Articles  >  Equipment
Building A Lifting Platform on a Slope
Greg Everett
September 13 2007

You want an outdoor weightlifting platform. Maybe indoor space is limited, or maybe you just want to boost testosterone with 20-rep squats in the sun. But for some silly reason, the folks who built your facility were concerned with water drainage and the area in which you want your platform is sloped. Sloped weightlifting platforms, it turns out, don't work well.

I ran into this problem when building a weightlifting platform for NorCal Strength & Conditioning. Overcoming the slope turned out to be pretty simple.

Following is a simple guide to building a weightlifting platform on a slope. If you don't have a slope and just want a platform, simply omit the timber support structure.

You will need:

  • Plywood – (4) 4' x 8' sheets ¾" thick CDX grade
  • MDF – (1) 4' x 8' sheet ¾" thick. Find a quality piece.
  • Timbers – (9-12) 4 x 4 deck pressure treated deck timbers.
  • 2 x 3 – (1) 8' pine.
  • Matting – Horse stall mats ¾" thick. You'll need 2 2'x8' pieces. Typically the mats come in 4' x 6' sections, so you'll have to do some cutting and pasting.
  • Drywall screws - 1 ¼" and 2"
  • Level
  • Drill/Electric screwdriver (if you're not Amish)
  • Circular Saw (if you're not Amish)
  • Water sealer
  • Paint brush

1. Seal the Wood

Get this over with right away because it's the most heinous part. Paint a coat or two of water sealer on the plywood and MDF. Make sure you get the edges and let it dry completely before screwing the sheets together.

2. Figure Out the Slope Particulars

You'll need to determine the slope of your surface before you can cut the timbers. There are elegant mathematical methods of doing this, but if you're like me, you're far too impatient to even consider them. Instead, we'll just use our gear to figure it out.

Lay one of your 4 x 4 timbers longitudinally over the slope. Place the level on it and shim the low end until the timber is level. Measure the gap between the ground and the bottom of the timber at the low end and there's your rise for the 8' run.

3. Mark and Cut the Support Timbers

Because we want water to be able to drain underneath the platform, we need the edge on the high end to be elevated as well as the low end. How much we can elevate it will depend on the slope we're on.

Measure the rise you found at one end of a 4x4 timber. Draw a line from this mark to the opposite corner of the other end of the timber – we now have the slope marked on the side of the timber. Unless your slope is greater than 4" over 8', this will leave some timber to provide our elevation for drainage. (If your slope is greater than 4" over 8', you'll need to use different support timbers)

Cut one of the timbers along the line you've drawn, lay it cut-side-down on your slope, and check its levelness. If it's off, you messed up. Fix your mistake before cutting the remaining timbers.

When all your timbers have been cut, you'll be left with some thinner pieces. We'll use them to add some extra support. Align each with the main timbers so the thicknesses match and mark them where you'll need to cut to get rid of the excess.

4. Build the Support Frame

Lay your cut timbers on your slope where you want your platform positioned because moving the assembly will prove difficult. You can use the pine 2x3 as a straight edge to align the ends of the timbers.

Once the timbers are arranged correctly, screw the 2x3 to the ends of the timbers at the low side of the slope.

Lay the short timbers alongside the main timbers to provide a little extra footing at the points at which the most force will be received.

5. Lay Down the Plywood

Now that we have the timber support frame laid out, lay two of the plywood sheets on top running lengthwise with the slope. Then lay the other two plywood sheets on top in the opposite direction. Square away all the edges and screw the sheets together and to the support timbers.

Note: You can assemble the plywood platform before laying it onto the frame, but be warned that an assembly of 4 sheets of ¾" plywood is a fairly cumbersome item to maneuver.

6. Lay Down the MDF

Lay the sheet of MDF lengthwise down the center of the platform, aligning the ends with the plywood edges with 2' on each side. Screw it down to the plywood.

Note: If you prefer a narrower lifting area, cut the MDF and mats accordingly. My suggestion is cutting the board to 3' 6" wide and the mats to 2' 3" wide each. I use MDF because it's a smooth, hard surface that needs no finishing, and is relatively inexpensive, so it can be replaced when needed without too much of a hit to the wallet.

7. Lay Down the Matting

Measure a 2'x8' section of horse stall matting for each side of the platform. Use a utility knife to make the cuts. Cutting is easiest if you first make a light score along the line you intend to cut, and then continue making light cuts within it. You can also spread the mat around the cut to allow easier blade travel by sliding a length of wood underneath just to one side of the cut.

Lay the matting along the sides of the platform snugly and screw it down.

8. Rejoice

Your platform is done now. Go grab something heavy and get to lifting.


Keep the platform covered with a waterproof tarp when not in use. The wood is sealed, but it's not sealed that well, and particle board does not get along with water.

