Cedar makes an excellent wood for building a hot tub. It is strong, lightweight and pleasing to the eye. Building a cedar hot tub from scratch is a fairly extensive undertaking, but for carpenters skilled in woodworking, it can make for an enjoyable challenge. In addition to the wood itself, you will need a number of items from your local pool supply store.
Things You'll Need
- Cedar wood suitable for cutting and shaping
- Tub bands
- Chine joists
- Carpenter's level
- Power drill
- 1 3/4 hp Water pump
- 1 2 hp Water pump
- Hot tub thermowell
- Hot tub filter
- Water heater
- Hot tub jets
- Suction fittings
- Hot tub skimmer
- Timer with manual on/off switch
- Epoxy sealant
- PVC piping
- PVC sealant
- Hole saw
Find a good spot for your hot tub. You want it on level ground capable of supporting the entire weight of the tub (100 to 150 pounds per square foot). A solid concrete porch is usually best. Make sure the spot is sheltered from the wind and elements as well; placing it close to the house will help ensure this.
Cut lengths of cedar wood or lumber to fit your hot tub. Dimensions will vary depending upon the size of your hot tub. You can use the following lengths as guidelines to construct a 6-foot diameter tub (smaller or larger tubs will have different dimensions):
1 tub bottom, 6 feet in diameter
1 circular bench section, 6 feet in diameter, 12 to 18 inches long
2x4 bench supports, 20/5 inches tall
3 chine joists to support the tub, 4 to 6 inches high. Two of the joists should measure about 3.5 feet long and the third should measure about 6 feet long.
24 to 30 fitted staves, each 4 feet high. There should be enough to cover the entire circumference of the tub evenly.
Punch holes in the tub bottom fitted to the size of the tub's suction fittings with a hole saw. They should be no further than 5 inches from the edge of the bottom, where they can be reached easily.
Use the hole saw to punch holes in the fitted staves where you will place your jets. You want two rows placed evenly around the circumference of the tub: the top row should fit the high-powered jets and the lower row should fit the low-powered jets. Low speed jets typically number about one half the number of high speed jets (6 to 8 is typical). Low speed jets should be between 12 to 18 inches from the bottom of the staves, while high speed jets should be 12 to 18 inches above them.
Cut a final hole in a single stave to fit your skimmer. It will be placed close to the suction fitting holes.
Place the chine joists on the ground in support of your hot tub and secure them to the concrete with bolts. The smaller joints should be placed on either end of the measured area, while the large joist needs to be placed down the dead center.
Place the tub bottom on top of the joists and secure it into place with bolts or nails. Make sure that the bolts or nails are pounded completely into the joists, so that no part of them sticks up.
Fit the suction fittings into the holes you have cut for them, and secure them to the bottom of the tub with screws and a screwdriver. Beware of over-tightening: the seal on the screws will become tighter as the wood begins to swell.
Ring the staves around the tub bottom, interlocking them with both the bottom and each other. Then slide a pair of tub bands over them--one about 20 inches from the top of the tub and one about 20 inches from the bottom--and tighten them until they are firm.
Hammer 6 to 8 nails just above the top tub band, and 6 to 8 nails just below it. Repeat the process with the lower tub band, making sure the nails are spaced evenly around the tub. They will hold the rings in place and keep the assembly from slipping.
Seal every seam in the tub with epoxy sealant to make it watertight. Keep the sealant warm by covering it if necessary and allow it to dry for at least 24 hours.
Fit the 2x4 bench supporters in a ring around the interior of the tub, equidistant from each other, and bolt them to the staves using screws. Make sure they don't cover any of the holes you have punched.
Slide the bench into the interior of the tub and bolt or nail it securely to the bench supporters. Make sure the bolts or nails are completely flush with the top of the wood, so they don't snag anyone who sits on them.
Fit the tub skimmer into its hole and screw it into place with a screwdriver. Apply waterproof sealant around the edges so it doesn't leak any water.
Connect lengths of PVC pipe to the suction fittings and the skimmer. Run them to a single larger PVC pipe (2 inches is typical) and mate them using t-fittings. Place PVC sealant on the connections to make them watertight.
Fit the hot tub jets into position in the holes you have punches for them. Use screws or bolts to secure them to the sides of the tubs, and apply sealant to the edges to maintain the tub's integrity.
Connect a PVC pipe to a pair of t-lengths and then connect the t-lengths to two of your jets. Repeat the process around the entire circumference of the tub until all of the jets are connected. There should be two rings of PVC pipes: one of the high-speed jets and one for the low-speed jets.
Attach the pipeline of the low-speed jets to a 3/4 hp water pump. Then connect the pumplines and the skimmer to the same pump. It should have housings that allow you to fit both of them into place. If it only has one housing, you can fit the jet pipe to the main pipe with a t-fitting, then run the main pipe into the pump.
Attach a water heater to a water filter, and then the filter to the 3/4 hp water pump using PVC piping.
Connect a thermowell to the filter with a line of PVC piping and seal the connection with sealant.
Attach a timer and control box to the water pump. You can set the clock on the timer to start the water pumping at regular intervals to help keep it clean.
Attach the high speed jets to a 2 hp water pump. This pump doesn't need to be attached to a timer. You can simply switch it on whenever you wish to use the hot tub.
Fill the hot tub with water and turn on both the pumps. Allow the water to heat up to an appropriate temperature (100 to 105 degrees F is optimal) and enjoy!
Tips & Warnings
- You may be able to buy a ready-made cedar tub, in which case you can disregard the steps detailing its construction. This is recommended for all but the most adept carpenters. Your hot tub needs to meet all local zoning laws and safety codes. Make sure you check with the local civic authorities and gain the proper paperwork before you build your cedar hot tub.
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