Day 4 of making the ladder (by alaric)
I wasn't scheduled another project day until later in the month, but I had some spare time and the opportunity to grab a volunteer (my father in law, Len) to help, so yesterday I mounted the ladder on the wall!
(Background: Days 1, 2 and 3).
The first step was drilling the holes. I held the ladder up against the wall, and checked it with a spirit level, while Len pencilled the holes in.
Then it was time to drill. I'm very fond of my SDS+ drill (as I have mentioned previously) so it was good to have an excuse to get Vera out again:
Without further ado, I started to drill:
However, disaster struck on one of the holes - the bit suddenly went sideways, into some kind of void inside the concrete blocks of the wall. Doh! I fitted a smaller drill bit and managed to drill back into the route the hole was supposed to take, then drill that out so the bolt could go in straight, but now it was in the middle of a much larger hole than intended so it would just rattle around and not hold anything.
Thankfully, I over-engineered the design so that it had far more mountings to the wall than it really needed, so none of them were all that critical. What I did was to jam a piece of wooden dowel into the misaligned part of the hole to fill much of the space, then squirt a load of fine mortar (2 parts sand to 1 part cement) into the rest. More on that later.
With that done, I could fit the anchor bolts to the ladder. The anchor bolts consist of a normal-seeming bolt that goes through the ladder, into a sleeve that goes into the wall. The sleeve is a metal tube, but at the far end is a conical nut that the bolt screws into. When the bolt is tightened the conical nut is pulled into the metal sleeve, forcing it to expand to tightly squeeze against the surrounding masonry.
So to start with, I put all the bolts through the ladder and screwed the sleeves on a few turns to hold them in place:
Then we lifted it up and guided the bolts into the holes and wiggled it into place. Of course, as it's nearly impossible to drill holes into masonry accurately, the holes were a few millimetres out from where the holes in the ladder are, so beyond a certain point the bolts started to chafe against the masonry and had to be tapped into place with a mallet:
All except the hole packed with mortar, of course, which the bolt just slid into squelchily.
Then we tightened the bolts - all except the one in the wet mortar; I'm going to give that a few days for the mortar to cure before I tighten it, otherwise there's no resistance to the expanding sleeve and it'll just squeeze the mortar out.
And then it was time for a test.
After gingerly doing a few pull-ups on the ladder, I climbed onto it. And then to check it's really secure, I put as much strain on it as I could by stretching myself out to get the maximum torque:
This failed to tear it out of the wall, so the next step was to actually climb up to the roof:
See how the top rung protects the gutter? That's careful design, that is! 🙂
However, it was cold, damp, and slimy up there, so I climbed back down and had some lunch. After lunch, I put some sealant around the edges of the mounting flanges, to prevent water getting in behind them where it might soak into the wall through the bolt hole, or lurk around and make the flanges rust. Also, I like sealant and will use it whenever I can:
This stuff is "frame sealant", which is specifically designed to join metal, wood and masonry outdoors, as opposed to the stuff you use in your bathroom. It's extra sticky to bond to awkward surfaces and extra stretchy to account for thermal expansion differences.
I also cut some small cubes of wood and pressed them into the open ends at the top of the ladder, packed with plenty of sealant. I tapped them in with a hammer to about a centimetre below the open end and squeezed more sealant in on top, and domed it slightly to keep rain from pooling.
Now that ladder is done, as soon as I get some time I'm going up there to secure part of the plastic sheet that's flapping up, and have a general poke around to see if I can find any holes to seal. With more sealant! Yay!
Also, I need to touch up the paint on the ladder in a few spots where I dinged it moving it around. Whoops!
Alaric, Building Maintenance, Metalworking | alaric | 
Mon 18th Feb 2013 5:23 pm
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