How much does a room addition cost in Renton, WA?

The average room addition in Renton, WA costs $122,820 in 2026. Costs range from $47,763 for a basic project to $272,933 for a high-end renovation. Renton is 36% more expensive than the national average of $90,000.

What is the labor rate for contractors in Renton?

The average contractor labor rate in Renton, WA is $44.98/hour, compared to the national average of $30/hour. For a room addition, labor typically accounts for 50% of the total cost, which is approximately $61,410 in Renton.

Are materials more expensive in Renton?

Renton has a material cost index of 123 (national average = 100). Materials cost about 23% more than the national average. For a room addition, materials account for 50% of the cost, approximately $61,410.

Do I need a permit for a room addition in Renton?

Yes, a room addition typically requires building permits in Renton, WA. The average permit cost in Renton is $1,646. Always confirm requirements with the Renton building department before starting work.

Is a room addition a good investment in Renton?

A room addition provides an estimated 55% ROI nationally. In Renton, where the median home price is $560,000, this project costs about 21.9% of your home value. This is a significant investment relative to home value — consider carefully whether the local market supports premium renovations.

Room Addition in Renton, WA — Costs $47,763 to $272,933

What does room addition cost in Renton? Average $122,820, ranging $47,763–$272,933. Labor runs $44.98/hr locally — 36% above the national average. Free breakdown with material + labor split.

Renton, WA Market

+36% vs national

Labor Rate

$44.98/hr

Material Index

123

Avg Permit Cost

$1,646

Median Home Price

$560,000

Renton is a mid-sized city in Washington with a healthy pool of local contractors. Homeowners generally have several options to compare for a room addition, which helps keep pricing competitive. At 36% above the national average, Renton is one of the more expensive markets for home improvement — driven primarily by above-average labor rates in the region. With a median home price of $560,000, this room addition represents just 21.9% of typical home value — a relatively small investment that can significantly boost curb appeal or functionality.

Low Estimate

$47,763

National: $35,000

Mid-Range

$122,820

National: $90,000

High End

$272,933

National: $200,000

Per Sq Ft

$273

National: $200

Duration: 3-6 months

DIY: Hard

Permits: Required

ROI: 55%

Room Addition Cost Calculator for Renton

Adjusted for Renton's labor rate ($44.98/hr) and material costs (index 123).

Project Size: 200 sq ft

50 sq ft1,000 sq ft

Quality Level

Mid-grade materials, good quality fixtures, standard options.

Estimated Total in Renton

$122,820

Based on 200 sq ft at mid quality, adjusted for Renton market rates.

Local Cost Breakdown

Labor (50%)$61,410

At Renton's average rate of $44.98/hr (50% above national avg)

Materials (50%)$61,410

Material cost index 123 (23% above national baseline of 100)

Room Addition vs. Home Value in Renton

Metric	Renton	National Avg
Room Addition (Mid-Range)	$122,820	$90,000
Median Home Price	$560,000	$350,000
Project as % of Home Value	21.9%	25.7%
Estimated ROI	55%	55%
Median Household Income	$68,000	$75,000

What Affects the Price in Renton

1Local labor rates ($44.98/hr in Renton)
2Material cost index (123 vs national 100)
3Square footage
4Foundation type
5Number of stories
6Roof integration

Popular Upgrades

Cathedral ceiling
En-suite bathroom
Walk-in closet

Other Projects in Renton, WA

Second Story Addition

$272,933

HardROI 60%

Accessory Dwelling Unit (ADU) Construction

$204,700

HardROI 80%

Swimming Pool Installation

$86,953

HardROI 40%

Garage Addition

$75,057

HardROI 65%

Home Addition

$108,096

MediumROI 60%

Inground Swimming Pool

$86,077

HardROI 43%

Attic Conversion

$75,797

HardROI 64%

Swimming Pool Construction

$68,907

Professional OnlyROI 43%

Room Addition in Other Washington Cities

Seattle, WA

$136,995

+12%Pop. 737,015

Spokane, WA

$124,305

+1%Pop. 228,989

Tacoma, WA

$108,180

-12%Pop. 219,346

Vancouver, WA

$115,260

-6%Pop. 190,915

Bellevue, WA

$134,610

+10%Pop. 151,854

Kent, WA

$107,805

-12%Pop. 136,588

Everett, WA

$118,245

-4%Pop. 110,629

Spokane Valley, WA

$122,880

SamePop. 103,597

Planning a Room Addition in Renton

Building permits are typically required for a room addition in Renton. The average permit fee in this area is $1,646, though costs vary based on project scope. Permit fees in this market are above average — factor them into your total budget. Plan for 3-6 months from start to finish.

A room addition is a complex project best left to licensed professionals. In Renton, skilled contractors charge an average of $44.98/hr, and the specialized nature of this work means cutting corners on labor can lead to costly rework.

For the median Renton household earning $68,000/year, this project at $122,820 represents a significant investment. Consider financing options or phasing the work to spread costs over time.

Room Addition — National Guide

See the full national cost guide with DIY tips, cost factors, and ROI analysis.

All Construction Costs in Renton

View labor rates, material costs, and project estimates for Renton, WA.

Explore All Project Cost Guides

Compare costs across 120+ home improvement projects in 3,636 cities nationwide.

View All Project Costs