Digging out basement and adding extension

We are looking at a gut renovation of a wood frame house and are considering (1) digging out the cellar so as to lower the garden level floor and gain some ceiling height (going from 7.5 feet to 8 or 8.5) and (2) adding a ten to twelve-foot extension on the back of the house, all 3 levels (garden, parlor, third floor). We have a good idea of what the gut reno would cost without these but we don’t have much intel yet on what these two additional things would run us. Is there any rule of thumb or does anyone have an educated guess as to a rough estimate of the additional cost of these two items on top of a gut reno? Thanks!

mstamib

in General Discussion 5 years and 11 months ago

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uchenna

in General Discussion 5 years and 11 months ago

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Hi RJP

The cost of digging down at the ground floor varies greatly depending on whether or not you need to underpin so that you do not undermine your neighbor’s foundations. If you don’t need to, this will be much more affordable work.

For reference – a 2 story & 8′ deep extension cost 600K in a recently finish project in our Boerum Hill neighborhood.

I would start with a zoning study to be sure you have enough FAR to do the extension.

Please feel free to contact me if you are looking for architectural advice.

Regards!
Polly Horne, RA
mph@polyarch.studio
www.polyarch.studio

bbrc

in General Discussion 5 years and 11 months ago

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I have not done this myself, but from the sounds of others’ advice on this forum, building an addition, particularly one with plumbing requirements, is a huge and costly undertaking, and adds not just to a renovation cost, but also has tax implications down the line. My guess is that, unless the location of this small gut-job is TO DIE FOR, you’d be better off buying a bigger house to start with. I’m sharing below a reference from a previous and recent post on this forum with a similar question (since there were many responses that might be useful to you). I’m sure others will have more info they could weigh in with, but here’s a jumpstart: https://www.brownstoner.com/forum/#!/general-discussion:vertical-addition-help-ge

mstamib

in General Discussion 5 years and 11 months ago

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Just to add some color, we would probably want to locate kitchens in the area of the extension (in garden and parlor levels-it’s a two-family home), but would consider not doing so if that added significant cost. The third floor extension would be used for bedroom only.