Large Scale Central

Polycarbonate vrs Acrylic for roof base

Just in the early stages in building outdoor structures.

Been working on a single stall engine house built in redwood and now need to find a material for the roof. I was thinking of either using a Polycarbonate or Acrylic sheet as the base and then using aluminum pieces glued to it to have the desired effect.

Was thinking about 1/16 inch thick material.

What suggestions do folks have on suitable rooking material that will stand up and not easily chip?

Stan

I use both of those materials in the sign business. For my uses there are pros and cons to both. Polycarbonate is much more resilient; resists cracking and breakage. Whites will yellow fairly quickly with sun exposure. Acrylic is more fragile, will shatter if struck. Whites /colors stay strong a very long time. 1/16" material of either type will need lots of support.

Rooster had issues with acrylic warping when used for buildings due to heat build up inside the structure. I’ve not seen similar issues in sign service.

If you can go thicker I’d probably used foamed PVC board. The 3mm sheet is close to .125" but is very floppy. 6mm (approx .25") is quite a bit more rigid. Depending on how big your roof will be I might be able to snag you a piece from an old sign and bring it to York if you are going. That goes for acrylic too, but I don’t have much thinner that 3/16"

Well, since the structure is redwood, I would continue with that…

BUT, that’s not really the question. I’m not sure what you mean by the comment “aluminum pieces glued to it to have the desired effect.” So, with THAT in mind, when I extended my freight house, I ended up using acrylic for the base of the roof, BUT, ended up using cedar shingles for MY desired effect.

I tried “scale” shingles, but they last about 60 seconds outside, so went with thicker ones. I do believe I got them from Ozark, but not sure if they are still available…

Jon Radder said: Rooster had issues with acrylic warping when used for buildings due to heat build up inside the structure. I’ve not seen similar issues in sign service.

Actually what I found out wasn’t caused by heat and you won’t find that issue in the sign business Jon…acrylic doesn’t like to lie flat outside period . There is also UV and non UV treated so if you are going outside I would go with UV treated. I will never forget the acrylic floor for Radders Cigar store…damn thing bowed up like a rainbow…SO I heated it up and slapped a cinder block on top making it flat…turned off the shop lights and returned the next morning only to find the cinder block teetering on top of a rainbow acrylic sheet.

Are you sheeting over the roof base and if so with what material ? Also what desired “effect” are you looking for on the roof? Standing seam would be a snap with PVC board as Jon suggested. I personally am a huge fan of the PVC board myself. We can talk at York if you are coming …will be there Friday and Saturday.

Thanks all for the suggestions.

We are thinking about a corrugated metal roofing but this will likely be small pieces overlapped so not water tight. The intent is to glue these to a base which will not chip. This engine house is part of our modules but for the most part will be used to keep a locomotive dry out on the layout. Since it will be moved around a lot chipping of the rook edges is one of our major concerns.

We will have it with us in York on our module, Hope to put the base on shortly after York so discussing it there would be most helpful.

Thanks

Stan

OK. So, with the acrylic base, it WILL be watertight! (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-foot-in-mouth.gif)I think your only concern will be the glue that you use. It should be UV resistant and last a long time. I have used the black E-6000 for many years with no problems. Using corrugated aluminum, there shouldn’t be anything to chip…although if you want a rust effect you can either use sheet steel or paint the aluminum. I used Sophisticated Finishes Iron with a rust overcoat on plastic and it has held up very well.

Here’s what it looked like before the paint:

After it is painted, you really can’t tell that it’s plastic. Should work just fine on aluminum as well, although I think there might be some other treatment available?

Thinking PVC as a base however that is only my opinion …

" Rooster " said:

Thinking PVC as a base however that is only my opinion …

If this is to be laser cut, no dice. PVC emits toxic fumes when laser cut.

Todd Brody said:

" Rooster " said:

Thinking PVC as a base however that is only my opinion …

If this is to be laser cut, no dice. PVC emits toxic fumes when laser cut.

Good Point !!!

Wasn’t thinking about that cause I don’t have one.

