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Home Square Footage: What’s Included?

If you’re buying or selling a house then it’s important to know from a value perspective what elements of a property real estate agents include in the square footage calculation.

Apart from the main house itself, the only elements of a property included in the square footage living space are porches and fully attached liveable extensions, such as enclosed sunrooms or four season rooms. All outbuildings, yard space, patios and decking areas are not included.

Let’s have a look at each element in turn, and consider why various things are or are not included…

Home Square Footage (What Outdoor Elements Are Included?)

What Outdoor Elements Do Agents Include in Your Home Square Footage?

Some outdoor elements are included in your home’s square footage while others are not. This can seem a bit arbitrary to the homeowner: why is a porch included but not the garage? To answer this question, we need to take a look at how home square footage is calculated in the US.

Whereas there isn’t a national standard way of measuring the size of your home, most realtors base it on something called GLA, which stands for “Gross Living Area”. This means that the total size of your home is calculated by the combined areas of the rooms that you live in.

So, based on that, a typical small home’s areas will be the sum of the square footage of the living room, the kitchen, the hallway, the bedrooms, and the bathroom. These are all the rooms that we use for everyday living.

What defines a room as living space? It has to be “finished” and it has to have the same heat source as the rest of the house. An unconverted attic or storage-only basement won’t count, neither will a garage (and we’ll come onto that in a moment). Essentially, you have to be able to live in it, all year round, so it needs properly constructed walls, floor and ceiling, and be warm.

It also can’t be an “ancillary” building. This means that to count, a space must be attached to the main residence. You may have a beautiful guest house in the garden, but if you have to step outside to reach it, it doesn’t count in the main calculation. This isn’t to say that a realtor can’t make a big deal about a “separate guest house measuring X square feet”.

But remember: don’t get too hung up on square footage. A large deck area or a pool house will add value in other ways, and a home isn’t judged solely on its square footage. That detached studio at the end of the yard may be just what buyers are looking for, even if it doesn’t technically extend the size of your home.


Yes, a porch does count as living space: provided it’s enclosed, completely finished, and shares a heat source with the rest of your home. It also has to be finished to a proper home standard, made from the correct insulating materials and with standard windows and doors. It cannot be a lean-to type structure.

Be honest. Could you feasibly spend an evening sitting in comfort in your porch, eating a meal or reading a book? If you don’t think you could, don’t say you can, as you’ll quickly be caught out by the realtor or purchasers.

Any Attached Outdoor Room With Finished Walls, Floors and Heating

So, based on our findings so far, what else counts as living space? Any attached rather than ancillary living space counts. That simply means, any liveable area that you can reach without having to leave the main house.

As we’ve discussed, a four-season porch counts, as would a properly constructed conservatory. If you have an attached garage that has been converted (into a study or bedroom, for example), this would count (again, provided it meets the correct construction standards and shares a heating system with the original house).


Sorry: even an attached garage doesn’t count as living space when it comes to calculating square footage. We know that quite often, everyday living items (spare freezers and so on) migrate into the garage; however unless it’s been converted from a garage into an actual room, it won’t count.

But don’t feel disheartened or rush off to get building quotes for a conversion. Many people like to have a safe, lockable space for their vehicles, and a garage is a handy storage area. Square footage isn’t everything.

Pool House

Unless you live in an incredible mansion-style home, we’re assuming that your pool and poolhouse are separate from the main house. So, they don’t pass the “same building” criteria, are unlikely to be on the same heating system, and let’s be honest, you couldn’t spend a comfortable night in a pool house.


This doesn’t count as part of your square footage, even though this is a finished building, and no doubt has plumbing, heating, and electricity for your guests’ comfort. The reason? It’s an ancillary building that is reached separately

Detached Family Quarters

You may be lucky enough to have an extra home in your yard, where perhaps elderly relatives or teenagers spend most of their time. This is a great addition to your living space, and certainly in terms of everyday life, gives you plenty of extra room.

But yes, you’ve guessed it. Because it’s a separate building, it doesn’t count as square footage.

Patio (Including Patio With Permanent Cover)

A patio is not a porch, and by definition, it’s not a fully enclosed space. It may be attached to your home, but it doesn’t have four solid walls and heating – and if it did, it would be a porch. A permanent cover doesn’t alter this fact, although it does make your porch more comfortable.


As decking primarily refers to a floored area, it doesn’t count as part of a building. Many decks are next to houses, and some even have some sort of shelter, but they don’t count as living space.

We’ll say this again, however: a good deck is a real asset to your home, both for daily life and to appeal to potential purchasers. But don’t use it as a means to add extra value to your property through square footage. Even if it has a fancy outdoor kitchen or a comfy living area, decking doesn’t count.

Backyard (Including Lawn & All Outside Space)

Yard size doesn’t count towards your home’s measurements: but the size of your lot can make a difference. If there are two houses of the same size, and one has a bigger yard, the largest lot is likely to command the higher price.

Curb appeal is also important here, and a lovely garden or large-sized yard can be a deciding factor. Purchasers will families or pets will love your large lawn, and an attractive outdoor seating area or kitchen could make all the difference.

Outdoor elements of home square footage


It may be your favorite place; however workshops, studios and sheds don’t count. They are separate from your home, they don’t tend to have very sophisticated finishes; and however much you may long to escape into your shed, you can’t actually live in it.

But the daily value of having your own workshop or outside studio? Inestimable. 

Sunroom or 4 Season Room

If your sunroom is a proper, finished extension, built onto your home and sharing its heating source, then yes, it counts. If it’s detached or unheated, or doesn’t have a quality finish, no it doesn’t. 

Like a porch, a lot depends upon the construction, and whether it feels like part of the house, rather than an add-on. 

Balcony or Terrace

These are both often part of the fabric of the building, so surely they must count as square footage, right? Again, no. Yes, they’re attached to the house and are reached through doors from the house – but could you spend a night on them? 

Your balcony or terrace won’t share a heating system with your home, and won’t be enclosed with permanent walls or a ceiling. If they did, they’d be rooms not outdoor spaces. The great news is that balconies add value to your home. If you have a large, modern balcony with great views and space for dining or a hot tub, this can be considerable. If your home is in a city and you have access to this extra, private outdoor space, it’s a huge bonus.


So there we have it – when it comes to assessing square footage for a property, enclosed porches and attached liveable extensions such as sunrooms and four season rooms count – and everything else doesn’t.

So while elements like decking, patios, large gardens and outbuildings do add value to a home – they are never going to be included in the main calculations of square footage for the main house itself.

So whether you’re buying, selling or are merely interested – this is definitely valuable information to have at your disposal. 🙂

Mark H.

Homeowner and property investor Mark H. aspires to bring you the very best outdoor living content, based on his years of experience managing outside spaces. Read more >