Home hydrotherapy for dog - what wood to use ?

[shd1970]

Hi there

So I’m looking for a bit of guidance regarding a small project that I have

I’m looking to make a hydrotherapy pool so my dog can use to get some exercise following a spinal stroke
What I am planning is effectively a 2400 long by 800 wide by 400 deep wooden box that I will then line with DPM and then fill with water to a depth of 200 mm
The depth of water is sufficient for my small dog just so it is weight-bearing and will help her to build back up some leg muscle

So my question is simply would OSB or plywood be the best wood to use?

As mentioned, I will be lining the box with damp proof membrane so the water will not be in contact directly with the wood

TIA

 

[freddiemercurystwin]

I think I'd be inclined to build it in 25mm plywood and line it with GRP, it would obviously need a bit more engineering than simply just four sides screwed together but this is how large (commercial) aquarium tanks are built.

 

[shd1970]

Thanks for the reply @freddiemercurystwin

I hadn’t thought of that approach and may be something to consider in the future if she takes to it but think at this stage I’m wanting something quick and easy
I was thinking of using two lengths of 18 mm thick OSB on the base and then single boards around the sides with some 90° brackets, and then sit it on some castors just to easily move around
Using an online calculator I worked out that it will take approximately 390 L so a fair bit of weight although spread over a large surface area so I’m thinking the weight is not really a problem but just to mitigate as I say the plan was to use Double thickness on the base

 

[endecotp]

You need battens or something around the top edge to resist the sides bowing outwards. Fix them solidly at the corners.

390 kg on castors sounds like quite a challenge.

 

[freddiemercurystwin]

390kg on casters will absolutely be a challenge! Think of a few ring beams or similar.

 

[shd1970]

The weight was one of my initial concerns, but then I started thinking about a small child paddling pool which will probably have even more water and subsequent weight and just being plastic it made me think that my design would be okay
I have been looking at castors and you can get some heavy duty ones, although they are expensive, but it might be that I can look at an alternative for that
I don’t need to move it far just to be able to pull it out from the garage wall just wall in use and then put it back to save space so as I say I could look at an alternative or just have it as I fixed container

This is what stimulated my thought to use this design although I would need the water deeper than this example :

 

[endecotp]

I guess it's not the castors per se that are my concern - as you say, you can buy some pretty sturdy ones - but rather the fact that once it's on castors the rest of the base is unsupported. So the OSB (or whatever) base is no longer just firmly sandwiched between the water and the ground, but rather it is holding the weight of the water up. You would need some bracing across the bottom to make that work.

 

[Harry Bloomfield]

I hadn’t thought of that approach and may be something to consider in the future if she takes to it but think at this stage I’m wanting something quick and easy

Buy an adequately large tarpaulin, big enough to cover the base, and rise up the sides. Then make your box shape, from mostly 3x2, along the long sides and base, to form the main frame. You infill then, with ply, or better OSB.

 

[endecotp]

Looking at your video, I think his castors may be ready-made dollys and he's chosen the width of the pool to suit them. Something vaguely like this:

https://www.screwfix.com/p/hilka-pro-craft-400kg-wheel-dollies-2-pack/77671

 

[shd1970]

It does look like you can get some 50 kg casters fairly easily to my thought was to have five on either side so just a 600 mil distance between to lesson any bend on the base but as mentioned earlier in the thread my plan was actually to use two pieces of OSB for the base for added strength and screw and glue

Are there Henry general thoughts as to whether OSB is any better than plywood? Considering plywood is obviously made from different layers laid at 90° to each other so as I understand it ply is physically stronger than OSB… Correct?

Thanks to all for input so far much appreciated