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.
Why Should I Turn My Deck Into a Sunroom?
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.
How Much Does it Cost to Turn Your Deck Into a Sunroom?
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.
Prepping to Build a Four-Season Room on a Deck
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.
Evaluate Deck Style
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.
Evaluate the Deck Foundation
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.
Make Sure the Framing Is Solid
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.
Choose the Best Type of Sunroom For Your Deck
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.
Four-Season Room
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.
Three-Season Room
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.
Glass Solarium
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.
Make Building Plans
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.
Apply for a Permit
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.