You may want to replace the particle board occasionally because it will likely chip and/or experience some water damage, replacement is inexpensive and easy to do.
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December 30 2010
Can you get away with 1/2" plywood covered with 1/4"?
Greg Everett
December 30 2010
Ryan - On a cement slab, yes. On a structure like this, I wouldn't.
February 11 2011
Do I need to be careful with the type of water sealer used on the ply board/MDF? I know you have to be careful not to make it slippery.
September 10 2011
hello Greg, i have some problems with English language. Can you make some pictures to the article?
Greg Everett
September 12 2011
Denis -There are photos but they went missing when we rebuilt the site. They will be back up as soon as we can find them.
Great Caesar's Ghost
May 14 2012
The suggestion to use drywall screws for an outdoor project is bad. They're called "drywall" screws for a reason, and there's a reason you don't see much drywall outside. You do however see a lot of decks outside, and they sell these things called "deck screws".
March 13 2013
How did you make the diagonal cuts on the 4x4's?
Greg Everett
March 13 2013
Handheld circular saw.
March 15 2013
Thanks for the reply. Seems like a tough cut requiring a pretty large diameter circular saw but then I don't have much experience with these things nor do I have the tools. Any suggestions on how I could get it done?
James Hitch
December 30 2013
Estimated cost?
May 25 2014
Do the 4x4 timbers cover the entire area below the surface or are they spaced out? It's hard to tell without the pics, but if they cover the entire surface that's a lot of 4x4s
Steve Pan
May 26 2014
Will -

They are spaced out but concentrated where the feet to reinfoce the areas that will take force. Under step 4 there are two pictures of the timbers on the bottom.
May 28 2014
Thanks Steve. I'm planning on doing this for my garage to make it as level as possible. Btw I cannot see the picture for some reason. It shows a little blue box with a "?"
June 11 2014
Just an FYI for anyone cutting horse stall mats: Using a jigsaw makes the task about 1000% times easier and faster.
January 4 2015
Hi Greg,
Thanks for this post (as well as all of your others). I'm looking to build a platform to use indoors and on a flat concrete surface. I assume that the construction you would recommend would be the same, I just wouldn't need the timbers. Do you still use MDF for the lifting surface on your indoor platforms or is there something else you would recommend? I'd prefer not to have to replace it over time...
January 5 2015
So without the slope just start at step 5?
Steve Pan
January 5 2015
DL -

That is correct.
Greg Everett
January 5 2015
Nick -

Yes. I like MDF primarily because it's inexpensive relative to good plywood and it also will lie perfectly flat, which helps. I have always used MDF on the platforms in our gym, the only exception being the 4 newest ones I built for our new location; however, I only used plywood for those because I had to use 1/2" rubber and couldn't get my hands on 1/2" MDF at that time. We've had the same MDF top sheets on the other 6 platforms, jerk block platform and pulling block platforms for over 6 years without needing to replace them. The edges are chipped of course, but it doesn't affect function at all.
January 6 2015
Thanks Greg, that is really helpful and probably saved me a bunch of money (unless I decided to go with an oak plywood purely for aesthetics).
Greg Everett
January 8 2015
Nick -
Forgot to add that I prefer also to cut the top sheet to 3' 6" wide rather than the normal 4', as it gives a bit more of a buffer zone for the bumpers to hit rubber. This makes it more costly due to the rubber widths and not being able to use exactly half of a 4x8' sheet of rubber, but worth it in the long run in my opinion.
January 14 2015
Greg - thanks for posting these plans and your many other articles. I recently moved and started my own gym at home and need a platform, but don't have the space for and 8x8 platform. Any thoughts on scaling it back to 6' in length? Should still be useable right?
Greg Everett
January 15 2015
Brian -

Usable but a bit sketchy with split jerks. Just be smart about missing lifts and don't die trying to save a lift that's going into the wall.
January 19 2015
I have planned to use these instructions to build outdoor fitness platforms on a trail for doing sit-ups and push-ups instead of lifting. Do you think this can be used for that? Also we probably won't cover them up in tarps so could you advise some stronger- more durable materials?
Greg Everett
January 21 2015
Kevin -

I would talk to a landscaper - they'll be able to give you much better info on building durable decking on uneven and unstable ground.
January 20 2016
How did you cut the 4x4 posts ?
Circular saw - had to make a pass from each side.

Greg Everett
February 29 2016
I'm pllanning on building an 8x8 platform in the garage but the floor has a slight slope( maybe 3/8" over the 8 foot span. Do you think ill run into problems(bowing, cracking) if i just shim the low edge? if so any suggestions ?
Try to support it as much as possible, and also consider adding another layer or two of plywood to stiffen it up.

Greg Everett
November 17 2016
how has the platform held up with the 9-12 pressure treated 4x4 timbers instead of more? obviously more is better, but for costs sake is 9-12 good enough? thanks
It ended up only being used for about a year since we relocated, so I couldn't tell you. The less weight is being lifted on it, the fewer timbers you'd need definitely - but if you've got some big boys dropped 180kg +, it's going to need more.

