cost of extensions

we're looking to make an offer on a house that's really small on a big lot in a beautiful, affluent, family-oriented neighborhood & great school district. we could move in right away with few immediate repairs and whatnot, but to accommodate a family, we would have to blow out the back of the house (plenty of room for it on the lot) or turn the attic into a second floor (i.e. blow out the entire roof).

we're looking to buy something now that's a starter home but can grow with us as we need more space and have the money to pay for it (rather than buy a starter home and buy a bigger house a few years down the road), so this is a pretty good situation because of the size of the property and the prime location. I just don't want to underestimate the cost of making a house bigger.

so, if i wanted to build and extension on the back that included, say, another bedroom (smallish, for a kid) a home office (also doesn't need to be huge), another bathroom, and in the process make the dining room area bigger, what price range am i looking at? TIA for any insight you can offer!

Re: cost of extensions

I see a few companies offering 1st floor extensions starting at $25k....and up. I think that may be for a basic room. I am sure it will cost a lot more. You have to also realize that since you are increasing the footing on your house that your taxes are going to go up a lot.

Is there a way to do a full dormer instead? If so your taxes wont go up as much. We are doing a full dormer on our house....just waiting on the permit.

Re: cost of extensions

my parents added on an extension fairly large dinning room with laundry room included, pantry, redid the entire kitchen, then added two porches and did the siding all over and that had cost them roughly $100K the taxes went up I think $450. I know its not the same thing as you are asking.

A room will not be much $25-25K then the siding if you need to do the entire house, if you can patch it then it will run you less, bathrooms is where it is $$$ from what i hear because of running plumbing, electric and then taxes since you get charged for every toilet.

Re: cost of extensions

I think you're probably looking at anywhere between $50,000 - $150,000 depending on things like square footage, moving or adding plumbing, quality of materials and scope of the change (ie: wood flooring vs. carpet, full master bath vs. small half bath added, quality of windows, type of siding, etc).

A few additional things to consider:
***The lot may be big but there may be other zoning issues - friends of ours in Massepequa had their addition delayed by almost a year as they had to go for a variance on a building moratorium in their area where no permits were being issued.
***If the house is old you may find that the renovations require a full roof replacement - our friends had to replace the entire roof even though they were only dormering out part due to the older style construction not meeting code - the partial work triggered a requirement to replace the whole roof.
***Building up will likely trigger a need to add reinforcement to the lower structure. We added a partial dormer - adding 6" x 20" of floor space to our farm ranch upstairs, and we had to spend extra support to the main beam running the length of the house - an extra $2500 expense between added materials and labor.
***Adding a bathroom may require upgrades to the cesspool or septic system.
***Does everything have a CO currently? Including basement renovations, porch or deck additions, etc.? We bought a house with a partially finished basement. Turns out that type of work requires a CO, the sellers never got one, but now that the town was in our house inspecting the other stuff they are required to inspect the whole house. We got nailed with an $860 fee/fine to get a Certificate of Compliance for the work the seller had done, and we had to pay our contractor for extra work to bring the basement into compliance - another $1500.

Not to scare you off - it sounds like a great plan. These are just some of the hidden suprises you get when you start renovating - the stuff that makes your budget increase by 20%.

Re: cost of extensions

I added a side extension on my current house and on my new house i'll be doing a full dormer.

On a side extension, expect to pay about 100-130 dollars a square foot, but also don't expect to pay less than 20k. My taxes went up on my side extension, but not by too much. I added 350 square feet and my taxes went up about $800 a year.

Going up for a full dormer I am expecting to pay between 100-120k, although I'd like to get these contractors knocked down to about 100k or maybe even less. It depends on how fancy you want to get with fixtures, finishes, etc.

Re: cost of extensions

this is all great information!

Re: cost of extensions

Another thing to consider if you want to increase the footprint of the house... our town has zoning regulations that the house cannot be more than a certain percentage of the total land area, and it can't be closer to the property line than a certain number of feet. If your plans don't fall within the parameters of your zoning, you'd have to get one or more variances and they don't have to approve those. We added another floor and had to support the lower levels. Also, you have to make sure your heating system and hot water heater are enough to handle the larger square footage.

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I don't have any experience in it, but a friend of ours is an architect and he said that after Katrina lumber and copper have skyrocketed and in reality additions are $200-400 sq/ft.

Re: cost of extensions

Re: cost of extensions

Posted by GoldenRod

Posted by KLSbear


***Adding a bathroom may require upgrades to the cesspool or septic system.

In the Town of Islip, they don't care how many bathrooms you have. It's the number of bedrooms (or rooms that can easily become bedrooms) that affect the septic system. If you have a 1 bedroom house, and 4 bathrooms, you don't need a big septic system. If you have 1 bathroom, and 7 bedrooms, you need a huge septic system. For my town, they assume 4 people per bedroom, so my office, library, toy room, are all considered bedrooms.
We had to install a septic system to handle 28 people living in our house! (I don't think the 4 of us will have to worry about filling the tanks up... )

We needed a variance to extend the house using the existing lines. Our house was too close to the back fence, according to today's code. It was also considered too tall, by today's code, even though the house has been that height for 20+ years....

Our addition was a lot, but we doubled the size of the house, added a bathroom, resided the entire house, reroofed the entire house, replaced every window, upgraded the heating and added A/C, etc, etc....

Re: cost of extensions

Re: cost of extensions

In addition to what other PP said, if you are extending up on the house (added a full dormer, etc..), you need to have an inspection (probably by a structural engineer) to make sure you house's foundation can support it.

Re: cost of extensions

You might have to upgrade your electical panel too. More rooms means more wiring connected to your panel. You can't overload the panel.

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Honestly if you are looking to buy this house, I would seriously consult an architect or a contractor. They will be able to give you the most complete estimate, and it will be worth the cost if you do decide to buy this house.

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I'm looking into putting an addition on also and was just told by the county health department that not only does an addition of any size trigger the requirement for a new septic system - and the filling in and official abandonment of the old one, but in my case because we have well water, that I have to connect to county water. Wow! That really ups the cost for me and was an unpleasant surprise.

Re: cost of extensions