Concrete slabs are the foundation most widely used by people who are installing a new hot tub. They are not necessarily the cheapest option, but they require little or no maintenance, which is very appealing. In general terms, hot tub pads should be at least 4 inches thick and capable of supporting in excess of 52.2kg. per square foot. The additional dimensions depend on the size of the hot tub and will determine the final cost of the materials. Pouring the pad is not overly difficult, but will require some skill to complete to a satisfactory level.
Calculate the dimensions of the hot tub pad and choose the installation site. The pad must be at least 4 inches thick and many people choose to leave a 1 foot border around the outside of the tub. For example, a 6 foot by 6 foot hot tub would need a 7 foot by 7 foot pad.
Clear the area of any plants and the first few layers of top soil down to a depth of at least 4 inches.
Spray some water on the area and begin compacting and levelling the ground inside of the installation area.
Place the 2 inch by 4 inch boards inside of the square to form a square frame. Use a level to verify that all of the boards are straight and level and nail the frame together.
Drive the metal stakes in around the outer perimeter of the structure until they are level with the upper edges of the wooden frame to give it more structural integrity.
Spread an even layer of crushed gravel inside of the frame.
Calculate the volume of concrete needed to complete the slab. The ratio of water to concrete has several variations depending on a variety of factors and a concrete calculator is helpful.
Mix the concrete in the wheelbarrow according to the calculations and the manufacturer's instructions.
Pour the concrete into the frame up to a depth of roughly 2 1/2 inches below the top edge of the frame walls.
Lay the wire mesh across the wet concrete and slowly pour the rest of the concrete until it reaches just below the top edge of the frame.
Tap gently around the outer frame with the hammer to release any trapped air bubbles.
Level out the concrete using the long 2 inch by 4 inch board and a sawing motion as the board is dragged across the surface of the concrete.
Run a clean broom across the wet concrete to give it texture. This will reduce the slipperiness of the concrete once it is in use.
Wait one full day and remove the frame from around the hot tub pad. If the frame does not come off easily, allow the concrete to dry further and attempt to remove it again.
Wait the amount of time that the manufacturer suggests before attempting to put any weight on the pad. The pad should be kept slightly moist with a fine mist during the waiting period. Use a hose and spray the mist over the pad for a few seconds each day.
It is not difficult to pour a concrete slab, but doing so incorrectly may cost more time and money than originally expected. Get a few professional price quotes before attempting to perform this project.
Fresh concrete can irritate the skin and protective gloves and eye wear are advisable.