Alternatives to MDF for outdoor use...

[mantonuc]

Hello everyone,

  I have a home project that I am considering doing.  I want to build a covered entry-way for the side door of my house.  I wanted to build some columns and have done so many times for use indoors...  The problem with the outside is that these columns will be exposed to a good deal of moisture.  I like using MDF (inside) as it shapes/paints well.  But, I have little hope that it will work well in an outside environment...  I was putzing around on the internet to see what I could find...  Basically I am looking for 4'x8' sheets of some type of material...  I came across several different products but was wondering if anyone has any experience with any of these or other materials to use...

    Extira...

    Medium Density Overlay (MDO), which is similar to MDF...

    Signfoam...

Matt

 

[tDot]

MDO works pretty well.  It is really a paper faced ply with an exterior glue.  I've built some exterior columns with it, and haven't had problems with it.

I've seen guys use MDX, which an MDF with a waterproof glue, but it is really designed more for bathrooms and humid interior areas. Not the exterior... though I've seen lots of guys use it, and I've torn alot of it out.

I dont have experience with the other products.

 

[peter halle]

Matt,

Assuming that you are talking about using the material to cover a wooden post - i.e. the finished cover is not carrying the weight - I personally would consider using a pvc product such as AZEK.  It is available in sheets as well as boards.

The advantages is that a cellular PVC product won't wick water up from the cut ends.  Part of the Gary Katz Roadshow edition that just started its new tour, is dedicated to building columns and planning and dealing with water issues.  His mockup was done with PVC and dominos. 

That being said, I have an outdoor storage cabinet built out of MDO. I like MDO, but although MDO is made with waterproof glue, the plies of the plywood still can absorb moisture.  I just replaced part of a sign (the backing) that was made of MDO.  The front looked great, but when you looked from the top edge, the exterior skin was there but it was hollow and rotten inside for about 1.5 inches.  MDO can also have voids in the plies.

Just a couple of thoughts.

 

[CECabs]

I've used the Extira outdoors and it works great. Its water and rot resistant so thats what its designed for. Just make sure you get a good paint coating on it just to be on the safe side. The longest I have had it outdoors is 1-1/2 years, but its in direct weather out in the open taking all the elements. Doesn't show any signs of being outdoors. Cuts and mills just like normal mdf and a little darker in color.

 

[Brice Burrell]

I'm with Peter on this one, Azek. I wouldn't consider any other product. You can get Azek in trim boards up to a 1"x12" or 5/4"x12", if that will do it for the width that would be the best rout. If your post is wider a sheet will do, 1/4"-1" thickness are available. It's not an inexpensive product but it will not rot. Expansion and contraction need to accounted for during installation. The stuff cuts with regular wood working power tools. 

 

[mantonuc]

Thanks guys, Azek sounds interesting...  How is it joined?  Will it take nails/screws?  By the way, these are not load bearing in any way...

 

[peter halle]

Matt,

I know that Brice, I, and others here, have installed miles of this stuff.  Nails, screws, glue, dominos, pocket screws, all work.  Here is a link to their website and installation videos:  http://www.azek.com/installation.html

I asked about load bearing because Azek is not designed for load bearing usage.

There are other links here on Azek.  I'll dig a few out and post again.

Peter

 

[peter halle]

Matt:

Here are some links:  

http://festoolownersgroup.com/home-improvement-other-projects/azek/

http://festoolownersgroup.com/festool-tools-accessories/azek-and-dominos/

A couple of tips - one I just learned at the Gary Katz Roadshow.  From Brice :  make sure if you use one of the dust extractors that you use an anti-static hose - azek sticks to everything. The one I just learned is that Azek has a grain just like wood.  Not in appearance, but rather in construction.

Azek and the cellular PVC products expand based on temperature.  According to Gary, Azek trim boards expand in the length but not in the width.  I certainly new that it grew in length, but always thought the growth would be proportional also to the width.  So if you buy a panel - 48 x 96 of Azek, which way will it expand?  That panel left out in the sun will grow in the 96 inch direction, it might then be 96.125 inches.

Hope this helps.  Let any of us know if we can help more!  

Peter

 

[Brice Burrell]

Peter, Azek having a "grain" if you will, is an interesting idea. It's believable because the stuff is extruded. Although my experience says it does expand in all directions. And having I've installed a ton of Azek sheets, they will expand along their width too. As much as the length, I don't know. I'll have to test that out. Thanks for posting this.

 

[peter halle]

Brice,

I was always under the impression that they would expand proportionately.  That statement from Gary made my ears perk up.

Peter

 

[Brice Burrell]

Brice,

I was always under the impression that they would expand proportionately.  That statement from Gary made my ears perk up.

Peter

I truly believe it does expand in all directions, it's the proportionately part I not sure of. Gary could be (mostly) right. 

 

[WarnerConstCo.]

I'm going to vote for Miratec.  I like Azek and the lot but, I also really like the Miratec.

It does not expand and contract like Azek type products and you can paint it with any exterior paint.
You are supposed to be very careful about what shade paint you use on Azek.

Oh, Miratec is about 25% of the cost of Azek.
It is available in the same sizes as Azek, it is smooth on one side and looks like a cedar grain on the other side.
They have 4/4 and 5/4 thickness as well (3/4" or 1")

 

[Brice Burrell]

I'm going to vote for Miratec.  I like Azek and the lot but, I also really like the Miratec.

It does not expand and contract like Azek type products and you can paint it with any exterior paint.
You are supposed to be very careful about what shade paint you use on Azek.

Oh, Miratec is about 25% of the cost of Azek.
It is available in the same sizes as Azek, it is smooth on one side and looks like a cedar grain on the other side.
They have 4/4 and 5/4 thickness as well (3/4" or 1")

Darcy, I hear you on the Miratec. The price is right and if properly sealed it can last a long time. However, I've torn out my share of the stuff that was water damaged (and replaced it with Azek). I'll only use it in areas that won't see much weather.

 

[WarnerConstCo.]

I have used it everywhere for an investor I do a lot of work for.

As with any product, if installed properly, you dont have any problems.

The only thing I don't like about Azek is with long runs and the expansion and contraction.

An 18' will move 1/8"+ in the winter.

 

[Jay Knoll]

I've uses Exteria for a couple of gates and an outdoor wet bar, worked great but it is heavy!  (especially the 1 1/2" thick sheets for the gates)  I seal the edges with epoxy before painting.

Jay

 

[Winchester]

I'm gonna also cast my vote to Azek