Soak up the sun year-round by converting your deck into a sunroom
Are you looking to enjoy the outdoors from inside your home—no matter the season? Consider turning your deck into a sunroom. But be warned: Learning how to build a four-season room on a deck isn’t a project for the average weekend DIYer. Converting your deck to a sunroom requires prudent planning, a healthy budget, and collaboration with contractors. Thankfully, the process doesn’t have to be overwhelming. This guide will help you learn how to build a four-season room on a deck and create a dreamy, sun-drenched space to enjoy year-round.
Turning a deck into a sunroom can make the space more functional in all seasons if the platform attaches to your home. Some of the most significant benefits include:
Increases home value: Sunrooms have an average 49% return on investment (ROI), perfect if you want to boost your property price. It’s one of many outdoor projects that boosts home value.
Better functionality: If your family is constantly tripping over one another, a sunroom adds extra practical living space and square footage.
Weather resistance: Since this type of sunroom is covered and cozy, you can use a four-season room on a deck when it rains, hails, storms, and snows. With proper heating, you can even use it in the winter.
Mood-boosting: According to Resources to Recover, the extra exposure to natural light can lift spirits, ward off seasonal depression, improve focus, and possibly even encourage a better night’s sleep.
The average cost to turn your deck into a sunroom is around $20,000, with most conversion projects totaling between $9,000 and $30,000. Of course, your total will vary depending on the quality of the existing deck foundation and the build's style, size, and finish.
Whether you have the skills to complete some or most of the work yourself also plays a significant role, as you could quickly pay double that—$50,000 or more, on average—to hire a professional to get the work done. Opting for high-end finishes instead could bring your project total to $80,000 or more.
Turning your deck into a sunroom isn’t a project to tackle off the cuff. It needs plenty of planning to make sure the build is safe, legal, practical, and comes in on budget.
If you have a damaged or particularly lightweight deck, ripping it out and starting the construction from scratch is often the best way forward. But well-supported decks of sturdy construction are good candidates for building a sunroom. Consider the following options based on your type of deck:
Raised, attached decks: This is the ideal scenario for converting a deck into a sunroom, as you want it to be level with and directly accessible from your home.
Wraparound decks: These platforms often circle the entire ground floor of your home. Building a sunroom along the full deck might be challenging regarding budget, building permits, and aesthetics, but building on just one section of it is possible.
Second-story decks: Supporting these elevated deck types is more complex, and building a sunroom on one might be impossible because of building codes. In these instances, you might be able to build a sunroom underneath it for a unique second-story deck idea.
Covered decks: Building a sunroom with this deck type depends on the existing roof construction quality and materials. If the roof is in good shape and suitable for covering indoor living space, then this option might save you some time.
Floating, close-to-the-ground decks aren’t attached to a house and don’t need complex footings to distribute the load. However, most homeowners build sunrooms on decks connected to the home.
These decks must have some footing to prevent the platform from sinking, but the foundations are sometimes not robust enough to cope with the extra weight a sunroom adds. If that’s the case, you might need to remove your deck and replace it with one that has solid footings suitable for supporting a completed sunroom.
If your deck isn’t supportive enough for a full four-season room and you don’t want to incur the added cost of removing it, you could also opt for a screened-in porch vs. a sunroom, which is lighter and faster to construct, although it may also be less useful.
You also want to ensure that your deck's framing can support the added weight of a four-season room. You might need to add extra joists and carrier beams, and additional supports on footings could be necessary. Getting this step right is critical for keeping your home up to code and ensuring that your family and home are safe. It pays to have a professional engineer assess if you can build on the existing frame and foundations or if they need reinforcing or replacing.
You’ll have to decide on the finish and functionality of your deck sunroom. Some sunrooms have almost entirely glass construction to let in the most light, and others have partially insulated walls beneath the windows and heating systems installed to stay snug in all seasons. Remember that these projects come with a premium price tag, so be sure to choose a build that fits your budget but also meets your needs and expectations for the space.
