Looking for some advise-
I’m using sheets of 3/4″ MDO plywood on the face of a new addition. We are going to be rabeting the edges of the panels so that when butted together it will create a nice reveal.
PROBLEM: By rabeting the edges I am eliminating the resign surface of the MDO plywood and am creating the protential for rot in these areas.
Could I do the same by using MDF panels? Can MDF panels be used on the exterior?
I’m trying to find a solution for no additional costs.
Thanks for everyone’s help.
I love reading all the posts.
Replies
First let me suggest looking at the "What's the Difference" piece FHB did on MDO vs. MDF in issue #92 - december january '95.
But as a short answer to your question MDF is basically just a very dense sheet of sawdust and when it gets wet it is going to eventually turn back into sawdust. MDF is meant for indoor use because its clean and smooth and therefore paints up really well with minimal work - while also cutting and machining like silk.
They make exterior MDF 4' x up to16'.
There is also Azek. Our quarrel with the world is an echo of the endless quarrel within us. - Eric Hoffer
soundslike a bad idea.
Not a good idea. I've used Med-X on exterior trim with some success but every now and then it fails.
There's an ad in the recent CWB magizine for a product called EXTIRA they tout MDF like cutting and edging properties. Comes a lot of sizes from 1/2"-1-1/4" thick.
Has any one elseused this product? What's your take?
http://extira.com/
Edited 10/28/2004 11:08 am ET by JAGWAH
I recently used Extira for some raised panels in a front entry. I wanted something stable that also would paint well. The panels were about 20" by 32".
My lumber yard recommended it, so I gave it a try. It works just like MDF ( dusty as he##), but is a little heavier.
Its in a somewhat protected area, and has only been up a couple of months, so its too early to tell how it will hold up long term.
haven't used MDO, but MDF is evil. Its bad enough inside, I sure wouldn't use it on an exterior.
I have used MDO as soffit panels on several jobs, and it was rated as exterior grade. A sign painter I know also uses exterior MDO for most of his exterior work. As long as you are using an exterior grade and priming/painting all faces and edges, it should bo ok. Much better the MDF, and lighter.
I think piffen has used it quite a bit on exterior projects. Maybe he'll chime in here.
Dave
MDO is an exterior product.
I've used both of the exterior mdf sheetgoods that were mentioned and had good luck with both.
MDX which stands for medium density exterior should NOT be used outside. Its not rated for it even though the name might have you thinking otherwise. Its ment for places like bathrooms and kitchens.
MDO (medium density overlay) would be your best bet for cost vs performance. Just make sure you paint the edges well and you should be fine.
Azek (as was mentioned) and its PVC cousins are the premo way to go and do come in 4x8,4x10 sheets. Alot more money than MDO but it will never rot. BTW you can only get it at lumber yards(special order for sheet stock) not the big boxes. HD sells something like, it but its a cheapo version.