Toe-Screwing Joist to Girder

[marinaman]

I have a client who asked me to review his arbor strucure. The structure is simply cantilevered wood columns supporting 2x8 girders that go around (4) sides.....that in turn, support 2x8 joist members at 16" o.c. There is no plywood or anything like that on this arbor.....this is simply an aestetic structure....intended to provide some degree of shade over an eating area.

The typical 2x8 joists are notched on their bottom by 1 1/2" as they cross over the top of the supporting 2x8 girder (the girder is let-into the bottom of each joist by 1 1/2"). The client does not want visible joist hurricane anchors to foul the appearance of the arbor. In order to make a positive uplift restraint connection, I am going to have to use wood screws at an angle (toe-screwing).

I was thinking of predrilling the holes from each side of each joist and toe-screwing down, thru the joist, into the girder below, from each side of each joist, with each screw embeded 2 1/2" into the girder below (starting about 1 1/2" up off the bottom of notched joist. I am not worried about rotation of each joist, as each joist is extensively laterally braced via blocking at 24" o.c.

I typically to not "toe-screw" in this fashion. I typically use Simpson uplift anchors 99% of the time.....but in this case, I can not. Are there any pitfalls to the use of toe-screwing thru pre-drilled holes that I should be aware of?

 

[UcfSE]

Just a question, can you drill vertically through the top of the joist down into the girder and use a long screw that isn't a toe screw? I can't think of any pitfalls to your proposal. I would try to follow the nds for toe nails and modify for screws if you can, that's all.

 

[BadgerPE]

I built something similar for an uncle of mine. I initially was going to do exactly as you stated, but then I realized it was going to be a lot of work. So instead I got some 1.5" wide, light gauge (16 or 18) flat strips from the local hardware store that had pre-drilled holes in them. Then after the joist was notched, I simply drilled two screws up into the joist. Then I set it on the girder and drilled two screws down into the girder. 4 total screws straight in were a lot faster than 2 screws at an angle with pre-drilling. The nice thing was that this was about 7' to the top of the girder, so by using the flat straps, none of the connections were visible from down below.

 

[hawkaz]

At my own house, I did the exact thing that UcfSE receommended. Worked great

 

[msquared48]

Don't take me the wrong way on this, but it would be best to screw from the top as mentioned.

Mike McCann
MMC Engineering

 

[4thorns]

Look into these

http://www.fastenmaster.com/details/product/olylog-log-home-fastener.html.

They don't need to be predrilled for log home applications but not sure how a 2x8 at 1 1/2" wide would handle it. Especially if it's PT lumber.

 

[woodman88]

I would use 3/8" (to 1/2") dia. by 6" long hardwood dowels inte 3.5" deep holes with exterior glue. This way you will not have any rust stains from the metal. But if they are going to paint it, then just have them putty the hurricane clips. They can even counter sink them if they want.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[4thorns]

Getting back to the original question..."Are there any pitfalls to the use of toe-screwing thru pre-drilled holes that I should be aware of?"
There is a very good chance that the angle you choose to drill at is going to be in line with the growth rings of the lumber due to the way it's cut. It's very weak. Even pre drilled there is the possibility of the wood splitting as soon as or shortly after the screw head makes contact. Whether it splits or not it's going to be a pretty weak connection. With that said, you would need have an idea of how much uplift it could possibly see to determine what is required to hold it down.

 

[BAretired]

The hardwood dowels sound like the best solution to me.

BA