How To Build A Room Under A Deck

The biggest advantage to building a room under a deck is that you can select the location of your structure. If you are planning on adding a room for family gatherings and parties, then build it into an existing porch or patio.

If you’re looking for a way to maximize usable space or just make your outdoor space more livable, adding a room under a deck is an option that could work for you. Whether it is a manor house, cottage or bungalow, the addition of a room under a deck may be exactly what you need. A fully finished room will certainly add value to your home if you plan to sell it. Even if you don’t plan on selling your home, having extra space for entertaining or simply enjoying yourself with family and friends could be ideal.

Adding a room under your deck provides extra space and privacy, and also adds value to your home when you sell it. Making a room under a deck is relatively easy, but requires some planning and preparation before you start. When building an area under your deck, consider making it larger than what you expect to need right away. The additional space may be useful in the future as your needs grow.

The living conditions in many parts of the country can be a little, well, damp. While you may want to get outside and enjoy all that lush green nature has to offer, sometimes it’s just too wet out there for comfort. Don’t let the rain keep you from being outside build a room under your deck instead.

Deck Size

When building a room under a deck, it’s important to consider the size of the deck and how much space you truly need. Of course, this is also important when building any type of house, but it takes on a new level of importance with decks. For example, if you have a small deck that can only comfortably fit one person at a time, then there’s no point in designing an elaborate and expensive room underneath it. You should just build an affordable box so that you can still use your outdoor space for relaxing as well as for entertaining guests.

When thinking about how big your room will be and what kind of door or window(s) will be best suited for it, keep in mind how large your chest-of-drawers or other furniture pieces are compared to their dimensions in real life (i.e., not their virtual representations). If necessary, measure them now so that later on down the road when everything has been built and installed into place under your new addition onto an existing structure such as one made out solely out of wood planks without any metal support beams underneath it yet still supports enough weight without collapsing because those who built them knew what they were doing when they did so.

Rain Protection

There’s one last thing to keep in mind if you want to create a room underneath your deck: weather protection.

A tarp is the perfect solution to protect your space from rain, sun and debris. A tarp can also be used as a door or window cover, if you need more airflow into your space. Of course, there are many other uses for tarps when building a room under a deck—like keeping insects out or wildlife off of your property—so let your imagination run wild.

Interior Walls

The interior walls of your room should be made of a material that is easy to clean, strong, durable and safe. The material you choose should also have the right appearance and texture so that it can work with your design plans.

Here are some materials that would make good interior walls:

  • Wood – Pine or cedar boards are popular choices for building interiors because they are inexpensive, easy to install and come in a variety of colors. However, wood can shrink over time when exposed to moisture; it also absorbs liquids such as stains from spills or leaky pipes which may need more frequent cleaning than other types of materials listed below.


Once you’ve determined the best material for your platform, it’s time to think about what kind of flooring you want to put beneath it. First and foremost, the flooring should be waterproof. You don’t want moisture seeping up through the cracks in your deck and pooling at your feet—and you definitely don’t want water from rain or snow to leak into the space below.

Second, it needs to be easy to clean—you know how dirty feet can get! If you plan on using this space as an outdoor room, then having a hardwood floor like cedar might not be ideal since pets tend to shed fur all over them (even if they’re wearing sweaters).

Thirdly, it needs durability so that it won’t warp under heavy furniture like dining tables and chairs. Fourthly, comfort is important if you’re going sit on this surface regularly; carpeting provides cushiness while tile makes things slippery when wet so make sure whatever type of material you choose has adequate cushioning properties before purchasing any products off-the-shelf as warranty policies will only cover manufacturer defects/defects which occur during manufacturing processes but not instances where there’s been negligence involved (such as dropping something heavy onto an unprotected surface). Lastly: ease of installation because who likes doing extra work.


Lighting is essential to having a functional room under your deck. You need enough light to see what you’re doing, but not so much that it interferes with sleep. A good rule of thumb is to have at least four feet of lighting at the base of each wall and five feet in between each wall. Make sure there are no dark spots, especially where people will walk up and down the stairs.

The walls should be lit so they are visible from inside during the day and when walking on them during night time activities like reading or playing games. If possible, install lights that turn on automatically when motion detectors detect someone approaching the area where they are installed (like next to stairs or doorways). This way there won’t be any surprises when guests come over late at night!

