# Two story house - tall platforms, open underneath



## darinlwebb (Aug 15, 2017)

I'm trying to figure out the best way to build this, not finding a bunch of definitive answers in books and online, but lots of ideas.

I'm building a two-story house, 12' x 16' house on a 16'x16' platform, on wheels obviously...

What's troubling me are the best ways to structurally support the upper level - lots of action up there - while still providing a relatively open lower level.

For the lower level, the design calls for ~7 walls on the SR and SL sides, with a perpendicular dividing wall 4' in, like so:

http://imgur.com/a/CpKAx

The 12' x 16' area above the walls needs to support flats, similar to the walls, as well as several actors.

Originally I was thinking stud walls for the walls. One of the side walls will have a window, and the back wall will have a door. Augmenting that would have to be columns throughout the lower level.

Another idea would be to build it like a free-standing deck - with three rows of columns SL, Center, and Sr, supporting left-to-right joists, upon which the upper level's platforms would be seated.

Has anyone build anything similar? Know of any resources for learning here?


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## BillConnerFASTC (Aug 16, 2017)

I think it would be easy to build using conventional stick framing, but having to be on a wagon probably makes that too heavy for a feasible number of affordable casters. A lot of air casters might work but $$. That would lead me to stressed skin panels - probably 4" foam and I'd try 1/4" ply but might have to go to 3/8 or even 1/2 for some parts. Lot of engineering. Not inexpensive no matter which way you go.


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## Quillons (Aug 16, 2017)

A learning resource might be Structural Design for the Stage by Alys Holden and Ben Sammler. 
Ch 3: Stress Analysis for Beams, with a section on overhangs and cantilevers.
Ch 6: Wood Column Analysis and Design
Ch 9: Steel Column Analysis and Design


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## bobgaggle (Aug 16, 2017)

You have any art from the designer? Would probably help to see what this thing is supposed to look like.


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## darinlwebb (Aug 16, 2017)

Quillons said:


> A learning resource might be Structural Design for the Stage by Alys Holden and Ben Sammler.



I just got this book last week. It's thicker than my college calculus book, and has just as much math :/


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## JonCarter (Aug 16, 2017)

darinlwebb said:


> I'm trying to figure out the best way to build this, not finding a bunch of definitive answers in books and online, but lots of ideas.
> 
> I'm building a two-story house, 12' x 16' house on a 16'x16' platform, on wheels obviously..."


Worked on a show which did this some years ago. Email me off board-- [email protected]


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## darinlwebb (Aug 17, 2017)

Thanks for the feedback everyone. Continuing with the stud wall plan, I upgraded the design to 2x6 framing for the SR and SL walls (keeping 2x4 for the interior wall). This helps support 2x6 joists running SR to SL.

Here's an exploded model, downstage to the lower left. The lower platform extends an extra 4 feet downstage from the rest of the unit, which is all stacked on the upstage 12 feet.

http://imgur.com/a/6W0zd

The window on the SL side is there to allow a slide from the trap door in the upper platform. The slide will turn 90 degrees downstage and continue to the floor.

We've got a while before we can start building this - apparently other folks don't want to work around a 12' x 16' x 20' box - so I'm going to continue workshopping this between myself and the scenic designer. Safety wins all arguments, and the interior designs are all still very flexible, and will work around whatever is needed structurally, I'd just like to keep the lower level as open as possible.

Oh, and I realized I didn't say what show. Sweeney Todd, not the musical. The large lower interior is the pie shop, directly above it the barber shop, both will see plenty of action.

On a lighting side note, we're thinking about hiding some LED strip lights or using practicals to get some illumination inside the pie shop, but otherwise just blocking to keep actors out of the shade.


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## RonHebbard (Aug 17, 2017)

darinlwebb said:


> I just got this book last week. It's thicker than my college calculus book, and has just as much math :/


 @darinlwebb *And your point?* 
Are you saying math's a good thing or a bad thing??
Did you ever open your "college calculus book"?
If math's not your strong point, maybe the book alone will be strong enough to support your set?
Possibly you're saying you won't let a little learning *hold you up* from building a set that won't *hold up* on its own?
@Quillons What's your take on the poster's comments Re: the the relative thicknesses of college level texts?
I've heard concerns expressed regarding the relative stress levels of attending various colleges but I remain naively unaware of any such comparisons regarding the relative structural supporting capabilities of their actual tomes.
I guess this lends a whole new meaning to the term: "supporting documentation."
Toodleoo!
Ron Hebbard.


