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How to DIY a weightlifting platform and which type of plywood to buy?

Hi,

I am thinking to build a weightlifting platform for my garage gym, something like this.

As you can see the bottom layer is built by about 2 x plywood.

I went to bunnings website and not sure which plywood to purchase. The thickness is also a bit strange, I couldn't find one that is an integer number, e.g. 10mm or 20mm or something. The reason is that I want to put a rubber gym mat on the sides, just like the one in the photo and usually the rubber gym mat has a thickness of 10 or 15mm.

Any advice on this?

Also, would like some suggestion on which drill I should purchase to put screws on the plywood.

Thanks a lot!

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EricL

Hello @bilcruise

Thank you for sharing your question about how to D.I.Y. a weightlifting platform.

I totally agree that the thickness of the plywood sheets is not even and requires a bit of a ponder on how to assemble them. I suggest building the platform in three pieces for ease of movement and transportation. It also makes it easy to repair once they wear down. If we use the Ultimate Flooring 1 x 1m Rubber Gym Tile - Black for the left and right of the platform which is 10mm thick combined with 2400 x 1200 x 12mm F8 Structural CD Plywood with a thickness of 12mm, it gives us a total thickness of 22mm.

We now need to find plywood that will fill the center of the platform close to the same height. I suggest using the Project Panel 1200 x 810 x 3mm Premium BC Plywood as a filler and putting the Project Panel 1200 x 897 x 7mm Premium Grade Radiata Plywood on top. When joined together 12mm + 3mm + 7mm gives us a total of 22mm.

I suggest a combination of Selleys 320g Liquid Nails Original Construction Adhesive and Zenith 8G x 20mm Countersunk Rib Head Chipboard Screws - 45 Pack to hold the entire assembly together. If you wish to have the platform thicker you can add more plywood to the bottom of the assembly. It sounds like a very interesting project to put together, we look forward to seeing your progress.

Let me tag our experienced member @TedBear for his recommendations.

If you need more advice or information, please let us know.

Eric

TedBear

Hi @bilcruise & thanks for the tag @EricL . I don't know the specific requirements for a weight lifting platform, but it sounds interesting, so I did some online research. Given the hard pounding that it needs to withstand, It seems that the bottom layers occupy the full length and width and are usually made of 4 sheets of plywood, with 2 sheets butted together with the seam running through centre, the length of the platform and the other 2 on top with the seam running across ways to lock it all together firmly. One lifter recommends using mdf as the centre strip for the top layer, (where you stand) as it is strong, smooth and also gives good grip. This can be bought in 9mm thickness, so if you use 10mm mats on the sides, you will have a mere 1mm difference, which, given the 2 different types of surfaces, won't be noticeable. The recommendation was to fit that top centre piece last by turning the unit over (with a few mates' help) and screwing in from underneath, ensuring that screw points don't stick through. You could do it from the top with countersunk screws if you don't mind seeing them. Any electric drill should be capable of drilling through the sheets. You'll need a countersinking bit to get screwheads out of the way.

(If you wanted to cut costs a little, you could use particle board for the middle layer, because the plywood is to prevent moisture from the concrete floor from damaging the wood, as would occur if you used particle board. But it maybe safer to stick to the recommended structure.)

bilcruise

Hey @EricL , thank you for the tips, mate. I think that's a good plan to start with. I agree with you that it's probably a great idea to build the platform in 3 pieces.

RE: rubber gym tile, do you offer a service to cut them to size?

bilcruise

Thanks @TedBear . Yeah I have seen some guys build it using 4 sheets of plywood, put together the way you explained. Just on the MDF for the top layer, I think I read it somewhere that MDF is better than plywood in a way that it is naturally straight - which is preferred for a weightlifting platform. Is this right?

TedBear

Hi @bilcruise

yes, I would say that MDF would be straighter, once locked into place, due to being a product where its manufacture can be exactly controlled by a machine and it also has no grain to make it want to bend with weather (etc) changes, whereas as plywood does have wood grain.

I am not sure of MDF's impact characteristics though... that may be why plywood is preferred for the area where the weights are going to land.

That's where grain would be better, since it can also spring back into shape if flexed, whereas a manufactured product such as MDF, being denser is more like glass (nowhere near as fragile of course), in that it has some flexibility but it may fracture suddenly if bent too far, or subject to much local impact.

I'll tag @EricL who may know more about that aspect of MDF....

EricL

Hello @bilcruise

It's great that you've received fantastic advice from @TedBear. Using MDF is a good option. I recommend using it as a spacer rather than being the main panel on top. Plywood has a high tolerance for flexing and friction, it can also take on the occasional water bottle spill. MDF often unravels under extreme friction and pressure and does not react well to water.

