Home Addition Cost 2026: $22,000–$83,000 Typical Range

One ground-floor home addition at a US single-family house — the shell, the finish, and the labor in one price, on a lot the crew can reach, with no second story — often clusters around $22,000–$83,000. That is the typical home addition cost. How much a home addition costs, in that scope, is that room, not a finished basement and not a detached garage. Home addition cost per square foot, for a ground-floor build-out, is $80–$200. Building up is $300–$500 a square foot. A room addition is $20,900–$72,600. A 12×12 at $80–$200 a square foot is $11,520–$28,800. A 20×20 at that rate is $32,000–$80,000. A second story of about 200 square feet is $60,000–$100,000. The wider national spread, about $4,000–$200,000, covers a small bump-out at the low end and a 400-square-foot second story at the high end. The space already under the house is the basement finishing guide. The vehicle building is the garage building guide. An existing bath is the bathroom remodel guide. These are typical planning ranges, not a survey and not a quote.

This page is one addition at one house. A bid may call it the home addition cost, how much a home addition costs, the home addition cost per square foot, a room addition cost, or a second story addition cost. The shell, the finish, and the labor are in the price when the number is the typical band. It is not a basement that is already there, which is the basement finishing guide. It is not a garage, which is the garage building guide. It is not a bathroom the house already has, which is the bathroom remodel guide. A bump-out the price left as a dormer or a balcony is a smaller product. This page does not price that bump-out as the typical band.

The price of the job is the room the crew builds and the hour that puts the labor in the price. The room is the first cut. Whether the shell, the finish, and the labor are already in the price is the second. A ground-level room, a 12×12, a 20×20, and a second story are ways to buy one addition. The addition replaces a different addition. It is not a second room under a price you already have.

The rows below are ways to read one job. They are not added together. The job table is one addition on a lot the crew can reach. The typical band is one ground-floor room, shell and labor in: that row in full. A ground-level reading replaces that rate from $20,000 to $80,000. A 12×12 at $80–$200 a square foot replaces it from $11,520 to $28,800. A 20×20 at that rate replaces it from $32,000 to $80,000. A second story of about 200 square feet replaces it from $60,000 to $100,000. Use a rate row only for a line the addition row does not include. A rate the proposal already includes is not a second line.

Job	Typical cost
Home addition, shell and labor in	$22,000–$83,000
Ground-level addition	$20,000–$80,000
12×12, at $80–$200 a square foot	$11,520–$28,800
20×20, at $80–$200 a square foot	$32,000–$80,000
Second story, about 200 square feet	$60,000–$100,000

Rate or added line	Typical planning range
Build out, per square foot	$80–$200
Build up, per square foot	$300–$500
Bedroom, per square foot	$80–$160
Bathroom, per square foot	$150–$200
10×10, build out	$8,000–$20,000
10×10, build up	$30,000–$50,000
12×12, second story	$43,200–$72,000
60-square-foot bump-out	$4,800–$12,000
300 square feet, build out	$24,000–$60,000
300 square feet, build up	$90,000–$150,000
400 square feet, build up	$120,000–$200,000
Room addition	$20,900–$72,600
Permits, if the price left them out	$150–$7,500
Site prep, if the price left it out	$1,500–$5,000
Architect, if the price left the plans out	$2,400–$14,000

The job rows replace one another. Do not add a 20×20 price on top of a standard addition for the same room. The rate row is a line the addition left out, or another reading of the same room. A rate the proposal already includes is not the rate row on top. A foundation the bid already folded into $22,000–$83,000 is not a foundation row on top.

A standard home addition — the shell and the labor in one price — is typically $22,000–$83,000. The floor of the row is the typical floor. The top of the row is the typical top. The whole row is the typical band. Twenty-two thousand can be this row at its floor. Eighty-three thousand can be this row at its top, or a 20×20 inside its overlap, or a second story of about 200 square feet inside its overlap. Ask which reading the bid is.

A ground-level addition is typically $20,000–$80,000. Twenty thousand is $2,000 under the typical floor and $16,000 above the wider floor. Eighty thousand is $58,000 above the typical floor and $3,000 under the typical top. The overlap with the typical band is $22,000–$80,000. From $20,000–$22,000 the ground-level row sits under the typical band and inside the wider spread. From $22,000–$80,000 it is inside the typical band. Twenty thousand can be this row at its floor. Eighty thousand can be this row at its top. A standard addition price does not get this row on top.