There are a few options you can consider for your sunroom.
These sunrooms include insulation and have the home’s central heating system tied in to keep the space usable year-round. Being able to soak up the sun even when temperatures plummet is a big deal. However, building this type of sunroom is the most expensive option.
If you live in an area with milder winter climates—or you just don’t need to use the room in the winter—you won’t need to blow your budget on extra insulation and HVAC functionality. Opting for single-paned glass and minimal insulation keeps construction simple and pricing conservative.
A glass solarium is unique because the entire sunroom is made of glass. By incorporating a glass roof, you’ll feel like you are inviting the outside in, but these constructions come at a cost, and the roof will probably need replacing more frequently than a typical sunroom.
A detailed plan, including measurements, construction style, and materials, is essential before you push on with the project. You can purchase affordable sunroom plans online and tweak them to suit your style and deck size. Alternatively, opt for a fully bespoke design from an architect or builder if you want a one-of-a-kind sunroom.
Hiring a sunroom contractor to check your plans or help you formulate them ensures they will be safe, functional, and fit with local building codes. Most contractors can even help you pull permits for your design once you’re comfortable with them.
Home additions require a building permit before you can start the construction work. The average cost of a building permit for a sunroom is around $1,400, but the total is usually a percentage of your build cost. Expect to pay somewhere between $450 and $2,000, depending on the complexity and size of the build.
Allow between two and eight weeks for the application process. Skipping this step can mean paying hefty fines and addressing potential problems with insurance or resale. If the build isn’t up to code, you might even have to rip the sunroom down.
Building a sunroom yourself, whether on top of an existing deck or not, can be complex, dangerous, and outside the skill set of most homeowners. The steps below will help you plan and keep track of the project, but leaving most of the work to a sunroom contractor near you will make your project go the most smoothly.
If the deck isn’t strong enough to support your sunroom, you must install additional joists and deep piers to keep things heave-proof and level. You’ll need the help of a contractor who can evaluate how much load will bear down on each pier and the required design best suited to offer strong support.
Your contractor will help you build the essential skeleton of the sunroom, called the framing. This rough frame includes wall lines, studs, roof trusses, wooden flooring piers, and joists. At this stage in the project, your contractor will also map out frames for all of the windows and doors in your sunroom and add additional framing supports based on the building code for each wall opening.
A protective sheath covering (often exterior grade plywood) attaches to the frame, holding the walls and roof in place. The contractor will then wrap it in a plastic barrier called house wrap to keep out moisture. Your builder will cut openings in this covering for door and window openings taking special care to wrap the waterproof liner around the insides of the entrances to prevent water from dripping behind the liner.
Depending on the style of roof you want on your four-season room, and how the contractor will connect it to your main house, they will install the top plate to tie your walls together, install the joists and ridge board, and join the rafters.
If you intend to use the space year-round, your contractor will also insulate the roof. Keep in mind that this step doesn’t apply to glass solarium sunrooms.
Finally, the contractor will attach the roof deck, lay down the underlayment, attach any flashing required, and install the roof shingles. Most homeowners choose to match the sunroom roof with their existing roofing, and the roofing on the main structure might need some minor alterations to attach correctly to the new area.
Installing your windows and doors is a big job for a glass-wrapped sunroom. It often takes multiple contractors to install delicate but heavy window panes into the framing, and they may need to bring in a crane if you’re building your sunroom on a second-story deck. It typically takes 30 to 60 minutes to install each window and between 1 and 3 hours to install any exterior doors and ensure they’re plumb.
Some sunrooms have walls made entirely of glass for maximum sunlight, while others have short walls that extend up from the deck below and meet the windows part of the way up the wall. If you have partial walls, your contractor will install siding over the house-wrapped exterior plywood and use trim siding pieces around windows and doors for a finished appearance.