I'm so sorry but there is not cutting service for the rubber gym tile. I suggest using the Stanley Retractable Knife to cut the gym tile. It is strong enough to cut through the thick rubber pile. Please keep us updated, we look forward to seeing your platform assembled.

If you need further assistance with this project, please let us know.

Eric

bilcruise

Awesome thank you @TedBear . Good to know the pros and cons of MDF.

@EricL Thank you! That knife looks good. Any ideas on how to secure the platform together given the 3 pieces structure?

EricL

Hello @bilcruise

Due to its combined weight, you will notice that platforms will stay in their spot when you drop your barbell on them. However, if you wish to secure them I recommend using Grunt 25mm x 5m Ratchet Tie Down Straps - 4 Pack and strap it along the perimeter of the platform to prevent movement. I suggest doing some test runs and see if you get movement while using the platform without the straps. You could also put an Ideal 1m Black Flat Surface Rubber Matting Sheet or similar under the platform to give it grip and prevent movement. Please keep us updated, we would be keen to see the platform while you assemble it.

If you need more advice or information, please let us know.

Eric

bilcruise

Thanks @EricL . I recently came across OSB board for an alternative to plywood. What do you think about that? Does Bunnings sell it?

bilcruise

By the way, this link does not work - https://www.bunnings.com.au/stanley-retractable-knife_p0203907.

MitchellMc

Hi @bilcruise,

Many thanks for your feedback on that link. I'll pass the details onto our team to look into. Here's an alternate link to our range of suitable Stanley Knife's.

We do sell Oriented Strand Board (OSB), but it sounds like @EricL's recommendation still lies with a material that has a solid timber skin coating like plywood. OSB, as with MDF, is a glued together material that can be susceptible to moisture and excessive wear and tear.

Please let us know if you have any questions.

Mitchell

bilcruise

Hi @MitchellMc , thank you. I actually went to Bunnings to take a look at your structural plywood the other day. I noticed the surface is rough and not sanded. It may be a dumb question but what is the easiest way to make it smooth?

MitchellMc

@bilcruise,

The budget structural ply is generally used for construction purposes and isn't necessarily finished smoothly. Coating it with something like Cabot's 1L Cabothane Clear Satin CFP Floor Polyurethane would smooth it out to a certain extent or, alternatively, an orbital sander would make quick work of it. You'll find smoother ply in our premium range, though there is also a significant price difference.

Mitchell

bilcruise

Thanks @MitchellMc , i just remembered @EricL suggested that premium grade plywood. i took a look again and realised the width is quite short, ~ 800-900 mm, whereas the structural plywood for the base has a width of 1200 mm. You guys don't sell custom sizes for those plywoods, do you?

For the orbital sander, would it do the job for the structural plywood? Or do I still need to coat it with that polyurethane after sanding it?

MitchellMc

@bilcruise,

We have 2440 x 1220 x 12mm AA Grade Mixed Hardwood Marine Plywood which has an exceptionally smooth finish.

The orbital sander has the ability to create a very smooth surface; it just depends on how smooth you want it. It would be worth considering whether the structural ply, sander and coating would cost you more than just purchasing the Marine grade ply I've linked to above.

Mitchell

TedBear

Hi @bilcruise , I am wondering why the ply needs to be smooth? The recommended method only has ply for the under base, which doesn't need smoothness. If you use a piece of MDF for the centre platform that you stand on, the structural ply underneath would be fine. (My apologies if I have misunderstood your current plans.)

bilcruise

Hey guys, just another question I forgot to ask. Do you think the combination of plywood + the dense rubber gym mat (weightlifting platform) is enough to protect my porcelain tiled floor (underneath the tiles is concrete slab)? I'll be doing weightlifting so some good amount of weight will be constantly dropped onto it.

MitchellMc

@bilcruise,

Not if you're dropping weights from waist height as is sometimes needed. It's a bit hard to tell. If they are older solid porcelain tiles with no air pockets under them, they might be fine, but I don't think I'd be comfortable in saying you won't see them crack.

Mitchell

bilcruise

Yeah that's fair enough. it's difficult to tell without trying it, which may not be a good idea 😋 Some folks suggested the following combo: EVA rubber mat, plywood then finally the rubber gym mat. But again, can't say unless you try it. This is the tile at my garage - https://www.tfo.com.au/product/luxor-grey-honed-concrete-look-rectified-porcelain-tile-3496/#/dfcompact/query=6944&query_name=match_and. Doesn't say whether it has air pockets or not.

MitchellMc

@bilcruise,

Sorry, the air pockets I referred to would be in the adhesive if it wasn't applied correctly.

The combo of mat, timber, mat, sounds like a good idea and would likely protect the tiles much better than simply a mat on plywood.

Mitchell

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