I'm building a floating floor to help with soundproofing a practice room. Using 2x4's as joists, and bought 3/4" thick 4' x 8' T&G plywood for subfloor, then Mass Loaded Vinyl mat, then 3/4" thick 4' x 8' MDF. The space is a perfect 8' x 8', so I thought it would be an easy build, but the T&G plywood is actually 48" from the tip of the tounge, so actually 47 1/2" wide, and the MDF is 49" x 97", one inch wider each way.
Why are these dimensions different, (like the 2x4 actually being 1.5 x 3.5) and how are they used in construction? Am I going to have to shave off an inch along the enitre width and length of the MDF?
2007-12-17 06:57:20 · 5 answers · asked by dale62676 2 in Home & Garden ➔ Do It Yourself (DIY)
yep board mesurment is set for construction, like a 2 x 4 is 1.5 wide so when they add 1/2 " you have 2 inches,
2007-12-17 07:06:47 · answer #1 · answered by William B 7 · 1⤊ 0⤋
The reason for your 2x4 being 1.5x3.5 is due to the measurement before and after planing. From a rough log, a true 2"x4" board is roughsawn. Then to smooth it out, it is run through a planer which takes 1/4" off each edge. To make it even more confusing, a 2x8 is 1.5x7.25...
As for your plywood sheets, part of the reason for the board being a touch smaller is to leave an expansion space. When plywood is set, it should be spaced at least 1/8" away from other boards to allow for the natural contraction and expansion of the wood.
Why is MDF 1" larger each way? The process for creating all wood sheets is done in a 49x97 area, and then 1/2" is sawn from each edge to create a smooth surface. MDF is a mixture of resin and sawdust . This combination produces a material that readily conforms to the edges of the area and does not need trimming to neaten it up. The cost would be rather prohibitive to trim millions of extra boards in a mill so savings are realized by passing the 49x97 board on to you. Also, since MDF is not used as structural material, it does not need to line up with joists or studs at the usual spacing of 12", 16", or 24".
Unfortunately you'll need to trim those MDF boards. Just be sure to trim a little more than an inch from each board. You'll want the MDF to not touch the walls of the room, otherwise your mass loaded vinyl mat will be pointless.
2007-12-17 08:33:49 · answer #2 · answered by Brian D 2 · 1⤊ 0⤋
Mdf Board Sizes
2016-09-29 06:17:16 · answer #3 · answered by ? 4 · 0⤊ 0⤋
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RE:
Plywood / MDF Board Sizes?
I'm building a floating floor to help with soundproofing a practice room. Using 2x4's as joists, and bought 3/4" thick 4' x 8' T&G plywood for subfloor, then Mass Loaded Vinyl mat, then 3/4" thick 4' x 8' MDF. The space is a perfect 8' x 8', so I thought it...
2015-08-19 05:50:10 · answer #4 · answered by Marleah 1 · 0⤊ 0⤋
I have always assumed MDF had the extra inch because almost all of it is cut into smaller pieces for cabinets etc and you can cut multiples of 12" , 16" and 24" and not have waste pieces left over.
2007-12-17 08:11:01 · answer #5 · answered by oil field trash 7 · 1⤊ 0⤋
The measurments are that way because it is a industry standard...one thing that you want to keep in mind...NEVER have the joints on 2 different materials exactly on top of each other....The joints should be offset for strength....
2007-12-17 07:23:51 · answer #6 · answered by ? 3 · 1⤊ 0⤋