Is epoxy something that is easy to DIY and are there recommended brands?

I would love to properly insulate the slab but I am not sure what the minimum loss of headroom would be? I am looking at the diagrams in Lstibureks's book but I am a little confused. I can lose 6 inches and still meet code but my family wouldn't be able to stand up straight.

See previous threads discussing epoxy coating.

Lstiburek's Builder's Guide diagrams rigid foam below the concrete. See pp. 181-182. Adding foam above the floor will, of course, reduce headroom.

One thing to keep in mind. Dr. Joe has reversed his position on the thickness of interior wall foam. (Scroll down to News Story #2.) He now agrees with critics that basement walls don't have to dry to the interior. So you can make the insulation as thick and tight and vapour resistant as you can afford. Still, avoid moisture sensitive insulation on the cold side and poly barriers on the warm side.

Would Delta FL with Laminate flooring over be a poor choice? Or would 1/2 inch of EPS with the thinnest layer possible of plywood over it work?

If you are concerned with headroom your best bet would be a floating vinyl plank or vinyl tile product directly on the slab. You can then place area rugs on that to increase comfort.

The potential problem with vinyl is that it traps rising water vapour leading to mould growth, discolouration of the vinyl and loosening of the tiles; all of which is why Building Science Corp. says, "Impermeable interior floor finishes such as vinyl floor coverings should also be avoided."

Laminate can be installed with a thin underpad directly onto Delta FL, according to Delta's manufacturer. But the risk you face in your cold climate without insulation under the wood (or the concrete itself) is condensation from moisture in the air.

would 1/2 inch of EPS with the thinnest layer possible of plywood over it work?

1/2" EPS= R2.3. So, no.

You can always take your chances and install what you want. Plenty of contractors will assure you, as they do on-line everywhere your turn, that it's perfectly OK, they do it all the time, no problems etc. etc.

When I was spec building, I did what other builders did, putting plush carpet and pad directly on top of new basement concrete. For a couple of years, fine. After that, not my responsibility!

@worthy, what would you recommend doing in a basement? Putting down XPS foam would also cause a impermeable barrier. How would that be any different than using a enhanced vinyl flooring product that is designed to be waterproof such as Mannington adura max or Karndean looselay,

Putting down XPS foam would also cause a impermeable barrier.

XPS is slightly permeable, thus allowing water vapour to dissipate slowly. At the same time, it is unaffected by moisture and the R factor the XPS provides keeps whatever material is above it warm enough to avoid condensation from forming.

It's not the vinyl that's affected--it's the adhesive that fails. This piece from Dr. Lstiburek details the problems of water vapour coming through a basement slab. (Though it deals specifically with improperly done slabs, the principles are the same.)

Loose-lay vinyl may handle the moisture better. However, your floor will likely require extensive work to achieve a level bump-free substrate.

Since you indicated some family members are more than 6'6" tall, I would suggest that tile over a crack isolation membrane might be the best solution. Or you could lay low-pile synthetic carpet without an underpad and just count on replacing it every few years. When I had rental properties, that's what I found myself doing because of tenant damage. Always lots of ends of lines, oddballs and returns available at discount stores and on Kijiji.

While xps below a subfloor looks like a good idea all the contractors I spoke to when getting quotes (who have collectively done many basements) all told me that in moderb homes they put whatever flooring directly the client requests on slab with no issues. When I brought up subfloors they all said it is a waste of money. Honestly I was a bit surprised by that as all three turned down additional revenue and said just to put the flooring on slab.

There's your answer: "Don't worry about a thing, every little thing's gonna be alright." (It's what you wanted to hear.)