Tips for Preparing a Floor for Screeding
It is vital to ensure that any floor preparation is laid correctly so that your screeding has the perfect base. Any errors at this point can mean that your screed may be weaker or crack in future. Below are some pointers to help you:
Think about your complete floor build up – what is the overall depth for your insulation, underfloor heating, screed, adhesive/glue and flooring. Bear in mind that you may have to take into account any existing door thresholds, adjacent room levels and ceiling heights. If your overall depth is minimal remember that insulations come in a range of thicknesses but the U value can remain the same, so still maintain your heat levels. Screeding also comes in a range of depths depending on the specific type so don’t assume that you have to have a 65mm thickness.
For a ground floor, make sure that you lay a damp proof membrane (DPM) usually a 1200 gauge. This will prevent any damp penetrating your flooring from below. The DPM needs to lapped at the edges of the walls so that any rising damp doesn’t bridge into the base from the sides. Roll out the DPM and secure around the wall edges with tape. It can be cut down to size once you have finished. Also remember to tape any joints together.
Insulations can be cut to size easily with a saw but it is quite dusty work so it is advisable to use a facemask or work outdoors. It works best if laid in a brick pattern as it is more unified. Any joints should be taped together.
Edging strips should be laid at the perimeters to prevent the heat spanning into the wall, this is normally 25mm thick. Another point to remember is that this should be thicker than the screeding and is cut down to size afterwards.
As obviously as it sounds make sure that the floor is clear of any mortar, dust or debris. The insulation needs to be laid as flat and evenly as possible, any movement at this point will mean that there will always be movement. The movement may cause the screed to crack in future, regardless of its weight, which is heavier when laid wet but becomes lighter once the water evaporates during the drying process. Walk over the sub-base and see if it is nice and steady. If there is any rocking in the boards put some sand underneath it to even it up. Also have a good look at the existing concrete base when first starting – is it reasonably level or sloping at certain points? If so, lay some compacted sand in the worse spots.
If using a liquid screed, a layer of 500 gauge damp proof membrane is required on top of the boards to stop this type of mixture corroding it and to contain the liquid which will seep into any gaps or holes. Again remember to lap the membrane around the perimeter. The use of a top layer of DPM is only required for liquid systems.
Once you have followed all of these procedures you are now ready to screed and this is where we come in. Let us know about your project and we can help install your perfect screeding. We can provide you with superb technical skills matched with experience and extensive knowledge all at a great price. So call us today on 020 7099 6264.
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