A 12×12 at $80–$200 a square foot is typically $11,520–$28,800. The room is 144 square feet. One hundred forty-four times $80 is $11,520. One hundred forty-four times $200 is $28,800. Eleven thousand five hundred twenty is $7,520 above the wider floor and $10,480 under the typical floor. Twenty-eight thousand eight hundred is $6,800 above the typical floor and $54,200 under the typical top. The overlap with the typical band is $22,000–$28,800. From $11,520–$22,000 the 12×12 sits under the typical band and inside the wider spread. From $22,000–$28,800 it is inside the typical band. Eleven thousand five hundred twenty can be this row at its floor. Twenty-eight thousand eight hundred can be this row at its top. A standard addition price does not get this row on top.

A 20×20 at $80–$200 a square foot is typically $32,000–$80,000. The room is 400 square feet. Four hundred times $80 is $32,000. Four hundred times $200 is $80,000. Thirty-two thousand is $10,000 above the typical floor and $51,000 under the typical top. Eighty thousand is $58,000 above the typical floor and $3,000 under the typical top. The whole row sits inside the typical band. Thirty-two thousand can be this row at its floor. Eighty thousand can be this row at its top. A 12×12 price does not get this row on top.

A second story of about 200 square feet is typically $60,000–$100,000. Two hundred times $300 is $60,000. Two hundred times $500 is $100,000. Sixty thousand is $38,000 above the typical floor and $23,000 under the typical top. One hundred thousand is $17,000 past the typical top and $100,000 under the wider top. The overlap with the typical band is $60,000–$83,000. From $83,000–$100,000 the second story has left the typical band and stays inside the wider spread. Sixty thousand can be this row at its floor. One hundred thousand can be this row at its top. A ground-floor price does not get this row on top.

Home addition cost

The home addition cost is this page when the crew is on the lot and the shell, the finish, and the labor are in the price. A bid that says home addition cost and a bid that says how much a home addition costs are the same dollars when the site, the room, and the labor match and the opening in the wall is already the room they are pricing. The typical band, $22,000–$83,000, is one ground-floor room. It is not a second room stacked on a foundation you already have.

The work is often weeks for a room the crew can reach, and the bid’s schedule is the one that counts. The shell is inside the addition price. It is not a second bill on a number that was already the room. Two hundred square feet at $80–$200 a square foot is a way to read the same footprint, not a second room. Two hundred times $80 is $16,000. Two hundred times $200 is $40,000, inside the typical band. The per-foot rate and the lump sum are two readings of one room. They are not added. A bid that already names $22,000–$83,000 does not get the foot on top.

How much does a home addition cost

How much a home addition costs is the room at one house. One ground-floor room, shell and labor in, is $22,000–$83,000. A bid that says how much a home addition costs and a bid that says home addition cost are the same dollars when the site, the room, and the labor match. A price near $4,000 should say a small bump-out at the wider floor, not the standard room. A price near $22,000 should say whether the finish and the labor are in. A price near $83,000 should say whether the number is this band at its top, a 20×20 inside its overlap, or a second story inside its overlap.

A 10×10 built out is $8,000–$20,000. The pad is 100 square feet. One hundred times $80 is $8,000. One hundred times $200 is $20,000. Eight thousand is $4,000 above the wider floor and $14,000 under the typical floor. Twenty thousand is $16,000 above the wider floor and $2,000 under the typical floor. The 10×10 built out sits under the typical band and inside the wider spread. Eight thousand can be this size at its floor. Twenty thousand can be this size at its top. A standard addition price does not get this size on top.

A 10×10 built up is $30,000–$50,000. One hundred times $300 is $30,000. One hundred times $500 is $50,000. Thirty thousand is $8,000 above the typical floor and $53,000 under the typical top. Fifty thousand is $28,000 above the typical floor and $33,000 under the typical top. The whole row sits inside the typical band. Thirty thousand can be this size at its floor. Fifty thousand can be this size at its top. A build-out price for the same 10×10 does not get this row on top.

