What would I use to secure a tongue and grooved Cyprus pine floor boards over concrete?

Question

I will also need to incorporate a water barrier under the timber

Answer 1

If you are putting down a vapor barrier(water), then put down a sub floor, with adhesive. You can then "toenail" your top flooring into the sub floor.

Answer 2

IS THIS IN A SUBBASEMENT? BELOW GROUND BASEMENT?
CYPRESS IS GREAT FOR WALLS AND CEILING LOOKS BUT I DONT THINK IT WILL TAKE THE WEAR AND TEAR ON THE FLOOR. IT IS A SOFT WOOD.
CONSIDER A LAMINATE FLOATING FLOOR AND USE THE CYPRESS FOR THE CEILING WITH A NATURAL OR WASH STAIN.

Answer 3

Beau R has the correct answer, you need some wood to adhere to.