Do I need subfloor in my basement? If so, what kind?

[Guses]

I am slowly finishing our bungalow basement as a hobby as time permits.

Having mostly completed the walls and ceiling, it is time to turn my attention to the floors.

I have read a bunch of information either way and it seems I can't get a straight answer as to whether I need or even want subflooring. If I do install some, I amnot sure what. Basically, I need help.

A few facts: We are located in the general Ottawa (Canada) area where we do get winters and cold. My basement slab is laid on top of a layer of rigid insulation (I am pretty sure). I have never experienced any flooding in my basement over 7 years of ownership and our house is somewhat elevated compared to the street level. We have a anti return valve pipped into our sewage line. I did a test where you stick a section of membrane to the concrete floor to see if moisture condensates on the plastic membrane, it did not.

We are planning to install ceramic tile in the bathroom and engineered hardwood elsewhere (sub 1$/sqft).

I am looking for help!

[wvgirl]

We installed tile right onto the slab, and used a waterproof underlayment under our engineered wood floors in our basement.  Still working after 6 years.  YMMV.

[Guses]

We installed tile right onto the slab, and used a waterproof underlayment under our engineered wood floors in our basement.  Still working after 6 years.  YMMV.

Thanks for the reply. Are you located in an area with harsh winters?

Do you recall what underlayment you used? Was it like a cork type membrane?

[wvgirl]

We are the in the mid-Atlantic, gets below freezing in winter.  The underlayment was a plastic, but I can't remember how many mils.  It is what was recommended by the flooring manufacturer for basement applications in our area.  I believe we found that info on the mfr website.

[Goldielocks]

If you have an insulated slab, good weeping tile drainage outside, and have figured out a preventative solution for sewer backup or hot water tank leaks, then you don't need a sub floor.  Just don't install wood floors directly to the slab.

I am in BC, and put in a subfloor because it was a 40 y.o. no insulation slab (cold), and quite unlevel.  No way could I install tile or laminate without a more expensive levelling.

I recommend no sub floor but use laminate and carpet with a great underpayment.  Warm and soft and quiet.  Modest price...fast install..Win, win, win ,win, win.