Outdoor classroom project - Advice needed

S

ScottCK

Active member
My sister is a science teacher at a local school and is working on an outdoor classroom. They have multiple different projects in the classroom like various habitats, hydroponics, .... She is now working on a solar power section. As part of this section, there is a water flew type element, where water will flow from one box to another (5 different boxes).

The advice that she needs is that the boxes will be made of wood and she wants to know what she can seal the boxes with that will make them waterproof. She was going to line them with plexiglass and seal with caulking but is afraid that she cant get the plexiglass cut as it is a 4x8 sheet of 1/8". I figured that because you all know how to build wooden boats that keep water out, that yall would have some thoughts on how to build wooden boxes that keep water in. I was thinking some sort of fiberglass resin (maybe thickened so it would stay on the vertical sides). Even considered FlexSeal (clear) from the TV commercials 😊 but don?t know if it actually works. All the labor is volunteer parent time so the skill base may not be there to do anything to technical or time intensive.

Clearly, as this is a school / teacher project budget is a major issue.

Any thoughts, ideas, or tips is greatly appreciated.
 
How long does it need to remain "waterproof"? How big are these boxes? Does it need to be plywood?

Exterior grade plywood has pretty tough glue. I'd be tempted to try build the boxes with exterior plywood and seal the joints with caulking if its just short-term project. For a long-term project you could coat one side of the plywood with epoxy and seal the seams with epoxy. But I'd look for something like plastic storage boxes for ease and lower cost.
 
If the boxes don't need to be made of wood, try half sections of plastic pipe. Maybe a local construction company has some 18-24" HDPE or PVC pipe laying around which they would part with for a good cause. Or the town road crew might have some. It can be cut lengthwise into two half sections with a circular saw or on a tablesaw. I've seen this done for a planter before.
 
As others have suggested, there are easier options:



https://www.homedepot.com/p/Bon-Tool-36-in-x-24-in-Utility-Tub-11-409/304245469
 
Dollar Store shoe boxes are an option. Small rectangular and watertight. Way cheaper then the cost of a sheet of plywood at the moment.

Rick
 
How big do the boxes have to be?

Do they have to be boxes? Can they be round? If they can be round, perhaps try 55 gallon barrels or 5 gallon buckets. The barrels I can find them on craigslist pretty easily and cheaply usually. Walmart sells the buckets usually for about $4 or so and lids can be gotten for them from hardware stores. If you need lids.

Another thought is look for aquariums on facebook marketplace or or craigslist

Home Depot sells some really nice black and yellow stackable totes that come in different sizes. I can usually get the 27 gallon tote on sale for about $10 a piece. There are smaller totes as well

All of those ideas might be cheaper than building boxes, especially depending on how big they are and the cost of wood. Plus they all start out waterproof and you don't have to do extra work to make them waterproof.

However, if she is set on making the boxes, I would consider looking at the rubberized roofing paint that can be painted on mobile home and rv roofs. Apply multiple coats on the inside of the box and she may not need to do the plexiglass inside it. Maybe a coat or two on the outside if she wants the box to hold up long term, just for protection. There is probably a primer that has to go on first. Painting would be within the skill set of most volunteers.

Otherwise fiberglass epoxy painted on in multiple layers (but that can get really expensive depending on how much is needed).

The plexiglass should be able to be cut at home depot or lowes. My stores have glass cutting sections and an 1/8" hasn't been to thin. Now the length might be a challenge but perhaps putting some masking tape or blue painters tape down where you want the cut to be made and using a skilsaw to cut the line might work. Or if you know anyone with a table saw., doing the same thing might work.

If you get a chance, I would love to see her outdoor classroom....maybe you could post some pictures.
 
the totes might work, the boxes are 18" x 24" (don't know depth) and are going to be connected with rain gutters. The RV roofing paint may also be a good idea as I know she wants to have the kids involved in the process. I think the reason for the "wood" is one of the dad's is a cabinet maker but the totes would be a lot easier, just dont know if there is a "look" she is going for.

Home Depot told her that they don't cut plexyglass.

I will ask her for some pictures

thanks for the inputs.
 
Try a roofing company. Rubber roofing material. I get scraps from the company for duck blind roofs, covers for log splitter etc. You can glue it down also.
 
sounds like she is going with wooden boxes and the rubberized RZ paint. Wants the kids to have an active role in making it.
 
Tupperware containers? Flexseal to seal the wood if she goes that route. I have a bunch of plastic used to marinate chickens and turkeys. Lots of choices other than wooden boxes I would think.

Mark
 
You could always staple glad bags inside the box frame. That should hold the water and only cost a couple of bucks. If all else fails, duct tape.
 
Good morning, Scott~


If I were making these I would seal the wood with straight epoxy. (I get mine - the 635 Thin with Medium Hardener) from U S Composites: http://www.uscomposites.com/epoxy.html



I would apply the first coat (on the inside only) BEFORE I cut any of the wood. I would use a foam roller cover on a 3 or 4-inch roller. A squeegee is handy to manage any puddles or dry spots.



After cutting all of the pieces - and labeling each piece, noting up and down, in and out, left and right - I would scuff sand (120-grit) each piece and wash with warm water to remove any amine blush.


I would also cut any openings for gutters or pipes before assembly - so the work can be done on the bench.


A second coat of epoxy could be applied now - again whilst everything is flat and on the bench. All edges should be carefully sealed with the resin.



When assembling the boxes, I would bed each mating edge in an adhesive caulk - 3M 5200 being the best - but there are probably some comparable PL products for less money.



[or you can use thickened epoxy on each joint and fillet the interior seams]



If the boxes will be outside for any length of time the epoxy surfaces should be painted (to protect from UV deterioration). Scuff sand, wash, then apply a primer and a topcoat - latex would be OK if you do not fill these with water for a week or so. (Although I remain an Old School devotee of oils....) I'd use a pale grey or white so algae growth and the like could be monitored.



The same paints can be used on the outside of the boxes. I would seal them with either epoxy or spar varnish first, however.


Plumbing joints can be sealed with any good silicone caulk.


Hope this helps!


SJS











 
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