So this happened…
This was flat when I glued a bunch of strips on to make a clapboard siding look. It’s been cold but not that cold.
Ironically the building out is fine. No warping.
a bit too much cement? 
I think it needs some structural support. the glue does have an effect, but if braced will stay flat.
if you are intending a flat perhaps as little as 1/2 thick bracing would work.
Al P.
Not really sure what the issue is. I think it might be a combination of the temperature swing from when I glued it until now, lack of bracing and the MEK along with the size.
I’ll see if I can’t flatten it out some and then when I glued it up to the rest of the building try my darnest to get it flat.
I wonder what would happen if I scored the backside in a couple places say like halfway through. I wonder if that would be enough to “destress” the bend.
I have some warping on the Burke. I had to go in and add an internal brace between the longer side walls and pull them back in. My roof also sagged so that internal brace is also a truss. That fixed most of the issue. But the unsupported corners of the false front are warping a bit. Not enough to care but they certainly are no longer flat. It is all the more reason I am liking the idea of a 1"foam backer to .020 styrene walls for the large buildings. I have a test piece of foam and styrene glued up with Titebond 3 per Eric Mueller’s suggestion. I haven’t checked it yet for adhesion but if what he reports is what I find and the bond is good then this will be how I proceed with larger flat walls. Not to mention .020 is a lot easier to work with than .125.
Devon,
Thanks for checking in. I’m wondering about using foam as well as a hard shell. Funny thing is, these pieces haven’t warped on anything outside and they are hardly braced at all. Mostly just butt joints. And the sizes of the pieces isn’t anything bigger than what I’ve already made.
The only thing I can think of is the thinner strips are shrinking at a faster rate than the thicker .125 sheet.
A little warping I kinda expected but when the main wall has such a curve it was a tad disconcerting.
This is the shorter wall that did the same thing too.
I don’t have a clue if this is even a thing with styrene, but some of the materials I use in sign construction are “directional”. That is to say that when they expand or contract they do it in known directions.
I wonder if perhaps the orientation of the substrate is different from the siding and as the siding adhesive cures it;'s pulling against the substrate.
Just a wild ass guess. But your warping does seem odd.
Well considering I am using .020 strips on .125 walls and am having the same issue id say it has something to do with the strips shrinking a different rate due likely to the MEK dissolving them. Maybe as they re-
solidfy they shrink?
I think you are correct. I learned over the years that most of the thicker “plastics” ( using term lightly) DO NOT like to lay flat after something has been applied to the surface of them. The expansion and contraction rates vary. Now if you are working with acrylic and not styrene I can tell you for sure that acrylic DOES NOT like to lay flat.
However as suggested if you make a light frame say 1/2" x1/2" and tack the material to it that should rectify the issue. You can also v-groove/flute the back side as thought but it will weaken it although it will work with v grooves just like the SR-71 fuselage.
Mind you I have only worked with this stuff since 2007 so I don’t have a lot of experience with it so I’m not asking for a debate only sharing that I agree with your thoughts.
What’s strange is the building I just finished for the MIK build shows no signs of warping. And I applied the strips on a flat wall and then glued it all up. There was a little warping but nothing this bad. And the wall sections are just about the same size too.
I wonder if the directional expansion has anything to do with it. Both pieces were cutt from the shorter side of the 4x8 sheet. But then again I have no clue the ordination of the stuff I used for the MIK build.
I might try gluing some bracing on the back after scoring them. Or keep my original idea of using some PVC lumber as a frame and glue these too the PVC frame.
I’ve had that problem with styrene outside myself. I’m not sure why it occurs, but I suspect that styrene isn’t “stable” enough to resist the weather–especially cycles of heat/cool where one side is in the sun and the other in shadow.
Bracing can help. If you’re building with sheets, you can make a mini version of an actual wall, where there are styrene “studs” mounted perpendicular to the sheet along the back to help give it more rigidity. I’ve had some success with that method. But just like 1:1 scale, nothing is permanent.
Solved this with some overkill…
I’m thinking I’ll frame the entire subassembly of this building with PVC lumber. Way overkill but what the heck. The rest of the mill is just corrugated cans so I don’t need to worry about styrene warping.
PVC glue stinks!
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DId you use PVC glue to adhere the PVC to the styrene? I didn’t have the best of luck with that either.
Yep. I use PVC cement. Seems to be holding fine.
Just for the record after talking to Craig offline he is using a PVC cement that is good for gluing PVC to ABS. I am pretty sure I am using a PVC to PVC only cement. And this very well might be why I am having different results. The added chemical for the ABS is likely what is reacting to the styrene. This could be an important detail for anyone looking to do the same as I am sure to be doing in the future.