Small-count truss job: crane or hand?

[Bob Dylan]

Span about 25 feet. Plate height about 13'-4". Seven scissors, 12/12 top chord, 7/12 bottom, to place, fix, brace. Inboard end where placement can start permits something to brace to. See pics. There is a gable-end truss as well.

For transport purposes, trusses top out at 11-feet height, and are top-capped. The underside rise is about 5'-0", making that ceiling height 18'-4".

No crane owned by framer, and no Lull or equivalent.

Rent the crane with each hour costing about 1.5 crew-hours? Or erect by hand?

[framer]

as long as you have a scaffold in the center, by hand should be easy.

[David Meiland]

The trusses will be about 12' tall, add that to the plate height and a guy will have to be standing about 20' above the deck to man-handle them near the ridge. That means scaffold stacked 4 frames high with guardrail and outriggers, plus an extension ladder to get up and down safely. I'd rather get the boom truck.... faster/safer/easier.

[jimAKAblue]

If you aren't familiar with setting trusses by hand, you probably should rent the crane. One note: there is no reason why you should install a bracket below the bottom of the trusses as you are showing. That would be a significant impediment and do nothing to stabilize the trusses. The scaffolding would also be an impediment and I wouldn't want one set up. In fact, if it was set up, I'd need it taken down to set the trusses.

The trusses and layout that you show is very basic with one exception: the trusses will be top heavy and have a tendency to roll upside down. They aren't exceptionally heavy if they are all 2x4 (or less) chords and therefore they could be set with three guys.

If you are setting them by hand, the steepness of the upper chord works to your advantage. If pressed, I could envision setting them with just two but three is safer/easier. Most guys would insist of having four. It all depends on how efficient you want to be, time wise.

The biggest issue is the tight space. With only 16' of room to work with, it will take a little co-ordination and some basic staging to get these things up smoothly. That's where truss handling experience comes into play. To get these set by hand, you'll probably have to stack them against the far wall with one end on the wall, peak up and the other on the ground. Then, when you set the truss, you'll have to know how to move them without the peak rolling around . To do that, we assign someone with the duty of supporting/stabilizing the peak while the other guy(s), move the truss into position.

The key to this entire operation is controlling the peak. With the set up you are showing in the sketchup, it doesn't look that hard. Keep in mind though, that I've probably set 1000 trusses by hand; many much larger and many two storys up and most were set with 4 guys or less.

I probably would only use 2 helpers on your set up, even if I had the other guy available. I'd work the peak. I wouldn't be standing on the top chord. I'd be standing on the 7/12 pitch (lower) chord. As soon as they got the peak into my hand, everything would be safe in in control; one end would be in the hands of a man on the wall, the peak would be in my hand and the guy on the ground would be able to walk up a ladder with the lowest end of the truss. If the truss was heavy, I'd help by lifting at the peak. If the truss was light, I'd just let him walk it up.

Once both ends were set on the wall, I'd lace the top, hanging a lacer over 25.5".The lacer on the top could be on the outside or maybe inside. I'd lace the bottom, probably in two places, leaving nothing hanging over.

Figure 5 minutes per truss including staging time.

Again, if you don't handles trusses all the time, these aren't the type/style to learn on. At 18' for the top chord they are small, so it's not impossible to learn on them but they are extremely top heavy and will want to rotate.

[Nate E]

Hand set them
-Nate

[THWagar]

I would set them by hand just for the scheduling factor.

Great diagram of the situation. My only thought is if your thinking of putting wheels on that scaffold and rolling it along, will there be any bracing for the walls that will be in way.

[Bob Dylan]

Crane schedule for day after tomorrow. Thanks for all who provided opinion.

With roof peak about 30 feet off ground, we'll take the opportunity to prebuild the gable with its lookouts, and sheath the gable end truss while we are at it. The subassembly will be the first thing that goes up. Pics attached of the on-the-ground build plan.

[jimAKAblue]

Crane schedule for day after tomorrow. Thanks for all who provided opinion.

With roof peak about 30 feet off ground, we'll take the opportunity to prebuild the gable with its lookouts, and sheath the gable end truss while we are at it. The subassembly will be the first thing that goes up. Pics attached of the on-the-ground build plan.