What is a four-season room without electrical service installed? After all, you don’t want to be without lights, outlets, and switches. Even if you have experience handling home wiring, we strongly recommend you hire a local electrician to complete any electrical work. A DIY job here might be tempting, but it’s usually not legal for a non-electrician to complete major work like this, and you could run into issues with homeowners insurance coverage if you do the work yourself.
If you want a full four-season sunroom, don’t forget to book a local HVAC contractor to install services to keep the space toasty during the winter and cool in the summer. You could either have them tie the space into your existing heating and cooling systems or install a mini-split just to keep the new area temperature controlled.
You’re almost done! Now is the time to furnish your sunroom with fun additions to make it feel homey. Plus, tackling these tasks on your own can reduce project costs. Some jobs you can tackle yourself include:
Floor installation
Light fixtures installation
Hanging window treatments
Adding furnishings
Trim or siding painting
There is no shortage of sunroom ideas for a bright and cozy space, so feel free to play around with the space, have fun, and make it your own.
Once you’ve transformed your deck into a bright sunroom, you can sit back and relax—for the most part. But don’t forget to keep on top of annual sunroom maintenance so you can appreciate the hard work for years to come. There are a few things you can do to extend the life of your home’s new add-on:
Clean gently and carefully: Keep heavy, scratchy ladders away from your delicate windows when accessing the walls or roof. Also, avoid abrasive tools and cleaning products that can mark your glass.
Oil mechanical parts: It's worth digging out some lubricant monthly to keep the window locks, hinges, and handles operating smoothly.
Trim those trees: You don’t want overhanging tree branches scratching your sunroom windows, holding moisture against your roof, or building a bridge to your home for squirrels and insects. Pruning wayward branches away from your new sunroom as part of your regular tree maintenance is a good idea, and it also helps avoid premature gutter clogging.
Annual inspection: It’s wise to inspect your sunroom once a year to look for problems. Check the windows and doors for signs of leaks, confirm that each outlet and light switch works properly, and test your heating and cooling equipment to ensure it’s functioning as intended. Catching problems early is one of the best ways to avoid serious issues and keep any repair costs down.
It’s true that you can save up to 70% on the total project costs by building a sunroom on your deck yourself. However, unless you're a construction guru, it’s a job best left to the professionals. The major technical work is easy to get wrong, and problems with poor foundations or framing can be dangerous and pricey to repair. You should also leave any electrical and plumbing run into the space to a professional, as problems can be costly and potentially cause issues with your local building department and homeowners insurance policy.
Even if you decide to take the plunge with a prefabricated sunroom kit, you’ll still have to rely on a professional sunroom contractor at some stages during the project. Have them assist with or at least inspect the foundations, and be sure to keep your project up to code by hiring professionals for all utility work.
Once the sunroom structure is done, feel free to flex your DIY muscles by installing sunroom flooring and drywall, painting, putting in light fixtures, and decorating your space to make it feel like a well-integrated part of your home.
Even if your deck is well-constructed with a solid foundation, it doesn’t always mean it can handle the extra weight of a large, insulated four-season room. Always call in a professional sunroom contractor to perform a deck inspection to evaluate the quality and structural integrity of the deck before building. You’ll often have to reinforce the foundations and joists, and with decks in poor condition, it might be better to tear them down and start again.
Yes, the weight of a sunroom will put a lot of pressure on the deck below, so ensuring solid footings beneath the deck posts is critical before any building takes place. Sometimes basic, lightweight, prefabricated sunrooms can sit on top of a deck with strong existing foundations, and you can get away without adding additional supports. Usually, though, the foundation will need reinforcement to support the extra weight.
Yes, In many cases, a sunroom is worth installing on a deck. Most sunrooms on decks cost around $10,000 to $140,000, so they’re pretty costly. However, a quality sunroom can offer around a 50% return on investment, making your home more sellable. Plus, if it’s a space you and your family enjoy relaxing in daily for years to come, it’s often worth the money, time, and effort, even without the added monetary value.
