laminate floor on slightly uneven slanting floor.

[Nick]

I'm looking to lay some laminate boards on a concrete floor. The floor has some minor deviations from a straight line of approximately max deviation of 3mm over 2.4m. This is just beyond recommended tolerances for the laminate.

Now on the internet a see that self levelling concrete (SLC) is recommended. However the floor is on a slight slope ~25mm over 2.7m width or the room, the slope is relatively constant/ i.e. in a straight line.

I'm not sure but I think using SLC means I would need to get rid of the slope as well as the relatively minor bumps and dips from linear.

The room is a study so I don't really care about the slope I just want the laminate to not creak and last a while. Is there a way to get rid of the minor deviations without tackling the slope?

I think I will probably move out in a year or two, would it be easiest to just lay the laminate as is?

[Tim Watts]

The usual way is to start the job with a 6' straight edge and a big pile of 1mm and 2mm card from an art shop. Cut card and pack any local voids. I've done this, twice and it's been fine for many years, both times. Bit fiddly, but in some ways easier and cheaper.

Check manufacturer's data for permissible variations in flatness (not level) over any given length.

[Andy Burns]

Will the length of the boards run along the slope, or across it?

[Nick]

Perpendicular to the slope, so I would say across it.

I presume you are suggesting curvature is more acceptable across the boards as they are only 192mm before they can accept a slight angle at the join. As opposed to 1200mm length wise

But the slope itself is straight. The problem is the slight dips and bumps.

So far Tim's solution sounds promising. At least I'm far less depressed now than I was this morning.

[Malcolm Race]

IIRC SLC is rally a self smothing compund whic will fill the hollows but not swlump down to the lowest point

Malcolm

[Dave Plowman (News)]

Laminate has zero stretch. If you want a decent job the floor will have to be flat to within the limits the makers say. A sloping flat floor wouldn't make any difference to the laminate.

It's one of these things where a carpet - which does stretch - could make more sense.