Calculating a House's Square Footage
July 29, 2008 9:30 AM   Subscribe

When calculating a house's square footage, does one include screened-in outdoor porch areas (with unfinished floors and no heating or other amenities)? Does one include separate garages (with no heating or other amenties)? Basements? Also, is there a definitive source I can point to for justifying any inclusions/exclusions re: the above to those who might question? Thanks!
posted by jimmyjimjim to Home & Garden (20 answers total)
Depends on who one is. I've seen realtors include individual shelves on a built-in bookcase, as well as the thickness of both interior and exterior walls. One of the biggest agencies here in New York advises its agents to add %6, as well as a disclaimer that square footage is approximate.
posted by StickyCarpet at 9:37 AM on July 29, 2008

The rules vary by state - for example, in some states basements count towards square footage, in others they do not.
posted by LolaGeek at 9:43 AM on July 29, 2008

I get the impression that different people use different methods of counting, which is problematic. From what I understand, most people measure the outside dimensions of the structure, and only include conditioned space. So your screened-in porch would not count in the stated figure, but certainly should be mentioned. Likewise any garage (attached or detached).
posted by adamrice at 9:45 AM on July 29, 2008

LolaGeek, any suggestions for how I could find the rules for my state (CT)?

Thanks, Adam, that makes sense. And stickycarpet, you've confirmed my suspicions!
posted by jimmyjimjim at 9:55 AM on July 29, 2008

The rules vary by state - for example, in some states basements count towards square footage, in others they do not.

Actually, the rules for counting don't vary by state so much as by community, and what your purpose for calculating square footage is. All the state agencies will care about is the "Building Code" definition of square footage, which is calculated to provide the building department with an idea of how many people will occupy a given space and how many exits are required. Typically, building code area is anything that has a roof (what acutally constitutes a "roof" is debatable with your building official), which means your porch and basement would count. The garage wouldn't necessarily count under this standard, since it would be a separate building.

To counter that, the planning departments of cities, counties and towns will mostly want to know what the square footage of a building is so that they know how bulky it is, and so they can gauge a building's size relative to the lot (a calculation known as Floor Area Ratio). For that measurement, everything within the building envelope and above grade would count, meaning that you wouldn't include the basement and porch unless they met certain exceptions -- in my area, if a porch is enclosed enough or a basement is exposed enough, it'll count. The garage would definitely count, since it's a built-up part of the site and not open space. All this varies per jurisdiction though, so the only way to really find out is to check at your local building department.

So, it really depends on why you're calculating your square footage. Are you trying to sell the house? If so, I'd list the porch, basement, and garage as separate items, especially so if the basement and garage are unfinished -- otherwise, you're being kind of sneaky and in that case why are you even bothering to ask here? If you're submitting plans for a remodel or something to the building department, you'll most likely need to list BOTH calculations, although you won't run into any trouble with the building code numbers unless your house is incredibly large and your building department will probably only care about their zoning regulations.
posted by LionIndex at 10:09 AM on July 29, 2008

I'm a house buyer. And I know that the square footage figure put forth by the seller is phony (I know this because I'm currently renting the property, and have measured!).

I want to begin negotiations with the landlord with ironclad square footage figures, which means figuring out exactly what standard practices are.

It seems like the garage, porch, and basement shouldn't enter into the total. thanks!
posted by jimmyjimjim at 10:14 AM on July 29, 2008

Square footage is typically recorded by the tax assessor's office. You should have the ability to look these records up online to get the "official" square footage for the dwelling.

Typically, it only includes finished living space. No garages, basements, etc.
posted by Ostara at 10:17 AM on July 29, 2008

It seems like the garage, porch, and basement shouldn't enter into the total. thanks!

Well, I don't know if I'd go that far. I don't know of any iron-clad rules for real estate listings, but if you're using those spaces, I think it's pretty fair that they're included somehow.
posted by LionIndex at 10:20 AM on July 29, 2008

My experience with buying & selling houses (in Toronto, ON & Sunnyvale, CA) is that square footage is supposed to be interior living space. Garages (attached and detached) and decks are not be included for MLS listing purposes. Basements are generally not included unless they are completely finished living space. For example, I looked at one house that had a finished, detached garage that was about 400 sq ft by itself but that number was not included in the listed sq footage of the house; the free-form description mentioned it. The house I eventually bought is a back-split - part of the house is about 75% below grade but that is included in the sq footage as it's fully finished living space. The basement in my old house was not included as it was only ~6' tall and extremely rough (there were patched of dirt floor in the basement when we moved in).

Some people take an envelope measurement to calculate sq footage, some add up the size of the rooms and add a fixed amount/percentage for hallway space, there are lots of ways to do it. I would not ever consider any sq footage measurement to be 100% accurate.

