"We started with a wooden deck and screened enclosure that was rarely used and ended up with a beautiful composite deck and sunroom that we enjoy daily. We greatly appreciate the skilled craftsmen."
Deborah Thomas
Verified Google Review
Sunspace Model 400 Insulated Sunroom
Sunspace Model 400 Insulated 4-Season Sunrooms in Maryland
A true year-round room. Thermal walls, Low-E argon glass, and an optional insulated floor keep it comfortable through Maryland winters. Authorized Sunspace dealer.
4.9 stars on Google•101 Google reviews•MHIC #91686
About the Model 400
Comfortable in every Maryland season
The Model 400 is a fully insulated sunroom built for year-round comfort. High-density three inch foam panels keep the room warm, and heavy-gauge three inch aluminum extrusions provide strong support against wind and snow loads. Commercial-grade thermal breaks in the extrusions reduce condensation and heat loss, and the windows use high-efficiency glass with Low-E argon gas for another layer of protection. Add the optional Therma-Deck insulated floor, available in R17, R26, and R35, for a strong, finished base ready for any flooring. For seasonal use, a two inch Patio Room wall option is also available. As an authorized Sunspace dealer, we handle design, permitting, and factory-trained installation.
- Three inch high-density foam thermal walls
- Heavy-gauge three inch aluminum extrusions for wind and snow support
- Commercial-grade thermal breaks reduce condensation and heat loss
- High-efficiency Low-E argon glass
- Optional Therma-Deck insulated floor in R17, R26, or R35
- Built for true four-season, year-round comfort
Why Custom Design & Build
A fully insulated, year-round sunroom
True 4-Season Comfort
Built to stay comfortable through Maryland winters and summers alike.
Thermal Walls & Glass
Commercial-grade thermal breaks and Low-E argon glass cut heat loss and condensation.
Insulated Therma-Deck Floor
Optional R17 to R35 insulated floor system, ready for any finished flooring.
Authorized Sunspace Dealer
Factory-trained installation from design through finish.
Recent Projects
A few of our recent sunspace model 400 insulated sunroom builds
Investment Guide
What does this typically cost?
$75,000 to $120,000 typical range
Final pricing depends on your specific design, materials, and site conditions.
Standard
12' x 12' (144 sq ft), typically $75,000 to $90,000. Final price in your written proposal.
Mid
12' x 14' to 14' x 16', typically $80,000 to $105,000. Final price in your written proposal.
Premium
16' x 20' (320 sq ft), typically $100,000 to $120,000. Final price in your written proposal.
Integrated railings add $2,500 to $5,000.
Frequently Asked Questions
Common questions, clear answers
How much does a Model 400 insulated sunroom cost?
A Sunspace Model 400 typically runs $75,000 to $90,000 for a 12' x 12' room up to $100,000 to $120,000 for a 16' x 20' room. Integrated railings add $2,500 to $5,000. You get a price bracket on the first phone call and a final written number after the site visit.
Is the Model 400 really year-round?
Yes. It is a fully insulated sunroom built for four-season use, including Maryland winters and humid summers.
What makes it insulated?
Three inch high-density foam wall panels, commercial-grade thermal breaks in the aluminum extrusions, and high-efficiency Low-E argon glass.
What is Therma-Deck?
An optional insulated floor system available in R17, R26, and R35. It gives you a strong, finished base ready for any flooring.
Can I heat and cool it?
Yes. Because the walls, glass, and optional floor are insulated, it holds heating and cooling well. It runs on its own dedicated system, such as a ductless mini-split, rather than tying into your home's HVAC, and we coordinate the electrical it needs.
Does it handle snow and wind?
Yes. Heavy-gauge three inch aluminum extrusions provide strong support against typical wind and snow loads.
How much more does a four-season room cost than a three-season room?
Roughly $35,000 to $40,000 more than a Model 200 of the same size, because of the thermal walls, Low-E argon glass, and thermally broken frame.
Where do you install insulated four-season sunrooms?
Throughout Harford, Baltimore, Cecil, Anne Arundel, and Howard County, Maryland, from our Fallston office.
What is the warranty?
The Sunspace limited lifetime warranty covers laminations and finishes, glass breakage in windows and doors, vinyl extruded components, and hardware and screen units for as long as you own the room. Insulating glass units carry a 15-year warranty against seal failure that causes fogging between the panes. Our installation is backed by our 2-year workmanship warranty, and we register the manufacturer warranty for you.
What Homeowners Say
Real feedback from Maryland homeowners
"Mark was fantastic to work with from start to finish. He's incredibly knowledgeable and took the time to explain everything clearly. The entire experience was smooth, professional, and exceeded our expectations."
Brandon Herd
Verified Google Review
"Loved working with Mark and his guys! Love our new sunroom even more! Mark was open and honest from the very first call, never salesy. He was a great resource in helping us finalize the design."
Eric Schuster
Verified Google Review
Learning Center
Four-Season Room guides
Sunrooms
Four-Season Rooms in Maryland: Insulation, Heating, and What They Cost
What makes a sunroom a four-season room, how it is heated and cooled, and what it costs in Maryland compared with a three-season room.
Sunrooms
How Much Does a Sunroom Cost in Maryland? 2026 Prices by Type and Size
What a sunroom costs in Maryland in 2026, by type, Sunspace model, and size: three-season, four-season, screen rooms, porch enclosures, and patio covers.
Sunrooms
How to Keep a Sunroom Cool in a Maryland Summer
Orientation, roof choice, Low-E glass, ventilation, ceiling fans, shading, and dedicated cooling: how to keep a glass room comfortable in July.
Sunrooms
Sunroom Flooring Options: What Works in a Maryland Sunroom
Tile, luxury vinyl plank, composite, carpet, and concrete compared for sun, moisture, and temperature swings in screen, three-season, and four-season rooms.
Sunrooms
Can You Heat a Three-Season Room? What Maryland Homeowners Need to Know
Your options for heating a three-season room in Maryland, from infrared heaters to ductless mini-splits, and why it should not tie into your home's HVAC.
Comparison Guides
Sunroom vs Three-Season Room vs Screen Room: Which Is Right for Your Maryland Home?
A clear comparison of sunrooms, three-season rooms, four-season rooms, and screen rooms: seasons of use, ventilation, heating and cooling, and price.
Ready to Build?
Let's talk about your outdoor space.
Start with a free phone conversation. We'll learn about your project, answer your questions, and help you understand what's possible. No pressure, no high-pressure sales tactics.
4.9 stars on Google • 101 Google reviews • MHIC #91686 • Locally owned and operated