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MDF Base Board

| Posted in Construction Techniques on May 8, 2003 06:01am

I was wondering. I worked for a guy a number of years ago. We were working on a custom home . He used MDF base moulding with mitres in the corners to be caulked by the painters later. WHich was all wrong to me,you rarely get a corner that is 90′. I always cope my inside corners.  He was the Boss.

I havent done any of that since, nor have i seen it. What does it look like , after it has been sitting for a few years.

Is that the standard way to install it? Anybody know, DO the joint stays tight? I guess MDF is supposed to be more stable.

 Anybody. been using this stuff.

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  1. Sethbenjamin | May 08, 2003 07:50pm | #1

    Well, what do YOU think those shoddy "leave it for the painters" joints look like a year later?

    I worked for a schmuck for a while who did things that way. I stuck to my guns and didn't get fired. Did ultimately go work for people who do good work, though. Life is too short to allow anyone to tell you to do bad work.

    So what if MDF is more stable? The flooring underneath it and the walls behind it aren't made of MDF. The aforementioned schmuck used MDF speedbase. I glued the outside miters with building adhesive (I might try hot glue today) and coped the insides. My work looked good the day I installed it, and it will look good for a long time. No caulk necessary, as should pretty much always be the case.

    MDF baseboard I thought looked OK, but it probably won't hold up so well in the long term, especially in houses with pets or kids.

    1. User avater
      scaly | May 09, 2003 06:39pm | #7

      "MDF baseboard I thought looked OK, but it probably won't hold up so well in the long term, especially in houses with pets or kids."

      Used it in a mud room and hallway at my last house. Ended up ripping it out a year later and redoing it in wood because it was destroyed from kids/ vacuum/ stuff running into it and busting it up. I'll never use it for base or casing again. Maybe crown since it never gets touched.

      1. User avater
        Mongo | May 09, 2003 09:22pm | #8

        For MDF base, I could see ripping half-inch or 3/4" stock to the height you need foor the base, then adding a poplar (or equivalent) base cap over it. The cap would hug the wall, eliminating the need for caulk.

        I'd never use a factory made "milled" MDF base with an integral MDF milled cap.

        I'd never use it where water could be a problem...basement, wet room etc.

  2. steve | May 09, 2003 02:46am | #2

    allways cope inside mitres, with practise its easier than mitreing anyway

  3. Turtleneck | May 09, 2003 03:11am | #3

    The trouble with coping MDF is that the smaller points of the cope really have no support. If you have coped MDF you have probably noticed how it shreds on the out-cuts. A mitered MDF corner is alot stronger, more stable and less likely to expand when painted.

    MDF should be mitered on inside corners. When cut and installed properly, there really isn't much of a gap. MDF is normally caulked continuously where it meets the wall so it is very little extra work for the painters to run a small bead down the miters as well.

    So you are probably talking about some guy who cut miters you could lose a pencil in. That is just shoddy work and yes, cheap caulking breaks down quickly and leaves yellow stains in the corners. 

     Turtleneck

    Its not a smile- its a cramp

    1. Edgar76b | May 09, 2003 05:26am | #5

      I no the caulk must be paintable what kind is recomended?

       Also  you spent a lot of time fitting two 45's into a 92' or an 88' corners. you can shim behind it. But that takes time. The only thing to do really is leave it loose. The  purpose of coping: It gives you the tightest corner, even when it shrinks, It looks tight. Also, Your angle becomes irrelevent.

      I like some of the ideas i have seen with MDF panels and Fire place surrounds. ANyone done any of that?Where there's A wheel there's a way, got any wheels?

      1. Turtleneck | May 09, 2003 05:31pm | #6

         

        I no the caulk must be paintable what kind is recomended?

        The painters here finish our baseboards with spray laquer. Some acrylic latex caulks react poorly with some of these finish products. Check with a paint store to see what proffessionals in your area are using.

        MDF doesn't shrink IMO. Usually the opposite is true and it swells like crazy in damp climates as Aaron mentioned in the previous post. Aaron also lives on the Pacific coast, MDF baseboard is not a particularly good product in damp locations.

        Undercut your miters by 1º to 1½º to help keep the miters tight. A little shimming is sometimes neccessary.

        I've done all kinds of mantles, panels, columns, entertainment units and bookcases with MDF. The stuff is a dream to router, join and sand. As I mentioned before, all of my installations are prepped and finshed with spray laquer by proffessional painters.  I believe there is an article in the latest or recent FH about sealing and finishing the open edges of MDF panels. Turtleneck

        Its not a smile- its a cramp

        1. Edgar76b | May 10, 2003 04:12pm | #11

          hey thanks for the input very informative.Where there's A wheel there's a way, got any wheels?