True, but only in California. Here in the East, we burn PVC scraps in the fire pit. Neighbors are always complimenting us on the aroma.

Jon Radder said:

True, but only in California. Here in the East, we burn PVC scraps in the fire pit. Neighbors are always complimenting us on the aroma.

Jon, I trust your judgment on materials, you use these plastics professionally, day in and out. So, the chlorine off-gassing doesn’t pose an issue, in your mind? Are you saying that all the dire warnings against lasering PVC are overblown?

I need to talk with you at York as well… You be there Thursday night, at the “Early Bird Social”?

Cliff Jennings said:

Jon Radder said:

True, but only in California. Here in the East, we burn PVC scraps in the fire pit. Neighbors are always complimenting us on the aroma.

Jon, I trust your judgment on materials, you use these plastics professionally, day in and out. So, the chlorine off-gassing doesn’t pose an issue, in your mind? Are you saying that all the dire warnings against lasering PVC are overblown?

I need to talk with you at York as well… You be there Thursday night, at the “Early Bird Social”?

Cliff - Yes I will be there Thursday with tongue firmly implanted in my cheek.

P.S. Don’t try this at home; Your mileage may vary; the chairman disavows all knowledge of these posts.

One thing about acrylic (don’t know if polycarbonate is the same), is that when I run it through the table saw to get it to fit into the laser cabinet, it always seems to chip that last corner exiting the blade. Granted, it’s a wood blade, (I don’t really have a choice) but just a consideration. This is not a concern for me because I rarely cut all the way to the corner with the laser, and if I do, Industrial Plastics has already cut that corner on their equipment which leaves nice edges.

" Rooster " said:

Actually what I found out wasn’t caused by heat and you won’t find that issue in the sign business Jon…acrylic doesn’t like to lie flat outside period . There is also UV and non UV treated so if you are going outside I would go with UV treated. I will never forget the acrylic floor for Radders Cigar store…damn thing bowed up like a rainbow…SO I heated it up and slapped a cinder block on top making it flat…turned off the shop lights and returned the next morning only to find the cinder block teetering on top of a rainbow acrylic sheet.

Interesting, and I’ve not noted this with any acrylic I’ve used. But I have few horizontal pieces.

I may just have to tell people that the acrylic trestle I’m making was designed by Salvadore Dali. Will be interesting.

Todd Brody said:

One thing about acrylic (don’t know if polycarbonate is the same), is that when I run it through the table saw to get it to fit into the laser cabinet, it always seems to chip that last corner exiting the blade. Granted, it’s a wood blade, (I don’t really have a choice) but just a consideration.

Depending on the tooth count on the blade I prefer a fine 12" 80 tooth blade but if you turn the blade around it shouldn’t do that. I personally don’t but I have. I Like to use 2" blue or green painters tape on both sides of the piece on top of the (chemcast) or factory paper backing.

Todd Brody said:

" Rooster " said:

Actually what I found out wasn’t caused by heat and you won’t find that issue in the sign business Jon…acrylic doesn’t like to lie flat outside period . There is also UV and non UV treated so if you are going outside I would go with UV treated. I will never forget the acrylic floor for Radders Cigar store…damn thing bowed up like a rainbow…SO I heated it up and slapped a cinder block on top making it flat…turned off the shop lights and returned the next morning only to find the cinder block teetering on top of a rainbow acrylic sheet.

Interesting, and I’ve not noted this with any acrylic I’ve used. But I have few horizontal pieces.

I may just have to tell people that the acrylic trestle I’m making was designed by Salvadore Dali. Will be interesting.

This was a piece about 12" x 18" I believe ??? not sure as I don’t have the model any longer.

There are lots of different manufacturers of acrylic and polycarbonite sheet. One manufacturer’s product might fail as Roo has experienced, while another brand nay not. Formulas are likely not 100% the same.

I build with wood, use plastic wood for the foundation and hardi backer board for the roof that I paint black or brown. The hardibacker board is dusty to cut so it is best scored and snapped but it holds up pretty good outdoors being water resistant so paint is needed. It is about 3/16 to a 1/4 thick and comes in a 3’ by 5’ piece for about $15.