Replies

1. 
   CarpenterJC | Jun 21, 2003 09:58am | #1

   Are you sure he didnt mean MDO Plywood?...I have never heard of using MDF on the outside..MDF if it gets any water in it at all will crumble and fall aprt very quickly...even with good paint I would think its risky at best.....I"d maybe talk to him and check just to be sure..but for Myself I"d never use it outside...hope this helps..

1. 
   IMERC | Jun 21, 2003 10:31am | #2

   MDF is used all the time outside around here. Even for corner boards and sill wraps. Keeps the repair clinic busier than busy.

1. 
   dmeenan | Jun 23, 2003 03:02am | #3

   ditto the comments above -- mdo plywood -- ok -- mdf -- no way -- why not just throw your money away now -- paint's gonna fail sooner or later and then the mdf is literally going to fall apart -- btw personally it would also make me very suspect of whoever suggested the idea...

1. 
   IMERC | Jun 23, 2003 04:42am | #4

   It's pretty universal.

   I don't do MDF any thing, Avoid OSB every chance I get. You get the drift.

   It's just a bean counter money thing.

   Edited 6/22/2003 9:45:26 PM ET by IMERC

1. 
   byoung0454 | Jun 23, 2003 06:09am | #9

   thanks

2. 
   byoung0454 | Jun 23, 2003 06:09am | #8

   thanks

2. 
   byoung0454 | Jun 23, 2003 06:08am | #7

   thanks

2. 
   jimblodgett | Jun 23, 2003 06:02am | #5

   At least one MDF manufacturer makes an exterior grade MDF they advertise is suitible for exterior applications like signs and billboards as long as all edges and surfaces are sealed properly.  If it will stand up to that kind of exposure, it sure seems like it would work for at least soffits and other trim that doesn't take rain.

   Google "MDF" and read up on it at various manufacturer's sites.  Then locate a local distributer of the brand that best fits your needs.  If you get stuck, e mail me and I'll dig out some site addresses, but you shouldn't have any trouble finding them.
1. 
   byoung0454 | Jun 23, 2003 06:08am | #6

   thanks

3. 
   starboardtacker | Jun 24, 2003 09:38pm | #10

   Exterior Rated MDF is called MEDEX.  It usually runs about $50-75 per sheet.  Trim material similar to MEDEX is available from various manufacturers in 1x and 5/4 thicknesses, usually pre-primed.  One that comes to mind is GP's Primetrim.  Ok product, but very hard to nail.

1. 
   byoung0454 | Jun 25, 2003 02:17am | #11

   thanks for the help

2. 
   xMikeSmith | Jun 25, 2003 03:52am | #12

   we use GP Primetrim for everything on our exterior trim except sills..

   it is more rot resistent than redwood or red cedar, it comes in 16' lengths, 1x or 5/4.. loves paint.. we back prime it and end prime all cuts..

   we've been using it since '95.. use a small head trim nail.. like a SS ringshank box..

    and it needs full support.. so we use 2x sub fascia and rake

   lots of guys use it that post here on BT..

    there are one or two competitors that i've seen at JLC-Live.. but so far , not much that would get me to switch...

   our  main alternative for good trim is Boston Cedar.. which is a factory primed finger jointed material.. I prefer the GP PrimetrimMike Smith   Rhode Island : Design / Build / Repair / Restore

4. 
   MrBill | Jun 25, 2003 04:52am | #13

   b,

    My house has MDF in all the places you mention. It is 25 years old and except for one small place where the original paint peeled and it absorbed moisture, it has been fine. I have painted it twice, once when the house was about 10 years old and again about 5 years ago. I will say that if the finish does come off for whatever reason, once it starts getting wet it swells up real badly. I replaced the one piece with MDF and have not had a problem. I am in Maryland so our weather is probably "average"

   Hope this helps,

   Bill

1. 
   Rubicon | Jul 02, 2003 12:21am | #14

   I'm searching for the best  option for the trim on my house. I have to get the house re-painted this year and am replacing all fascia and adding bandtrim, with the long-term goal of replacing ALL the siding in the next 5-7 years.  I'm leaning toward fibercement because it is fireproof (I live in the foothills of Colorado where our house is in prime fire country) and holds paint well - or so the literature says. 

   Should I go with fiber cement for the trim now? Or something like GP's Primetrim? How well does Primetrim hold paint? I've had to paint the cedar siding I will soon be covering up every three to four years!!! If the paint fails on this trim and it's Primetrim, will the material also fail?

   Thanks for any help.

1. 
   Piffin | Jul 02, 2003 12:31am | #15

   I wouldn't even dream of using plain MDF for exterior. Primetrim and MEDX are made for it and they do fine. All you have to do is sneeze on the regular to make a pattern swell up..

   Excellence is its own reward!

1. 
   edwardh1 | Jul 02, 2003 04:47am | #16

   exterior MDF = wallet vacuum.

   why use it? cheaper?maybe its cheaper cause its cheaper