Granny annex cost

Furn462

Hi,

I appreciate that this is a bit of a "how long is a piece of string" question but hopefully someone can help! I'm looking at building a granny annex for my father-in-law in Herefordshire. This would involve knocking down a current garage and shed (bit of a lean-to) and building in its place a two-storey building with garage and living room downstairs, and en-suite bedroom and kitchen upstairs. Footprint will be effectively the size of a double garage. Electric and water supply in place.

If anyone could give a best guess of total cost or £/sq mtr.

Many thanks,

Andy

K-rado

Hello. As the building will be habitable, it will need to be designed and constructed in accordance with the current building regs and therefore the build cost will be on par with the construction of a new 2 storey house. I appreciate that the ground floor will be a garage and therefore will not require the same amount finish as the upper floor. With this in mind, you should deduct approx 20-25% of the area build cost. e.g. if your granny annex will be 6 meters x 6 meters, then, with out the benefit of your exacting plans, it is fair to assume that the total potential habitable area could be in the order of 72m2. applying a build cost, in the order of £1000/m2, the overall build cost should be in the order of £72,000. Less the fitout to the ground floor area, then I would expect to pay in the order of £63k + Vat, excl professional and statutory fees and any demolition, site clearance works. As a guide, I hope this helps but bear in mind that there are 1000's of factors that could affect this price. Never the less, based on the above size, 2 stories with a hipped roof, the price could be anywhere in the region of 50 to 75k. Happy to point you in the direction of a good architect and builder. Cheers K.

ormus

you can do that for half that price. for a small annexe.
the average garage size is about 9 sq m. so 4x9 = 36 sq m.
therefore say 36k. for the basic structure.