cabin floor sealant?

[Gone Fishen]

The main floor in the cabin is to have tile so I am going to install 1/4 backer board on the entire floor. Now the question is the top floor or upstairs. I am going to install carpet there so I want to place a plywood top on the sub-floor. I am going to install the plywood at 90* to the current flooring and install the plywood in a 'brick' fashion. Now the question is what type of sealeant should I place on the plywood before installing the pad and carpet? I would ask the guy's at HD but sometimes I get funny answers. Ideas? Thanks.

[Band_Member]

I've never heard of anybody who has applied a sealant to underlayment (plywood). Only if there was an excessive gap between sheets they might lay down some aluminum flashing so you don't feel the gap through the carpet and padding.

Go with 5/8" underlayment. Around here it's known as 5/8" AC/PTS.

On edit: I'd lay down the underlayment the same direction as the subfloor which should be perpendicular to the floor joists. Leave about 1/8" between sheets on the butt ends and about 1/16 on the sides between sheets. Cut about 1/2" short of wall plate. The trim will cover the gap and you need the spaces for expansion. You don't want the underlayment to buckle.

Stagger the first sheet of underlayment over the joints of the subfloor below and go from there. Use ringshank nails and nail every 5 - 6 inches. If you can, borrow or rent a nail gun and go at it good. You won't regret it later (at least that's the way I do it with my own house).

[Gone Fishen]

I had not heard of the sealeant either so I ask questions. New question. What do I do about the stairs? I have no problem installing the 5/8 sheets but the top deck of the floor will be 5/8 inch higher if I do this at the stairway. They recommended the 90* to the subfloor panels. Thanks for the reply.

[MarkEkberg]

I would throw down some liquid nails. It will stop squeeks.

Use screws that are long enough to go through both flooring material and into the joists.

[Band_Member]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MarkEkberg</div><div class="ubbcode-body">I would throw down some liquid nails. It will stop squeeks.

Use screws that are long enough to go through both flooring material and into the joists. </div></div>

Everywhere else use nothing longer than a 2" undelayment nail otherwise you risk hitting anything that may be attached to the underside (pipes, wires, etc.) especially if the original poster's cabin is post and beam construction and the underside is exposed.

Case in point, recently we nailed off some underlayment for a tilejob in an older Lindal Cedar Home. The setting on the gun left a few of the 2" nails about 3/32 below the bottom of the subfloor. Just sio happened one nail perforated the hot lead in a 14/2 Romex. A few days later the tile guy's helper found out about it when he was grouting and touched up against the gas line. [img]/forums/images/%%GRAEMLIN_URL%%/laugh.gif[/img]

The few nails that were protruding through were not an issue because it occurred in the basement ceiling in a utility area (thus the wire nailed to the underside of the floor). You couldn't really even see them.

[Pappy19]

My son-in-law installs tile and carpet for a living and he says he doesn't use a liner or sealer on tile except for showers. The grout needs to breath, so no liner or sealant on regular tile floors like kitchen, halls, etc. He does use a liner/barier on wood floors.