Home Addition Cost in Houston [2025 Data]

The average cost to build a home addition in Houston is $28,022, and most projects total somewhere between $12,978 and $43,380. Your price will depend largely on the type of home addition you want, the size of the space you’re adding, and the quality of the materials you choose, both inside and out. The cost of living in Houston is more than 5% lower than the national average, which contributes to below-average totals.

Home Addition Cost Factors

Building a home addition in Houston, Texas, is a complicated project, so there are many factors you’ll need to consider if you want to get an accurate estimate. The size of your addition and where you build it on your property are the most significant cost factors, but you should also think about material quality, permit costs, and more to dial in an accurate total.

Size

Home additions cost between $40 and $120 per square foot if you’re building out and between $150 and $300 per square foot if you’re building up. The cost to add a 10x10 room to a home in Houston costs an average of $8,000 if you build out and around$22,000 if you build up.

Luckily, most homeowners in Houston will have some additional property to accommodate bumpouts and even standalone accessory dwelling units (ADUs) to add square footage. The average lot size in the city is 0.15 acres or a little over 6,500 square feet, and the average home, which is 2,100 square feet, takes up just 16% to 30% of the property. You’ll be restricted somewhat by setback laws in Houston, but in most cases, you’ll have enough room to build out and save.

The type of room you’re adding on will also affect your per-square-foot costs. Where in those ranges your total falls also depends on the complexity of the room and its finishes. For example, adding a bathroom will often cost more than a bedroom since it requires additional plumbing and electrical work.

Materials

As you can imagine, it takes many kinds of building materials to complete a custom home addition. Material prices vary widely, so your price could push closer to $43,380 if you choose luxury or high-end materials at each step of the way.

Choices for interior materials like flooring, fixtures, cabinetry, and countertops are all based on personal preference. On the other hand, exterior materials, which need to withstand supercell thunderstorms, extreme summer heat, and above-average rainfall, play a larger role in local home addition costs. We’ll include some common exterior materials and their costs in the tables below to give you an idea of how they can affect your total.

Foundation Materials Cost:

Insulation Materials Cost:

Roofing Materials Cost:

Siding Materials Cost:

Window Frame Materials Cost:

When in doubt, ask your home addition contractor what materials will provide the best value. They’ll typically recommend mid-grade or high-end materials that can withstand the occasional extreme weather in Dallas, but they may be able to recommend more affordable materials that still provide good resistance and value.

Type

The cost to add on a room varies based on the type of home addition you’re looking for. Building out from your existing property is simpler and almost always more affordable than building up, which is why it’s good news that most Houston homeowners have ample space on their plots to build a home addition. Bumpouts and detached garages will almost always cost less than half of what a second-story addition would cost.

The type of room you’re adding will also affect your costs, regardless of the type of home addition you choose. Rooms like kitchens and bathrooms require plumbing work that a bedroom doesn’t, while an unfinished attic home addition may not require electrical or HVAC work that a bedroom needs. The cost per square foot for your home addition will vary based on utilities and the finishes required for how you plan on using the extra square footage.

Site Prep

On average, site prep for a home addition costs between $1,500 and $5,000. You may not need any site prep in some cases, while other home addition projects may require grading land, demolishing concrete patios, removing trees, and other work that can add to your total. Houston is well-known for having a high clay concentration in its soil, which makes excavation challenging and expensive. If you need land leveling or excavation to build a crawl space or basement foundation for your bumpout, your site prep costs could be much higher.

Building out is more common in Houston since most homeowners have good-sized lots and ample room to house additional structures, and because it’s much more affordable. Therefore, you’re more likely to need to pay for site prep than homeowners in areas with smaller lot sizes who have no option but to build up. Even accounting for the added cost to prep the site, you’ll still pay less to build out.

Permits

All major home improvement projects in Houston will require building permits, which means you should budget for building permit fees to get the most accurate pricing possible. Houston bases permit fees for home addition construction on the square footage you’re adding, so you should use the city’s permit fee calculator to get a personalized estimate. Just as an example, for a 500-square-foot addition, you’re looking at permit fees totaling $420.62.

Home Addition Pro Costs

Hiring a home builder in Houston to handle your home addition will cost you between $11,200 and $16,800 for labor alone, which means labor accounts for 40% to 60% of your total costs. The cost of living in Houston is a little more than 5% lower than the national average, which helps bring labor costs below the average, as well. Labor is still costly, but it’s worth hiring a pro for such an involved project, and most aspects of the job are illegal to complete yourself anyway.

You should also account for sales tax for the most accurate price possible. The sales tax rate in Houston is 8.25%, which includes both state and city taxes. Be sure to budget for an average of $2,311.82 to account for tax.

Does a Home Addition Increase Property Value?

A home addition will boost your home value significantly, as adding living space is one of the best things you can do for property value. On average, a home addition provides a return on investment (ROI) of between 20% and 50%, so the average project in Houston will add between $5,600 and $14,000 to your home value.

With real estate prices in the city averaging $370,000, that means a home addition will boost property value by between 1.5% and 4%. Choosing more energy-efficient materials that can help reduce cooling costs through the brutal summers can help increase ROI even further.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We survey real Angi customers about their project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We pair this data with research from reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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