I just received a sample pack from one of my suppliers with MDF interior moldings (casing, base, chair rail, crown, etc). I am sourcing out material for a high end condo project. Anyone have any experience with MDF moldings? These are factory primed and really look like nice profiles and are less expensive than finger jointed pine! I am concerned with long term calbacks relating to shrinking/expanding and splitting. I have used MDF on many other projects but we milled on site 4 x 8 boards mostly for raised panel applications.
thanks
Alex Gluck
Replies
Honestly?
MDF has no grain, so it doesn't expand of shrink unequally "across the grain", or on a bias, as wood trim does.
I glue all joints, and I've never, ever had an MDF miter open up, and this includes non-air conditioned houses where interior humidity levels can vary by quite a bit over the seasons.
I use an oil-based primer. With a latex primer, all bets are off.
One weakness of MDF is that it can fracture when whacked on the edge or corner. The faces of the MDF is pretty tough.
I also keep it away from water.
I have no reservations using MDF for buit-up crown applications.
Door casings? It may suffer. Though I have used MDF for the casing, then protected the outside edge with a poplar back-band around the casing.
Baseboards? Depends. Should be okay, but outside corners can abrade and wear down to bare MDF if vacuum hoses (central vacs) or similar are repeatedly dragged around the corners.
MDF? Good and bad.
Just like wood.
Use it wisely.
Mongo
Long, thin pieces of MDF are a pain to work with. Really flimsy (sp?)
I tried to hang some MDF crown by myself one time, just about drove me crazy
“The richest genius, like the most fertile soil, when uncultivated, shoots up into the rankest weeds..” – Hume
JM -
If you hang any more MDF crown, try something like this to hold it in place. It sure makes life easier. - lol
I make these from scrap and attach them to the wall a little below the final position of the crown. Then, I sorta "roll" the crown onto the brackets and start nailing from one end using one hand to move it into place and the other hand to use my nailer.
That board at the top of the wall is a backer. I use backers on all walls so I have something solid to nail to wherever I need a nail. This eliminates having to find studs.
Edited 3/8/2007 9:13 am by Dave45
>> attach them to the wall a little below the final position of the crown.
How? do you need then to patch the walls or you have a non-disruptive method you can share?
I was thinking about a nail/screw that can be driven into the joists above the base of the crown, where it will be hidden. Then the brackets are ""hooked" onto the nail using a thin sheet metal piece fastened to the back of the wood bracket. Walking and fastening away from the corner, everytime you reach a bracket, you hold crown with one hand, unhook bracket, then fasten crown with other hand.
Most of the crown jobs I've done so far have been in rooms that were going to be painted so I just nailed the brackets to a handy stud. One job had freshly painted white walls but a little lightweight spackle hid the holes nicely.
I need to start doing that, thanks.
What's the dimensions of your backer, for 3" crown and 4" crown?“The richest genius, like the most fertile soil, when uncultivated, shoots up into the rankest weeds..” – Hume
MDF crown would be ok. I was in a high dollar condo, 2 months after it was first occupied, and the mdf base was in really poor condition. It was very badly damaged by the vacuum cleaner. I suspect chaor rail would be prone to damage, as would door trim.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I use mdf mouldings daily and the single biggest problem I have with them is the raised bump that occures with every nail driven in. The mdf doesn't have any "give" and always mushrooms up. It needs to be lightly sanded and filled in order to look good after paint. My painter, as good as he is, never ever preps those nail holes well enough on the first go around and I end up chasing his guys around with some sand paper and onetime spackle and touching up the holes. Other than that it seems to hold up ok. Just need to be weary of those sharp outside corners.
I like MDF for things that don't get a lot of abuse - e.g. crown molding, window casing, etc. I'm not a big fan of MDF baseboards, chair rails, or door casing becaue it seems a little fragile. I'll soon be replacing a whole house full of MDF base because of the "dings" in it from several years of vacuum cleaner and kids toys collisions.
Hello All
I use a lot of light weight MDF crown molding and have only favorable things to say about it. It is easy to work, does not split, copes easily and does not mushroom around nails.
I will not use it for base or casing because it is soft and easily damagec.
Two things I do not like;
When you use a nail gun it leaves a raised area.
When you try to nail the miters together on casing it splits the casing on the end.
Only problem I've had in installation was the occasional split. Works fine, haven't had any problems with it so far. I have no problems using it, aside from maybe very wet applications like a bathroom.
I have used MDF extensively for trim. My only concern with using it is when you have a long run of baseboard or crownmoulding. Because it shrinks longitudinally, long runs can open up at joints or corners despite gluing and nailing.
I try to introduce steps or changes in direction, to give the trim some "elbow room" when experiencing changes in relative humidity.
This is seldom a problem in residential construction unless the runs are long. It is more of a problem when using MDF in commercial and institutional setting when the walls are often 30 feet or more in length.
To address the mushrooming issue mentioned by another posting, use headless brads or 23 guage pins and the nail holes will behave. I always set my crown into a bed of latex caulk on both wall and ceiling and the nails only act as a clamp until the caulk/adhesive dries. I often do the same behind the top of my baseboard.
Another tip, after priming, I use auto body glazing filler (not bondo)to fill my nail holes. It hardly shrinks, dries fast and doesn't swell any wood fibers. If you have glued the trim and used 23 guage pins you don't even need putty.
I don't want to repeat what others are already saying, but I typically avoid MDF for trimwork because I find it harder to cope cleanly, and it has a tendency to split.
That said, I will use it from time to time - it's especially nice if you are going around curves because it's flimsy.
The downside to this flimsy feel is that 16-footers are like wet spaghetti, and I've found that MDF base hugs to closely to the imperfections in a wall during installation - FJ pine is a bit more ridgid, so you can hide some of the imperfections.
Justin Fink - FHB Editorial
Your Friendly Neighborhood Remodelerator
MDF crown can just be mitered for inside corners because it doesn't change shape with the seasons like wood. I've done it that way 100+ times with no issues, even years later.