How to protect outdoor hard legs from the elements

Anybody have any good options for protecting plywood built hard legs in an outdoor venue from the elements? One of my performing spaces is revamping the hard legs and in the past whatever they skinned them with (Plywood I believe) has had a tendency to warp. I'm looking for a material of some kind that can be applied to a skinned surface to create a smooth seamless finish for painting and lighting. I've attached a photo to give an idea of what it's doing and what we'd like to eliminate. You can't really see the hard legs because we hid the seams with the bamboo, but on the back wall you can see the warped seams and the shadows that it causes when we light it. Several companies come in and use this space, so it has too ba a material that will hold up and can be painted over repeatedly.

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Thanks in advance for any help!
STEVE
 
Welcome to the Booth! Stop by the new member forum and introduce yourself.

I've never done this, but my thought would be to make some calls to you local fiberglass supply/boat repair sorts of shops. I'm thinking some sort of resin product used as a paint might be a good solution.
 
Which elements are the most important to protect against? Rain, wind, direct sunlight, heat, cold? Are the legs hard because they're outdoors, or because they need to resist collision damage?

One way to make the surface smooth and seamless, and mostly resistant to all of the above, would be to add a thin rim around the existing hard legs, and then stretch fabric over it. The underlying hard leg would resist structural and wind forces, the fabric would provide a paintable surface, and the rim would hold the fabric away from the warping of the wood below. Filling the bottom 4' or so with wood that does touch the back of the fabric will minimize collision damage, although tearing might still occur.

There are some 1/4" and thicker sheet plastics available, but direct sunlight can cause sagging issues similar to water warping of wood, although backpainting with light colors can minimize this.

If you really want bulletproof, a steel frame, sheet metal, and Bondo come to mind, but that would be pricey, heavy, and harder to modify later.
 
If the plywood is warping or deliminating from the wicking of moisture, you can seal the cut ends of the ply wood with an epoxy penetrant (consolidants). The are several products on the market for doing so. I like the Advanced Repair Systems products. Not exactly theatre related, but I have used it to repair many rotten window sills.

Bottom line, seal the cut edges and paint.
 
Plywood or luan and rain don't mix. It de-laminates the plys causing warping. Not really the material to use. My 2 cents... PVC sheets and a steel frame. It won't weigh any more then a traditional flat. Use .049 MT1010 steel. After it is welded up, plug the ends and paint the entire frame with an epoxy sealer. If you need rigging points, put those in and seal around them. T-Nail the PVC down and you should be set. I would probably stretch muslin around the entire thing and change that out at the beginning of each season.
 
I suppose you could also try marine-grade plywood. I've not used it, but I would suspect it would hold up better to moisture. We've also used a product called Exterra (I think) which is an exterior grade MDF. Unfortunately I can't really report results until later this spring when we head back out to all the theme parks and see how things held up. So I'm no help at all, really.

PVC does stand up to water, but I have seen it buckle with sun exposure. But that was unframed cutouts--might be OK with good steel framing, as Footer suggests. I think all three of these options will be in the $80/sheet range.
 
I suppose you could also try marine-grade plywood. I've not used it, but I would suspect it would hold up better to moisture. We've also used a product called Exterra (I think) which is an exterior grade MDF. Unfortunately I can't really report results until later this spring when we head back out to all the theme parks and see how things held up. So I'm no help at all, really.

PVC does stand up to water, but I have seen it buckle with sun exposure. But that was unframed cutouts--might be OK with good steel framing, as Footer suggests. I think all three of these options will be in the $80/sheet range.

The only issue with marine grade plywood is its heavy as hell. I have seen more then one pontoon nearly sink because they were re-decked with marine grade plywood instead of regular ply. I don't know why it weighs so much more, but it does. Its also extremely expensive.
 
There are several Outdoor Grades of MDO < Medium Density Overlay > Beautiful surface, you'll have to seal the ends and sides as it's a water repellent but not waterproof product. Outdoor is very hard on materials but if build, seal then base with an oil based or outdoor grade latex house paint you should not be getting that kind of warping. Making sure nail holes are covered, seams are caulked and that the surface is thouroughly primed should be buying you more than one season out of a cover.
 
The MDO that Van is talking about is generally used for billboards so it should survive quite a while. It does require primimg all the edges, plus the back. It comes in 1/2" to 5/4" and in sheets from 4x8 to 4x12. I assure you that a 5/4" 4x12 sheet is bigtime heavy, not to mention expensive.
 
Reading this thread one idea came to mind which you may want to consider....Line-X or Rhino spray...the spray on poly that is used often as an indestructable truck bed lining sprayed on--these companies make many different textures and finishes from rough to smooth etc and that have numerous applications for industrial needs beyond truck beds..its rock solid durable, cut/dent and water proof. The application will add weight but practically anything you do to either change material of your legs or preserve them will add some weight. Sometimes used on outdoor speakers and outdoor surfaces--there are many variations of LineX or Rhino to choose from...its a slightly pricey one-time application--but it lasts and takes a beating. Not all of the finishes takes paint well--so you should probably contact Rhino or LineX and ask for more info..but regardless one thing you can do is spray line your hard legs so they are protected...and then for every show you simply face them with muslin and paint as needed...and then remove the muslin at the end of the run etc.. But using one of those company spray on products may be a solution to consider for your need..


Just an idea while passing by...hope it helps. Good luck! :)



-w
 
The only issue with marine grade plywood is its heavy as hell. I have seen more then one pontoon nearly sink because they were re-decked with marine grade plywood instead of regular ply. I don't know why it weighs so much more, but it does. Its also extremely expensive.


FWIW....as I understand it...the reason Marine grade ply is heavier and more costly is where regular ply has larger core gaps the marine ply has smaller to no core gaps (the cores are where you can trap moisture and lead to warping and separation)--so there is more wood since there is less core gap....plus add the heavier waterproof resins & glues used to bind instead of the usual urea-formaldehyde glues to make--and there is your extra weight and cost... Its a lot more dense ply compared...



-w
 

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