some time ago i inquired about fastening some steel plate to the sides of some 100+ year old, full dimension, rough cut oak floor joists to stiffen them up. I've decided to sister them with like sized (2x8) wood instead. These are the second story floor joists and they are 2x8 and span 15.5 feet. I've got the ceiling out on the lower level and want to stiffen them up before i go back with new ceiling. My question is, what is the best way (and frequency) to attach them? Screws, nut and bolt, nail, glue, etc?? It's a balloon style house and i'll be able to set the new sisters up on the ledger board like the originals. My main concern is pulling them together in such a fashion as to best create a "oneness" .
The Best way to get the right Info, you need is to call your City or State Planning, and Development Services Division, Public Works and Engineering Department,
And Set up for a inspector to come out and see your needs it is a good $35 to $60
Your pay a Construction Company to send one of their inspector, For about $100 to $500..
For no will need able to tell you Screws, nut and bolt, nail, or glue, etc.. With out looking and inspecting it first.
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I copied this out of a web page and they may have just the application you are describing. I also know that some engineers have called out nails and clinching them. That is driving the nail through both members and the part that sticks out, bend over...... I like the screws most of all. john
some time ago i inquired about fastening some steel plate to the sides of some 100+ year old, full dimension, rough cut oak floor joists to stiffen them up. I've decided to sister them with like sized (2x8) wood instead. These are the second story floor joists and they are 2x8 and span 15.5 feet. I've got the ceiling out on the lower level and want to stiffen them up before i go back with new ceiling. My question is, what is the best way (and frequency) to attach them? Screws, nut and bolt, nail, glue, etc?? It's a balloon style house and i'll be able to set the new sisters up on the ledger board like the originals. My main concern is pulling them together in such a fashion as to best create a "oneness" .
nevermind on the link. I found them. They looks suspiciously like the SKS product. My local lumber yard is listed as carrying both, so i'll go take a look. THANKS!
nevermind on the link. I found them. They looks suspiciously like the SKS product. My local lumber yard is listed as carrying both, so i'll go take a look. THANKS!
You might also look at Simpson strong-drive screws:
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I originally used these to attach seismic hold down anchors and have been a believer since then. They're self drilling, drive easily with a drill/driver (with a hex socket adapter), and are very strong. The strong drive screws are available in the home centers where the metal brackets are located. They're designed for sheering situations, so they should work great for sistering joists. I use them all the time for a variety of tasks.
Most home centers carry both TimberLok and Strongdrive screws. Compare both and use whichever one is available in the length you need at the lowest cost.
I believe it is important to use dry lumber in a situation like this, so that the new members don't shrink relative to the old members.
Best practice would be to jack each floor joist to remove the dead load deflection, install the new sister, and then remove the jack. That way the new and old joists share in carry the dead load. If you don't do this, the new joist won't carry any of the existing load. Of course, if you only want to stiffen the floor system for live load, then that wouldn't require jacking.
As for the connection between the joists, I would just use nails. E.g. two rows of 16d nails (0.162" x 3.5"), top and bottom 1" in from the edge, and 16" o.c. in each row, installed from the face of the new joist. While other fasteners have a higher capacity, like Simpson SDS screws, lag screws, etc., you have plenty of space for fasteners, and so you can just use more nails. In my opinion that makes for a more redundant connection. The higher capacity fasteners make more sense where space is limited relative to the load, like in a holddown.
One wrinkle in all this is the issue of splitting the old joists. If you have to predrill for each fastener, then there'd be a labor savings in using fewer, higher capacity fasteners.
Alternatively, using nails of a smaller shank diameter may allow you to avoid splitting without predrilling. If so, the nail capacity is proportional to the shank diameter, so again you can just use more nails. I.e. you could use 16d box nails (0.135" x 3.5") and just use
1.62/1.35 = 1.2 times as many. You could even use 10d box nails (0.128" x 3") and just use 1.62/1.28 = 1.27 times as many. [Note that the required penetration for the nail to develop its design capacity is 10 times the shank diameter. Thus 0.128" x 3" nails are OK for a
1.5" thick side member: 1.5" + 10 * 0.128" < 3".]
So I suggest a little experimentation to determine what size nails can be used without splitting the old joists.
As for the use of adhesive, in principle it seems like a good idea but I don't really know.
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