Joists hangers

[Sasha]

Can I use screws instead of nails to attach joist hangers to joists?

[G Henslee]

Yes, of the proper length, etc.

[DiezMon]

I'm no engineer, but some manufacturers recommend a certain type of nail/screw. I think it's a shear strength issue...

Tim

[Duane Bozarth]

Yes...there will be allowed sizes(lengths)/material/strength reqm'ts listed...

Don't use a drywall screw, iow, even if it long enough.

[RicodJour]

Why would you want to?

R

[frank-in-toronto]

i'd guess because general opinion is that screws hold stronger than nails. when you break off a few just tightening them by hand, you realize that they are made from low stength material that is unsuitable for any important holding task.

my experience is with roberson wood screws available in canada at hd and cdn tire. there may be better but i can't find them. ....thehick

[PipeDown]

Sometimes you don't have room to swing a hammer but you can get a driver in there.

Sometimes the vibration from hammering can knock other stuff loose (like plaster) particularly in remodelling.

Screws allow for (easy) disassembly if you goof or just change your mind. (the main reason I use them inside)

More holding power particularly in soft woods

Use steel screws labeled for general carpentry use. I use 3" #8 screws for most interior joining (I am a homeowner not a contractor). Drywall screws are made of a weaker alloy and with less metal since they only need to hold up a modist load.

Screws are a little slower to use than nails though and cost a bit more

[BP]

It is the diameter of the fastener that is most important factor for installing hangers. That is why they require the special 10d x 1.5" nails. An 8d common nail is not the same and does not meet the design criteria for sheer strength. Simpson is very clear on this. If you use screws then the core of the screw (the center part, without grooves) would need to be the same diameter as a 10d nail, which means approximately a 3/16" lag bolt. You'd then have to drill out every hole in the hangers, because they are not big enough. A joist hanger can reach it's design loading only when every nail hole is filled. That is why cheap hangers have so many holes. You might be able to get an engineer to certify that the screws you are using have an equal sheer strength as a 10d nail. Regular joist hangers are designed to support vertical loads. They are not specifically designed to handle horizontal forces of any magnitude. There are special hangers and connectors made by Simpson and others to do that.

[Warren Weber]

I used DECK screws on hangers for a very large deck. Maybe because I did not know better. Inspector passed it and still holding up for 8 years. W W

[Waldo]

Good post, BP. Very informative.

BP wrote:

[RicodJour]

Which would totally change the load capacity of the hanger and expose bare steel. Extremely bad idea, and I'm sure you're not recommending it.

Why does the hanger quality or price (not sure which cheap you mean) have anything to do with the number of holes? A certain number of fasteners are required to develop the rated load capacity - that's the only determining factor on the number of holes in a hanger.

R

[Tony Hwang]

Hi, I like to use spiral nails. Tony

[RicodJour]

I've never seen 1.5" hot-dipped galvanized spiral nails. In any event, it's unnecessary. Spiral nails, like screws are meant to keep the fastener from backing out. If you use the 1.5" joist hanger nails, they're not backing out. There's not enough embedded length, and if you've ever tried to pull one of them you know the galvanzing might as well be glue.

R

[BP]

No, not recomending it. Anyone crazy enough to drill out every hole in every joist hanger probably can't read.

The quality of the hanger, and it's price, is determined by the type and gauge of steel they use to manufacture them. Cheaper, weaker steel would fail sooner with 6 nails in the hanger than a hanger that was made with stronger, thicker steel. The manufacturers compensate for this by increasing the number of nails in order to receive the same design rating as the competition. Unfortunately, most framers do not/will not fill every hole in a hanger with 12 holes so the hangers will not deliver full design loading. Fortunately, these things are way over-designed, so we don't see any buildings falling down. But they over-design because they compensate for real world factors like framers not putting all the nails in.

I had an inspector fail a frame once because of the joist hanger nails, citing the info above. That when I checked it out and found him to be correct.

[Calvin Henry-Cotnam]

So too would be a good building inspector! When we built our home, our inspector checked that the proper nails were used for the joist hangers.

Mind you, the special nails on Simpson hangers are for holding the hanger on the ledger board. The two (or four, depending on size) angled nails that hold the joist onto the hanger may be regular common or spiral nails.

[Phil]

If your build accuracy is good, you could probably sit them on blu-tack and they wouldn't move. Might not pass inspection tho.

[Duane Bozarth]

Only the shaft of the screw is bearing the shear load...if it is of equivalent diameter and and strength, the shear strength at the hanger will be as high as the nail. It wouldn't be out of the question to use a SS screw that would have higher shear strength at the same diameter...

[Phil]

The screw / nail bears some of the shear force - the clamping force of hanger against joist (both faces) also bears some, and probably this clamping force is higher if using modern twin helix screws tightened correctly.

[Duane Bozarth]

Yes, there's much more than I mentioned, just pointing out it wouldn't take anything close to a 3/16" lag to get equivalent shear strength to a

10d common nail...

[BP]

"the clamping force of hanger against joist (both faces) also bears some" You have GOT to be kidding....