Per SQ Cost

[jjohnston7]

I am looking to build a house. And am trying to figure out what it would cost to push a wall out 2 feet. Its a 988sq ft per level split entery house. If I take the cost of the house divided by 1,976 sq ft would that be a good estimate of cost to push the wall out. meaning take that per sq ft number and multiply that by the extra square feet added?

125k house
1,976 Sq Ft (un finished basement)
$63/sq ft.

$63 * 50(sq ft added with pushing wall out) = $3,150

Is that accurate, or would it be different because of the basement not being finished?

[Don_P]

It depends on which wall structurally. If you go one way you're probably close, if you increase girder, joist, rafter spans then you are probably very light as they will not only get longer they will get bigger.

[jjohnston7]

It would be an exterior wall on the left side of the house. The side the bedrooms are on if that helps...

[Rich]

Whose left side? Is it the eave side or the gable side?

[jjohnston7]

It would be the Gable Side.

[Rich]

Not as difficult to extend on the gable side. But I'm going to say your $63/sf is a little light. Your first floor is quite a bit more expensive that an upper floor because of the excavation and foundation.

[jjohnston7]

I was thinking of just the main floor not foundation and bacement. Have it overhang...

[Rich]

That means you will need to cantilever joists. Rule of thumb is 3-1 for cantilever. So for 2' cantilever would be 6' back inside the house. Hopefully there is no finished ceiling in the basement with easy access and the floor joists run perpendicular to the gable wall. If not, $63 / sf isn't going to cover it either. I would venture a guess that they run parallel with the gable wall though. Which means you're cutting back into your floor to run a header to hang the new cantilevered joists off from.

See attachment.

If the final configuration looks like the top cantilever you should be able to do it fairly easily, but if it looks like the one on the right side it will be much more difficult.

[jjohnston7]

Yes, there is not a finished ceiling in the bacement, because the house hasn't started to be built yet. I just have a quote of what the cost to build would be as is, and I was trying to get a rough idea of what the total would be with that wall 2' farther out.