Quick Comparison
- Most Affordable: 3-Season Sunroom ($15K-$30K)
- Best Value: Family Room Addition ($40K-$80K)
- Most Complex: Second Story ($100K-$300K+)
- Best for Multi-Gen: In-Law Suite ($75K-$150K)
- Fastest Build: Sunroom (6-10 weeks)
Not all room additions are created equal. A sunroom costs a fraction of a second-story addition, but they serve very different purposes. Understanding your options helps you choose the right addition for your needs and budget.
According to HomeGuide, home additions cost $125-$250 per square foot nationally, but the specific type of addition dramatically affects both cost and timeline.
"The right addition isn't always the biggest or fanciest one. It's the one that solves your actual problem. I've talked plenty of homeowners out of expensive second stories when a simple bump-out gave them exactly what they needed."
Complete Addition Comparison
Here's every major type of room addition compared side-by-side. Costs are specific to the Kansas City market:
| Addition Type | Cost Range | Timeline | Complexity | ROI |
|---|---|---|---|---|
| 3-Season Sunroom | $15K-$35K | 6-8 weeks | Low | 45-55% |
| 4-Season Sunroom | $35K-$80K | 8-12 weeks | Medium | 50-60% |
| Family Room | $40K-$80K | 10-14 weeks | Medium | 55-65% |
| Bedroom Addition | $35K-$70K | 10-14 weeks | Medium | 50-60% |
| Master Suite | $75K-$150K | 12-18 weeks | High | 55-65% |
| In-Law Suite/ADU | $75K-$175K | 14-20 weeks | High | 60-70% |
| Home Office | $40K-$70K | 8-12 weeks | Medium | 50-60% |
| Second Story | $100K-$300K+ | 16-24 weeks | Very High | 50-65% |
| Attic Conversion | $25K-$75K | 6-10 weeks | Medium | 55-65% |
| Bump-Out (50-150 sq ft) | $15K-$40K | 4-8 weeks | Low | 50-60% |
Addition Types Explained
Sunroom Addition
$15,000 - $80,000Sunrooms are the most popular first addition for Kansas City homeowners. According to Angi, 3-season rooms cost $8,000-$50,000, while 4-season rooms with HVAC run $20,000-$80,000.
Best For:
- • Extra living/entertaining space
- • Indoor-outdoor connection
- • Plant lovers and natural light
Consider If:
- • Budget is limited
- • You don't need year-round use (3-season)
- • You want fastest ROI timeline
Family Room Addition
$40,000 - $80,000The workhorse of room additions. A family room adds functional living space that integrates fully with your home's HVAC, electrical, and design. Typically 200-400 square feet.
Best For:
- • Growing families needing more space
- • Entertainment/media rooms
- • Open floor plan expansion
Typical Features:
- • Full HVAC integration
- • Vaulted or standard ceilings
- • Fireplace options
In-Law Suite / ADU
$75,000 - $175,000Self-contained living spaces are increasingly popular for multi-generational families. According to HomeGuide, ADUs cost $100-$300 per square foot for full independent living spaces.
Typically Includes:
- • Bedroom + full bathroom
- • Kitchenette or full kitchen
- • Private or shared entrance
- • 400-800 square feet
Best For:
- • Aging parents
- • Adult children
- • Rental income potential
Second Story Addition
$100,000 - $300,000+The most complex and expensive option, but ideal when you can't expand your footprint. Adds significant square footage without using yard space. Requires structural engineering and often temporary relocation.
Best For:
- • Small lots with no room to expand
- • Adding multiple bedrooms/baths
- • Doubling living space
Considerations:
- • Structural engineering required
- • May need foundation reinforcement
- • Longest timeline (4-6 months)
Which Addition Is Right for You?
You need more space for entertaining → Family room or 4-season sunroom
You have aging parents who may move in → In-law suite with full bath and kitchenette
You need another bedroom on a budget → Attic conversion or bump-out bedroom
You want to maximize resale value → Master suite or additional full bathroom
You work from home and need quiet → Dedicated home office with soundproofing
You have a small lot but need lots of space → Second story addition
Timeline Breakdown
Timeline varies significantly by addition type. Here's what to expect from start to finish, including design and permitting:
Frequently Asked Questions
What is the cheapest type of room addition?
Sunrooms (3-season) and bump-out additions are typically the most affordable, starting around $15,000-$25,000. They require simpler foundations and don't need full HVAC integration. Attic conversions can also be cost-effective if the space exists.
What type of addition adds the most home value?
Primary bedroom suites and in-law suites/ADUs typically add the most value because they add both square footage and functional bedrooms/bathrooms. In Kansas City, these additions often recoup 50-65% of their cost at resale.
How long does a typical room addition take?
Simple additions like sunrooms take 6-10 weeks. Standard room additions (family room, bedroom) take 3-4 months. Complex projects like second-story additions or in-law suites take 4-6 months. Add 2-4 weeks for permits and design before construction begins.
Is it cheaper to build up or build out?
Building up (second story) avoids foundation costs but requires structural engineering and often temporary relocation. Building out requires new foundations but has simpler construction. In Kansas City, building out is typically 20-30% less per square foot.
Do I need an architect for a room addition?
For simple additions, many contractors provide design services. For complex additions (second story, major structural changes), hiring an architect is recommended. Most jurisdictions require stamped drawings for permits regardless of who creates them.
What permits do I need for a room addition in Kansas City?
All room additions require building permits in Kansas City. Depending on scope, you may also need electrical, plumbing, and mechanical permits. Your contractor typically handles permit applications. Fees range from $200-$1,500 depending on project value.
Can I add a bathroom to any room addition?
Yes, but it adds $15,000-$40,000 to your project cost depending on bathroom size and distance from existing plumbing. Half baths are more affordable than full baths. Bathrooms significantly increase the functionality and value of additions.
What is the best room addition for working from home?
A dedicated home office addition ($40,000-$70,000) offers the best work-from-home environment with soundproofing, dedicated electrical, and separation from living areas. Alternatively, a sunroom or converted space can work for less demanding needs.
Next Steps
Ready to explore your options? See the types of additions we build with examples and details on each type. We offer free consultations to help you determine which addition best fits your needs and budget.
About the Author
Bob Coulston, Owner of Coulston Construction
Bob has built every type of room addition over 15 years in Kansas City, from simple sunrooms to complex second-story expansions. His team specializes in seamless additions that look like they were always part of your home.
Learn more about Bob →