cost of extending a room

Manhattan? Anywhere between 50 and 100k.

Hopefully you already know that if the existing exterior wall is load bearing, you won't be able to knock it down.

It's in Manhattan. I think the exterior wall is load bearing. So, I guess the option is to add a sunroom kind of space without removing the exterior wall. Thank you for the replies.

Anything is possible with enough money. A structural engineer could determine if the wall is load bearing, and if so, what kind of beam would be needed for support if you did remove the wall.

Is it a townhouse? If it's load-bearing, just add an I-beam. That's pretty common. Look around the backs of neighboring townhouses - an increasing number have full-width extensions. Who is your upstairs neighbor? The roof of the extension could be a nice deck, get them to share costs.

Yes, it's a townhouse. Sharing the cost with the upstairs neighbor sounds like a great idea. We are just wondering which makes sense to spend money to gain 90 square feet or move to a bigger apartment. Eventually, we may need to move, but do you think the added space is a good investment to raise the value of the apartment when we need to sell?

I wouldn't do it for 90 feet. Unless it was an extra bedroom. Also, check with neighbors to see if they want a larger living room.

You don't own the building and yard. The condo or co-op does. You need to read the governing documents to find out whether your rights to the yard (if any) allow you to build on it.

If a co-op, it might be happy to sell you additional shares and let you expand into its yard.

If a condo, the yard is probably a limited common element. If you can build on it, the condo would amend its declaration and maps, increasing your PCI and decreasing the other unit owners'.

"Is it a townhouse? If it's load-bearing, just add an I-beam."

Easier said than done. Adding an I-beam adds stress to the side walls. If renovation_novice is in the first floor of a five-floor townhouse, "just an I-beam" could result in buckling the side walls.

Again, a very common project.

How big is the apartment? A 6' x 15' room does not seem like it would add much value, unless the apartment is a studio or small one bedrooom. If you can blow out the wall (and I agree that an i-beam is a pretty common project) and reconfigure the apartment in a way where the extra space would be more meaningful, maybe it's worth it.

Absolutely no way you will do this for $50k, though. Minimum $100k once you add in architect, structural engineer, and all of the various fees involved.

Also you should understand how many additional shares you'll get and what the impact will be on maintenance. You'll likely be charged a straight square footage formula, when in reality a room that's only 6' deep is not going to be as valuable. If you do go with a sunroom route, I'd argue for some type of discounting (try for 50% and negotiate to 75%) to accommodate that you probably can't/won't want to use the room year-round.

"Again, a very common project."

Because it has been done in *some* projects, you can't assume it can be done in all projects nor in this project without knowing much more about the structure and personally inspecting the building in question. Renovation_novice did not state whether the load-bearing wall supported, say, the entire structure or a later addition, which makes a profound difference. Nor did he/she state the age or type of construction -- is it masonry or frame; again, critically important. And what about the foundation? Adding an I-beam creates new stress points on the foundation, which it might not be able to support.

While *some* exterior load-bearing walls have been removed in *some* projects, how many can't be approved and permitted? What was the cost for those? What percentage are approved versus those which are not? Structural engineers and architects usually don't work on a contingency basis, so Renovation_novice could spend considerable sums on a stillborn project.

Then there's the issue of liability -- let's say the project is approved. Half-way through, a wall collapses nonetheless. That happened last year on an UES townhouse when part of a load-bearing wall was removed during the construction process. Yes, ultimately, a court might find the contractor and/or structural engineer was liable, but that won't prevent the homeowner from being sued, because in litigation you go after every possible deep pocket.

Let's say construction goes without a hitch. But, two years later, doors and windows upstairs no longer fit properly. Plaster walls crack. Neighbors want restitution. Again, renovation_novice would be an attractive target in litigation. Yes, the contractor and/or structural engineer might ultimately be liable, but that won't stop someone from also suing the homeowner who removed the load-bearing wall, because litigation is all about targeting every possible deep pocket.

I'm a lawyer, not a structural engineer, so I'm not a construction expert. What I do know is that the case law is full of "simple" construction projects that went awry, causing injury and damage to unrelated third parties, resulting in expensive litigation.

As a first step, Renovation_novice should get expert advice from someone who inspects the structure in question. Seeking drive-by opinions from unnamed anonymous posters on an Internet forum who have no familiarity with the building in question is not the place to start.

Original poster asked about costs - of course, there is always a chance that the project will be disapproved. As far as townhouse buildings go in Manhattan, the vast majority are NOT frame and were built within a narrow time frame. I keep a very close watch on TH renovation and extension project filings on the Upper West side. I haven't seen an extension disapproved for structural reasons on the UWS in last 10 years. The DOB doesn't seem to question the opinion of a structural engineer that the owner has hired. As far as lawsuits go, I don't know if they are common. The most famous stalled project is Ann Curry's on 71st - btw, she demolished much of the back wall and was unlucky enough to have litigious neighbors. My hypothesis as far as lawsuits go with TH projects us that you are more likely to be sued if you live next to owner-occupied buildings. Definitely, a good knowledge of who your neighbors are is handy in a project like this.

