How to Lay a Concrete Base for a Hot Tub

Welcome to our step-by-step guide on how to lay a base for hot tubs, using our aggregates that we sell and deliver to you. 

You will learn how to lay a ground area down with concrete, so that you can transform an area of your garden into a space for relaxing and socialising in the warm bubbles of a hot tub. 

This guide is great for those who have swimming pools and want to get the full package, those who host BBQs or those who want to make their garden more exciting. Having a hot tub is a great way to socialise or spend time with your partner/family, but it’s not just a case of buying one and that’s it… you will need to lay down a concrete ground area first, which this guide will teach you how to do yourself.

Why is a solid base important for a hot tub?

A solid and level base for a hot tub is vital as if the ground area is sloping or not laid properly, this will apply unnecessary strain to one side of the hot tub which will result in it breaking - this is very dangerous if a person is in or near the hot tub. It also needs to be solid and level so that it can support the hot tub itself and keep the water level.

What are the benefits of a concrete hot tub base?

When a concrete base is used and done correctly, the area is completely smooth and level, which creates an even base for the hot tub. A patio made from bricks or slabs may overtime break or become weathered, which causes risks for having a hot tub on top, as it won’t be level or could get damaged.

Is laying a concrete base for a hot tub easy?

Yes… If you follow our clear and simple guide on how to lay a concrete base, you will be able to create a stable and stylish area for your hot tub without stress or confusion.

Let's get everything we need together

Tools List

• Safety goggles
• Protective gloves
• Knee pads
• Builder's line
• Builder's square
• Shovel
• Wheelbarrow
• Tape measure
• Straightedge rake
• Wooden spacers
• Club hammer or Rubber mallet
• Earth rammer or Vibrating Plate Compactor
• Spirit level
• Bucket
• Soft brush
• Trowel
• Watering can
• Hammer
• Large screed

Materials List

• Wooden marker pegs
• Sub-base - MOT type 1 hardcore
• Concrete mix (5:1 sharp sand & cement) - (aggregates)
• Timber offcut (if using concrete to make the patio, you’ll need 5 timber beams/planks - 4 to make a square base, 1 to bind the square in the middle)
• Large headed nails or screws
• L bracket
• ??? Optional hire of cement mixer
• Plastic sheet and bricks

Health & Safety

• Don’t work aloneIt’s a two person minimum job
• ChildrenMake sure that children are not near the workspace and don't let them handle the tools
• ChemicalsAlways read labels of hazardous materials and wear protective clothing like gloves and goggles
• LiftingAlways bend at the knee, not hunching your back over - don’t lift heavy items alone
• Power toolsAlways wear safety equipment and understand how to use the tools properly first

Method

Step 1: Preparing for the sub-base

• Make a square/rectangle frame that matches the desired size of the concrete base using your timber beams. 
• You’ll need to nail them together or use an L bracket and screw in place, as well as one timber beam going through the centre (horizontally), this may require you to saw them to the correct length
• The timber framework will need to fit inside the dug-out area with spacing around the outside and the depth slightly coming above surface level
• Check the shape is even/square by using your builders square to check the angles of the corners - a tip, if you measure the diagonals of the builders square and make sure every corner is the same length, then it’ll be perfectly square
• Put aside the framework for a while
• You’ll now need to mark out the area for where you want the base for the hot tub to be. To do this, take your wooden pegs and hammer one in each corner of the area and use your builders line (or string) to go around all of the pegs, creating the shape outline that you want the shed base to be  
• Check the shape is even/square by using your builders square to check the angles of the corners. 
• You’ll now need to measure how far to dig down in the desired area giving enough room for the sub-base and concrete
• 75mm for sub-base (MOT hardcore) + 75mm for concrete = 150mm (15cm)
• Using a spade/shovel dig down to the correct depth. Use a ruler or measuring tape to make sure it’s the correct depth
• You can now remove the wooden pegs and builders line

Step 2: Laying the hot tub patio sub-base

• Mark the sub-base depth on a few wooden pegs and hammer them around the dug out hole, this is so you can see where to fill the sub-base to. 
• Using a wheelbarrow, tip the sub-base/MOT type 1 hardcore into the area, so that it’s just above the marked area on the pegs
• Once the area is filled, remove the pegs and use a rake to even out the sub-base
• Put on all your protective gear, including industrial ear muffs if you have them
• Follow the instructions from your vibrating plate or earth rammer and go over the sub-base area with the power tool, as if you were mowing a lawn, until all of the sub-base is flattened, smooth and even (use spirit level to check)

Step 3: Filling with concrete

Fantastic news! Did you know that we deliver ready-mix concrete to your home or commercial property across the area? So getting everything that you need to lay your concrete base is right where you need it and the right time. 

When you choose Concrete 247, you are making your project as stress-free as possible. 

• Make sure you are wearing all protective gear - gloves, boots, googles - wet cement can cause burns, so always wear gear and wash your hands regularly
• Avoid concrete drying on your tools
• First you will need to take your timber frame that you made earlier and align it on top of the sub-base so that there is some space on the outside of the dug-out hole
• If making the concrete yourself: mix your concrete in a mixer or by hand in a wheelbarrow (depending on how big your job is, this will alter your method choice) - this will be 5 parts sharp sand or ballast with 1 part cement and the amount of water required (see cement packaging)
• Wet the sub-base with a watering can
• Gradually pour the concrete onto the sub-base bed (this will require two people) and level it out as you go along with a shovel - work in small sections rather than the whole area
• Use the shovel and stab the concrete up and down with it, particularly around the edges, to remove air bubbles
• Use a rake or the shovel to spread out the mixture and smooth it
• The concrete will need to be about 2cm above the timber frame
• When all concrete is laid - with a helper, glide a screed or timber/tamping board along the top of the concrete (the screed/board will need to be longer than the edges of the framework so it can sit on top of this as you glide it)
• This should create a smooth top but if not repeat the process (add more concrete if there are dents)
• If you’re happy with the finish of the concrete, go along the edges with a trowel, neatening any unevenness

Step 4: Protecting the patio as it dries

• Create four stacked-bricks along each side of the patio so that they are several inches taller than the patio
• Take a timber and line it up over the bricks so that it goes down the centre of the patio
• Place a plastic sheet over the patio, so that it goes over the bricks and timber, not touching the patio surface
• Way the plastic down with more bricks and set to dry (a concrete patio will take approx 2 days)

Step 5: Removing the concrete form

• After the concrete has had plenty of time to dry, the timber frame that was made to use as a form for the concrete now needs to be removed 
• Take a hammer or rubber mallet and tap all of the sides of timber, to loosen it up a bit
• Remove any screws or nails that were used to put the frame together
• The wood should have come loose by now, so use the end of the hammer to insert into any dents between the wood and the concrete and pull the wood off (carefully)
• Repeat until all the form is removed

Congratulations!

With this guide you should now be able to create a concrete patio/ground area that is the perfect fit for your hot tub. Soon you’ll be having a soak by yourself to relax, or having friends over for drinks (and to show off your new tub)... let the fun begin!

If you’re based in Portsmouth, Fareham, Southampton, Eastleigh, Totton and other surrounding areas, we deliver ready-mixed concrete to your door. Should you choose to mix it yourself and seek any further professional advice on laying a patio or what aggregates to use, please do give Concrete 247 a call and we’d be more than happy to help.