Adding an Extension

Can anyone help me estimate the cost to add a two-story extension to a brick townhouse? We’re talking 20 feet wide, 13 feet deep. (We have checked the FAR and there is no legal issue with doing this.)

rana-foroohar

in General Discussion 9 years and 11 months ago

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randolph | 9 years and 11 months ago

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> @CarmenR
> fighting about sprinklers

depending on your carrying costs it could make more financial sense to put in a sprinkler system than spend 8 months fighting it while making mortgage payments.

CarmenR | 9 years and 11 months ago

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> @randolph
> is this what takes so long, that they have to run the project past some sort of zoning approval or community board?

We did not experience that and I don’t think that’s the issue with anyone we know- they’re going through more run-of-the-mill BS (fighting about sprinklers in a single family home is the big one that comes to mind.)

randolph | 9 years and 11 months ago

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> @CarmenR
> adding extensions

the house next door to ours has been trying to get their alt1 for a horizontal and vertical extension approved for a few months now, and when i look it up on the DOB site it says

“Development Challenge Process is pending Zoning Approval”

is this what takes so long, that they have to run the project past some sort of zoning approval or community board?

CarmenR | 9 years and 11 months ago

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> @randolph
> this is not necessarily true. my alt1 was approved recently in under 2 months but I am not adding an extension I am only reconfiguring an existing 2 family from double duplex to triplex w garden apartment.

Fair enough. We have two neighbors who have been waiting over 8 months for their Alt1 approvals (one is over 12 months at this point,) but both of them are adding extensions. YMMV.

randolph | 9 years and 11 months ago

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> @CarmenR
> Also remember this is an alt-1 which is taking people 6-10 months for approval these days.

this is not necessarily true. my alt1 was approved recently in under 2 months but I am not adding an extension I am only reconfiguring an existing 2 family from double duplex to triplex w garden apartment.

rana-foroohar | 9 years and 11 months ago

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Thanks, this is very helpful. And so glad to hear this doesn’t require an Alt-1 permit! We are not changing the number of floors, units, or arrangement (it will stay two-family, with a duplex over a simplex), so it sounds like we’re in the clear.

rana-foroohar | 9 years and 11 months ago

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Thanks, this is very helpful. And so glad to hear this doesn’t require an Alt-1 permit! We are not changing the number of floors, units, or arrangement (it will stay two-family, with a duplex over a simplex), so it sounds like we’re in the clear.

jimhillra | 9 years and 11 months ago

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CarmenR is correct. We generally tell clients to expect around $300/sq ft for new construction, but note that this does not include the foundation. We figure about $150/sq ft for the foundation, assuming a crawl space, a bit more if a fully excavated cellar. This does not include underpinning, which you may need if either of your neighbors has an extension is in any way built deeper than your home.

However, it does not necessitate an Alt 1. The Alt 1 comes in if you are changing the number of floors, number of dwelling units, or arrangement of dwelling units (say switching a duplex over a simplex to simplex over duplex, etc). If you add a 3 story rear extension onto a 3 story building, but leave the dwelling unit count and arrangement the same, you can avoid the Alt 1 new C of O.

CarmenR | 9 years and 11 months ago

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It’s hard to say how much specifically the extension would cost, however I would say $300 per sqft minimum for new sqft. You’ll need many more professionals when you start adding sqft. We did a 21×10 3-story extension and I would say the cost of that specific component was around $300-$325 per sqft not including soft costs. Also remember this is an alt-1 which is taking people 6-10 months for approval these days.