I’ve gutted my bathroom down to the studs. The walls will be covered with drywall and tile. Before this happens I’d like to cover the walls with plywood to give them more lateral strength (I live in Los Angeles in an older house). Is this a problem? The area with tile on it will be covered in wonderboard or mudded (it depends how plumb the walls are).
On one of the walls I’d like to use screws to attach the plywood. Are there any recommended screws ? I know this can be a touchy subject (nails vs screws) but the plaster on the opposite side of the wall is in tough shape and attaching the plywood to the wall with nails is sure to knock some of the plaster off the wall.
Thanks
Replies
Matt, sounds workable to me , I would want to use ceramic coated 1 5/8 " deck screws.
I've skinned one entire bathroom and several showers with 3/4" cdx.
Deck screws are the way.
No worries.
Is there anything else to use other than deck screws? My concern with them is that to get the screw reasonably flush with the plywood you need to sink it through the first layer of the plywood. My understanding of shear walls (not that these are true shear walls) is that they get their strength through the number of plys in the plywood. If you puncture a ply you've lessened the strength of that connection. Are there any screws that have a head similar to that of a nail? If you use steel studs for a shear wall what kind of screw would you use?
I'm sure somebody with more expertise will come along to answer this, but, while I see your point, I don't think it matters at all. We've put plywood and OSB up on some
In the end, I don't think the small holes the screws and their heads create make any difference. I guess if you installed them right next to one another you'd kind of be perforating the plywood and lessening it's strength. And if you're that concerned about it, I guess you could go with fewer screws and more construction adhesive.
I recently saw a documentary about factory-built homes (not trailers; modular homes) that are being built and put up along the gulf coast of Mississippi (which was hit harder by Katrina than New Orleans was). They were relying HEAVILY on construction adhesive (PL, I believe) in the construction of these homes. They explained that it was largely responsible for these homes being able to withstand Katrina-type hurricanes. Everything was getting glued. They didn't even screw in or nail the drywall to the stud walls--it was just glued in place.
When I reinforced my attic truss structure, my contractor, the structural engineer and even the screw company whose screws I was using all agreed that the bond the construction adhesive was creating was far superior to any screws or nails I could use. The way they talked, the screws were really only holding the pieces together until the adhesive dried.
But, if you're relying primarily on plywood, and you're already gluing it, any additional effort and money would almost certainly be better spent on the proper Simpson metal reinforcement pieces.
When I first bought my house I had to replace part of the foundation. At the same time the house was bolted and the cripple walls covered in plywood. I remember the structural engineer making a big deal about not penetrating the first layer of plywood with the nail head, as it affected the effectiveness of the plywood.http://www.abag.ca.gov/bayarea/eqmaps/fixit/ch3/sld063.htmIt's because of this that I'm trying to find a screw that I can use.Thanks,Matt
Thanks for posting that. I would have never thought that could be a big concern. It's hard for me to believe that the nail or screw head penetrating could be such a big issue when the rest of the nail or screw is already in there. But I'm no engineer.
I guess the other choice is to do some very careful nailing and use a lot of adhesive.
It's less the screw, it's more the tool you use to attach it with.
At HD (and most other stores) you will find the Senco 200 plug in screw gun. It actually will place the screw flush, proud, or just below the surface of the plywood or OSB - it adjusts to what you want, and cost $79. It uses screws rated for exterior shearwall use - you would use 2" screws for 1/2" ply.
Otherwise, if you were carefull you could also use an impact driver. When you are close to the end you ease off the trigger and you can set them perfectly every time. An impact driver will cost more - depending on your cordless tool setup - but is useful for many more projects.
At $6 a 4'x8'x7/16" sheet, OSB is currently the cheapest sheet good you can buy... it's also designed to be used for shearwalls. I just redid a bathroom and sheeted it with OSB. Then I put a layer of Ice & Water Peel & Stick roofing material over all of it. I had an extra roll left over from my roofing project. Any water is stopping at the drywall in my bathroom!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
If you are really concerned about penetrating the top ply (which I personally wouldn't worry about with 3/4") you could look at GRK's line of cabinet screws. Pricy, but a super product with a large head.