A 60-square-foot bump-out is $4,800–$12,000. Sixty times $80 is $4,800. Sixty times $200 is $12,000. Four thousand eight hundred is $800 above the wider floor and $17,200 under the typical floor. Twelve thousand is $8,000 above the wider floor and $10,000 under the typical floor. The bump-out sits under the typical band. Four thousand eight hundred can be this size at its floor. Twelve thousand can be this size at its top. A 10×10 price does not get this size on top.

Eighty-three thousand plus $83,000 for a second room at the typical top is $166,000, which is $83,000 past the typical top and $34,000 under the wider top. That $166,000 is two rooms. It is not one standard addition. A number above $200,000 should name more room, a second room, a basement finish, a garage, or a bathroom remodel. Ask which reading the bid is.

Home addition cost per square foot

Home addition cost per square foot is a reading of the room, not a second room. The build-out rate is $80–$200 a square foot. The build-up rate is $300–$500 a square foot. A bid that says home addition cost per square foot and a bid that says home addition cost are the same dollars when both readings are the same room and the labor is in. A price near $80 should say the build-out rate at its floor, not a room with the labor left out on top of a lump sum. A price near $500 should say the build-up rate at its top.

A bedroom is $80–$160 a square foot. That rate replaces the $80–$200 build-out rate. It is not a second room. On 200 square feet, two hundred times $80 is $16,000, and two hundred times $160 is $32,000. Sixteen thousand is $12,000 above the wider floor and $6,000 under the typical floor. Thirty-two thousand is $10,000 above the typical floor and $51,000 under the typical top. The overlap with the typical band is $22,000–$32,000. From $16,000–$22,000 this bedroom sits under the typical band. From $22,000–$32,000 it is inside the typical band. A $80–$200 price of the same 200 square feet does not get $80–$160 on top.

A bathroom is $150–$200 a square foot. On 100 square feet, one hundred times $150 is $15,000, and one hundred times $200 is $20,000. Fifteen thousand is $11,000 above the wider floor and $7,000 under the typical floor. Twenty thousand is $2,000 under the typical floor. The 100-square-foot bathroom sits under the typical band. On 200 square feet, two hundred times $150 is $30,000, and two hundred times $200 is $40,000. Thirty thousand is $8,000 above the typical floor. Forty thousand is $43,000 under the typical top. The whole 200-square-foot bathroom sits inside the typical band. A bedroom rate does not get the bathroom rate on top.

A 300-square-foot build-out is $24,000–$60,000. Three hundred times $80 is $24,000. Three hundred times $200 is $60,000. Twenty-four thousand is $2,000 above the typical floor and $59,000 under the typical top. Sixty thousand is $38,000 above the typical floor and $23,000 under the typical top. The whole row sits inside the typical band. Twenty-four thousand can be this size at its floor. Sixty thousand can be this size at its top. A 200-square-foot price does not get this size on top.

Room addition cost

Room addition cost is the room at one house, not a remodel with a new room named and not priced. When the room and the labor are in the price, that cost is $20,900–$72,600. A bid that says room addition cost and a bid that says home addition cost are the same dollars only when both bids are that room, or only when both bids are the typical addition and the numbers still match. A price near $20,900 should say a room addition at its floor, not a standard addition with the labor in. A price near $72,600 should say a room addition inside the typical band, not the typical top.

Twenty thousand nine hundred is $1,100 under the typical floor and $16,900 above the wider floor. Seventy-two thousand six hundred is $50,600 above the typical floor and $10,400 under the typical top. The overlap with the typical band is $22,000–$72,600. From $20,900–$22,000 the room addition sits under the typical band and inside the wider spread. From $22,000–$72,600 it is inside the typical band. Twenty thousand nine hundred can be this row at its floor. Seventy-two thousand six hundred can be this row at its top. A standard addition price does not get the room row on top.

A 12×12 and a 20×20 are two readings of a room addition. The 12×12 at $80–$200 is $11,520–$28,800. The 20×20 at that rate is $32,000–$80,000. They replace the room-addition lump sum when the bid is that size. They are not added to $20,900–$72,600.

