension 36m2 (9x4) ground floor area.

Height: 5m + (1m risers)
Width: 4m
Depth: 9m

Front: 4m = 9 blocks across
6m = 27 blocks high
= 243 blocks

Back: Same as front
= 243 blocks

Side: 9m = 21 blocks across
6m = 27 blocks high
= 567 blocks

2100 blocks
+ 20% (wastage + internal walls @ ground floor) = ~2600 blocks

+ Cement
+ Sand
Sills + Lintels

Concrete for foundations: 1m x 0.3m x 17m = 5.1m3 concrete
Filling

Wire mesh
Radon barrier
Sump
Insulation: Floor + Walls
Fixtures & fittings
DPM
Concrete(floors)

2nd floor:
Joists, Ties & stuff, T&G

Attic:
Joists, Ties & stuff, T&G

Hipped roof:
Rafters, Ties & struts, Hangers, Felt, 2x1s, Tiles
Fascia & Soffet

Red bricks (Front up to ~2m)
Dry dash (rest)
Patic Doors

Windows
2 x bay windows (front upper & lower)
1 x large window (bedroom, rear)
1 x small window (utility room, rear)


Radiators 2m x4
Electrical fittings: lights x 5, double sockets x 12

ccsolar

Hi Gurgle.
Concrete for foundations: 1m x 0.3m x 17m = 5.1m3 concrete
Filling
I assume from the above you are putting in strip footings.
The ground needs to be very good for this otherwise go for the raft foundation, a bit more expensive but well worth it in the end.
Have heard of a few extensions pulling away from the main building with this method.
Do you have an engineer to consult on this?


CC

Gurgle

ccsolar wrote: »

Hi Gurgle.
Concrete for foundations: 1m x 0.3m x 17m = 5.1m3 concrete
Filling
I assume from the above you are putting in strip footings.
The ground needs to be very good for this otherwise go for the raft foundation, a bit more expensive but well worth it in the end.
Have heard of a few extensions pulling away from the main building with this method.
Do you have an engineer to consult on this?


CC

I don't recognize either of those terms.
I'm a while off getting an engineer in... still 'discussing' single-storey or 2-storey with the Mrs.

We got draft plans done up a couple of years ago for a 2-storey, so just running off them for the moment to get some idea of costs.