Changed my mind about using MDF for a workbench top after one rainy weekend

I always thought MDF was the cheap way to go for a flat work surface. Then I left my shop window open during a storm and the whole top swelled up like a sponge near the back corner. It cost me about $40 to replace the sheet and three hours of my Saturday to cut and screw down a new one. That's when I realized spending $60 on a sheet of 3/4 inch plywood with some polyurethane would have saved me the headache. Has anyone else had MDF fail on them in a damp garage or basement?

3 comments

3 Comments

the_karen5d agoTop Commenter

Did you seal the MDF before you put it in that shop? I've had an MDF workbench in my basement for six years now and it's still flat as the day I built it. I put two coats of cheap oil-based primer on every single edge and surface before assembly. That's the real trick with MDF. It's basically compressed cardboard, so it sucks up moisture like a straw if you leave it raw. Your plywood idea works too but MDF is way flatter straight from the store and doesn't have those voids you find in cheap plywood cores. A little prep work goes a long way with this stuff.

the_karen5d agoTop Commenter

Six years is a decent test, but what's the humidity level in that basement? Mine spikes to 60% in the summer and I've had MDF swell even with primer if I didn't get the edges good enough. Did you use a specific brand of primer or just whatever was on sale?

wendy725d ago

Wait hold on, you had MDF in a basement at 60% humidity for six years and it didn't swell? I'm seriously impressed because @the_karen mentioned edges being the danger zone and I've had MDF puff up on me just from a humid garage for a few months. That oil-based primer trick must be the magic bullet, I only ever used acrylic and it wasn't enough for sure.