Home Addition FAQ & Cost Guide

Our estimates are based on 2026 material indexes and localized labor rates for your specific zip code. While highly accurate for budgeting, they are preliminary ranges. Actual costs can vary based on site conditions (like soil quality), specific high-end finish choices, and local contractor availability. We always recommend getting at least three professional quotes.

Yes. Almost all home additions—whether it's a new room, a garage, or a second story—require a building permit from your local municipality. Our calculator estimates include a standard allowance for permit fees, but these fees can vary significantly by city. For detailed guidance, check out our Building Permit Guide.

Standard assumes mid-range materials available at big-box stores (e.g., LVP flooring, fiberglass showers, laminate or basic granite counters).

Premium assumes high-end finishes (e.g., hardwood floors, custom tile showers, quartz counters, custom cabinetry). Premium finishes can increase the total project cost by 30-50%.

Timelines vary by complexity. A simple room addition typically takes 3-4 months. A kitchen bump-out or bathroom addition often takes 4-6 months due to plumbing and electrical work. A second-story addition is a major undertaking that can take 6-9 months or longer.

Our estimate covers construction hard costs. While we factor in a small buffer for permits, hiring a licensed architect or structural engineer typically costs an additional 10-15% of the total project budget, which you should plan for separately. See our permit guide for more details on the professional services you may need.

Our calculator supports a wide range of projects including:

• Room additions (bedrooms, offices, playrooms)
• Kitchen bump-outs and expansions
• Second-story additions
• Sunrooms and screened porches
• Detached and attached garages
• In-law suites or accessory dwelling units
• Bathroom additions

Simply select your project type and square footage to get started. Use our project checklist to plan your addition from start to finish.

Your zip code is crucial because labor rates and material costs vary significantly by region. We use real-time labor index data to adjust estimates for regional differences in contractor rates, prevailing wages, and local market conditions. For example, construction in urban areas typically costs 20-40% more than rural areas due to higher labor costs and availability of contractors. Check our state-specific guides for California, Texas, Florida, and every other state.

Yes! Once you've generated your estimate, you can use your browser's print feature (Ctrl+P or Cmd+P) to save it as a PDF or print a physical copy. You can also take a screenshot of your results to share with contractors or family members. Your estimate will remain available for 90 days if you bookmark the result page.

Our calculator supports three common foundation types:

• Slab: Concrete pad foundation, most economical at $4-8 per sq ft. Simple to build but limited flexibility.
• Crawl Space: Elevated foundation on short posts, mid-range at $6-10 per sq ft. Good for moisture control and utility access.
• Basement: Full depth foundation with potential living space, premium option at $12-18 per sq ft. Provides storage and climate control benefits.

Your choice depends on local building codes, soil conditions, and whether you want additional storage or living space.

The calculator allows you to add optional features including:

• Full or half bathrooms
• HVAC (heating/cooling) systems
• Skylights and additional windows
• Electrical upgrades and outlets
• Plumbing extensions and fixtures
• Decking or porches
• Kitchen installations with cabinetry and appliances
• Accessibility features

Each add-on updates your estimate in real-time so you can see the cost impact immediately.

Economy finishes use basic, budget-friendly materials (vinyl flooring, basic drywall, standard paint). Costs roughly 30% less than Standard.

Standard finishes use mid-range quality materials (laminate counters, fiberglass fixtures, quality paint). This is our recommended option for most homeowners.

Premium finishes feature high-end materials (hardwood or luxury vinyl plank, quartz counters, custom tile, high-end fixtures). Costs 30-50% more than Standard.

Choose based on your budget and long-term home value goals. Premium finishes offer better durability and aesthetics but may not return 100% ROI in all markets. Use our ROI calculator to compare finishes and project home value impact.

Yes, your privacy is our top priority. We use industry-standard SSL encryption to protect all data you enter. We never sell your information to third parties, and we only use your zip code and project details to generate accurate cost estimates. For more details, please review our privacy policy.