How To Add A 20x40 Addition To My House

Building a xx×twenty room improver can requite y'all the extra space you demand in your house, and information technology's a lot cheaper than buying a new home. Most homeowners spend from $42,000 to $88,000 to add a room of this size. The national average 20×20 room addition cost is $65,000.

The rate breaks down to nearly $fourscore to $200 per square foot for an average toll of $140 per foursquare foot. To figure out the approximate price of a larger or smaller room addition, simply multiply the foursquare footage by $140.

How much does a 20×20 room addition cost?

National boilerplate cost: $65,000
Typical price range: $42,000 – $88,000
Extreme depression stop: $xv,000
Extreme high end: $200,000

These prices include the materials and a full general contractor's labor costs. But go along in heed, every option you lot make nearly construction methods and materials tin raise or lower that cost.

For example, if you add on a prefabricated or modular room on the first floor instead of a custom build, the projection may simply cost around $15,000. But building a xx×20 second floor with more than expensive construction materials, several plumbing fixtures, and intricate electrical work might increase the price to as loftier as $200,000.

We'll break downward the toll factors slice by piece to help y'all estimate how much your specific room addition will cost. We'll too become over the costs of other common home additions.

Cost Breakup for xx×20 Room Addition

What exactly goes into the cost of a room addition? From the foundation to the roof to the inside of the walls, a new room needs countless pieces installed. For a project of this scale, you'll usually hire a general contractor, who will subcontract specialists for electrical work, plumbing installation, and similar jobs.

Yous can estimate your upkeep past looking at the boilerplate toll of each element of construction. Y'all may even observe ways to save money on your project.

Construction ELEMENT	AVERAGE COST
Windows	$193 – $845 per window
Insulation	$200 – $1,600
Building permits	$250 – $850
Doors	$393 – $2,013 per door
Site preparation	$400 – $800
Drywall	$600 – $1,200
Electrical piece of work	$630 – $1,930
Covering	$800 – $viii,000
Siding	$800 – $x,800
Plumbing	$975 – $2,900
Flooring	$1,100 – $iv,500
Interior painting	$1,216 – $three,269
HVAC ductwork	$1,933 – $4,767
Foundation	$2,400 – $6,200
Blueprint	$2,740 – $ix,450
Framing	$2,800 – $5,200

Windows

Windows come in many sizes and styles, from a large motion picture window offering a view of the forepart yard to a bay window protruding from the wall to create a reading nook. Each type of window comes with its own installation needs and costs.

You can expect to pay between $193 and $845 per window, including materials and labor. Custom designs and more involved installations (like bay windows) will fall closer to the high finish of that range.

Insulation

If your 20×20 room addition will be a living space – such as a living room, dining room, or bedroom – rather than a garage, you'll need to install insulation. Insulation volition keep the room libation in the summer and warmer in the winter, putting less strain on your HVAC system and lowering your energy usage.

You have a few options for blazon of installation. Common types, from least to almost expensive, are batt insulation, diddled-in insulation, and spray cream insulation. For a 20×20 room, the full cost of installing insulation volition range between $200 and $1,600. Your cost will depend on the type you lot choose and your contractor's labor rates.

Building permits

Though non technically a part of the structure process, a building permit (or multiple building permits) is a necessity for a structure project of this size. Your contractor can usually pull permits from local municipalities more easily than you would be able to on your own. The exact permit yous need and its cost will depend on where you live, but most homeowners pay between $250 and $850 for building permits.

Doors

To install a door in an existing wall, your contractor will have to knock out a portion of the wall. If your contractor is building a new wall with a door, they can leave space for the door during construction. With labor rates and the cost of the door itself, installation will toll from $393 to $2,013 per door.

Site training

If y'all're "edifice out," or expanding your home forth the ground, you'll showtime have to get rid of any obstacles. This can mean simply excavation up a few bushes or a flower bed. In that example, you tin can probably relieve some money and do the work yourself.

But if you're building into a wooded surface area and yous need several trees removed, you'll need to hire a professional land clearing service with the necessary training and equipment. Land immigration for a home addition will cost somewhere betwixt $400 and $800.

Drywall

Most structure codes require drywall, but even if they didn't, you would still desire to install it for function and advent. A finished room needs drywall within, especially considering of its fire resistance. Whether your full general contractor installs the drywall or they rent a drywall subcontractor, this office of construction volition cost betwixt $600 and $i,200.

Electrical work

No matter how yous plan to use your new room, it volition likely need electricity for lights and ability outlets. In about cases, your general contractor will rent a separate electrician for this part of the chore. Consummate electrical work for a 20×20 room will typically cost from $630 to $i,930.

