J-Bolt Installation

[burger]

How did you locate your J-Bolts?

I'm having a new slab poured later this week; the contractor recommended using stringline as a guide. Anyone used any other techniques?


Thanks,
Ed

 

[d110pickup]

How did you locate your J-Bolts?

I'm having a new slab poured later this week; the contractor recommended using stringline as a guide. Anyone used any other techniques?


Thanks,
Ed

My building required 24 J-bolts in a particular pattern in order to support the posts. The concrete contractor used 1/2 plywood to make locaters for the bolts. Look thru my garage build thread; there are a few photos there.
Mike

 

[burger]

Mike,

Thanks for the reply. I should have specified in my original post that I'm using the j-bolts for sill plates and not posts.


Thanks,
Ed

My building required 24 J-bolts in a particular pattern in order to support the posts. The concrete contractor used 1/2 plywood to make locaters for the bolts. Look thru my garage build thread; there are a few photos there.
Mike

 

[boiler7904]

I'd use stringline - maybe set your nails a day or two in advance so you're not trying to race time with the concrete setting up.

I'd also do the layout of each bolt location directly on the concrete form a day or so in advance - maybe spraypaint each spot so it stands out.

When the mud starts flowin, you want to have to do as little layout and thinking as possible. Concentrate your efforts on pour day to making sure everything is pitched the way you want it to go and doesn't have low spots where water will puddle.

 

[kutza]

My building required 24 J-bolts in a particular pattern in order to support the posts. The concrete contractor used 1/2 plywood to make locaters for the bolts.
Mike

This is what we have done, for a steel trussed building.

 

[Don T]

Hey Burger,

Boiler7904 had some good ideas... On mine I bored and set anchor bolts at each end of the sill plate boards and every 4' on centers. Took a good half day to set about 80 of them. Not hard to do when the concrete is still a little green.

BTW - The 31 Chev fenders etc. I got from you a while back worked out well. Haven't worked on the car for awhile, been to busy building my new shop.

 

[MustangRick]

I have wondered about this before... can you drill the sill plate and assemble the J hooks on the board ahead of time? Then, right after the concrete is pored, you set the sill on top and settle the J hooks into the concrete? This way the hooks are lined up with the board. I would think you would want to put plastic around the board so that you could take it back off after the hooks are set to put your seal on. You would not have a way to level off the concrete that the j hooks flush out, but that should be a known amount per hook.

 

[Bigger Hammer]

I'd use stringline - maybe set your nails a day or two in advance so you're not trying to race time with the concrete setting up.

I'd also do the layout of each bolt location directly on the concrete form a day or so in advance - maybe spraypaint each spot so it stands out.

When the mud starts flowin, you want to have to do as little layout and thinking as possible. Concentrate your efforts on pour day to making sure everything is pitched the way you want it to go and doesn't have low spots where water will puddle.

great ideas here and to add to it, pull your string line nice and tight and you can snap a line on the surface of the concrete. Be sure to do a rough figure of your framing layout so that your bolts land in a cavity instead of under a stud.
And if you spray paint your layout on the form be sure to spray it on the back side of the form and not the top since the top will most likely get covered with concrete anyway. I can't remember how many times I've had to search for marks on top of a concrete covered form where my guys didn't bother to mark the side as well.

Mustang Rick: In theory that is a good way to do it but when you go to layout your pre bolted plate you still end up pulling a string line. If you don't have perfectly straight lumber you have no leverage to straighten it out as you would if the concrete was already hard.

 

[Vermaraj]

I have wondered about this before... can you drill the sill plate and assemble the J hooks on the board ahead of time? Then, right after the concrete is pored, you set the sill on top and settle the J hooks into the concrete? This way the hooks are lined up with the board. I would think you would want to put plastic around the board so that you could take it back off after the hooks are set to put your seal on. You would not have a way to level off the concrete that the j hooks flush out, but that should be a known amount per hook.

