With March Madness going on, I am getting more and more people asking about house plans with indoor basketball courts. I have built several of them now and have tried different techniques. A number of our designers and architects have designed homes with the court in the basement or lower level. In many cases, these are luxury-sized homes like this 5 bedroom home with an indoor basketball court. However, not every home needs to be so large to accommodate the room. We have also built smaller homes with indoor basketball courts under the garage or in a basement that is part of a sloping lot. I tend to like these options because it means virtually any home plan can have an indoor basketball court.
As I have mentioned before, we built our personal home about nine years ago. We built it with an indoor basketball court and have loved it. We live in an area of the country where we have cold long winters. It is so nice to have a place for our family to be active. A home gym can be used for so many activities like basketball, racquetball, gymnastics, climbing, skating, and even golf. We hit those yellow foam golf balls in ours. We are building a few homes this spring with courts in them. Both of them will be underneath a suspended slab below the garage.
As far as the specs go when designing an indoor gym, these are some things we have learned. You really need a minimum height of 16 feet. To achieve this, you will need to pour your footings as a monolithic pour. That simply means you pour the floor of the gym 4 inches thick, except at the edges it will be 10 inches thick. The 10 x 20-inch concrete on the edge will have horizontal and vertical rebar like a regular footing. Also, where the wall sits you will need to use a keyway where the foundation walls will be. The keyway simply leaves a 2-3 inch groove in the footing so the foundation wall concrete can mold into the footing, thus creating a unit that works together. This also helps seal the bottom of the wall so water shouldn't get in.
The foundation walls will need to be engineered. My engineer requires the walls to be the regular 8-inch walls, but the rebar is placed every 12 inches, both vertically and horizontally. The rebar at the top of the wall will need to stick above the walls so it can be bent over and tied to the concrete of the garage floor.
We have our suspended slabs made off sight. They bring in the “pre-stressed concrete slabs” and install them with a crane. We then seal all of the joints, then bend all of the rebar over and tie in the horizontal rebar. This creates a 12-inch mat of rebar through out the entire floor. We then pour a 4 inch sloped floor over the pre-stressed concrete and matted rebar.
One thing to note, the pre-stressed concrete is about 12” thick. That means you need to have 9-foot basement walls, or set the gym an extra foot deeper. Otherwise you will have to step down when you enter your home from the garage.
We have found that a thin layer of carpet on the walls of the gym will greatly reduce the noise and make it cozy. We also like having carpet on the floor. The only thing bad about carpet is the rug burn you can get when you fall. However, our gym is 26 x 30 feet, so there isn't enough room to get running full speed. In the nine years we have been here, we haven't had anyone fall and skin a knee. That isn't because we don't use it. In fact our gym gets used nearly everyday. I would say it is used year round an average of two hours a day.
Now I know my directions may not be that clear, but I am a builder, not a technical writer. Just know that most any plan with a garage could easily be adapted to have an indoor basketball court under the garage. You will need to get with a local engineer to help you review your plan. Just explain how we are doing it and he will understand all of the terms and guidelines you need in your area.
Another thought to consider: To have a gym under the garage, you will be digging over 16 feet in the ground. Many areas have water tables well above the 16 feet. All of the homes we have done are on the benchs of the mountains in Utah. These are areas where there isn't going to have a water problem. Usually we try and find a lot where it really drops off, so we don't have to dig and haul away 16 feet of dirt. Sometimes we get really good deals on these lots, because they drop off too much for a typical house.
Be cautious when digging and forming the tall walls. You certainly want trained professionals to do this type of work. You should also consider placing a temporary fence around the deep hole. Make sure to schedule everything out so that you can get the deep hole, backfilled and covered as quickly as possible.
Many keep asking about the cost to build a gym. Of course every part of the country is different. I know that my raw cost to build a gym under a garage is in the neighborhood of $25,000 - $30,000. However, in my neck of the woods, it increases the property value much more than the money invested. They make great spec homes because the profit margins are much greater.
One last thought, about lighting and heating. Because these rooms are so deep in the ground, they won't need central air and may not need any heat. You can do forced air, but a better alternative is to have in- floor-heating.
The lights need to be low profile, like florescent lights. You can get florescent lights with a wire cage around them. You can also have glass block put in towards the top of the walls to shed some natural light in the gym.
Hopefully you love your indoor basketball court like we do.