Subfloor Then Spacers Over Joists Under Flooring

Inspect the subfloor from below and note the direction of the joists.

Subfloor then spacers over joists under flooring. With the above specs the flooring should be installed perpendicular to the floor joists. I m putting down a laminate floor over a 3 4 plywood subfloor that is over a unconditioned crawlspace in north florida. On wood frame floors the subflooring provides a continuous structural surface over the floor joists. Always store floor panels under cover.

Not letting a subfloor dry. The flooring can be laid parallel to floor joists but you may need to add a 1 2 inch layer of plywood diagonally or perpendicularly to the joists or install a brace between the joists. Avoid using green joists for your floors but instead use sturdy performance tested lumber. The subfloor is the decking installed on top of flooring joists.

This permits the floor to flex and expand a little as necessary. Use trus joist tji joists or kiln dried performance tested lumber such as weyerhaeuser framer series lumber which is more dimensionally stable than green lumber. The subfloor is the foundation beneath finish flooring materials. The manufacturer of the flooring suggests a 6 mil plastic underlayment for the flooring to block moisture but my concern is the potential for damage to the plywood by locking any moisture in.

Layering makes it easier to change the visible floor if you tire of the look or if it has become damaged. The vapor barrier is just beneath the subfloor but on top of the joists. The finished floor is then installed on top of the subfloor. This method of laying a sturdy subfloor on top of joists and then topping the subfloor with a cosmetic only flooring top creates a tighter stronger structure.

In basements and in homes with slab on grade foundations the subfloor may simply be a concrete slab. There was never any insulation installed under the floor. It is flexible it can be changed out it is inexpensive. Would 15 tar paper be a viable alternative to use.

The crawl space has a scratch coat of cement on the floor. The thickness of plywood panels in a subfloor is regulated by the. A 3 4 inch plywood subfloor on a joist structure with 24 inch spacing needs the extra thickness of cementboard or the floor will flex and the tiles will crack. Wet lumber may lead to dimensional changes as the joists dry resulting in nail pops and floor squeaks.