MDF Exterior?

boman47k

A while back I bought some 1x8 boards I thought were wood. Got a good deal at $10. When I started loading them, I thought they seemed a little flimsy. After getting them home Iand looking more closely, it appears that they are mdf. Th eguy had told me they were used for casing. My guestion is, anyone use this on exterior such as facial boards? That is what I had in mind when I bought them for my shop. I did cut and router a few for baseboard in my bath. They were preprimed, but I primed them again on all surfaces. They seem to work well, altough I think I should have gotten the routered area a little smoother.
I have since read a little about this type board, and am glad the wind was blowing toward my truck and away from me when I did the routering. That truck was covered with dust. From now on I will wear protection with this stuff. I'm thinking this Mdf at least. It is some kind of hard composite.

reveivl

It is, unfortunately for you, not suitable for exterior application, It will get water into it and disintegrate.

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boman47k

Kind of what I was thinking too. Although, I did read somewhere online about some of being use outside I think. No matter at the price I paid, I can find a use for it. Think it can be used in unheated but dry areas? Such as shelving for shop or truck? I did see in the k&b forum where someone uses it for baths I think. Hmm, thta might have been kitchens. I think it was Mike F.

skymaster

Mdf for exterior use is branded EXTERA or close to that if you Google Exterior MDF it should bring you to their website.There are a few different brands, not cheap. Is there a reason you wanted to use it outside?
JackM

MKamis

If you want a smooth exterior board, I can't see any reason not to use Hardi-planks. They're a little more of a pain to cut and handle, but what an awesome way to make your work last and look good, and not need frequent painting/caulking, and not get hit by insects, etc.

Obviously I have used this on my own home, and I love it!

Murphy

They put a boatload of that MDF out here on the outside of homes, then they barely painted it. I am always pulling that crap off 500k homes.

boman47k

"Is there a reason you wanted to use it outside?"

several 10 or 12 foot pieces for 10 bucks plus some door jam. Stumbled across these and thought it would be good, cheap fix for the shop.

Toothpick

Sure it's not Miratech (sp?) ? That's an exterior grade product that is used exterior trim. It's real heavy and has a nasty dust when cutting. It's real similar to masinite as far as the makeup goes.

boman47k

not really sure. It is a hard like composite material. I was told it was used to make casings. Not sure the guy that sold it to me knew either. It is very dusty when routed. After reading a little on mdf, I am not sure I want to use it anymore for interior. Seems it never stops gassing?

tcleve4911

Hello Boman
Go with your gut. MDF = medium density fiberboard.......It's not meant for ext or wet areas. It soaks up water like a sponge. Deal or no deal..you wouldn't put olive oil in your crankcase would ya?

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Grumpy

We did cedar siding on a very high end residential addition. The site super wanted us to do some kind of square box molding but couldn't give me a drawing or picture of how he wanted it to look. He got all frustrated and flustered and said "just install the siding and I will do it myself" Anyways ontop of our siding he installed some MDF molding and it looked like dung until it was painted, then it still looked like dung, but less of a dung.

I saw it a few weeks ago just driving past so I decided to check out our work, anyways his moldings caught my eye. They looked like dung again.