My feeling is that you can't have it both ways--I wouldn't want screws protruding at all because then your Wonderboard will be held off the plywood by the screws. If you use thinset between plywood and Wonderboard, it may be okay.
The good thing about screws (compared to nails) is that they won't work their way back out to crack tile later (more of a problem with floors though, I would guess). The other way would be to use some sort of panhead screw and leave the heads proud, then fur between them with something like strips of 1/8th inch hardboard or similar, then put on the Wonderboard.
BTW, how are you attaching the Wonderboard--I assume you don't want to nail that either? I guess you can either drive screws till they're flush, or even use the screws that have little fins under the head to countersink themselves as you drive them.
matt, I'll have to defer to the other guys, I don't deal with screwed up shear walls.Mongo
Lateral stiffening is a good idea. Plywood would work fine. Drywall screws are brittle and would be a poor choice. Deck screws may be fine. I'd suggest gluing the plywood to the studs with PL Premium adhesive, too.
Some James Hardie products are rated for use in sheer walls. I don't know if their tile backer is, but their website might discuss it. http://www.jameshardie.com
I've thought about gluing the plywood to the studs, in addition to the nails/screws, but what if for some reason it needed to be removed in the future? Wouldn't it be impossible to remove if it was glued on?
Of course there's always that chance that it will need to be removed. But by that logic we shouldn't be glueing down our subfloors and other parts of the structure. Sometimes the benefits far outweigh the drawbacks. However in your case I do feel the adhesive would just be a 'belt and suspenders' approach and could perhaps do without it.View Image
I live in San Diego and have been doing some reinforcing while I'm remodeling my home.
My contractor and I have been installing (at his recommendation) a lot of Simpson pieces to add shear strength. They only require a narrow diagonal cut (like that of a circular saw) accross the studs to install them (and the appropriate Simpson nails). Both my contractor and the structural engineer I've consulted are big fans of the Simpson products for earthquake reinforcement.
I don't know if you're talking about installing tile directly on drywall, but I would never do that in a wet enviroment unless I was using the Kerdi product (or something similar). I know installing on greenboard is common practice in some parts of the country, but it isn't the best practice if you want to keep the tile for a long time.
Metal is always a great product in an earthquake prone environment. Metal can bend and flex and can maintain it's strength. Wood flexes some. Concrete crumbles.
Just thought of a very simple solution--rent a nailgun and nail your plywood to the studs with 6 penney ringshank nails, four inches apart on the edges and six inches in the field. That should hold it! Won't affect the plaster on the other side either, since the nails go in so fast, not like using a hammer. Then put on the Wonderboard and tile. Nailing the plywood with a nailgun will only take a minute or two.
I dunno Danno.... nailing into old, hard, dry lumber can make a real mess. What I find is that if you turn the pressure down enough to not make a mess of the other side of the wall (or blow through the skin of the ply) the nails end up proud half the time. And then you're back to the hammer. The force from the gun driver has to go somewhere... and old wood doesn't absorb much of it... so the force gets tranferred to the plaster on the other side of the wall anyway.
I tend to thing the OP (and the rest of us) are over thinking this at this point. It's been an interesting discussion, but we're running out of ways to skin this cat. Me? I'd glue it and run some 2" deck screws in there and just set 'em flush with an impact driver. Perfect? Maybe not. But a pretty good set of belt and suspenders none the less.View Image
matt19
If you are really concerned about strength of connection, you should predrill the plywood. It does two things.. first the tear out that weakens the plys as a drill wedges it's way through the wood fibers is eliminated. Second stand off, where a thread or so my protrude because the screw is captured away from it's mounting point on the stud is eliminated..
Stand off is seldom an issue on decks since you are standing on them as you fasten however no such possiblity exists on walls.. (Unless you got a bargin on that anti gravity superman suit <grin>)
Massive strength improvement, plus easier removal should that ever be needed.. The diamter of the hole can be fractionally smaller or the same size as the shank of the screw..