Thank you all for expert opinions. I'm a bit overwhelmed to digest all the information, but I will take all into consideration. We own the backyard. The co-op's board of director recommended we extend the room; otherwise, we wouldn't even dream about it. The apartment is a small one bedroom. So, extra 90 square feet does make a difference but obviously not a lot of a difference. We are running out of space and we thought one of the solutions is to build it out. Our building doesn't have the extension wing that most of the brownstone buildings have. So, I think we can extend out 6 feet as long as we keep 30 feet to the adjoining property. (I haven't fact-checked but this is what we were told.) I searched the Internet but couldn't figure out the cost since this is a pretty unique situation.

If extending the room is too complicated, we can probably live with attaching a sun room kind of addition, which can work as a dining room if we can figure out how to get heat in the room in the winter. I've seen a sunroom next to the wing (bedroom) in a ground-floor brownstone apartment which was built out, and somehow the room is heated. So, we can do something similar.

Fear of litigation aside, here are some factors that go into determine size of extension:

1. 30 foot clearance from back of property - this is going to be true for most 100' townhouse lots.
2. Landmarks approval - subject to review even though it's not visible from street. Landmarks is now concerned with a growing doughnut effect in TH yards.
3. Party wall considerations. Consider reaching out to neighbors to see if they will consent to one so you get a few more inches of room.
4. Zoning - does your building have sufficient FAR to build out your 6 foot extension?
5. Foundation - your upstairs neighbors (all or some) may be interested in bumping out 6 feet.
6. Don't forget that your boiler needs an outside vent.

I am curious about one thing - are you on a 100 feet lot. If so most THs are built 50-ish feet deep. Wondering why your yard is 36'. Personally, the risk reward wouldn't be worth it to me for 90 sq. feet.

A bit off topic - does anyone know if an extension was built back during original construction (100 years ago) to 10 feet from the back of the property, would you need to remove the extension if you do a major renovation?

Thanks.

Thanks nyc10023. How does party walls give a few more inches of room? I'm just curious. In any case, I'm getting discouraged to seek to build out. After all, the cost and the risk factors don't seem to worth the extra 90 square feet although it would be nice to have.
We are in one of a few THs next to each other and with all these combined, maybe it's about 100 feet across. I believe our TH (it actually comprised of 2 TH units and our apt occupies one of them) is the only one with 36 feet long backyard. I don't know why but I know it's rare.

Pawn_Harvester, no, as long as the building complied with the code in place when it was built. That assumes "major renovation" doesn't cross the line into what'd be called reconstruction.

E.g., 107 W 82nd is trying to get approval to add a 650 ft² penthouse on its roof. The various agencies have some quibbles, but there's no question of having to raze the part of the building that covers what'd now have to be a 30' yard.

Then again, the law does strange things. E.g., for years the state said it was OK to luxury-destabilize an apartment in a J51-benefited building, as long as the J51 benefit was reduced proportionately, but then a court came along and said Oops, everybody was wrong, they shouldn't have been allowed to decontrol.

"the only one with 36 feet long backyard."

Another factor to consider is this: would a possible addition diminish what makes your unit particularly distinctive -- that back yard? The addition might add value to the space but it also might *decrease* the value concurrently because you no longer have as large a yard.

I know people who would never consider a first-floor unit *unless* it also has outside space. If you gobble up that outside space with the addition, are you creating yet another less-than-entirely-desirable first-floor unit?

I have been working with Brooklyn townhouse clients, and it's a whole different world, it really is -- I would suggest consulting with a broker who specializes in houses in your area because that's the person who can really price these kinds of improvements.

That said, my blind guess is that a simple 6 by 15' sunroom wouldn't be worth it, but spending six figures to push the kitchen back into the extension probably is.

ali r.
DG Neary Realty

I think you're missing my point about 36'. That seems short to me for an 1890s TH on 100' lot. Curious about the style. Center stair? Low stoop? English basement?

To FP's point, for valuation, you really need to find a TH co-op specialist in your area.

PawnHarvester, my building had a basement extension that was built all the way to the property line (92' deep) in the 70s. It's actually a really cool space -- reminds me of a California ranch house in the middle of Manhattan. The bedrooms have skylights and sliding doors that open to a bamboo-filled side yard that's about 8' deep. When the building went co-op, this space could not be sold because of C.O. issues. Not sure whether it was never filed or what. So it was rented as "commercial" space for 10 or 15 years until somehow the owner got a C.O. for it in the early 2000s. Not sure what was involved. The apartment has since been gut renovated (with DOB-issued permits) without issue.

nyc10023, I really don't know the architectural style of our building, but it was built in 1893. I'm not sure about 100' lot thing. Sorry, I just thought it may be about 100' when we combine all the adjoining THs, which are very similar in style.