Securing the Joists

05 Nov

I’ve kinda worked out exactly how to secure joists using the stirrups I have concreted into the ground. I thought I’d do a quick post showing the exact steps to make it easy for anyone else who wants to do it.

First, I assembled the required tools for the first part of this.

  • Hammer Drill – preferably corded
  • Masonry drill bit
  • Screwdriver – phillips head
  • Hammer (for persuasion)
  • 2 screwhead dynabolts
Using the masonry brill bit, drill holes into the concrete through the base holes of the stirrup. Make sure the holes are deep enough to fit the dynabolts in. Also, wiggle the bit around a little so that the hole has enough room for the dynabolt to go in.
The dynabolts work by tightening up and expanding when you screw them in. Make sure that the dynabolt is tight, but not yet expanding before you place it in the hole. Push the bolt into the hole until it’s difficult to push in any further.
Then use the hammer for a little gentle persuasion to push the bolts right down, fully into the hole. If the hole is deep enough, it should go right to the bottom and then be ready to expand.
Once the bolts are all the way in (and try not to damage them with the hammer), use the screw driver to tighten them up so that they expand and hold the stirrup firmly to the concrete. Don’t worry if they are a little raised because we’ll lift the joist up off the ground anyway.
Speaking of which, to raise it up a little off the ground, we just need to put the bolts in once the gap is until the joist. To do this, just grab a handful of dirt to rest the joist on while we measure up where to put the bolts.
Next to make sure that the joist is the right height, we need to measure the level across this joist to another. To do this, put the joist in (there has to be another joist next to it that’s te right height) and then the bearer across the top. Sit a spirit level on the top to make sure it’s level, using more dirt under the joist (or less) to make it level. Try to have the joist in the right place where it would be bolted when doing this.
Wile the joist is in place, shuffle it around to make sure it’s exactly where you want it. Then put a marking on one side. Once marked (I’ve used a plus sign), draw around where the bolt holes are using a sharpie (marker). Make sure the joist is flush up against one side of the stirrup. There will be a gap on the other side of the stirrup and marking it there will make it less accurate. That’s why we mark the “good” side.
As above, once it’s marked, we can drill the holes through. The best way to do this is with a drill press that will ensure that the hole is the right angle. I don’t have one, so I just use the drill. However, because we marked the other side, we can tell how far off we are.
As carefuly as you can, drill through starting on the side with the marking. Use a drill bit that is the same size as the bolt, that way you get a nice tight fit.
Once those holes are drilled, remove the shavings and turn the whole thing over. We want to see how far off we were from the other side.
You can see in the photo above that I was pretty much on the mark with one of the holes, but the other was a little off. I’m going to use the good one to put the bolt through. Once through, I’ll be able to match up exactly where the other hole should go and then fix the other hole.
In the above photo, I have got the nut, bolt and shifter ready to get it through the hole. The next step is to sit the joist back in the stirrup (remember to brush the dirt away) and screw the bolt through the hole.
Keep screwing the bolt all the way through to the other side (you should need to use the shifter if the hole is nice and tight). When it reaches the other side of the joist, make sure the bolt goes through the bolt hole on the other side.
Next, while it’s in there, we can now work out exactly where the other hole should end up so we can put the other bolt through. To do this, the first step is to get that spirit level and put it against the side of the joist and move the joist (pivoting on the bolt) to make sure it’s standing up straight.
We need to make sure that the stirrup is sitting flush on both sides to fix the other hole, so it helps to put the nut on the bolt. To do this, firstly screw the bolt on finger tight then get a shifter on the other side of the joist and attach it to the nut. Tighten it up until the stirrup is sitting flush against the joist.
One you’ve tightened it up, take it back one half twist and just make sure that it hasn’t moved – get the spirit level back on it again.
Now we’re going to us the other side of the stirrup to where we marked to start our second hole. This is so the two bolts are done up on opposite sides. Also because the hole on the marked side should be right anyway. Get your sharpie and draw around where the hole is so you know where to widen the hole.
Once that is done, unfortunately, you’ll have to unbolt the bolt again and take it out. Then remove the joist and lay it down ready for drilling.
You can see that it’s a fair way out. I’m using a size 16 hole cutting bit. If the second hole is too big it doesn’t matter because the first bolt olds it perfectly, the second bolt just keeps the stirrup closed to support the weight. Drill through expanding the existing hole.
Now you can put the joist back in place, put the first bolt through, and then put the other bolt through from the opposite side. Don’t forget to use the spirit level in between to make sure it remains level.
You can see in the photo above that although the stirrup isn’t level, the joist is and that’s what is important. Next do the final check to make sure that with the bearer on top, it’s still level.
And then you move on to the next joist and start all over again. 🙂
Next post – putting the bearers together.
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Posted by on November 5, 2011 in Decking [COMPLETE]


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