Covering

Installing a roof for a room addition follows the aforementioned principle as installing siding. For a cohesive look, you'll need to lucifer the new roofing material to the residue of your home. The full cost of the roof will depend on which material you use. With materials and labor, you could spend $800 to $viii,000 for roofing.

Siding

Since you want your new room addition to look like it'south always been a part of your home, it'south best to match the siding to the rest of the business firm.

The toll of installing 400 square feet of siding varies by material, anywhere from $800 to $10,800. Natural stone, which can reach almost $thirty per square human foot, is the virtually expensive option. Vinyl, aluminum, and cobweb cement siding are the nigh affordable.

Plumbing

Depending on the type of room, you may need new pipes installed. For example, a living room won't accept a sink, toilet, or other features that require new plumbing. But you might take something less traditional in heed for your room addition – such as an art studio with a sink for cleaning up. That volition need a h2o hookup.

Depending on the specific fixtures your room needs and the piping necessary, you lot might pay anywhere from $975 to $ii,900 to install plumbing for a xx×20 room improver.

Flooring

The purpose of your new room will determine the type of floor you should install. For case, in a family room or other living space, you'll likely choose carpeting or wood flooring.

Carpet is by far more affordable, but many homeowners adopt woods (or imitation wood) considering it's easier to clean and has a more than upscale advent. Depending on the specific flooring you choose, yous'll pay between $one,100 and $iv,500 for a xx×xx room.

Interior painting

Looking for more of a cease than drywall tin can offer? Y'all tin paint your interior walls in the color and stop of your selection to customize the space. Hiring a professional to paint your walls will cost virtually $1,216 to $iii,269.

This is another function of your room addition projection where you can salvage meaning money by going the DIY route. Painting indoor walls is a fairly piece of cake job for most homeowners. You lot could spend less than $100 on paint, compared to the thousands you would spend if you paid a professional to exercise the work for you.

HVAC ductwork

Yous accept a couple of options for heating and cooling the new room. The simplest (and commonly cheapest) road would be to purchase a window Ac unit and plug-in heater for the room.

Alternatively, your contractor or a subcontracted HVAC pro tin install ducts in the walls during structure and connect them to your home's existing HVAC organization. The ductwork to efficiently regulate temperature in a 20×20 room would cost about $1,933 to $four,767 to install.

Foundation

One time the land is clear, the next stride is laying the foundation for your new room. This is where "building upward," or calculation a second story, can save money compared to building out. When you build up, you won't have to lay new foundation, simply you may have to reinforce the existing one to make it strong enough to hold the extra weight.

Building upward isn't always allowed. You'll take to check your local building codes and HOA rules to notice out if yous can add a second story to your home. If edifice up isn't an option – or if yous only don't like the idea of adding a 2nd flooring – expect to pay well-nigh $two,400 to $6,200 to lay a new foundation for your add-on.

Design

The first pace to any architecture project is pattern. How volition the new room fit with the rest of your home? How can you arrive look like a natural part of the house instead of a tacked-on afterthought? Your full general contractor should exist able to answer these questions and describe up your blueprints.

For more complicated projects, or if y'all desire the best design possible, you might need to hire a separate builder or draftsperson to create the room addition for yous. Nigh of the time, these design services toll 10% to 17% of the total project. On boilerplate, that comes out to about $two,740 to $nine,450 depending on the scale and complexity of the room.

Framing

When information technology comes to framing, you tin can choose between a less expensive stick-congenital wood frame and a more expensive but sturdier cinder block frame.

We recommend a cinder cake frame for areas with high humidity, where excessive moisture in the air can cause wood to rot. The sturdier foundation too works best in places where destructive weather such as hurricanes or tornadoes is a business organization.

Framing volition ordinarily cost between $2,800 and $5,200 for materials and labor, with wood frames closer to the low end of that range and cinder blocks at the high finish.

Other Home Addition Costs

When adding onto your home, the possibilities are endless. A 20×twenty room is a pop multi-use addition, but your project could be any shape or size. Now, we'll go into the boilerplate costs of more specific improver projects, from a full in-law suite to a sunroom to a modest bump-out.

TYPE OF ADDITION	Average Cost
Dormer	$3,000 – $8,000
Balcony	$3,600 – $nine,000
Bump-out	$four,000 – $xxx,000
Laundry room	$v,000 – $7,500
Mudroom	$vi,800 – $xv,400
Porch	$13,500 – $27,000
Cantilever	$15,000 – $25,000
Garage	$nineteen,450 – $42,377
Bathroom	$21,000 – $lx,700
Sunroom	$21,000 – $68,300
Kitchen	$41,000 – $69,500
Main suite / master bedchamber	$42,200 – $98,250
In-law suite	$sixty,700 – $111,700

Dormer add-on

Y'all've likely seen minor triangular or round-topped nooks, ordinarily with a window, jutting out from the roofs of homes. These features, called dormers, are common in homes with steep roofs. A dormer tin can create extra storage infinite or allow you to add a cozy window seat.