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## darinlwebb (Aug 17, 2017)

RonHebbard said:


> @darinlwebb *And your point?*



Oh calm down 

I just thought it was funny that the book suggested was one that I had just recently picked up. I loved calculus, and I'm excited to dive in to the book. That said, to use that book to help me with this problem would be an incredibly time-consuming endeavor because that would be starting at square one, and in the end would primarily serve to help me come up with less expensive and more efficient designs. Because I haven't become an expert on the topic, this design is going to probably end up being heavy, expensive, and more sturdy than it needs to be.


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## BillConnerFASTC (Aug 17, 2017)

It looks like your 2x6s are 2 ft on center, which is equivalent to 2x4s 16 inches on center. This kind of bearing wall does depend on sheathing to support the floir above. Dont overlook that.

I question the 2x6 joists spanning 16' - a lot. Without looking, 2x10 seems close if 16 inches on center. May be an application for TJIs. (Or stressed skin panels.)

I also suggest you early on calculate the weight of the entire unit with props and, if on when moving, performers. More load on edges with bearing walls. A lot of casters and it will not be easy to move. I hope it is a atraight line move so you could add a hand winch. 

Just saying, dont put off castering till last. It is the bigger challenge compared to building two stories.


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## BillConnerFASTC (Aug 17, 2017)

Checked some span tables. No 2 SPF - typical of grade and specis in big box stores - 2 x 12 16 inches on center for 16 ft span. Home depot lists a doug fir that might make it in 2x10. This is a good calculator: http://www.awc.org/codes-standards/calculators-software/spancalc


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## Quillons (Aug 17, 2017)

darinlwebb said:


> I just got this book last week. It's thicker than my college calculus book, and has just as much math :/



I haven't looked through all of it (I'm able to look at an e-copy through my school library), but... yeah. It's a textbook. From the classes I've taken so far I think this book combines Statics, Mechanics of Materials, and maybe a Structures class (Physics and some Calculus being pre-requisites). Call it a long-term project and look up youtube tutorials as you read.
And apparently I should have taken calc at your school!


darinlwebb said:


> I loved calculus


O.O
But in all seriousness, if you actually liked calc, you will be able to work your way through this. It may be rough at times, but you got this.


RonHebbard said:


> I remain naively unaware of any such comparisons regarding the relative structural supporting capabilities of their actual tomes.


I've got a nearly 1000 page Materials and Processes in Manufacturing you may like...
Or I could head over to the physics department and find a book on anti-gravity (or some such). I would guess that most actors wouldn't come near it with a ten-foot stick; therefore due to the anti-gravitational properties of the book and the reluctance of the actors, no structure is needed at all! Actors will merely float over and around the book!


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## BillConnerFASTC (Aug 17, 2017)

I believe the book was based on the "structures" classes at YSD. It was published well after I, along with my trusty slide rule, took the class. I'm still enthralled by stressed skin panels and how far something wooden and so thin can span, which is my clearest memory from the classes.


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## darinlwebb (Aug 17, 2017)

Thanks @Quillons for the overview. That gives me some expectations and I was also thinking of planning my reading of it to be more 'class-like' and supplemented with other reading/viewing.

@BillConnerFASTC - I appreciate the questioning of the materials choice. That's something I'll look in to, especially the span tables and making sure the joists are properly sized. When it comes to the stud walls, I was partly looking at just increasing the square inches that the joists would have available to sit on (bearing length?), and I wasn't super comfortable with them resting on a 2x4 top plate. Thanks a lot for the link to the AWC site, lots of good reading there.


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## RonHebbard (Aug 17, 2017)

Quillons said:


> I haven't looked through all of it (I'm able to look at an e-copy through my school library), but... yeah. It's a textbook. From the classes I've taken so far I think this book combines Statics, Mechanics of Materials, and maybe a Structures class (Physics and some Calculus being pre-requisites). Call it a long-term project and look up youtube tutorials as you read.
> And apparently I should have taken calc at your school!
> 
> 
> ...


***************************************************************************************
@Quillons : *In all BUT seriousness;* What you're saying is "therefore due to the anti-gravitational properties / magnetic *reluctance* of the book AND the *reluctance* of the actors, no structure is needed at all! Actors will merely float over and around the book!"
Understood, got it and essentially correct, right?
*Masterfully explained for us mere mortals AND with nary a need for Calculus.* 
Are you sure you want to continue working in engineering rather than progressing into lecturing? 
Anyone possessing your 'natural gift' for elegantly simplifying, expressing and explaining complex cross-disciplinary concepts perhaps ought to reconsider their end goals.
*Keep it up Quill, your humor is much appreciated.* There still may be a position at Tait in your future.
Toodleoo!
Ron Hebbard.