          1. Turtleneck | May 11, 2003 05:06am | #14

            hey thanks for the input very informative.

            Glad I can be of some help, don't forget the dust-mask. Breathing that super fine dust will wring the sap out of you. Turtleneck

            Its not a smile- its a cramp

    2. buildbetter | Jan 29, 2005 11:53pm | #19

      I haved noticed on some of my Jobs that the MDF seems to blister around the nail head do you know anything to prevent this and also what type of caulk works best with MDF , preferably with no water in the base

      1. gordzco | Jan 30, 2005 12:59am | #22

        Hey doc, this is a blast from the past a few things are different (like my moniker) but MDF is occationally a pain,

        First I'll ask a question. What size nail holes are you filling? Was the MDF nailed with 16ga or 18ga pneumatics or hand nailed with 2"/ 2½" finish.

        Was the MDF primed before filling?

        Did the painter sand the filler flush after it had hardened or did he wet wipe?

        Some guys swear by one way of doing things, me? I'll try anything once, if it works...why not?  The job I just finished had an inexperienced painter, (it was out in the country, for a friend of a friend...) He had no idea how to fill and didn't have any so I threw him a tube of Elmers wood filler and told him to go for it. The casing and base was pre primed and I nailed all of it with 18ga pins. (back glued the casings, thin base 4" and  3 pins per stud). He light sanded and brushed all of the casing and trim and it looked pretty good. Not showhome good but it was passible for white trim. White trim is very forgiving, fill wise.

        Darker colors on trim are a nightmare for painters and nail holes need to be filled twice to combat shrinkage. On jobs where there would be several coats of laquer, the painters would use automotive glazing putty (the red stuff) between coats of laquer to fill any minor imperfections.

         

         Be Constructive

        Gord

        St.Margaret's Bay NS

        1. buildbetter | Jan 30, 2005 06:56pm | #23

          Thanks for the response , My Trim carpenter used 18g with nail gun , yes the painter primed it with sherwin williams primer ill have to check to see the exact type, but he didnt use red putty or fill the second time which i believe might be the answer:) Thanks for the pointer.

           

          "Measure accurately once or measure twice"

          1. gordzco | Jan 30, 2005 09:27pm | #24

            The red, Glazing Putty, may not be the answer.

            It is common, when filling a nail hole, to use the thumb or forefinger to smear the filler over the hole. This, in itself, may leave an indentation, or the filler shrinking as it dries may leave an indentaion. Indentations can also be caused by sanding filler with soft sponge pads instead of stiffer folded sandpaper. The spongepads under pressure will follow the contours of the nailhole and taking the path of least resistance, remove some of the filler inside the hole.

            Filling twice is an option, and is better achieved with two colors of filler, so the painter will know where he's been and where he's going. Should the painter charge extra for filling twice to achieve a higher quality finish, the second color of filler proves to the customer, the work is being done.Be Constructive

            Gord

            St.Margaret's Bay NS

  4. User avater
    AaronRosenthal | May 09, 2003 04:17am | #4

    I'm doing a job in a house right now that has MDF baseboards downstairs, MDF door trim and (!)MDF faced doors.

    I got the job because after a water problem (masive swelling) I replaced the baseboard with tight grain fir.

    My reward is a $15000.00 rebuild of a room, redoing the deck and building a new wine room.

    It pays to replace MDF.

    Quality repairs for your home.

    Aaron the Handyman
    Vancouver, Canada

  5. migraine | May 10, 2003 01:18am | #9

    Will never use it again.  In my home or a clients.  If the client says that is all they can afford, then they can not afford me either.   Last job I used it on , the molding was purchased by a the home owner and they bought it at Home Depot.  The stuff had such a thick/hard primer on it, the stuff blew up around the nail holes.  The painter lost his #*! on the job.  He didn't know that the job looked like and bid it blind.  Waited till the job was half done and then asked the owner for more money.  The owner said "NO".  I wound up helping him fill holes for about 4-5 hrs on my own time, (for free)  I felt sorry for him.  Even after the job was done, you could still see dimples and craters.  Have you ever seen what this stuff will do in a kitchen or a bath?

    Remember, if you don't like the stuff later on, you have to remove, replace, and worst yet, repaint.

    1. User avater
      scaly | May 10, 2003 04:27am | #10

      "Remember, if you don't like the stuff later on, you have to remove, replace, and worst yet, repaint."

      Yep. That's what I did.

