Drainfast Ltd asked us to create clear step-by-step instructions on how to install a floor drain, combining information taken from product data on the clients’ website and some existing but incomplete instructions to produce a guide that can be easily understood even by persons unfamiliar with the task.

How to Install A Floor Drain

Before installing a floor drain it is important to make sure you have the correct type for the job. This will be governed by several factors, including:

  • Anticipated flow volume (for example, industrial washdown processes, irrigation in commercial nurseries and garden centres, swimming and showering facilities in the leisure industry, average and peak rainfall if situated outside)
  • The composition of the floor into which the drain will be installed
  • Any load-bearing requirements (pedestrian, light industrial or heavy industrial)
  • Environmental regulations concerning effluent control, filtration and separation
  • Any other national or local planning regulations and building codes

If you are uncertain about the most appropriate floor drain for your project, we strongly recommend you discuss this with a specialist drainage products distributor such as Drainfast, who will be able to calculate your requirements based on the above considerations, their experience and their product knowledge.

So, once you have selected the correct floor drain for the job, you can install it as follows:

  1. Before starting the installation, we recommend you trial-assemble your floor drainage system to familiarise yourself with how the components fit together and ensure the floor drain is compatible with the rest of the system.
  2. Once you are satisfied with the general fit, if the drain has been supplied with a spigot you can screw this into place, using a suitable sealant to ensure a watertight joint.
  3. Check that there is enough space between the finished floor level and the top of the drain outlet pipe for the assembled floor drain and any additional extensions. When fitted correctly
    • the top of the flange on the drain body will be level with or lower than the floor’s waterproof membrane
    • the top face of the grating or drain cover will be flush with the finished floor level, and
    • any side inlets will be positioned so there is a fall between them and the outlet gully
  4. Connect the drain body to the drainage pipework, using the spigot adaptor if applicable.
    • All Frost floor drains are compatible with solid floors, but if the floor is a timber deck, use a wide-flanged body and consider reinforcing the cut timber edges surrounding the drain.
    • The flange can then either be drilled through and secured with suitable fixings, or held in place with an underdeck clamp such as our models 33.9610 or 33.9620.
  5. Once the drain is securely in place, dress the waterproof membrane over the flange in accordance with the manufacturer’s instructions. Make sure the membrane is not obstructing the outlet and the flange is level with or below the membrane.
  6. If the floor drain features a square grating, before fixing the drain to the floor make sure that when the height adjustment is rotated to its finished position (see stage 8 below) the edges of the grating will align with floor tiles or paving slabs, if used.
  7. Bolt the membrane clamping collar to the floor drain body using the fixings supplied with the drain. If the waterproof membrane is thin, consider reducing the length of the fixings to prevent any perforation of the membrane that may cause leaks.
    • Note: some clamps are reversible to increase the amount of available height adjustment and ensure the drain sits at the correct level in relation to the finished floor. In some cases, the membrane clamp must be used to connect the grating to the drain body. An example of this is the Frost 31.1024 which features a larger sump.
  8. Fit the floor drain grating or rodding eye to the body of the floor drain, using the height adjustment to ensure the top of the grating or rodding eye is flush with the finished floor level.
  9. Use the cam-type height adjustment screws provided to lock the grate at the required level.
  10. Lay your floor screed and apply the floor finish around the grating or cover. If sheet vinyl or similar flooring material is used, dress the finish over the grating bezel and clamp it in place using the integral clamp ring.
  11. Fit any additional removable accessories such as funnels, sediment buckets, etc. to your floor drain.

Your roof drain outlet installation is now complete!