MDF for shelving

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Forum topic by Lifesaver2000 posted 11-27-2009 01:39 AM 3233 views 0 times favorited 4 replies Add to Favorites Watch
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556 posts in 3288 days

11-27-2009 01:39 AM

Topic tags/keywords: mdf question shelves

About 9 years ago, I installed built in shelving into an addition to my house. The shelves were made of 1×10 pine that the local building supplier sold as “shelf boards.” While not exactly furniture grade stuff, they were flat, straight and smooth, requiring only a little round-over on the edges and light sanding before painting to match the wall they were attached to. I don’t remember the exact price, but I do remember it seemed pretty cheap for what they were. The final product turned out very nice.

I am planning to start a remodel of a bedroom this winter. One wall will have a fold up bed, with built-in looking floor-to-ceiling shelves on each side, similar to those in the addition. One problem I have found though, is that the building supplier no longer sells these “shelf boards.” What they want to sell as an alternative is a 1×12 board that is no where near the quality of the other boards. They are neither flat, straight nor smooth, and the price is quite high, at least to me, about $20 for an 8’ board. I live in a rural area, and don’t have a lot of choices. The Home Depot 25 miles away doesn’t really have an equivalent to those “shelf boards” that I have found, so I have been looking at using 3/4 inch MDF. Since the shelves will all be painted anyway, I’m not concerned about anything like grain or things of that nature, and I can get what amounts to 5 1×10 boards from one of their $23 49”x97” sheets.

The questions I have are:

1) How does the strength of MDF compare to pine lumber the same size? The shelves I built 9 years ago are supported at about 2ft intervals, and have been able to handle full loads of heavy books without even a hint of bowing or movement. How will MDF handle this type of load, and will it bend over time? Would I need to support it at closer intervals?

2) I live in an area where the humidity varies quite a bit throughout the year. It can be as low as 25 to 30 percent in the winter, and up to 60 percent in the summer inside the house (my A/C is set up to keep the humidity level down even if the temp is cooler than the thermostat setting, so it never gets over 60 to 65 percent.) Will this much of a change cause problems with the MDF?

3) Any other problems I should be aware of? I’ve read about the dust production when cutting/routing, and also about how this stuff wears out blades/bits faster than the pine would. I have read conflicting reports concerning getting a good paint job on it though. Some say it takes paint great, others say not so much, and most say that getting the edge to look good is the hardest part. I have read a few tricks for sealing the edges, such as glue mixes or sheet rock mud. Anyone here have any experience with this?

I realize this isn’t exactly the kind of “fine woodworking” that is usually discussed here, but I have seen from reading through the forum that there is plenty of knowledge available, so I am hoping to tap into that knowledge base so I can save some time/money/frustration. Thanks in advance for any help you can give.

4 replies so far

View Lifesaver2000's profile


556 posts in 3288 days

#1 posted 11-27-2009 01:55 AM

That is certainly a good start. The sag that it shows for the MDF is quite a bit more than for any of the pine lumbers, but still a reasonable amount. Got that site bookmarked. Thanks!

View FirehouseWoodworking's profile


720 posts in 3449 days

#2 posted 11-27-2009 02:38 AM

Lifesaver, welcome aboard!

I liked Barry’s post of the Sagulator and that looks like a great tool!

Having never previously used anything as scientific as that, I think 2 feet is too great a span for bookshelves, regardless of the material (given nominal 1” thickness.) Even more so when using MDF. My suggestion to you, and what I have always done, is to add stiffeners front and back.

Using 1” (nominal) poplar, available at the big box stores and lumber yards, I’d cut them down to 1” (actual) width and attach them front and back underneath the shelf. The rear stiffener was set in 1/8” from the edge. The front stiffener was set back 1/4” to 3/8” from the front edge, depending on the edge treatment the client wanted. Most of the time, it was a bullnose on the shelf. Just becarefull that the stiffeners do not interfere with the shelf pins that hold the shelves in place.

Another alternative was when the shelf would get a lot of wear and tear. In those cases, I would add the front stiffener to the front edge of the shelf. I would make it out of 1”x2” (nominal) poplar. The other thing I’d do with these shelves was to cover the top surface (and top edge of the front stiffener) with white Formica. This prevented all the ugly scratches and marks left on the painted surface. It worked really well and the clients were very happy. Take a sample of the Formica to the paint dealer and they can match the exact shade of paint. It blended extremely well.

Just my thoughts based on experience. Good luck.


-- Dave; Lansing, Kansas

View Lifesaver2000's profile


556 posts in 3288 days

#3 posted 11-27-2009 04:29 AM

The older shelves I referenced are 4 feet long, with a cleat attached to the wall along the entire back side and to the vertical supports at each end, and then with a 1×4 vertical support in the middle of the 4 foot span. As I said, this design has held up to heavy loads for a while, and I specifically did not want any type of cleat or support along the front of the shelves. I do agree that the 2 foot run for the MDF will be too long though, based on the Sagulator, so I will probably have to go with supports every 16 inches if I use the MDF.

View jaydub's profile


63 posts in 3290 days

#4 posted 11-29-2009 12:25 AM

I used MDF for some built-in shelving in a closet in our place. Certainly nowhere near the load required for the books, and nowhere near as wide a unit. That said, my two cents is that with setting the shelves into a dado cut into sides and back of the unit, and then applying an approrpriately rabbeted solid wood faceframe you can help support the shelves, and remove any diffuculties in achieving the edge you want in the MDF. From my experience, poplar and MDF both take paint very well. Sounds like I’m on Firehouse’s bandwagon…

Happy building!

- jw

-- happiness is a sharp plane iron

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