Instructions for pouring in floor heating slabs
Floor heating slabs represent a layer of concrete poured over the PEX tubing. After the aggregate and insulation are installed, wire mesh is laid down and the PEX pipes form a pattern over it which is called manifold and allows the concrete to be heated. It is attached to the wire mesh before the wet concrete is poured.
So, you will start by putting down a layer of aggregate for the foundation of the floor base. You will use a rake to level the aggregate and you will need to cover it with 1 inch XPS insulating foam if you live in an area with warm climate or with a 2 inch XPS insulating foam for colder climates.
Now, you will have to roll and flatten the concrete wire mesh. Also, you will need to lay out the PEX radiant pipes in a pattern over the wire mesh. You will need to attach the manifold to the mesh using plastic zip ties or rebar ties. Now, you will need to pump air using an air pressure gauge after you connected the PEX pipes to the manifold box. The pressure must be 50 psi. you will need to check into the next morning the pressure again and if you notice a loss of more than 5 psi, you know that you have a leak in your system. So, you will need to tighten the connections again and wait for two hours for another checking. If there is still a leak, you will need to check the connections of the PEX pipes and fix the problems using a repair coupling. After that, you will release the pressure down to 25 psi.
To protect the copper manifold from accidental overflow during the concrete pouring, you will need to insert a newspaper into the tubing into the place where it enters the manifold. Now, you will need to add thin plastic strips to the wire mesh if you want to create control joints for the concrete floor. These joints will separate the concrete layer into small pieces which will be able to handle with the moving of the building foundation. You will need to mix the concrete with water in a wheel barrow. You will use a shovel to push the concrete out on the floor. You will need to pour a 1 ½ inch layer on concrete and after you poured a quarter of the surface. You will need to lift the wire mesh into the middle of the concrete layer. This fact will ensure that PEX pipes are placed into correct position into the concrete. Now, you will need to make the surface of concrete as smooth as possible using cement floats and trowels.