Second story addition cost

Second story addition cost is the room built up, not a ground-floor room with a stair named and not priced. A second story of about 200 square feet is $60,000–$100,000. A bid that says second story addition cost and a bid that says home addition cost are the same dollars only when both bids are that second story, or only when both bids are the typical room and the numbers still match. A price near $60,000 should say a 200-square-foot second story at its floor, or a ground-floor room inside the typical band. A price near $100,000 should say a second story past the typical top.

A 12×12 on the second story is $43,200–$72,000. The room is 144 square feet. One hundred forty-four times $300 is $43,200. One hundred forty-four times $500 is $72,000. Forty-three thousand two hundred is $21,200 above the typical floor and $39,800 under the typical top. Seventy-two thousand is $11,000 under the typical top. The whole row sits inside the typical band. It is not the ground-floor 12×12, which is $11,520–$28,800. Forty-three thousand two hundred can be this row at its floor. Seventy-two thousand can be this row at its top. A ground-floor 12×12 does not get this row on top.

A 300-square-foot second story is $90,000–$150,000. Three hundred times $300 is $90,000. Three hundred times $500 is $150,000. Ninety thousand is $7,000 past the typical top and $110,000 under the wider top. One hundred fifty thousand is $67,000 past the typical top and $50,000 under the wider top. The 300-square-foot second story does not sit inside the typical band. From $90,000–$150,000 the job has left the typical band and stays inside the wider spread. Ninety thousand can be this row at its floor. One hundred fifty thousand can be this row at its top. A 200-square-foot second story does not get this row on top.

A 400-square-foot second story is $120,000–$200,000. Four hundred times $300 is $120,000. Four hundred times $500 is $200,000. One hundred twenty thousand is $37,000 past the typical top and $80,000 under the wider top. Two hundred thousand is the wider top. The 400-square-foot second story does not sit inside the typical band. From $120,000–$200,000 the job has left the typical band, and the top of the row is the wider top. One hundred twenty thousand can be this row at its floor. Two hundred thousand can be this row at its top. A 300-square-foot second story does not get this row on top.

A second-story rate that starts at $200 a square foot, on 200 square feet, is $40,000. Forty thousand is $18,000 above the typical floor and $43,000 under the typical top. Two hundred times $300 is $60,000, the floor of the 200-square-foot second-story row. Those are two readings of one second story. They are not added.

What the range includes

The typical band assumes one ground-floor home addition. The shell is in. The finish is in. The labor is in. The lot is reachable. No second story has to be framed. A ground-level reading is in the band only from $22,000 to $80,000. A 12×12 at $80–$200 is in the band only from $22,000 to $28,800. A 20×20 at that rate is in the band. A room addition is in the band only from $22,000 to $72,600. A second story of about 200 square feet is in the band only from $60,000 to $83,000. A basement finish, a detached garage, and a bathroom remodel are not in the band.

How long the work takes depends on the room, and the bid’s schedule is the one that counts. A room the crew can reach is often weeks. A second story is often longer. The time is a way to read that room. It is not a second clock on a price that was already the room. The next room is not in this price.

The floor of the wider spread, $4,000, is a small bump-out at the published low. It is not a standard room someone discounted. The 60-square-foot bump-out starts at $4,800, which is $800 above that floor. The top, $200,000, is a 400-square-foot second story at its top. It is not the room row plus every add-on. Eighty-three thousand plus $7,500 for permits is $90,500, not $200,000. Eighty-three thousand plus $83,000 for a second room at the typical top is $166,000, not $200,000. A number above $200,000 should name more room, a second room, or a job past this page. Ask which one.

None of the bands include permits on a room the bid already priced, except where those permits are a line the price left out. The permit line is $150–$7,500. One hundred fifty is $3,850 under the wider floor. Seven thousand five hundred is $3,500 above the wider floor and $14,500 under the typical floor. Twenty-two thousand plus $150 is $22,150, inside the typical band, only when the $22,000 left the permits out. Twenty-two thousand plus $7,500 is $29,500, inside the typical band, only when the $22,000 left the permits out. Eighty-three thousand plus $150 is $83,150, which is $150 past the typical top and $116,850 under the wider top. Eighty-three thousand plus $7,500 is $90,500, which is $7,500 past the typical top and $109,500 under the wider top, only when the $83,000 left the permits out. A bid that already names the permits does not get this row on top.

