HOW TO BUILD A HOT TUB PLATFORM - Having a Hot-Tub or a Jacuzzi in your garden is such a good way to relax at the end of the day and with friends at the weekend. However if you have a Hot-Tub or Jacuzzi you really need a good base to sit it on. The guide below provides instructions to help you build one. This project does require a lot of physical work and you should take your time and wear appropriate safety equipment. Get some friends in to help you if you can.
Measure the area you will need. This will be determined by the size of your Hot Tub or Jacuzzi. You should leave at least 2 feet of extra overlap space for stability. For example if you have a Hot Tub or Jacuzzi that is 4′ x 4′ then build your platform 6′ x 6′.
Decide on where you want to place your Hot Tub or Jacuzzi. It should be on level ground, although building the base will take care of that. Also it needs to be close to water and power outlets.
Mark out the chosen area by placing four wooden pegs at each corner of the measurements you have for the length and width – remember to add an extra 2′ to the size of the Hot Tub or Jacuzzi size.
Now tie string around one peg and string a line to the next peg, wrap this around the peg and continue with the remaining pegs until you have completed the shape that you have pegged out.
Note here that the shape of your platform does not have to be square; you can if you like make a hexagon or even a circle. Another method for marking out the area is to use marking paint.
Now that you have the area clearly marked out you can dig out the soil. If this area is on grass then use a spade to cut around the shape and then remove the turf. Dig out the area to a minimum depth of 18″.
You need to ensure that you do dig out to at least this depth in order to create a soil base that will support the weight of the Hot Tub or Jacuzzi when is it full of water and people. The overall weight can be considerable so it is important to ensure the base is strong enough to support all the weight it will take.
You will now need to create forms using plywood around the shape that you made. The plywood needs to be the depth of the area you dug out. Secure the forming using wooden stakes at 1′ intervals around the area.
Take your spirit level and make sure that the timber forms are level all the way around and check they are level with one another. You can do this by placing a length of timber across the area and then placing the spirit level on this. If the plywood forms are not level, use a mallet and gently tap them down until all the plywood forms are level with each other.
Once you have leveled all your plywood forms around the area place 2″ of builder’s sand to cover the bottom of the area. Compact the area using a wooden damper, a damper is a long wooden handle that is attached to a flat piece of timber. If the area is of a considerable size then you might consider hiring power compactor, you can hire these from any good DIY Tool Hire company.
When the sand is all compacted and firm add 14″ of aggregate. Again tamper this down so that it is reasonably compact. It’s now time to mix up sufficient concrete to cover the entire area.
Remember that once you pour the concrete it needs to be wet enough to find its way through the aggregate. Note that another method is to mix concrete and aggregate together but by compacting the aggregate beforehand this provides for a stronger base. Also if the area is particularly large you can make up a rebar cage, place this onto the sand bed and then mix and pour the cement aggregate.
The choice is yours and the overall size of the platform will dictates which method will provide the strongest solution for the size of base you need to build.
Pour the concrete is one go and move the concrete around with a rake as you pour. This part of the job is much better achieved if you have someone else to help you. Once you have poured the entire concrete take a length of timber that is long enough to span both sides of the base with a little overhang either side.
Starting at one end, and working along the area, use the timber to tamper down and screed the concrete. Tampering and screeding will ensure that the concrete is compacted through the aggregate and level with the top of the timber forms. If you have tampered and screeded the concrete properly you should see a film of water appearing on the surface of the concrete. This is perfectly normal and you should NOT try to remove it.
You now need to let the concrete cure (harden). Note here that pouring concrete on a very hot day is not a good idea. The sun can dry the concrete out too quickly which will result in the concrete not curing properly.
The classic sign for this cracking or crumbling of the concrete. Concrete that has not been cured correctly is nowhere near as strong as concrete that has; so take this into account when pouring your concrete.
To help your concrete cure properly take a garden hose and attach a sprinkler head. Set the sprinkler head to a fine mist setting and turn it on. You want to keep the surface of the concrete covered in a film of water while it cures. As concrete cures it changes colour from a very dark gray to a very light dusty gray when completely cured and it is then you can use the base.
Now that your base is completely finished and ready for using you have a choice. You can place your Hot Tub or Jacuzzi on this platform or construct a timber platform so that the Hot Tub or Jacuzzi is raised off the concrete base. How high you raise this will be entirely up to you.
Constructing a timber platform is much nicer, especially when stepping out of your Hot Tub or Jacuzzi as the timbers are softer and more comfortable than bare concrete under foot.