All,
My home inspector has informed me that my 1959 house needs some seismic improvements.
The joists rest on the concrete foundation around the perimeter, and on short posts in the crawlspace, which in turn rest on concrete blocks. Everything looks fine, but the posts are only connected to the joists with one nail. The inspector recommends connecting the posts to the joists with ‘more nails’.
My questions:
a) Should I toe-nail them on all four sides, or consider simpson strong-tie? Would a basic plywood plate on either side of the joist be sufficient? Recommendations on type of nails are also welcome.
b) if I should use a strong tie type, then which one? Nailing lots of nails into the post and joist is obviously much more work, and those plates are no bargain either.
c) Should I consider shear panels for this floor?
Thank you for your opinions,
Wouter
Replies
If you can, drill holes thru the posts and joists and bolt them together. A carriage bolt works well; it locks itself into place and won't easily turn as you tighten.
Second option- use the self-drilling screws meant for hanging deck ledgers (LedgerLock screws ). Get yourself a cordless impact driver to run them in. This is a fairly simple, but effective method.
BTW, I'm not real impressed with the inspector telling you to just use more nails.
"BTW, I'm not real impressed with the inspector telling you to just use more nails."
Key here is "home inspector" not building inspector.
Grunge on. http://grungefm.com
The inspectors recommendations are a joke.
If you truely have seismic concerns a few more nails into the top of an otherwise non-connected post will do nothing but provide you with exercise. You said the supporting posts just rest on concrete blocks in the crawlspace. That, to me, means only that the span of the joists has been reduced to simply support a dead load.
Knowing your location would probably help.
How the perimeter of your house is connected to the foundation would be of more interest, as would the type and frequency of the whole house uplift connections and the shear paneling or bracings built into the exterior walls.
I would first determine how you would keep your house from sliding or rocking off its foundation before investing in a single ineffective nail.
With 1959 wood, pretty dry, I recommend pre-drilling holes for nails and screws. 75% shank diameter for nails, 1/8" for timberlok screws.
IMO adding "more nails" is a joke. There would be close to no added benefit in terms of seizmic conditions. OTOH, I agree that if you live in an area with seismic activity, you really should do something. Look into what Simpson has for these types of applications.
I agree with most of the other members that have replied, but I'm a just a little confused about your statement rgarding the joist and post connection. Normally I would expect that your posts are supporting a beam that in turn support the floor joists, no? I see no benifit in providing a post to support a joist. Am I missing something?
Structurally I would also question your comment regarding the column sitting on concrete blocks. Concrete Blocks are not intended to act as footings (not in my part of the country) they can crack and are subject to failure.
My two cents.
mykola
We're going to get a proper assesment done by a structural engineer. It seems there is some confusion, both on my side and with the forum, on what would be good to do.To answer some questions:- we live on the San Francisco peninsula (San Andreas fault)
- The perimeter is supposedly bolted to the foundation, although the wall construction has not allowed me to check this.
- As you can tell, I'm not a builder...so I may get terms wrong.
- The 'concrete blocks' are also sold as footers I think. They are about 10inches on a side, and have a wooden platform on top. I'm sure this is not up to code in 2006...but it may have been fine in 1959.Thank you for all your comments.
I assume that "concrete blocks" means poured concrete pads.
Practically speaking, you'll have a hard time getting more nails in there and having them do any good. Better to browse the Simpson aisle at your local megastore and pick out some sort of anchor you can make work for your case. Thru-bolting is good, but if you can get about four hanger nails solid into each end of the anchor then you're probably fine.