Screeding and Screed
A lay persons guide to understanding the issues of screeding prior to laying sheet vinyl. What to expect.
definition | types of sub-floor | diy or professional | preparation | the screeding | links
Definition of sub-floor
When carpet salesmen say sub-floor they mean the floor you actually stand on when any existing loose floorcoverings are stripped away. This can be timber floorboards or a solid floor of some kind - probably sand and cement or concrete. In this context we are concerned with the hard floor surface you want to lay vinyl on (see hardboarding for timber floor preparation).
Types of common sub-floor that you may encounter
Your kitchen (or possibly bathroom) solid floor will probably be unsuitable for laying new sheet vinyl upon. It may be tiled or left with the remnants of previous floorcoverings (ie plastic tiles or glue). Sometimes the floor may still be bare sand and cement in which case you will probably notice some loose "crumbs" from the surface.
Older floors may show a black residue which is the old bitumen that was used to previously affix tiles. Perhaps the floor still has remnants of tiles, both the harder brittle type or the more flexible thermoplastics.
All these descriptions signify a floor that will need a self-levelling screed applied to it in order to make the floor smooth enough to receive new sheet vinyl.
DIY or professional floor preparation?
The short answer is professional because a less than satisfactory screed job will mean getting professionals in anyway - sheet vinyl really needs perfection and all but the most competent of DIY'ers will probably fall short of the mark.
If problems are discovered after the new vinyl is fitted it will probably add the vinyl to the cost of what will need to be replaced. Employing professionals means the fitters or shop will be responsible to you in the event of a problem.
Deciding upon which screed and which primers you need is a job for professionals - what if you want to lay vinyl on top of old ceramic tiles? There are different materials for different problems. The right choice is about it continuing to perform for years after. Whereas latex screed was the traditional choice, now the new water based screeds have taken over.
Preparation of floors prior to screeding
Firstly the floor will need to be stripped of everything loose. This includes old carpet, loose vinyl and broken tiles. When everything possible to remove has gone, it must be decided if any priming or sealing is to be done.
Priming is to ensure the screed will bond to whatever is left. Sealing is to bond porous surfaces so loose dust is "glued" down and the moisture is not drawn out of the screed too fast.
Living through the screeding
There are two types of screed, water based and latex based. Water based is odourless whereas latex based does smell of ammonia, so ensure good ventilation if the fumes are likely to upset you.
In general both types will cure enough to be walked on in five or six hours. Fish and chips is a good move if it is your kitchen being screeded and make sure you have a kettle handy. If it is a bathroom, make sure you will have access to toilet facilties - arrange to perhaps visit a friend.
Useful screed links
Screed calculator - workout screed quantities
Screwfix - buy self-levelling screed
Guide to Ardex screeds - consult this list to identify which Ardex screed does the job
Blog Articles