At UK Screeds we install the very finest flowing screeds which are self-levelling, because, of course, they are in liquid format. However, we go one step further, as we use laser screeding which levels the surface of the screed to a level of SR1, and you cannot get any better than that.
However, liquid screeds are composed of gypsum and when this dries it forms what is known as an anhydrite screed which also produces a layer of laitance on the surface of the screed. These are particles that form during the drying process. The amount of laitance that is produced can vary according to the circumstances, but however much or however little is produced, it must be removed before attempting to install the final floor surface, whatever that may be. This means that the screed will need sanding before proceeding further.
Floor sanding should be carried out using specialist floor sanding machines in order to ensure the laitance is removed in its’ entirety. It should be done between 7 – 10 days after the screed has first been poured. The first job is to sweep the entire screed surface in order to remove any sharp objects such as nails which could damage the sanding machine. Floor sanding is best carried out by professionals such as ourselves. It might look straightforward, but as with many things it is best done right.
We will sand the floor using a diamond cutting pad, and this is done in stages using finer grit down to the last stage so that the finish is absolutely smooth and all possible laitance has been removed. Once this has been done, a calcium sulphate compatible primer should be applied to the floor, but only after the screed has completely dried to the recommended levels. After this, it is fine to add the final flooring surface, whatever that may be – tile, vinyl, carpet, hardwood, flags, or whatever has been chosen.
Floor sanding is an important element of ensuring the perfect finish of the final floor and giving it maximum life. If you have any questions about floor sanding, please contact a member of our technical support staff.