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## BillConnerFASTC (Aug 17, 2017)

For thought, traditional western framing for house building generally presumes a double top plate (someone will correct this terminology as house building has more names for parts than theatre does) with 2 x 4 studs 16" oc and a rim joist and then the joist can then land anywhere on the plate If you use "optimum value engineering" framing it uses 2 x 6 studs 24" on center, a single top plate along with rim joist, but requires the joists and studs align. (More to it but really affecting you.)

Yes - the 2 x 6 vs 2 x 4 studs reduce span 4", from approx 15-7 top 15-3, and provides a little more bearing, but house framing has relied on joists bearing on 2 x 4 plates for a long time without major problems. Plus, looking around, its hard to find sawn lumber that will span 16' on 24" centers without getting into 1 and better or select structural grades - which I don't think I've ever seen other than in span tables.


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## Crisp image (Aug 17, 2017)

I have made something like it for Addams family. Although the unsupported span was only half of what you want. The materials I used was a stick frame that was made to be 1200mm square column at each end that had supporting wheels mounted underneath on Laminated vernier Lumber (LVL) and then used engineered timber 'I' beams (45mmx 200mm) to support the load. The I beams are light and strong I had 4 at 400mm centers to do my job. you may be able to get the same style of beams that are larger for the span but lighter than solid timber. I can pick up each 4800mm beam at the balance point with one had and carry them easily.


The beams were only supported where the door recess is but canter levered over the rest of the ends of the set. See the next photo


I hope this gives you some ideas on making your set. 
Regards
Crispy


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## darinlwebb (Aug 24, 2017)

After reading up on engineered I-beams and the benefits of 2x6 vs 2x4 studs, as well as reviewing some of the design requirements (requests) for height and lack of support columns/legs, I've adjusted the design.

Everything is 16" on center, with some slight exceptions. Most joists are now 9.5' engineered wood I-beams, except the outer beams and two inner beams (might switch the inner beams too).

Walls are all 2x4.

These changes have significantly cut down on weight. What you see in the photos, not including the bottom platforms, would weigh in at about 1,040 pounds. I need to finish the math for the rest of the unit and figure out what casters are going to look like. Prior designs would have been closer to 1400 - using 2x6 studs and 2x12 joists.

http://imgur.com/a/MstC2

My original plan was to sit regular 4x8 platforms on top of the joists, but now I'm tempted to just skin the top of the joists with 3/4 ply. Cuts down a lot of weight, and I could use that platform inventory elsewhere.


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## BillConnerFASTC (Aug 24, 2017)

Looks good. Just follow all the rules for the TJIs - squash blocks at bearing points, blocking, and deck glued IIRC. Its a great product but highly engineered and much less tolreant than sawn lumber to varying details. And i believe mixing sawn lumber with engineered is risky because it changes size so differently.

The thing that always deterred me from using them was the gluing, which made strike longer and basically meant no salvage of materials, all dumpster.


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## Crisp image (Aug 24, 2017)

Glad the I beams are OK for you. I would like to ask why you have used full timber beams around the edge? I have not done any of the computations for your design so I am not sure of the span or the loading. When I used the beams they were at 16in centres (400mm in metric).
Make sure you share some photos of the finished set.
Regards
Crispy


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## darinlwebb (Aug 26, 2017)

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.


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## Crisp image (Aug 26, 2017)

darinlwebb said:


> 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.


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## Crisp image (Sep 16, 2017)

Is there an update on this build?


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## darinlwebb (Nov 17, 2017)

Crisp image said:


> Is there an update on this build?



Yes! Coming soon!

The piece was a success for Sweeney Todd, and it's being re-used this weekend for our freshman production of Treasure Island.


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## darinlwebb (Nov 17, 2017)

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:



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!


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:



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.



All fixed in the ugliest way imaginable 



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.


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.



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:


Youtube video of strike:


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## Crisp image (Nov 17, 2017)

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


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## kicknargel (Nov 19, 2017)

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.


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## JonCarter (Nov 19, 2017)

Crisp image said:


> 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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## darinlwebb (Dec 4, 2017)

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?


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## Crisp image (Dec 4, 2017)

darinlwebb said:


> 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.


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## JonCarter (Dec 6, 2017)

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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## bobgaggle (Dec 7, 2017)

JonCarter said:


> 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?


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## Crisp image (Dec 8, 2017)

bobgaggle said:


> 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.


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## RonHebbard (Dec 8, 2017)

Crisp image said:


> 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.


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## cdiamondz (Oct 30, 2018)

darinlwebb said:


> 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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