making barn door out of sheet mdf

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Forum topic by badlash posted 04-12-2018 01:12 PM 3092 views 0 times favorited 21 replies Add to Favorites Watch
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5 posts in 656 days

04-12-2018 01:12 PM

Topic tags/keywords: barn door mdf question

I’m making some barn doors 4×7 an 6×8 for a customer, they want them traditional rail and style construction with 3 and five window panes at the top. i was planning on using 3 layers of mdf 1/2, 3/4, 1/2 with the mid layer solid 3/4 (except windows) then rails and stiles sandwiched from 1/2. the main issue with mdf are screws holding but i dont think this will be as big of an issue with barn door straps. I’m still a little wary because i have never done this before. will the sizes look ok if i fill and prime them properly(i dont want to see lines), will i get cracks between rail sand stile like wood doors?

any advice of different building techniques would be greatly appreciated.

thanks john

21 replies so far

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Bill White

5242 posts in 4571 days

#1 posted 04-12-2018 02:06 PM

Are they gonna be exterior doors?

-- [email protected]

View PCDub's profile


153 posts in 855 days

#2 posted 04-12-2018 02:11 PM

yeah, don’t use MDF if they are outdoors…

View Robert's profile


3605 posts in 2091 days

#3 posted 04-12-2018 03:21 PM

By “sizes” I assume you mean sides. If you use enough coats of primer and sand that will probably work but I wouldn’t trust it.

There are several ways so size the edges for example: shellac, wood glue, epoxy resin, auto body filler, dry wall compound. I’ve even used caulk.

If you sand the edges first, then apply a thin layer of wood glue followed by several coats of primer it will look pretty good.

You could also consider applying a thin edge banding.

Don’t know about water based paint I only used oil based paint on MDF.

MDF comes in thicknesses up to 1 1/4” I think. Have you thought about that?

-- Everything is a prototype thats why its one of a kind!!

View ArtMann's profile


1462 posts in 1427 days

#4 posted 04-12-2018 03:50 PM

I think you need to do some experimentation before you commit to this type of construction. That is the only way you are going to know for sure how the whole thing is likely to turn out. Your approach is quite novel and it might just work but I wouldn’t stake a business reputation on it until I was confident of success. It isn’t that easy to laminate sheets of MDF so that there are no cracks. The problem is strong clamping over such a wide area. Just weights will not be adequate. I would be tempted to use a grid of 18 gauge pins to fasten the pieces together tightly and then just finish over them. When I built a large router table from two sheets of MDF, I used screws on the under side to hold the sheets together.

If these are exterior doors, then stop immediately. They are guaranteed to fail and in short order.

View Mario's profile


191 posts in 4007 days

#5 posted 04-12-2018 04:17 PM

I’ll go a little farther, stay away from MDF for any kind of door… just isn’t a suitable material for doors even if you are using solid rails and styles, there is too much material failure risk involved and the amount of effort required to build them would better be applied in a quality lumber door or a dressed up hollow core one.

View Bill_Steele's profile


636 posts in 2342 days

#6 posted 04-12-2018 09:05 PM

Like the others have said—I would not suggest using MDF (medium density fiberboard) for any exterior application—it does not do well with moisture. You might consider MDO (Medium Density Overlay)—I understand that is a good choice for exterior use.

All that MDF will be very heavy. I don’t think MDF holds screws nearly as well as plywood or regular wood—I’m thinking about where the hinges are screwed into the door. Maybe you could build the frame of the door from wood and then use MDO for the panels?

View Woodknack's profile


13026 posts in 2991 days

#7 posted 04-12-2018 09:31 PM

Ye ol’ traditional MDF barn door with windows. Something like this? Build it from solid wood + ply and you’ll both be glad. Don’t use construction lumber or it’s likely to warp.

-- Rick M,

View badlash's profile


5 posts in 656 days

#8 posted 04-12-2018 09:34 PM

they are interior

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5 posts in 656 days

#9 posted 04-12-2018 09:42 PM

this is the style of door i am trying to recreate. The doors will be interior.

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5 posts in 656 days

#10 posted 04-12-2018 09:44 PM

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2839 posts in 2907 days

#11 posted 04-12-2018 09:54 PM

MDF is fine for that because it will stay flat. BUT you will see the gaps in the edges SOMEWHAT. If you glue the panels well at the edges it should be minimal but I think it may still be visible. Make them aware of that and if it’s not acceptable than you have to make real frame and panel doors and the price goes up.

View badlash's profile


5 posts in 656 days

#12 posted 04-12-2018 09:57 PM

the stiles and rails will only be around 6 inches and i have alot of clamps so i thing i could make that aspect work, i was toying with the idea of a solid insert where the straps screw into the door, wasn’t sure though. if i was to go the wood route what would be a good low cost stable wood to use as i will be painting it any ways. I kind of liked the idea of having the door be 3 layers so the middle layer is totally solid and shouldn’t move. would there be another composite that would be better for this? I also live in calgary canada which is very dry so i’m not as worried about moisture

thanks for all the imput

View Lazyman's profile


4546 posts in 1998 days

#13 posted 04-12-2018 09:59 PM

Make sure the client isn’t expecting real wood. If I was commissioning a door (or building it myself) I would want wood.

You can use Bondo to fill the crack between the layers on the edges, then sand and paint. You may also need some screws to help clamp down the fake rails and styles if you cannot clamp appropriately when you glue them down. Recess the heads and fill them with bondo as well. I would experiment with that on a small scale first to make sure you can get the look that you want. To get a nice consistent finish, you may need to apply a skim coat of bondo over the entire surface before sanding. BTW, you could do the same faux R&S approach using plywood instead of MDF. I’ve seen people hide the rough edges on painted plywood using bondo before.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Loren's profile


10477 posts in 4259 days

#14 posted 04-12-2018 10:08 PM

The edges will be tougher with a solid wood
edgeband and it would get rid of concerns that
gaps in the lamination may cause witness lines
through the paint. Bondo works of course but
I doubt it has the toughness at the corners
solid wood does.

View 000's profile


2859 posts in 1510 days

#15 posted 04-12-2018 10:51 PM

I would use the 3/4 mdf in the middle with no problem.
But I would use hardwood for the frames on each side. Poplar or soft maple would by my first choices.
Clear pine might be my second choice. It’s softer but easier to find the wide pieces you need.
I would do as Loren says and edge the 2 long sides with hardwood.

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