  6. jimwright | May 10, 2003 06:05pm | #12

    Yo Muleskinner, Ive installed alot of mdf trim, it can look nice if proper time is spent on it. The problem is most builders use it as a cheap alternative, dont want to pay to have it installed properly. Most painters caulk it, I say no because the caulk pulls away as the building moves.(did you ever notice we never caulk stained wood to walls, why do we have to caulk painted trim?) As a side point, if you can't cope an inside corner, go to work at McDonalds. Heavy X out.

    1. Edgar76b | May 11, 2003 03:36am | #13

      "Hey heavy and a bottle of bread,"

      I always wonder if I am iterpriting the tonal qualities of messages here . I guess it is just a limitation of the written word. Anyway thanks for the input everybody.

      I have not installed MDF except for that one time and to be honest I am not that attracted to it as a base board , . But recently , i am interested in things I have read about building up mdf panels, Doors with MDF on one side and Oak and A half raised panel on the other side. I've seen some beautiful fire place face frames, and panel walls too.

       With our environmental issues and the recycling aspects, It makes sense. Like anything, If it actually works. I would like to use it more. 

      AS far as caulking painted base moulding the real reason is to ease the transition between the wall and the moulding otherwise you have a gap which looks like a black line. I have caulked stained casing already with a fine neat bead of clear silicone. It takes on the color of the stain . not for every situation. Clear Phoenoseal is king.

      Also if you have a balloon framed apartment like I do caulk will help keep the second hand smoke from coming upstairs.             Maybe

      Edited 5/10/2003 8:40:25 PM ET by MuleSkinner

    2. buildbetter | Jan 30, 2005 12:00am | #20

      What type of caulk is the preferred when using MDF , it seems to me that some types of caulk blister where the nails have entered?

  7. triplenet | May 11, 2003 05:34pm | #15

    I used MDF trim on a duplex I built for my kids a few years ago.  It was cheaper and primed so I thought I'd try it.  It drove the trimmer nuts as it's dusty and has the rigidity of a wet noodle nailed on the wall-buy a few extra cases of caulk!  Because it is so flexible, they minimize the groove on the backside making it more difficult to install casing.  You need to be sure all drywall cuts are clean and flush with jambs. Nailing leaves "mushroom" holes that need sanded before caulking.  The stuff is too soft and dents easily.

    No way would I ever use it again.

    Bob

    1. Edgar76b | May 11, 2003 05:53pm | #16

      Thanks Bob, That prime factor is a big Plus , but the mushrooms suck I remember that now. Where there's A wheel there's a way, got any wheels?

      1. andybuildz | May 11, 2003 06:37pm | #17

        Mule,

            I did a whole 4000' sq ft house with it. ( A spec house of mine...see website below).

        NEVER AGAIN!!!!

        It looked great for the money. Big wide fancy door casings and nice base molding but....

        As was formentioned here "mushrooming" around nails and hard to sand out due to the hardness of MDF and the hard prime coat.

        If in fact you do use it one bit of advice dont even TRY and hand nail it. Serious mistake. You HAVE to use a trim nail gun!!!!

        For the crown and chair rail etc etc I used wood.....what a relief.

        Coping is always the way to go no matter what and theres no question in my mind about that.

        For MDF especially buy the coping attachment for your jig saw.

        Be wood

                Namaste

                          andy 

         

        In his first interview since the stroke, Ram Dass, 66, spoke with great difficulty about how his brush with death has changed his ideas about aging, and how the recent loss of two old friends, Timothy Leary and Allen Ginsberg, has convinced him that now, more than ever, is the time to ``Be Here Now.''

        http://CLIFFORDRENOVATIONS.COM

        1. Turtleneck | May 11, 2003 07:29pm | #18

          The nail holes are a problem but only because the painters treat MDF like it was wood. A little putty wiped off with a finger, sand with a sponge and paint... WRONG!  MDF, unlike wood, has a hard smooth surface, its more like your car. After the nail holes are puttied and sanded, they need to be filled again with glazing putty ( the red stuff they use for fixing scratches prior to painting a car) and sanded flat. The painters should be paid a little more for their 4-6 hrs of  trouble.

          The finishers also have to know how to make it easy on the painters, by not using nails over 18ga on large flat exposed areas. Miters need to be tight. They should also not nail into moulding detail. As a finisher myself, I try think of how I would fill and smooth those areas if I was a painter. So I use a little more glue and less nails where possible.

           Turtleneck

          Its not a smile- its a cramp

          1. buildbetter | Jan 30, 2005 12:06am | #21

            I have found what you have said to be true when using MDF before i told my painters to putty etc. What brand name putty do you use or recommend and what type of red Putty brand:)?Thanks

             

             

             

             

            " If you dont care or dont know how to do it the best it can be done get out of the way"

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