Ok, so I am a bit out of my element here. My current idea is a cmu structure with furring channels and hardboard siding painted with chalkboard paint. Budget may mean building a PT wood structure instead of cmu.
Seriously Bruce, if this is a school spec a chalkboard, don’t jury-rig it, its not worth the aggravation or the liability.
I would suspect that any interior chalkboard or chalkboard paint would not last more than 2 or 3 years outdoors, which is less than ideal for a school. Consider framing slate chalkboard material.
However, a porcelain-on-steel chalkboard might be successfully used outdoors if it has a durable backing and edges protected from rust undercutting.
This is closer to what I was thinking:
Based on the size of the panels and thickness of the panels, and the texture of the panels, looks like split slate.
Mr Payne, that is very cool, I expect that by reaching out to the various manufacturers you will find the information you seek or just hang on for a few days, 4specs devotees will continue to post here.
Use of small slate panels like those in the link should make this a fairly simple construction – and very durable. It’s interesting that cleft finish is used in the example. It obviously works, although honed finish is traditional for slate chalkboards.
I specified something similar to this for covered outdoor study areas for a local community college life sciences building. However, it was paint on sheet metal. I haven’t checked to see how they are holding up, but the intent was to repaint them on a periodic basis.
There is quite a difference between natural slate and painted hardboard when it comes to outdoor use and longevity. Probably quite a difference in cost as well, but you’re probably aware of that.