Noisy floating wall anchors

Question

In Colorado basement walls have to be floating. Basically they are suspended from the floor joists, with a vertically movable anchor into the base plate, in case the slab moves due to expansive soil. More info/diagram is at http://www.asktooltalk.com/questions/faq/framing/floating_walls/floating_walls.php

I've got my walls up and anchored with 60d nails into the base plate. The problem is that when you walk across the floor above the new walls, there's enough flex in the joists to move the walls, and the 60d nails squeak against the floating bottom plate.

I tried drilling some of the bottom plate holes larger and putting a 5/16" T-nut in, in hopes that a smaller area of metal-on-metal would be quieter than 1.5" of metal-on-wood, but no such luck.

Any suggestions to quiet these down? It needs to provide a fairly snug fit to the 60d nails to minimize side-to-side and back-and-forth movement, but still be quiet. My next thought is finding a nylon spacer that fits around the nail and putting it in the hole, and possibly wrapping the nail with slippery tape (e.g. http://www.leevalley.com/us/Wood/page.aspx?p=32182&cat=1,43455,53293&ap=1). I don't want the tape to work it's way off in a year though...

Answer 1

After a lot of time wandering the faster aisle at my local Ace, I ended up finding a rubber grommet that fit snugly around the 6d nails I am using. I then took the grommet and found a fender washer that fit the grommet inside it (ended up being a 1/2" washer).

Then I drilled a hole in the floating bottom plate large enough for the grommet to drop into (about 5/8"), so the washer would sit flush against the top of the 2x4. I set the washer/grommet in there and pre-drilled 2 holes through the washer. Finally I screwed the washer down with 2 pan head screws to hold it in place. Before I drywall over everything I'll spray the washers with some Armor-All just for grins.

I haven't had any problems with noise with this approach, and the wall doesn't seem to move any more than it did when it was spiked the normal way. I also stiffened up the entire wall assembly by toe-screwing every stud into the top and bottom plate with some heavy-duty SPAX screws, so that the nails didn't work their way loose.

In regards to Michael Karas' suggestions, stiffening the floor seemed like overkill. I've never felt movement in the floor from above, and even having a 175-lb. person jumping on the floor upstairs I couldn't see movement in the floating walls.

Answer 2

So I'm sure you have already closed up your walls by now, but I had the same problem today and wanted to contribute in case anyone else runs across this.

Drill the hole in the bottom plate the same size as the nail or slightly undersized. (.238) is the diameter of a 60D nail, and also a B size drill bit. I couldn't find a "B" drill anywhere so I used a 15/64 instead (.234). This actually created a much more solid feeling wall and got rid of the noise.

I was concerned about the tightness of the nail, but when I looked at what our builder did to some existing walls I could see they did the same thing. There was no gap around the nail like my first attempt.

Answer 3

As a first approach I would suggest that you investigate why the hanging wall structure is allowing movement. If that wall structure is built properly it will act as a vertical plane that stiffens the floor structure so much that any joist movement virtually eliminated. As recommended at that link any wall board attached to the hanging wall must be both glued and screwed to the studs. It is also important that this vertical plane be attached to the joints in a way that keeps it tightly fit to the bottom of the joists. The reference link stresses the use of metal strapping for this purpose.

If the construction details of your site are such that the joists and hanging wall are still able to move then I would suggest that you investigate ways to stiffen the joist structure that the hanging wall attaches to. If you can eliminate the flexing it should stop the corresponding movement on the 60d nails.

The joists themselves can be made stiffer by adding additional joists next to the ones already in place. The greatest amount of stiffness can be realized by using a glue lam beam that is cut to size instead of just regular framing lumber. This would apply primarily for the case where the joists run parallel to the hanging wall.

For cases where the hanging wall runs perpendicular to the joists there can be stiffness added by two techniques. Full width blocking can be cut and nailed in between the adjacent joists. Alternatively cross bracing can be installed as X's of flat 1x3's installed between the adjacent joists. The cross bracing may very well be easier to install after the fact than the full width blocking, especially if there is existing electrical wiring or water pipeing installed between the joists. The blocking or cross braces will spread loading from above over multiple joists and help to reduce the amount of flexure.