The most important thing for successful vinyl floor laying, is the substrate preparation. In the following we will discuss the most important points – resinifying cracks, applying the correct primer and levelling the substrate.
Vinyl flooring Substrate: resinify cracks in the screed
Cracks in the subfloor of our vinyl floor (screed) are completely normal. These often occur with freshly laid screeds as a side effect of drying.
However, cracks in the screed also occur during the renovation of old buildings – e.g. after the removal of an old carpet – cracks in the screed. However, a finished substrate for vinyl floors must not have any more cracks.Cracks in the vinyl floor Substrate must be sealed with a special resin before laying a vinyl floor – otherwise the two separate parts of the screed will move and the filler applied later will flake off. Not a good base for a vinyl floor. In order to close the cracks in the substrate, they must be cut open with a cutting tool (e.g. Flex) and then sealed with a so-called “casting resin”.
Attention: It is essential to determine beforehand whether the screed is a heated screed. If so, under no circumstances should the Flex be unpacked. This should only be done by an absolute expert who has consulted a specialist for heated screeds beforehand. Otherwise the screed will be flooded faster than we would like.
Vinyl floor substrate: Resinize cracks – checklist:
- An angle grinder angle grinder/cutter (so-called “flex”) with concrete cutting disc (alternatively a concrete milling machine)
- A very good extraction for the angle grinder
- shaft connector (or steel nails à 100 mm)
- A casting resin for screed renovation
- Some quartz sand
- A steady hand
So far, so good – away with the cracks in the ground
In order to close the cracks once and for all (and to finally be able to use the base for our vinyl floor), we first have to unpack the good old flex.
Now we mill along the complete crack once with the flex and a concrete cutting disc. A Flex with extraction is recommended, because otherwise the whole room will be too dusty from top to bottom.
Create cross connections in the underground
Then we mill cross to the crack in the subfloor, approx. every 50 cm a small separating cut into the screed (length approx. 15 cm). The whole thing should look something like a badly sewn scar 🙂
Now we cleanly suck out the complete, separated crack including the cross cuts.
We then place so-called shaft connectors (usually made of sheet metal) or alternatively one steel nail of 10 cm each in each of the cross cuts of the substrate.
The sense: The synthetic resin alone is not sufficient to join the two halves of the screed. Metal must be brought in for reinforcement. The synthetic resin is later only intended for fixing and as a filling material for the crack in the vinyl floor substrate.
Mix the synthetic resin for the vinyl floor substrate.
In any case, it is recommended to use a special casting resin for screeds. Polyester putty is rarely used for this purpose. However, this is not liquid enough to completely fill the crack in the substrate. It is therefore not advisable.
The casting resin is usually a so-called 2-component casting resin. It is therefore mixed from 2 components, which then carry out a chemical reaction. You usually have about 20 minutes time to process the brew – after that it becomes tough and then hard.
Attention: Mixed casting resin becomes very hot during curing. The surplus in the can/bottle must therefore be stored outdoors – away from flammable objects.
Now we pour the casting resin into the previously sucked out crack and into all cross cuts.
There, almost done. Now quickly scatter quartz sand over the freshly resinified crack. Otherwise the filler will not hold later, because the casting resin is eel-smooth after hardening.
Priming vinyl floor substrate
Before we can lay the vinyl floor on the subfloor, the vinyl floor must be levelled out subfloor. And before we can do this, the substrate must be primed. As a rule, two scenarios are possible:
- We have an absorbent substrate (e.g. screed) for our vinyl floor
- We do not have an absorbent substrate (e.g. tiles) for our vinyl floor
Correct reading. Tiles can be leveled over (and can thus serve as a base also as a substrate for vinyl floors) – if the correct primer is used.
We mix the primer and apply it with a foam roller over the entire surface of the substrate. Done.
Levelling vinyl floor substrate
Now the substrate must be completely leveled or leveled. This means: remove any unevenness from the substrate so that it does not matter.
For this purpose, a cementitious levelling compound is mixed. This should then be applied to the substrate later with a strength of approx. 3-5 mm.
We need to prepare the substrate for the vinyl floor:
- A good stirrer (If necessary, a powerful drill with stirring attachment)
- putty, bag by bag
- Water in large buckets (calculate the water requirement beforehand!)
- A (toothed) squeegee for spreading the filler
- One spiked roller for deaerating the filler
It is best to use two people to fill the substrate. Otherwise you will start to sweat a lot, because you are constantly busy fetching water, but at the same time you should actually stir again, so that the putty does not dry up.
In addition, the power of the drilling machine must not be overestimated . Many a drill has given up the ghost when mixing putty.
If in doubt, better use an agitator.
The most important thing:
- The levelling compound must be stirred properly – otherwise granules will form on the surface
- The levelling compound must be evenly distributed
- avoid “piles”
- “wet in wet” work. Under no circumstances should the filler material dry on the edges.
- The amount of water must be kept to 100% – simply read/comply with the manufacturer’s instructions on the packaging
Prepare the vinyl floor substrate: Smoothly sand down the levelling compound
When the entire surface has been filled and then allowed to dry through, it must still be sanded clean.
To do this, we take a single-disc machine (with suction) and place a coarse grinding disc underneath (grain 24 or 36). Now we drive the complete screed with it and remove last unevenness as well as granules etc.
A good single disc machine costs well over 1000,- Euro. It is therefore advisable to borrow them from the local DIY market. As a washer you need a grinding wheel with very coarse grit – K24 or K36. This can also be purchased from the rental service.
Afterwards everything still has to be sucked off. The substrate for our vinyl floor is finished.
Continue with the laid vinyl flooring using the vinyl cutter.