Don't set that gable first!

Set and brace the trusses. It will only take a few minutes to run the lacers on the bottom chords. Then, when you set the gable, you will have a solid framework to stand in/on, and brace to.


When I first started using cranes to set the trusses, we followed the same patterns as we did when we set by hand. It was a rookie mistake. Because our gables were always standing before we set the trusses, we automatically set them first before we set the trusses. That created a situation that put braces in the way. Sometimes, it blocked out the vision of the crane operator. It took me a few sets with the crane to discover that it's significantly easier and faster and safer. to set the gable last.

Do you have some reason why you think you should set the gable assembly first?

[Bob Dylan]

You're right, Jim. We'll go in to out, and swing the gable last.

[David Meiland]

It depends a lot on where the boom truck sets up, and where the trusses are. Furthest truss from the boom goes up first, and if it's one of the gables you can fly it over with some legs on it to nail to the outside of the wall. From there, start setting commons and tying them together with 1x.

[jimAKAblue]

.... if it's one of the gables you can fly it over with some legs on it to nail to the outside of the wall.....

There are several reasons why I'm not fond of this approach. 1) it takes time to nail the legs on. 2) it takes nails to nail the leg on. 3) it takes time to remove the legs. 4) it takes a ladder to remove the legs. 5) it creates holes in the housewrap. 6)the holes have to be patched in the house wrap. 7)it takes a ladder to patch the holes in the house wrap. 8) legs don't properly plumb the gable without additional bracing. 9) If you add additional temp bracing, it takes more time. 10) I've had a set of trusses fold up due to inadequate bracing. I refuse to work on trusses that don't have a solid anchor point.

For the record: I do not agree that the original anchor point drawn by OP is safe. When I set my first truss, IT WILL BE ROCK SOLID, especially at my lacer points. THERE ARE NO EXCEPTIONS, unless the trusses are small that they are the exception! The top heavy scissor trusses do not fall into the "these are small and light and we can skimp on the first anchor" rule.

For the record #2: I was not in charge when the trusses folded up. I was there with my guys to assist another foreman. We set the trusses and he had to pull a few braces: probably to replumb the gable. The gable just toppled off the wall and the trusses laid themselves down. No one was hurt but I learned a lesson (I was an apprentice) that I never forgot.

One of the most significant advantages to setting the gable last is the ability to quickly receive it, and brace it rock solid within one minute of it arriving, all while the crane still has it. I have locked in HUGE gables in seconds simply because we have all the assembled trusses locked in behind us. We lay a brace down on the bottom chords and nail an angled brace up to the gable, after plumbing it with a level. Rarely do we ever have to touch that brace again. Typically, we will have a strong back (L style) securely fastened to large gables and the bracing is attached near, or on, the "strong back". The bracing stays on as a permanent brace that solidifies the gable studs forever.

I've done the "nail some legs on it". On rare occasions, it's still a good solution. It's one to keep in the bag o' tricks.

[jimAKAblue]

Just elaborating on the anchor point.

In the second picture of the OP's sketch, he shows the top lacer being anchored to a "2x10". When I ran my crew, I would not accept that as being a "anchor" point. I insisted that every anchor point that held a truss system had to be solid with ZERO give. To achieve that in the sketch shown, I'd insist that the lacer be run back all the way to the ridge or an additional brace run down to the deck at the point that the lacer caught the 2x10 rafter.

I suspect that the OP would do the same and the pic is just that: a pic.

[Chopper]

It depends a lot on where the boom truck sets up, and where the trusses are. Furthest truss from the boom goes up first, and if it's one of the gables you can fly it over with some legs on it to nail to the outside of the wall. From there, start setting commons and tying them together with 1x.

David, I work for a truss and panel mfg. I've seen a lot of trusses and gables flown up and set the way you describe. Your also right, it depends on where the crane and trusses and can be set relative to the building.

I would almost always get a crane to set trusses. It's almost always faster and I believe safer.

[Bob Dylan]

Yesterday, crane arrival 1:00 pm, departure about an hour later. The pic shows the last thing raised, the gable endwall truss and first inboard common, with its array of lookouts and fly rafters all attached.

[David Meiland]

Nice wall-walker scaffold, I wish it was mine...