Calculation a dormer onto your dwelling will unremarkably cost about $3,000 to $viii,000, and y'all can oft save on construction costs if you add it at the same time as a roof replacement.

Balustrade improver

A balcony is a relatively uncomplicated improver that gives you more than outdoor living space and doesn't require laying or reinforcing a foundation. Most homeowners pay between $3,600 and $9,000 to add a balustrade to a 2nd-story dwelling. Your price will depend on the size of the balcony and the structural materials you use, usually wood or steel.

Bump-out

If your home needs more infinite but you don't have the money to add a whole new room, you lot could consider a crash-land-out instead. A bump-out extends an existing room and tin can range from 2 anxiety up to 15 feet.

For a larger bump-out, you lot would have to add together more footings and extend your foundation, which would significantly increase costs. Depending on size and design, a crash-land-out can cost anywhere from $4,000 to $30,000.

Laundry room add-on

Nearly laundry rooms are pocket-sized and simple, oftentimes under 50 square feet. They typically characteristic waterproof floor, hookups for a washer and dryer, and cabinets or other storage infinite. The average laundry room addition costs $5,000 to $7,500.

Mudroom addition

A mudroom is a designated place to exist messy – perfect for homes with lots of children or pets. It's a pocket-sized entrance room where you tin can shop dirty shoes, coats, and umbrellas to go along them from mucking up the rest of the house.

Some typical features of a mudroom include durable and piece of cake-to-clean flooring, coat and purse hooks, and cubbies. Most homeowners spend about $half dozen,800 to $15,400 to add a mudroom.

Porch addition

Many people dream of owning a home with a front end porch where they can sit in a rocking chair and enjoy a repose afternoon. Y'all can achieve that dream with a new porch addition for nigh $thirteen,500 to $27,000.

Your porch could be a pocket-sized space surrounding the front end door, a wide veranda wrapping around the unabridged dwelling, or anything in between. The toll of your porch addition will depend on its size, design, and the materials used to build it. Any porch (if well-built) will boost your home's curb appeal and increase belongings value.

Cantilever addition

With a little help from physics and an experienced builder, you can expand a 2d-story room without having to lay a new foundation. A cantilever is a modern feature involving a projecting beam attached to the wall of your home on i stop and hanging in empty infinite on the other end. Whether information technology'due south an choice for your home depends on specific measurements that your home designer can help you effigy out.

Cantilever additions can be user-friendly considering they don't take up whatever ground infinite, only they have to be small for the beam to back up them. About of these additions extend only most two feet, and they cost anywhere from $fifteen,000 to $25,000.

Garage improver

Similar in-police suites, garages can be attached or detached. A discrete garage will cost more considering your contractor volition take to build all 4 walls and the rest of the structure from scratch. Other factors like size, structure materials, and the extras volition likewise affect cost. Nearly garage additions cost between $nineteen,450 and $42,377.

Bathroom addition

Bathrooms are typically smaller than about other rooms, but they tin can exist expensive to install because of all the plumbing fixtures. At the very to the lowest degree, your plumber will have to install pipes for one sink and one toilet for a half-bath. More than luxurious bathrooms might include two sinks, a walk-in shower, a bathtub, and a toilet.

Larger bathrooms with more features will take more materials and more piece of work to install, so they'll exist more expensive. A unproblematic one-half-bathroom volition toll shut to $21,000 to add on to your home, while a more involved full bathroom could cost upward of $60,700.

Sunroom addition

Sunrooms, sometimes chosen Florida rooms, are spaces to savour the outdoors without actually having to go outdoors. A sunroom will unremarkably feature big windows, screen walls, or fifty-fifty a roof and walls lined completely with glass panels. Yous tin build your own custom sunroom or purchase an easier-to-assemble prefabricated kit.

Most sunrooms will cost between $21,000 and $68,300. A four-season sunroom volition need an HVAC hookup for heating in wintertime, so construction will cost more than than a 3-season sunroom. Sunrooms will besides exist more expensive to build in severely cold climates, where the structure has to adapt snowfall load.

Kitchen addition

Kitchens accept a lot of appliances, which means a lot of wiring and plumbing backside the scenes (in other words, behind the walls). That's why building a new kitchen or expanding your existing kitchen will likely cost more than a simpler room such as a chamber or living room.

Almost kitchen additions cost between $41,000 and $69,500. That total toll includes an boilerplate space of 100 to 200 foursquare feet, general room finishings, cabinets, countertops, and new appliances.

Master suite / master bedchamber add-on

A master sleeping accommodation has a private bathroom fastened. A master suite is substantially the same thing, only larger and with more features, such as walk-in closets or even a kitchenette.

