Before beginning a floating floor installation, you must verify that the flooring you purchased suits this method. For example, solid wood floors cannot be floated because of their high expansion rate; instead, they must be affixed to the subfloor by nailing or gluing.
Only engineered wood floors are created by adhering a thin layer of wood—a veneer, or “stave”—to several layers of plywood—are suitable for floating. This results in an exceptionally sturdy structure that can be installed while floating, thanks to its multidirectional nature.
Now that you know your flooring can handle this installation, you must check that your subfloor is up to the task.
The subfloor for a floating floor can be made of wood, concrete, screed, or a combination of the three; however, it must be level and flat, with no variances more significant than 2 mm over a distance of 1.5 m.
If the subfloor needs to be leveled, several options are available. Using a 3mm ply or hardboard, you can “ply over” floorboards that are cupped and crowned or convex and concave. Use 18-gauge, 18-millimeter staples or annular ring shank nails no longer than 20 millimeters to secure the ply or hardboard. Because water and gas pipes are occasionally slotted into the joists beneath the floor boards, it is crucial that these fasteners not protrude too far into the subfloor.
If the floors are uneven, you can use a thicker sheet of ply (9–18 mm) to even them out. However, remember that the higher the finished floor level, the wider the ply sheet must be.
Latex leveling compound, preferably a two-part combination suitable for use over timber (we typically use Adtitex yellow bag and black bottle), should be used to smooth out any unevenness in the floor once the ply has been installed. Always use Bal R1131 or Arditex acrylic primer to prepare the wood to be latex.
All door frames, null posts (null posts should only be undercut by 10mm. Any further will make the position unstable), and architraves must be undercut after the floor is level. This is crucial because it provides a space for the wood to expand and a smooth final product. We use a unique tool called an undercut saw, which is essentially an inverted circular saw with a sole plate that can be adjusted to remove the necessary amount of material to bring the floor up to the desired finishing level. If you don’t have an undercut saw, a tiny piece of flooring lying on top of the underlay will do the trick; after you reach the right height, you can undercut it with a small handsaw resting on top of the flooring and underlay. In other words, if your floor ends at the threshold leading into the kitchen, you should only undercut as far as the threshold. Always leave a 25–30 mm space between your new floor and any preexisting flooring, such as tiles, to install a graduated door bar.
It’s possible that even after undercutting using a hand or undercut saw, there will be some remaining wood or frame you cannot see through. The remaining bit of wood can only be removed with a unique tool called a “Fein Multi Master,” which has a tiny, reciprocating blade that can fit into tight areas. The initial expenditure of £180/$220 for one of these tools is not worthwhile if you are only working your floor and not doing this as a job. In this situation, you could use a sharp chisel to carefully chip away at the remaining wood or frame until you’ve finally removed it. After you’ve undercut everything, use a narrow chisel (narrower than the cut you’ve made) to “knock out” the bits of frame/wood. Take your time and eliminate as much as possible; the less wood to work with later on during floor installation, the better.
In order to underlay your floor, you should roll out the underlay throughout the surface and ensure that it reaches the edges without flapping up. Putting down underlay before installing a bed is a bad idea because it will get in the way of the cutout frames and the null posts.
Underlayment on a screed or concrete floor requires a DPM (damp proof membrane); we advise using a DPM-equipped product like Treadaire Boardwalk or Timbermate Excel; joints and seams should be sealed with vapor or Duck tape.
You’ll need to install one if the underlay you’ve ordered doesn’t come with a DPM already attached. Use 1000-gauge polythene and vapor tape or Duck tape to seal any seams.
Taping the underlay together at approx. 300mm intervals on a timber-suspended floor are sufficient to keep it in place until the bottom is installed; a DPM is not required.
After the underlay has been laid, the flooring can be fitted. Locate the longest straight wall first; your flooring should parallel this wall. Working around the pipes supplying the radiators at the beginning of the line is more accessible than at the end.
Start by laying down a row of boards with the grooved side facing the wall; when you reach the row’s end, you’ll need to cut the last board into place; this may be done with the following measurements: If the floorboards have a tongue, the final panel should be placed with the end groove against the wall you will be finishing. Leave a 10mm space between the groove end and the wall, and then draw a line on this board parallel to the end of the board on the floor to indicate where the excess must be removed. It may sound complicated, but if you’re unsure how long each row should be, measure it with tape and use the leftovers to begin the next row.
After you’ve set two rows, use plastic spacers (found at most hardware stores) to leave a gap between the floor and the wall measuring roughly 10 mm for expansion. You shouldn’t stress too much if some spots measure more than 10 mm or less than 5 mm, as long as no spot measures less than 5 mm or more than the thickness of the skirting or beading you’ll use to hide the expansion gap. Covering a large area requires rigorous adherence to the expansion gap.
Keep the expansion gap consistent around the room, stagger the joins of each row by at least 300 mm, and be careful with the boards you choose to install, discarding or hiding any that are excessively dark or have an unusual grain pattern.
Don’t forget to install a door bar, so leave a space of around 35 mm between the new wood floor and the old one. The new wood flooring is recommended to end about 5mm inside the door jambs. This is done so that the floor can conceal the door bar and soundproofing can be maintained. You shouldn’t be able to see any other beds from the other rooms while all the doors surrounding the floor you just installed are closed.
Your floor should now be installed entirely; after leaving the installation wedges in place for at least 12 hours to allow the glue to set, you can remove them and install the skirting or beading.
Welcome to Floorcraft in Farnborough, Hampshire, where I serve as the Managing Director, Gavin Winder. For over a decade, I’ve been sourcing and installing natural and engineered wood flooring. After installing more than 15,000 square meters of flooring, I consider myself an expert on the subject and its many difficulties.
Floorcraft Ltd. provides discounted solid oak floors, hardwood floors, laminate floors, and wooden floor accessories throughout the United Kingdom.