None of the bands include site prep on a price the bid already built, except where that prep is a line the price left out. The site-prep line is $1,500–$5,000. One thousand five hundred is $2,500 under the wider floor. Five thousand is $1,000 above the wider floor and $17,000 under the typical floor. Twenty-two thousand plus $1,500 is $23,500, inside the typical band, only when the $22,000 left the prep out. Twenty-two thousand plus $5,000 is $27,000, inside the typical band, only when the $22,000 left the prep out. Eighty-three thousand plus $1,500 is $84,500, which is $1,500 past the typical top and $115,500 under the wider top. Eighty-three thousand plus $5,000 is $88,000, which is $5,000 past the typical top and $112,000 under the wider top, only when the $83,000 left the prep out. A room that already names the prep does not get $1,500–$5,000 on top.

None of the bands include an architect on a price the bid already built, except where those plans are a line the price left out. The architect line is $2,400–$14,000. Two thousand four hundred is $1,600 under the wider floor. Fourteen thousand is $10,000 above the wider floor and $8,000 under the typical floor. Twenty-two thousand plus $2,400 is $24,400, inside the typical band, only when the $22,000 left the plans out. Twenty-two thousand plus $14,000 is $36,000, inside the typical band, only when the $22,000 left the plans out. Eighty-three thousand plus $2,400 is $85,400, which is $2,400 past the typical top and $114,600 under the wider top. Eighty-three thousand plus $14,000 is $97,000, which is $14,000 past the typical top and $103,000 under the wider top, only when the $83,000 left the plans out. A room that already names the plans does not get $2,400–$14,000 on top.

None of the bands include a basement finish, which is the basement finishing guide, often $30,000–$40,000 for about 1,000 square feet of open plan, inside a wider spread of about $15,000–$75,000. Thirty thousand is the floor of that typical band. Forty thousand is the top of that typical band. Twenty-two thousand plus $30,000 is $52,000, inside this page’s typical band, $12,000 past that guide’s typical top, and inside that guide’s wider spread. Twenty-two thousand plus $40,000 is $62,000, inside this page’s typical band and $22,000 past that guide’s typical top. Eighty-three thousand plus $30,000 is $113,000, which is $30,000 past this page’s typical top, $87,000 under this page’s wider top, and $38,000 past that guide’s wider top. Eighty-three thousand plus $40,000 is $123,000, which is $40,000 past this page’s typical top and $77,000 under this page’s wider top. That sum is an addition plus a basement finish only when each bid left the other out. A basement price that already includes the addition does not get this page on top. The basement is space the house already has. The addition is space the house does not have yet.

None of the bands include a detached garage, which is the garage building guide, often $15,000–$40,000 for one two-car garage, inside a wider spread of about $7,200–$84,500. Fifteen thousand is the floor of that typical band. Forty thousand is the top of that typical band. Twenty-two thousand plus $15,000 is $37,000, inside this page’s typical band and inside that guide’s typical band. Twenty-two thousand plus $40,000 is $62,000, inside this page’s typical band, $22,000 past that guide’s typical top, and inside that guide’s wider spread. Eighty-three thousand plus $15,000 is $98,000, which is $15,000 past this page’s typical top, $102,000 under this page’s wider top, and $13,500 past that guide’s wider top. Eighty-three thousand plus $40,000 is $123,000, which is $40,000 past this page’s typical top and $77,000 under this page’s wider top. That sum is an addition plus a garage only when each bid left the other out. A garage price that already includes the room does not get this page on top. A two-car garage on that page is $15,000–$40,000. A 20×20 room on this page is $32,000–$80,000, which can overlap the top of that garage row.

