Building a platform

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Forum topic by DaveM123 posted 05-09-2021 02:19 AM 315 views 0 times favorited 5 replies Add to Favorites Watch
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110 posts in 412 days

05-09-2021 02:19 AM

I have been asked to build a platform that will be roughly 5 foot by 3 foot. It will sit on a sloping floor. The back of the platform will be 12 inches off the floor and the front needs to be 14 inches off the floor in order to be level. I plan on building the frame out of 2×3s or 2×4s with a 3/4 inch plywood top. Has to be strong enough to hold two adults. My question is what angle do I need to cut the support braces for the frame. Hope this makes some sense.

-- Dave

5 replies so far

View pjones46's profile


1002 posts in 3762 days

#1 posted 05-09-2021 02:31 AM

Which side is 12” and which is the 14”. Is one of the the 3 foot sides at 12 and the other at 14 or is the 5 ft sides? You can use trig to calculate what you need or set up the plywood and measure the distances.

-- Respectfully, Paul

View Madmark2's profile


2841 posts in 1707 days

#2 posted 05-09-2021 05:27 AM

Make the platform level and square, just one set of legs is longer.

Bevel the bottom on the feet using run / rise. Draw it to scale and use a bevel gauge to pull the angle off the drawing. Transfer the angle to the saw and trim the bottom of all four feet at this angle. Trim one pair 2” shorter than the other and you should be able to make a level platform with square sides.

-- The hump with the stump and the pump!

View DaveM123's profile


110 posts in 412 days

#3 posted 05-09-2021 11:32 AM

Thanks guys. Think I got it!

-- Dave

View JIMMIEM's profile


212 posts in 1960 days

#4 posted 05-09-2021 11:33 AM

Lay a 2×4 on edge. Position it so it runs in a straight line from the top of the slope to the bottom of the slope. Stand one of your 2×4 frame boards on its end so it is straight up and down (vertical) and place it against the board on the floor. Draw a line on the vertical board where it meets the top edge of board on the floor. This is the angle to cut the leg so it will sit on the sloped floor and be level at the top.

View Knockonit's profile


853 posts in 1321 days

#5 posted 05-09-2021 12:47 PM

build it square and even, cut shims for support area, meaning frame work, one can do on top or on the bottom, cover with ply or what ever, easier than ripping every joist.
rj in az

-- Living the dream

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