I’m about to finish trimming out my living room which is of fairly decent size. For the door and window casing, I’ve used a paint grade pre-primed colonial moulding. I plan on framing and trimming out the rest of the room with crown and a wainscoting. For the crown, my wife is pushing me for dental crown…even though painting it will be a major pain (don’t own a sprayer.)
I have really irregular ceilings and walls. Not flat at all. Should I stick with the pine? I was think I might want to go with the MDF since it’s slight flexible and would follow the contours of ceiling and walls. Is that thinking flawed?
I was also thinking the MDF would be more stable throughout the seasonal changes. I’ve had some gaps appear in the rest of the house where I have used paint grade pine; I simply filled in with caulk and touched up the paint in those spots.
One more question, what do you use to glue an MDF scarf joint? I tried to standard Elmers wood glue once but it simply just absorbed into the cut.
Thanks in advance for your help.
Replies
As crown sits up and away from most hazzards, just about any material is fine. MDF is heavy, and you need to buy the paper-wrapped preprimed stuff to get a good finish IMHO. I really like the newer plastic and foam moldings, but they're not cheap.
Weldbond is one choice for adhesive, great shelf-life (even after it's open), and has many other uses. Gap-filling instant glues work too, but they're maybe a little unforgiving for your purposes. Skip hot glue, too expensive for one job.
Phill Giles
The Unionville Woodwright
Unionville, Ontario
I Installed MDF trim in my basement and regretted it ever since. It's easy to nick and does not look good when you do (brown and fuzzy and no good-looking way to repair it). Stick with wood.
Concerning your crown molding I would also use wood especially if your ceiling is wavy. The straight wood (with caulked seams) will give your ceiling the sloptical-Illusion of being flat.
If you do end up using MDF trim make sure to keep it dry. Mine got wet in transit and I did'nt allow time for it to dry out before installation. It left 1/4" gaps in the the mitered joints. Ugh. Let in acclimate inside for a couple of days before installation.
Wood, and nothing but. Don't be misled, I used MDF on casing a door opening a few years ago because it was available. A few months ago I was in the clients house and noticed the miters had opened. The house is 50 years old, so no settling issues. Also, the stuff dimples where you shoot a nail into it. Not a big deal, but a pain nevertheless. I've sworn off all MDF molding since.
I've seen the other comments against MDF. I've used it for many projects, with no problems. My Bostitch finish nailer does not leave any dimples. MDF is ideal for crown as it is very dimensionally stable. I use Titebond on any scarf joints, and also shoot a couple of brads with my brad nailer to hold it while the glue dries.
"Preach the Gospel at all times; if necessary, use words." - St. Francis of Assisi
I made all my own casing in my house with three quarter MDF, and bisquited all the joints. I know it sounds like overkill, but it is extremely stable and I have had no problems with joints opening. I would stay away from thinner MDF.
Ditto what the last 2 posters said. For gluing the joints, try using 2 applications of glue- 1 to seal the MDF & 1 to actually glue it. Another option is to use an adhesive caulk like polyseamseal for gluing & caulking everything.
I thnk it does not finihs as nice as preprimed
also my finish guy will use it , but does not like it for one reason.
He says he gets more nail gun blowouts with the mdf so he has to hold his hands further away
I myself have not had a problem with it, just pasing on what he said