It’s also important for people using their rooms as living spaces that there’s enough natural light coming in through windows so furniture pieces aren’t just sitting in darkness all day long–this can cause eye strain over time which isn’t very comfortable either.


Ventilation is crucial to the overall comfort and safety of your room. If the air can’t circulate, it will become stale and humid, which in turn creates mold and mildew. Ventilation also keeps dust from collecting in corners, keeping them clean so that you can enjoy your new space without breathing in allergens or lung irritants.

There are several ways to add ventilation:

  • Windows provide natural ventilation by allowing fresh air in from outside and exhausting stale air out through cracks around windows or doors. They’re also great sources for passive solar heating or cooling depending on season; during summer months when trees block most direct sunlight from reaching the windows, you may want to close them so that you don’t spend too much on electricity cooling down your home (and vice versa).
  • Fans take up less space than windows but still allow for cross-ventilation throughout the room. They create negative pressure inside relative to outdoor pressure—when this happens air flows into homes through open doors/windows/vents while simultaneously flowing out through other openings like chimneys/skylights which push hot humid outside air out of homes while drawing cool dryer inside ambient temperatures back towards these points where they enter at lower pressures relative to areas closer towards exterior walls where there isn’t any opening available yet since they’re farther away from exterior walls than other openings such as door frames leading into living rooms where traffic tends not only bring dirtier particles


To get the most out of your outdoor space, you will want to consider adding some form of heating. There are many options available that range from simple and affordable to luxurious and expensive. Here are a few common choices:

  • Heating with a heat pump or electric baseboard: This type of heating is generally the least expensive option for outdoor rooms and is easy to install yourself if you have electrical experience or can find someone who does. You can also buy kits that come with all of the parts needed for installation and just need some basic tools for assembly. These systems do require electricity, but they’re usually still much less expensive than other forms of indoor/outdoor heating. If you have any concerns about safety when it comes to wiring up this kind of system yourself, talk with an electrician first before making any decisions.
  • Wood stove: Many people choose this option because it’s convenient since there aren’t many moving parts (aside from adding wood every so often). It’s also cheaper overall compared with propane heaters since there aren’t any fuel costs involved (although buying firewood will add up over time). Having said that though…you’ll have some ongoing maintenance responsibilities too since these stoves need regular cleaning & upkeep in order avoid creosote buildup within their pipes which could lead back into dangerous situations down road if left unchecked long enough.


  • Electric
  • You’ll need to run electricity to the new room, either overhead or underground. This can be done with conduit, which is a metal tube that’s buried underground and then covered with dirt.
  • Water
  • Whether you’re building a room above or below ground level, the water supply will be important. If you’re adding a room under a deck, it’s likely that there’s already an existing water line to your house nearby. If not, it’s best to hire professionals for this task as they know what kind of lines must be added for things like showers and toilets.
  • Sewer
  • If your new structure is going over ground level, then you’ll need sewer lines too (unless you’re planning on using an outhouse). The same goes if your home doesn’t have one already; in this case, call in professionals who will install pipes from your house all the way out into the street where they connect with city sewage systems (if available).

Stairs & Doors

When building stairs, it’s important to ensure they’re wide enough. The National Association of Home Builders recommends that the treads on stairs be 36 inches wide and the rise between each step be no greater than 8 inches.

Stairs should also have a handrail on both sides, which can be made of wood or metal. The height of stair railings should be at least 34 inches from their lowest point (if you use balusters) up to 36 inches for open steps.

The width of doors is another critical element when it comes to building rooms under decks: if your deck isn’t level with the ground, you’ll need more space for the door so you can open it without hitting something like your deck railing. Doors must also have threshold clearance—or an opening in them just large enough for someone’s foot—so make sure there is plenty of room around them before installing them in your new space.

Building a room under a deck will help keep you dry on rainy days.

Building a room under a deck will help keep you dry on rainy days. In order to do this, you’ll need to use waterproof materials that are resistant to water and moisture. These include plastic, vinyl, or wood panels. You can also use fabrics such as canvas or tarpaulins as well as rubber mats and tarpaulins for your flooring if you choose not to go with hardwood planks.

Final words

The key points to remember when building a room under your deck are: 1) Consider your local building code restrictions or guidelines; 2) Remember that moisture control is essential for any area, especially one that is not naturally protected by a roof; 3) Develop a plan and stick with it so you don’t have surprises later on down the road; 4) Make sure you have all of the materials before starting work.

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