Two story house - tall platforms, open underneath

Ugh... I misunderstood the availability of I-Beams in my area. Cost goes through the roof once I factor in handling fees and packaging fees for not-a-full-pallet orders.

Looking back at 2x10 for the joists and rim boards. A couple hundred pounds heavier. Still need to do the math on those casters.
 
Ugh... I misunderstood the availability of I-Beams in my area. Cost goes through the roof once I factor in handling fees and packaging fees for not-a-full-pallet orders.

Looking back at 2x10 for the joists and rim boards. A couple hundred pounds heavier. Still need to do the math on those casters.
Was that from your local Hardware and timber place? Try looking at a local truss manufacturer. That is where I got mine from.
Another option is floor joists constructed by the truss manufacturer. Usually 4x2 top and bottom cords with a pressed steel web in between. The truss mob should also be able to do computations for span and load for you with their software. a 250mm high truss (10in) can span 5000mm (not quite 17ft) at 450mm centers (18in).
90x35 (top and bottom cord) MGP10 (Timber Grade) 5000 (Span at 450mm Centres)
http://trussform.co.uk/site_images/Easi--Joists.JPG
Got to be worth a look.
 
Is there an update on this build?
 
Thanks again everyone for your advice. I learned a lot on this build, and am very happy with the results.

I'm not ready to stop learning though, so please, constructive feedback is welcome!

Part 1 - Planning

You all saw this already, scroll up. TL;DR I needed to build a 12-ft by 16-ft two-story house on a 16x16 rolling platform featuring a trapdoor, slide, and stairway. The big challenge was the fact that the lower level needed to be as open as possible, meaning all upper deck support would need to come from three stud walls in an "H" configuration.

Part 2 - No Plan Survives Contact With The Enemy

We realize three fundamental truths at the exact same time.

Number One
We build our sets in a shop with
a door to the stage that's a ten-foot width.

Number Two:
We share the stage with orchestra, vocal, and band
So a set piece on the stage for months cannot stand

Number Three:
If we wait till their off which is what they seek
Then we've got to build this monster in just over a week

Part 3 - Change of plans

So, there's a nook on the stage where our orchestra shells live. During vocal, band, and orchestra concerts, they'll be using the shells on stage, which means...

If we shrink the house to be 12x12 on a 12x16 platform, we can squeeze the set piece into the nook, and nobody will mind. This means we can spend a month building making mistakes instead of a week.

Behold, a new design:
Screen Shot 2017-11-17 at 12.12.52 PM.png

With this change approved by the TD and Director, we go shopping.

Part 4 - Boy that's Wobbly

We build the side stud walls. Then we build the interior stud wall. I'm an idiot and we build the interior wall 2 inches too wide. Fortunately, making a stud wall shorter is super easy.

With the stud walls up, we install the rim boards. The original design had them as being 2x10, but now that we've only got a 12' span instead of 16', I can get away with something smaller. We rip them down to 2x6, which gives us a pile of extra 2x4ish lumber that I'll use later for the ladder.

After the rim boards came the two outer joists, giving us a full square up top. We filled in the rest of the joists, and added the small interior wall that frames the slide.

Keep in mind we're using screws, which makes this take a lot longer. Somebody convince me that I won't hate myself at strike if I use nails next time.

Behold!
initial framing.JPG

With all that up, the wobbliness is unfortunately too much. We need to keep these stud walls from flexing and parallelogramming. Gimme better words for those phenomena, please. Two things solved this problem:

1. adding the upper deck, this keeps the whole thing from twisting around it's Z-axis, which I previously referred to as 'flexing'.
2. adding diagonal braces in the corners of the side walls, this helps prevent those walls from skewing aka parallelogramming. Or is it called racking?
3. probably didn't do much, but plywood skinning parts of the interior wall probably helped too.

Part 5 - Chutes & Ladders

The final set will have upper level 'sidewalks' that access the exterior of the barber shop (in future steampunk london, there are sidewalks on the second floor, duh), but we're also going to need a way upstairs on the platform as well. That's coming in the form of a ships ladder.

I found some really great videos online. This one I liked the most. In hindsight I wish I would have gone to the effort to route slots for the treads, or even carve a dado for each. While the kids installed the upper deck, I threw this together:

ladder.JPG ladder2.JPG

Lets fast forward a week or two and revisit why I should have taken the time to properly secure those treads. Turns out two 4" screws from each end isn't enough.

uhoh.JPG uhoh2.JPG uhoh3.JPG

All fixed in the ugliest way imaginable :(

braceallthethings.JPG

That all happened while we were working on the slide. This idea changed a lot, and required some tweaks along the way. The general idea is that the top half of the slide is inside the structure, is accessed from a trapdoor upstairs, and sends you out the side of the house.

I build the framing, guess what, more 2x4.
slideframe.JPG

We installed a sheet of plywood that had been sanded like crazy, painted, and then slicked with a coat of clear poly.

But we built our slide too slippery and too steep, you can't control your descent at all, which means safely falling is impossible. We opted to just shorten the slide and drop the top down a foot, reducing the angle to something more manageable.

The bottom half of the slide is attached to the side of the set when needed using some gate latches. It's another slippery sheet of plywood, the shallower angle means the actor can let gravity do it's work without having to worry about slamming in to the ground.

slide.JPG

Part 6 - Make it pretty!

