anchoring 2 bottom plates to the foundation wall
scott1000
| Posted in Construction Techniques on
I’m building a garage and was planning on using 2 bottom wall sill plates. The one sitting on the foundation and sill gasket would be pressure treated and then the next one reg. My question is should the foundation bolts go through both plates. If so do I build the wall by bottom nailing the regular sill plate to my studs and then top nail this plate to the pressure treated plate once wall is up and bolted to the foundation. In addition if the foundation anchor bolts are going through both sill plates should I use 8″ or 10″ anchor bolts. I will verify my inspector when he comes by to inspect my forms but I would sooner get it right so I can build some credibility with him. Any help would be most appreciated. Thanks!
Replies
umm why?
Umm why? good question to be honest that is one thing I'm trying to figure out. I've seen it done both ways. Along the way of planning I've got it in my head that I should be going with a double bottom plate. Is it really needed? I'm in Vancouver, BC.
Clarification would be most appreciated. I'm building the garage because I don't have the money to pay someone else but I want to do it right. I'm an open book and would love to hear from others.
Thanks!
Scott
I think you'll find that putting down the pt plate first with the j bolt nuts and washers countersunk is the faster way to go since it allows you to put the plate down dead straight, build the wall and easily stand it up and nail it down. The problem with that is the pt plate will shrink a lot and the nuts will be lose with no way to snug them up. There is nothing wrong with doubling up the bottom plate of your wall and standing it and sliding it down over the j-bolts, except it's a pain in the rear and if your holes aren't right it's a real pain, and to get it dead straight requires another step and it's always harder to tweak a double plate straight. If you cover the nut on a j-bolt with another plate you will probably have to drill an access hole so the nut can be seen and tightened for the framing inspection.
I've normally added the pt plate to the bottom of the wall plate and lifted the wall with a forklift so it was easy to set in place. You can probably use a pt plate as the only plate but you'll need to use nails approved for contact with the pt so I think it's easier to double the plate. If you do this the holes have to be perfectly aligned - more than once when guys haven't been careful we've had to screw with the hole or even cut off a j-bolt in the middle of putting a wall up (and a threaded rod epoxied in to replace the cut j-bolt).
Many times a garage requires seismic anchors that join the framing to the foundation for sheer walls, at least on the short sheer walls on either side of the garage door. These have a threaded rod that gets epoxied into the foundation and the other end goes through a bracket attached to doubled studs or a 4x4. Just make sure if you need these that the j-bolts aren't in the way of where the threaded rod goes and honestly j-bolts are redundant if the threaded rod is there so I leave the j-bolts out completely in those areas. It is possible to get long correctly sized j-bolts for the seismic anchors and cast them in your concrete, but they have to be within 1/4" of perfect and that rarely happens so I think it's faster, easier and in the end less expensive to drill and epoxy in threaded rod. Simpson's catalog does a great job of explaining the installation of these.
Um why? is right
What's the point of this?
All you need do is fasten your bottom PT plate to your wall studs with some HDG or stainless nails and stand it up.
What can you possibly gain with 2 bottom plates?
Joe H