So garage, deck & unfinished basement are out for listing purposes. I do not know if this is a rule but it is my experience after looking at several hundred MLS listings.
posted by GuyZero at 10:35 AM on July 29, 2008

In my state, for the purpose of calculating price per square foot in the sale of of real estate, the square footage is calculated from the heated area as measured on the outside of the building. If the basement is heated it would be included, and if the garage is heated it would be included. Heated means a permanently installed heater, not something that you plug into the wall and put away in the summer. There are professional measuring services (costing about $50 or so) that can be called in to do the measuring if you want some outside authority to point to.
posted by yohko at 10:41 AM on July 29, 2008

thanks, all

yohko, what do you call such services (so I can try to look one up in my area)?
posted by jimmyjimjim at 10:44 AM on July 29, 2008

Measuring services usually advertise directly to the real estate industry and are generally one or two person shops. I´ve never tried to look one up in the phone book and don´t know if they would be in there. You might need to do some networking. Try calling an appraisal office and asking if they can perform measuring services for a structure only, and ask them if they know of anyone if they can´t do it themselves.
posted by yohko at 10:54 AM on July 29, 2008

My understanding as a house buyer and seller in Los Angeles, and as a homeowner who remodeled and had to have her house reassessed for tax purposes, is that square footage only includes permitted areas of the house - permitted by the county tax assessor as living space, not as storage space or something else. So if your screened-in porch was built by the owner without building permits, then it doesn't count. So for example our garage does not count, even though its part of the house structure and not a separate building, because its not considered "living space" by the county. You should go online to your county tax assessor's website (if they have one!) and see what the official square footage is. If there's no website you will have to go to the building dept and ask to view the house permits. Actually, as a prospective homeowner you should go and pull all the permits anyway, to see what the house's history is.
posted by Joh at 11:01 AM on July 29, 2008

So if your screened-in porch was built by the owner without building permits, then it doesn't count.

If they built a screened-in porch without building permits, that's a whole other (much larger) problem. It still wouldn't count per the assessor because it's not conditioned living space, but a porch structure or garage would definitely be permitted, especially so in California.
posted by LionIndex at 11:24 AM on July 29, 2008

I believe that GuyZero is correct. Unless the basement is a walkout, that area (finished or not) does not go into the MLS listing. Also, garage space (attached or not), decks, porches etc... do not count. These items will be factors in the total sale as features of the property but not as square footage. For example, sometimes you will see a listing 2300sq/ft + 400sg/ft indicating that there is a out building/sunroom/finsihed basement etc... This is similar to bedroom listings of "3+2" indicating that there are 3 traditional bedrooms and 2 "bedrooms" in the basement or other non-standard location.

I am not sure if you will get " ironclad square footage figures" by any means but at least you will have a strong number to compare with other listings. Good luck on the negotiations.
posted by saradarlin at 12:11 PM on July 29, 2008

A licensed real estate appraiser would be a definitive source for calculating square footage in your locale.
posted by TedW at 12:32 PM on July 29, 2008

As a real estate broker, I will chime in here and agree that it varies from area to area. Here in Missouri, the general rule is that only heated spaces are included in the square footage - doesn't include garages, porches (unless it is closed in and heated), decks, etc. That being said, we have two areas for square footage in our listing service. The first is total approximate square footage, which includes all finished and heated area plus unfinished areas that could be heated (such as an unfinished basement). Then there is a breakdown section for Finished and Unfinished square footage on each level of the home. My own home, for example, would be in the 4500-4600 square foot range, consisting of 2300 finished space on the main level and 2200 unfinished space in the walkout basement. Some real estate agents will often overstate by including garages in the total square footage number, so it isn't conclusive even in the industry.

Tax assessors will sometimes look at just the exterior dimensions of a home, which means it overstates the square footage in terms of real estate listings and especially so with houses that are "cut up" - meaning they have lots of corners on the exterior instead of a rectangular shape. The benefit to the assessor is that they then have more square footage to assess and tax.

Take a tape measure to the areas in question, and you'll be in good shape. If you were really serious about finding out the area of a home, you should locate the original blueprints (although these are not always accurate for the final product) or hire an appraiser as noted by TedW.
posted by shinynewnick at 12:52 PM on July 29, 2008

Several people have said it already, and I talked with my wife, who is a realtor when this came up in a water cooler coversation at work last week but the answer is 'conditioned space.'
posted by fixedgear at 1:15 PM on July 29, 2008

Thanks, all, for a real good thread....which will surely be of handy use to others blasting thru in future with the same question!
posted by jimmyjimjim at 5:32 PM on July 29, 2008

LionIndex I think you misunderstood my post, we are agreeing. The garage (permitted) does not count because it doesn't have a living space permit. It does have a permit, but not the right kind to count in the square footage.

And as for unpermitted screened porches - not unusual and not really a big issue. Many people around here build porches, master suites, bathrooms etc unpermitted. Unpermitted doesn't mean it wasn't built to code (but of course there's no guarantees since there was no oversight). Many people build unpermitted structures up to code but don't get permits because they don't want the property tax hike.
posted by Joh at 2:11 PM on July 30, 2008

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