That's it for the construction, now for some final photos!

Imgur Album because I ran out of images for this post:
https://imgur.com/a/IHOXI

Youtube video of us testing the slide, stay tuned to the end for a close up of the floor:
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Youtube video of strike:
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Nice post. The set looks really good. Thanks for putting it up.
If you nail it will be quicker but when it comes time to strike you will spend the saved hours pulling nails and making it safe again. I have done that except I cut the nails so I didn't have to pull them at the time but regretted it later when reusing materials later. Stick with screws.you can reuse them if they are still in good nick and they hold in a different way for joining frames when the join will not be seen I use roofing screws. Good positive hex heads.
Regards
Geoff
 
Flipping through the pics before finishing the post, I thought, "those stair treads are a problem." Then I flipped to the next picture. How did I know? I learned the same hard way myself way back when. No one was hurt by my mistake, and hopefully not here either, but it's a lesson in the seriousness of what we do.

It's the screwing into end-grain that doesn't cut it. Brackets like you did, or blocks work. I wouldn't dado, because you're losing thickness in the stringer. I like to do a second stringer, cut into sections that fit the full distance between the treads, for a sort of built-up dado.
 
If you nail it will be quicker but when it comes time to strike you will spend the saved hours pulling nails and making it safe again.

Nail it, and at the strike have the crew strike and park a bunch of the chorus (or cast) in a corner with nail pullers clearing lumber. Back in the day the strike party(ies) never started until the T.D. declared the strike complete. Never had a problem getting help clearing lumber, taking out trash, sweeping up, etc., etc.

As to stairs, a 1/4" dado holding treads in a 2x12 1-storey stringer will hold all the load you can put on the treads. Run a piece of 1/4" all thread from side to side below every other tread (washer & nut on the outside) to hold it together.
 
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I'm super excited to build another set of stairs, now I've got some options! I was leaning toward the dado or laminated blocks option that kicknargel suggested, but I'm curious about what you're describing JonCarter. Are you saying cut a small dado, fit the treads, and then in order to prevent the stringers from separating run a long threaded rod from stringer-to-stringer under each tread?
 
I'm super excited to build another set of stairs, now I've got some options! I was leaning toward the dado or laminated blocks option that kicknargel suggested, but I'm curious about what you're describing JonCarter. Are you saying cut a small dado, fit the treads, and then in order to prevent the stringers from separating run a long threaded rod from stringer-to-stringer under each tread?
Every other tread.
 
Yep, @darinlwebb, the ready thread keeps the stringers from spreading. 1/4" rod is enough; use 3/8" if you don't believe it. Just use good-sized fender (1" dia min.) washers under the nuts on the outside of the stringers.
 
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Yep, @darinlwebb, the ready thread keeps the stringers from spreading. 1/4" rod is enough; use 3/8" if you don't believe it. Just use good-sized fender (1" dia min.) washers under the nuts on the outside of the stringers.

you'll see this in wooden A frame ladders a lot. I've never done it on scenic stuff because fender washers and nuts on the outside of the stringer is generally an eye sore for the designer. I guess if you want the stair to break down for shipping it makes sense? But why would you want to do that?
 
you'll see this in wooden A frame ladders a lot. I've never done it on scenic stuff because fender washers and nuts on the outside of the stringer is generally an eye sore for the designer. I guess if you want the stair to break down for shipping it makes sense? But why would you want to do that?
Screw through the stringers into the treads will do the same thing. Fill the heads or screw from the back and skew them. If the dado is a good fit the screws really hold little load and stop things coming apart. Every tread will be easy.
 
Screw through the stringers into the treads will do the same thing. Fill the heads or screw from the back and skew them. If the dado is a good fit the screws really hold little load and stop things coming apart. Every tread will be easy.
@Crisp image I've seen the All-thread and fender washers technique used on escape stairs to permit them to be more or less 'flat-packed' for storage in tight for storage venues. Two across (front & rear) under the highest tread and likewise two more under the lowest tread. Occasionally two more approximately half way up. Tight, square and solid yet easy to disassemble and reuse with virtually no damage from repeated assembly and disassembly. One more useful technique to file away.
Toodleoo!
Ron Hebbard.
 
2. adding diagonal braces in the corners of the side walls, this helps prevent those walls from skewing aka parallelogramming. Or is it called racking?
3. probably didn't do much, but plywood skinning parts of the interior wall probably helped too.

Just leaving a note that the phenomenon you're talking about is indeed called "racking" and the plywood sheathing is common practice in the construction industry when a house is sheathed with foam board rather than strictly plywood. The corners are composed with half the thickness being plywood and the second half being foam board. In the construction industry, typically it's plywood sheathing that controls the racking, however it also occurs that occasionally a metal brace is attached to the studs on an angle.

Important note as far as from a construction standpoint: unless joists are being placed directly in line with studs, the top plate must be doubled with the second top plate being offset. I'm sure I'm preaching to the choir with this one, however I have personally seen some strange things come from those who were confident in their abilities and knowledge on use of stud walls.

Note: I assume no responsibility in how the information I have provided is used, shared, or understood. Use any information I have provided at your own risk.
 

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