Chappo wrote:
I am sure their beds where lined with plastic?
Just normal treated plywood will do the same job ,,,they wasted a lot of money for no reason.
You ,,,I believe are wanting material as a TOP cover ,, steam up condense and water plus nasties back.
Also to be used as walk-=ways....... Steel mesh ,, I think TCLynx called then cattle gates? cattle ???
Sling cheap pond-liner underneath to catch the dirt etc.
Cheap as chips and no nasties.
My hot-house central walkway will have same
I have always believed that two heads are better than one and brainstorming is better still. This is one of the reasons why I joined the forum.
Yes, the plywood was painted as well as lined. I will do more research into the manufacturing of these products. As you pointed out very correctly, there is the risk from condesation, if the product is not completely safe. I don't think that regular plywood would be as sufficient however, even if it was painted, as it is likely to eventually deteriorate with the excessive moisture and regular painting maintenance is not desirable, if there are better alternatives.
Walkable steel mesh are called catwalks and in some cases, grates- and are used for stairs, crossings and open drain covers. Although I do have some catwalks in my design for viewing down into large tanks and as an area to keep plumbing and O2 inlets out of regular foot traffic, I don't think they'll will work well for the open raceways, even with a double layer of plastic. This is my reasoning- the plastic will degrade and require eventual replacement and leave the raceways exposed to contaminates falling through the grating as well as sunlight to generate algae, unless you buy EPDM (a high expense). And as far as opening up the raceways, a double layer would be a hassle to remove and replace. It is a good suggestion but one layer is better for convience, if at all possible.
Even if the marine grade plywood is not a viable option, I'm sure there are wood alternatives as boat docks and piers are made of wood and constantly exposed, either through direct contact or through moisture. There is also the option of solid metal covers, although painting will still be required, unless one went with stainless steel or aluminum.
At least you gave me something to think about- thank you for your imput, Chappo.