Building a new main suite or primary sleeping room includes the same costs equally a bathroom, with the boosted cost of materials and electrical work for the fastened bedroom. Depending on the size and complexity, calculation a main suite or master sleeping accommodation to your home will cost anywhere from $42,200 to $98,250.

In-law suite addition

An in-police suite, too known equally an "accessory dwelling unit," is an extra structure on your belongings. It can be fastened to the house or detached, and include a full kitchen and bath. Someone could live there seperate from the residents of the main house, which makes these suites popular with multigenerational families living together.

Because an in-law suite is essentially a small dwelling unto itself, calculation one on your belongings costs from about $60,700 to $111,700. They're ordinarily worth the high price tag considering they increment domicile value significantly. Some municipalities or HOAs won't allow in-law suites, so bank check local regulations before you go your heart set on one.

Build Upward or Build Out?

When you build up, y'all add a room to your existing second story or add a second story to a ane-story home. Edifice up eliminates the need to aggrandize your habitation'south foundation, which could shave more than than $6,000 off your full construction cost.

If you don't have much footing space on your property, building up gives you the opportunity to augment your home without cut into an already limited yard. In some cases, you may accept so little space that building up is your merely option for adding on to your dwelling house.

Building upward isn't necessarily less expensive than building out. Your home's foundation may non be strong enough to behave the weight of an added story, in which instance yous would have to reinforce it with boosted materials. Reinforcing an existing foundation tin sometimes cost as much as laying a new one.

Note: Some cities and HOAs have rules about the top of your home that could limit your options for building upwardly. You'll also need to keep the size of surrounding homes in mind, since building a two-story dwelling house in a neighborhood full of one-story homes could negatively affect your property value and decrease the return on your investment.

Well-nigh homeowners volition choose to build out, or add another room at the ground level or on a cantilever, extending the house lengthwise instead of heightwise. A cantilever tin only deport limited weight, so most build-outs will exist on the get-go floor. That means your contractor would accept to lay a new foundation.

Building on the ground besides means you have to have enough infinite for the improver on your belongings. Even if you think you lot have the room, make sure the new room wouldn't add too much to the impervious cover percent, or the amount of ground surface on your holding that can't absorb water. Otherwise, you might bailiwick your property to flooding and poor stormwater runoff direction.

xx×xx Room Addition Cost by Location

Toll of construction materials and labor rates vary significantly based on where you alive. While the national averages included in this guide are a good benchmark, y'all might end up spending much less or much more than our cost estimates because of your location.

Labor rates in a big city with a high cost of living will be higher than those in a small boondocks. Climate can also bear upon costs. If you live in an area with frequent snow and freezing temperatures in winter, y'all may demand a particular type of foundation or roofing material that costs more than than some options available to homeowners in mild climates.

If you lot live in an area that sees hurricanes, tornadoes, or severe winds, you lot'll demand a sturdier structure fabricated with pricier materials. A weatherproof room addition will definitely cost y'all more.

FAQ Well-nigh Room Additions

1. How can you save money on a room addition?

A habitation addition is a huge project that requires a contractor. It'southward non a elementary DIY home improvement chore. If you're nervous about the cost of hiring a contractor, here are some things you as the homeowner can do to cutting costs:

— Prep the site yourself by removing landscaping and other obstacles in the way of construction
— Tear down walls and haul debris to the dump yourself
— Clean up the site at the end of every day so your construction squad doesn't have to
— Do your own finish piece of work such every bit painting, sanding, etc.

2. Are architects or draftspeople needed for additions?

You don't necessarily have to hire an architect or draftsperson for your home improver project, merely their expert eye for home pattern can make the finished production look a lot better. An improver designed by an architect is more likely to catamenia well with the rest of your home.

3. Does a room improver add together value to your dwelling house?

Yes, an addition increases a dwelling house's square footage and therefore boosts resale value.

Determination

The overall cost of adding a 20×twenty room to your dwelling house depends entirely on what you lot plan to use the room for and what features it needs. Well-nigh homeowners pay a general contractor betwixt $42,000 and $88,000 for the materials and labor required to build an add-on of this size. The rate for a general room addition is virtually $80 to $200 per square foot.

For an accurate estimate of your upkeep, yous'll need to know specifics nearly the construction materials your project volition use. And remember, other kinds of addition — such as a new garage, kitchen, or sunroom – each have their ain price indicate to keep in mind.

Main Photo Credit: Jon Hurd / Flickr / CC BY 2.0

Jordan Ardoin

Hashemite kingdom of jordan Ardoin is a author and indoor found enthusiast hailing from Florida. In her spare fourth dimension, she enjoys chasing her two cats around the house and trying to keep her houseplants live.