None of the bands include a bathroom remodel, which is the bathroom remodel guide, often $10,000–$25,000 for a mid-range bath that keeps the layout, inside a wider spread of about $3,000–$80,000. Ten thousand is the floor of that typical band. Twenty-five thousand is the top of that typical band. Twenty-two thousand plus $10,000 is $32,000, inside this page’s typical band, $7,000 past that guide’s typical top, and inside that guide’s wider spread. Twenty-two thousand plus $25,000 is $47,000, inside this page’s typical band and $22,000 past that guide’s typical top. Eighty-three thousand plus $10,000 is $93,000, which is $10,000 past this page’s typical top, $107,000 under this page’s wider top, and $13,000 past that guide’s wider top. Eighty-three thousand plus $25,000 is $108,000, which is $25,000 past this page’s typical top and $92,000 under this page’s wider top. That sum is an addition plus a bathroom remodel only when each bid left the other out. A bathroom price that already includes the new room does not get this page on top. A new bathroom at $150–$200 a square foot is a reading of this addition. It is not that remodel with a different name.

The band is the addition price. A coupon on the room is not subtracted. Read the form before you take a number off the bid. A credit you have not received is not inside the planning range. This page does not price a coupon, and it does not name a percentage of the cost that comes back at resale.

Warranties are part of the contract, and this page is not a reading of one company’s form. A room, when the company offers a return for a line the crew missed, is about that line. Read it. The return visit is not a dollar line in the planning range.

A standard homeowners policy is built around sudden and accidental damage. A room you chose to build is the kind of project those policies commonly leave with the owner. A storm that damages a covered structure, when the form responds to it, is a different question from a room you are buying. Read the form before you treat the policy as the budget. The $22,000–$83,000 band is not an insurance estimate.

This page does not price a city’s fee on top of a complete room price, except where that fee is the permit line the price left out. A room that already names a fee does not get that fee on top.

As a cross-check, not a bid: one ground-floor room, shell and labor in, is $22,000–$83,000, the typical band. A ground-level reading is $20,000–$80,000. A 12×12 at $80–$200 is $11,520–$28,800. A 20×20 at that rate is $32,000–$80,000. A second story of about 200 square feet is $60,000–$100,000. Permits the price left out are $150–$7,500. If a bid and that reading are far apart, the bid is a different room, a left-out permit, a second room, a basement finish, a garage, or a bathroom remodel.

What moves the price

Driver	How it changes the bid
The room	One ground-floor room, shell and labor in, is $22,000–$83,000, the typical band. A ground-level reading is $20,000–$80,000, and the typical band includes that row only from $22,000 to $80,000. A 12×12 at $80–$200 a square foot is $11,520–$28,800, and the typical band includes that row only from $22,000 to $28,800. A 20×20 at that rate is $32,000–$80,000, inside the typical band. The room picks the row. It is not a second bill.
The footprint	Two hundred square feet at $80–$200 is $16,000–$40,000. A 12×12 at that rate is $11,520–$28,800. A 20×20 at that rate is $32,000–$80,000. A 10×10 built out is $8,000–$20,000. The footprint is a reading of the room. It is not a second bill on a room that already names it.
The story	A second story of about 200 square feet is $60,000–$100,000, and the typical band includes that row only from $60,000 to $83,000. A 400-square-foot second story is $120,000–$200,000, past the typical band, and the top is the wider top. Building up is $300–$500 a square foot. The story picks the row. It is not a second bill on a ground-floor room.
The use	A bedroom is $80–$160 a square foot. A bathroom is $150–$200 a square foot. On 200 square feet the bedroom is $16,000–$32,000 and the bathroom is $30,000–$40,000. A completed price of $22,000–$83,000 already holds a use the bid named. One hundred fifty dollars is the bathroom floor. It is not a second bill on that lump sum.
The permits	Permits the bid leaves out are $150–$7,500. One hundred fifty is under the wider floor. Seven thousand five hundred is $14,500 under the typical floor. The permits are inside the room price when the bid names them. Twenty-two thousand plus $7,500 is $29,500 only when the $22,000 left the permits out.
The site	Site prep the bid leaves out is $1,500–$5,000. An architect the bid leaves out is $2,400–$14,000. A completed price of $22,000–$83,000 already holds that line when the bid named it. Eighty-three thousand plus $14,000 is $97,000 only when the $83,000 left the plans out.
The second room	Two standard rooms at the typical top are $166,000, which is $34,000 under the wider top. That reading is two rooms. It is not one standard addition.
The other job	A basement finish is $30,000–$40,000 on the basement finishing guide. A two-car garage is $15,000–$40,000 on the garage building guide. A mid-range bathroom remodel is $10,000–$25,000 on the bathroom remodel guide. A basement the bid is finishing, a garage the bid is building, or a bath the bid is remodeling do not get this page on top when that price already includes the room.

