mechanical strenght of mono-comp. polyurethanic foam?

[sbrofio]

Hi, I'm going to build the background of my orchidarium. The sizes are 150 cm tall (59 in) x 105 cm large (41 inches).

I'm wondering about the mechanical strenght/solidity of a 130x105x10 cm (51x41x4 inches) panel of foam.
I've got 20% little (diploprora, amesiella) plants, 70% medium (botanic phals and similar) plants and 1 big Vanda (4/5 kg - 8/10 pounds) I'd like to hang to the wall.

So the question is: does a nail put in a foam-wall resist to the weight of the big Vanda?

I'm not sure but I think the answer is no, so I'm thinking about build a skeleton of metallic net - hydraulic hoses - metallic net, like a sandwich. As nails, I'll use long piece of iron wire linked to the front and rear net.

What do you think about this idea?

example of the inox steel net http://www.wire-mesh-fences.com/phot...tone_works.jpg

something similar to what I want to do http://img683.imageshack.us/img683/1265/img0179qv.jpg

[rcb]

Whether PU foam will be strong enough depends on the property that it was designed for. PUs can be formulated to be extremely strong, or extremely weak. The packaging or data sheets should list the strength.

[sbrofio]

Hi Renee, thank you for answering.
Yeah, I know, but I couldn't find any info, neither of the producer site.
I just know this PU foam can work very good and long in very moist place (as as orchidarium).

I decided to build a frame (or chassis, don't know the exact corresponding english word) in wood, use metallic net for rear and front wall and then use foam to cover everything.

Also metallic net gives me the possibility to create different shapes.

I'll post some pics as I'll make the work.

[spetrizio]

you can find technical details for Sika foams here:

Schiume | Sika Italia S.p.A.

it is 4-8 N/cm2

8N is cca 0.8 kg

[TheEndPhase]

I think the setup you described would work: mesh and piping sandwiched in foam. I would ask, though, if you're just absolutely married to foam. You could use polycarbonate sheeting, for instance, painted any color and finish you like and use small galvanized bolts/nuts to hang your plants. Wouldn't something like that be easier/faster to build? Even if you kept the foam, and just put small polycarbonate panels in the back to hold your bolts (or whichever fasteners you like) that would distribute your big plants' weight over a larger area of foam and should be solid. Washers on the front side would keep the bolts from wiggling so they don't tear the foam up. There are probably infinite ways to build the piece you're wanting....

Whatever you do, though, I would say to never trust something like foam to hold any kind of fastener for anything. Foam as a really bad tendency to not do well in general when it's attached to anything harder than itself, which is lots of things because foam is squishy - doubly so when your talking about something that would move, or have it's load change all of the time (like the difference in weight between your vanda when it's wet and when it's dry) I think your fasteners will pull out and leave ugly torn-up holes, so you'll at least need to anchor them with another material, or just skip the foam altogether.

Hope that helps.