Greg Everett
May 24 2017
I built a raised platform and when I drop the weight it's bounces very inconsistently (moving left to right and vise versa) making a set with multiple reps a pain. Any recommendations to make the bounce more consistant?
You'd probably just need to have a totally solid base, but usually uneven bouncing is from the weight actually being dropped crooked - happens on regular platforms all the time.

Greg Everett
June 6 2018
I’m trying to build a platform in a garage where the floor is uneven and has a bit of a slope. Was planning to build a frame using 2x4s spaced 16inches apart, and use shims to get it level and then 2 layers of OSB and topped with plywood, all 3/4ths thick. Do you think that will be strong enough? Not going to be dropping huge weights, maybe 250lbs from shoulder high and perhaps a deadlift gone wrong at 450 or 500.
No, you'd need 2x4s closer than 16" OC. I'd go absolute minimum 12" OC, but the more 2x4s, the better. You can also concentrate them under the area where the plates land and do fewer where you'll be standing.

Greg Everett
July 4 2019
If this is inside a garage with a sloped floor, are there any extra steps I can cut out since water and drainage aren’t concerns?
July 4 2019
Also forgot to add that we will be putting a squat rack on the platform and also deadlifting in front of the rack on the platform. We want to keep it as low as possible to not lose headspace. We don’t ever drop the weights, just normal lifts, so not sure if that means we just need it be level but not so much padding? Trying to make this a simple and fast as possible but still quality of course. Thanks for any thoughts you have.
If you're not going to drop weights, you don't need quite as much structure, but I wouldn't really change the base, just maybe do only 2 layers of ply, the top layer being the lifting surface. You're still going to punch holes in the platform lowering a heavy DL if it's too thin, and if it's not stiff enough, you're going to end up with low spots and/or flexing under your feet while lifting.

Greg Everett
March 18 2020
Any idea how to get the give or flex out of the center of the platform? I have support beams going all the way across the width of the platform at multiple points, including through the center, and they are all flush with the ground around the perimeter, the only exception being the center. I think this is likely due to the slight warp in the plywood. Maybe screwing the center into the cement floor, before I put the final top sheet on? Thanks for your help.
Yeah if the ply isn't flat it's going to be tough unless the underlying structure is attached to the floor. You can try using 3/4" MDF on top because it's heavier and naturally lies flat - and even double it up. I'd rather do that personally than screw into concrete.

Greg Everett
March 23 2020
What are your thoughts on using yellow-tongue flooring instead of ply for the base layer?
Don't see why it wouldn't work, but I've never tried it or seen it done. Would be really important to have at least 2 layers lying perpendicularly to each other for stability.

Greg Everett
June 24 2020
Hi Greg. Thanks a lot for this. Fantastic! I am thinking to use something very similar to what you have outlined here, as base for an above ground pool. The pool is 12 feet in diameter and holds about 3000 gallons of water. The reason is I only have one place to put it and that is in my carport, which unfortunately has a slope which produces about a 3.5 inch difference from the high to low side of the pool. Anything above two inches is considered unsafe. What do you think? Would something like you have outlined here work for this?
Should be fine - 4x4s are more than strong enough, especially considering they're not suspended like joists but supported directly by the ground for the entire length. I'd just keep them maybe 12" on center at the most depending on what the structure of the pool is - I have no idea how rigid and strong the bottom is. Definitely err on the conservative side--don't want 3,000 gallons of water escaping.

Greg Everett
June 24 2020
Sorry, I should have added it would be a platform about 15 feet square.
Daven Brigham
July 16 2020
Hi Greg, awesome article, it's a huge help in pointing me in the right direction. I'm planning on building an outdoor platform on a flat area of my backyard, however I live in a fairly wet region with plenty of rain and snow all year. I was hoping the 4x4s underneath would help keep my plywood from direct contact with the ground, and therefore mitigate and mold/mildew damage. Obviously I'll have to do a little more work on sealing and maintenance each year but I'm ok with that. Would you still recommend going with MDF for the top layer in this situation?
November 18 2020
This is so helpful. I am planning on doing something similar but no wood platform.. (just stall mats for the top layer). With that in mind, and my purpose being indoor (creating a multi-use platform for a garage gym that will be 8' x 12'... my question is about the necessity of 2 layers of plywood (or OSB). Do you think with this same design and my application, 1 layer of plywood plus 1 layer of stall mats is sufficient, or do you think that extra layer is important?
Dan - That is really up to you, having 2 layers provides more stability for the platform itself. you'll be dropping weights on it quite often, so that extra layer comes in handy when it comes to absorbing the weight and will keep it from moving depending on how level the surface is.

Alyssa Sulay