The room is the first cut, and it is not a room you add to itself. A standard room at $83,000, and a 20×20 at $200 a square foot, can be talked about in the same bid. They are not the same room twice. Eighty thousand is the 20×20 top. Eighty-three thousand is the typical top. Ask which room is in the price.

The story is the second cut. A room at $60,000, a 200-square-foot second story at $300 a square foot, and a ground-floor room inside its overlap can share the neighborhood of those dollars. One is inside the typical band. One is the second-story floor. One is the ground-floor row. The higher number is not a typical room that someone misread as a second story.

The same room in a lower-cost area and in a high-labor city can sit at opposite ends of $22,000–$83,000 without either bid being wrong. Ask whether the price is the room, the story, or both, and ask whether permits, a second room, or a second story is in. Basement finishing, garage building, and bathroom remodel are the projects that meet this room and are not the room. Price them on their own pages. Two bids that disagree about the room, the story, and whether the labor is included are not the same job.

DIY or hire

Hire the addition. A foundation that has to carry the room, a roof tie-in that has to keep the water out, and a circuit that has to be inspected are where a small miss becomes a second visit. The labor, the shell, and the finish are the job. A Saturday with a stack of studs on a soft lot is where those three get missed.

Painting a room the crew has already closed in, where the city allows it, is a different product. That paint is not the addition with the labor in. On the one pro addition, one ground-floor room is $22,000–$83,000. That is the labor for the room and the shell.

Do not treat the lumber alone as the room. If the foundation, the roof, and the finish still have to be done, you are pricing a crew’s job without the crew. The person on the build should say what happens if the foundation or the tie-in is wrong. Moving the furniture is the owner’s part. A receipt for a stack of studs is not this installed price.

Repair or replace

Build the addition when the house is staying and the lot, or the structure, can take a new room. A repair on a sound room the house already has is not this band. A quote near $4,000 should say a small bump-out at the wider floor, not a standard room. A quote near $22,000 should say whether the finish and the labor are in. A quote near $83,000 can be a standard room at its top, a 20×20 inside its overlap, or a second story inside its overlap. Ask which reading the bid is.

Price a 12×12 at $80–$200 on $11,520–$28,800. Price a 20×20 at that rate on $32,000–$80,000. Price a second story of about 200 square feet on $60,000–$100,000. Price a room addition on $20,900–$72,600, and do not read that room as the standard band with a different name. Do not read a basement as the addition with a different name.

Send the basement to the basement finishing guide, typically $30,000–$40,000. Send the garage to the garage building guide, typically $15,000–$40,000. Send the existing bath to the bathroom remodel guide, typically $10,000–$25,000. If the same season includes any of those, they are separate scopes. Do not fold them into the addition price.

How long a room lasts is not a number on this page. A one-house addition is not a warranty that a tie-in will never leak. A new season of weather is not a warranty that the finish will never need paint. The bid’s scope is the work you bought.

How to use this number

Ask two or three builders for a written price that names the room, whether the price is a lump sum, whether the shell, the finish, and the labor are included, whether the permits are already inside the price, and what happens if the foundation or the tie-in is wrong. Compare one ground-floor room, shell and labor in, with $22,000–$83,000. Compare a ground-level reading with $20,000–$80,000, a 12×12 at $80–$200 with $11,520–$28,800, a 20×20 at that rate with $32,000–$80,000, and a second story of about 200 square feet with $60,000–$100,000. Keep the shell and the labor inside those rows. Put left-out permits at $150–$7,500, left-out site prep at $1,500–$5,000, and left-out plans at $2,400–$14,000, on their own lines.

A very low bid on one room is a reason to ask whether the labor is included, not a reason to celebrate. A quote near $4,000 should say a small bump-out, not a crew on a standard room. A quote near $22,000 should say whether the labor is in. A high bid should point at a 20×20, a second story, a 400-square-foot second story, or the labor market. Two or three local bids on the same room, the same story, and the same finish are the number that matters. How this site sets the band is explained on the methodology page.