House build cost: Are estimates based on internal floorspace or exteral space

EagerBeaverton

Potentially silly question...

When you see posts saying it costs, for example, €1500 per square meter to build a house, is that per square meter of internal floorspace or per square meter of total space the house takes up (inclusive of external walls)?

Gumbo

It’s irrelevant as it’s just a beer may calculation to see if your expectations are in the ball park.

*but usually internal floor space. In Dublin, it’s €2k or there abouts.

EagerBeaverton

Sorry should have clarified, it was more what the quotes refer to rather than the actual cost itself I was curious about.

We got a couple of ball park quotes over the phone directly from builders for a potential new build (not in Dublin) and I always thought the quotes were for the entire space the house took up inclusive of outer walls. Just dawned on me when reading a few posts today that the costs seem to typically refer to the internal floor space excluding outer walls which has a sizeable difference on total cost.

Gumbo

EagerBeaverton wrote: »

Sorry should have clarified, it was more what the quotes refer to rather than the actual cost itself I was curious about.

We got a couple of ball park quotes over the phone directly from builders for a potential new build (not in Dublin) and I always thought the quotes were for the entire space the house took up inclusive of outer walls. Just dawned on me when reading a few posts today that the costs seem to typically refer to the internal floor space excluding outer walls which has a sizeable difference on total cost.

You can’t build the inside floor area without the external walls so quoted should include them.

EagerBeaverton

Gumbo wrote: »

You can’t build the inside floor area without the external walls so quoted should include them.

Cheers, yeah we were only getting ballpark costs per m2 from builders rather than quotes on a full plan.

An example plan we have is 260m2 total space but is 210m2 internal floor space - that 50m2 in the difference would equate to up to €100k extra so that's why I wanted to double check!

SOPHIE THE DOG

EagerBeaverton wrote: »

Cheers, yeah we were only getting ballpark costs per m2 from builders rather than quotes on a full plan.

An example plan we have is 260m2 total space but is 210m2 internal floor space - that 50m2 in the difference would equate to up to €100k extra so that's why I wanted to double check!

Based on Gross Internal Floor Area.

scwazrh

Always internal floor space .

dubrov

Estate agents normally quote total area of the structure less the external walls.
Internal walls don't count which makes sense as they can be removed in many cases.

In term of the estimates you hear, they will be on the low side. People like to brag about how cheap it was to build their house and conveniently like to leave out engineer, architect, council, water, electricity, landscaping fees plus work they did themselves.