Not a bad idea, but you will run into a few problems. Compacting and finishing the concrete and putting in the sill seal will be difficult using this method. The bigger problem, is squaring up the sill. Even the best foundation usually need to be squared using the 3-4-5 triangle method.

A good way to set j bolts is to pour and consolidate the concrete. Then finish the top smooth and wet set the j bolts. Come back after it dries and snap your square string lines. Set the sill against the jbolts and mark the center lines. Then come in with a block of wood against the string line to mark the other center line. Set the seal and drop the sill plate over the jbolts.

 

[Junkman]

With the advent of the new adhesive concrete mixes for retaining threaded rods today, I would just pour the concrete and then wait a day or two to set the bolts. I drilled holes into the concrete and then set the threaded rods into the high strength adhesive and after they set up, I was unable to pull them loose no matter how much I tried by tightening the nut on the stud. In my case, I was setting steel plates, so there was no compression like there would be with wood. I figure that if these adhesives are good enough for holding down machinery in factory floors, then it should be good enough for holding a wooden wall to a concrete wall.

 

[burger]

I'd use stringline - maybe set your nails a day or two in advance so you're not trying to race time with the concrete setting up.

I'd also do the layout of each bolt location directly on the concrete form a day or so in advance - maybe spraypaint each spot so it stands out.

This is exactly what the concrete guy suggested. I'm glad to hear others use this method.

 

[burger]

A good way to set j bolts is to pour and consolidate the concrete. Then finish the top smooth and wet set the j bolts. Come back after it dries and snap your square string lines. Set the sill against the jbolts and mark the center lines. Then come in with a block of wood against the string line to mark the other center line. Set the seal and drop the sill plate over the jbolts.

What do you mean when you say "set the seal"? Am I missing something?

 

[boiler7904]

What do you mean when you say "set the seal"? Am I missing something?

You want to put a foam or self adhesive rubber seal between the concrete and the bottom plate. Without the seal, there will be irregular gaps between the two which will create drafts in winter.

Another option is to caulk the inside and outside of the joint between the two. If you go this route, wait until the roof is on so you aren't holding any rain water on the slab with the plates.

Dow Foam Sill Seal

 

[burger]

Thanks for the advice. I'll price out the Dow stuff but probably end up using caulk.


Ed

You want to put a foam or self adhesive rubber seal between the concrete and the bottom plate. Without the seal, there will be irregular gaps between the two which will create drafts in winter.

Another option is to caulk the inside and outside of the joint between the two. If you go this route, wait until the roof is on so you aren't holding any rain water on the slab with the plates.

Dow Foam Sill Seal

 

[Krodad]

Like Junkman said, setting rods in epoxy is a great way to go, or, like I just did this summer on a big gazebo, you could use the Simpson Strong Tie "Titan" anchor bolts. They sell them in pairs at Lowes, and they are the galvanized version, so okay for treated wood sill plates. I love the things, and they use standard size masonry bits for the holes. You use an impact wrench to drive them in.

Why try to locate j bolts when you can finish the concrete easier without them, and take your time and put them where you want them after the fact.

 

[boiler7904]

Like Junkman said, setting rods in epoxy is a great way to go, or, like I just did this summer on a big gazebo, you could use the Simpson Strong Tie "Titan" anchor bolts. They sell them in pairs at Lowes, and they are the galvanized version, so okay for treated wood sill plates. I love the things, and they use standard size masonry bits for the holes. You use an impact wrench to drive them in.

Why try to locate j bolts when you can finish the concrete easier without them, and take your time and put them where you want them after the fact.

Depending on location and wind design criteria for the location, epoxy anchors may not be allowed by local code. Since the entire state of NJ is considered coastal, the required minimum wind design is between 90MPH and 120MPH according to the 2006 IBC.

The other thing to make sure you get right is the steel anchor and bolt material with the current generation of treated lumber. The chemicals in the treated lumber that's been available for the past 2 or 3 years will corrode regular galvanized steel in a year or less. In Simpson's case, you need to use Zmax coated steel or stainless steel anchors and the appropriate bolt / nut.