How to install flooring over a sleeper subfloor?

Question

1970s subfloor basement construction

I'm currently redoing my basement and after removing the carpet I come across particle board nailed on top of 1.5 x 2.5 wood batons that are screwed into the concrete slab.

To redo the floors:

I would remove the particle board regardless because the previous owner spilt water and the particle board just soaked it up and has become lumpy on certain spots.

Afterwards I’m not too sure:

1. Can I screw OSB directly to the batons and then put laminate on top?

2. Do I need to remove the 1.5x2.5 wood batons and then put plastic underlayment + OSB?

3. Can I tile on the concrete slab after installing Ditra or do I need to put underlayment + OSB + Ditra then tile.

House: 1970s construction Geography Eastern Canada 4 seasons

Thanks!

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Answer 1

If the lumber on the floor is not rotten after 50 years, no need to remove it.

What you might well want to do is fill in between it with 1.5" insulation board, because the odds that there's insulation under the floor 50 years ago are slim, and it's likely to be uncomfortably cool. That would also lean against tiling directly on it, unless you are quite sure you don't mind the floor being cool (good in summer, perhaps, if it doesn't actually condense on it - otherwise not so nice, generally.)

Answer 2

Around here (Canada may be different) that would require either pressure treated lumber against the concrete, or sill gasket beneath the "batons." Maybe that is PT, and it just looks like regular lumber because it's 50 years old. But yes, as long as it's flat, you should be able to replace the particle board with 3/4"(ish) OSB.

Now, you mention laminate and tile. If there's no moisture coming up through the slab (and there wouldn't be any moisture from curing after 50 years), you could simply put your laminate and/or tile right on the slab. But if you have moisture (from groundwater), that's a different story.