Replies

1. 
   Scooter_ | Jun 04, 2001 05:50am | #1

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   50" is too much for 3/4" MDF, but we don't know the design. Your contractor could be doubling up the MDF and putting hardwood on the front and back, stiffing up the structure. So I can say for sure.

   I do this all the time, and rout a couple channels in the MDF and put cheap threaded rod between two layers of MDF. Heavy, but very strong.

1. 
   Skip_Keith | Jun 04, 2001 06:38am | #2

   *Will the shelves be fixed or adjustable? If they are fixed either material will work but I would add a 1x2 to the front set with the 2" inch turned 90 degrees to the shelving material. I prefer plywood to MDF. Skip

1. 
   Mike_Smith | Jun 04, 2001 01:58pm | #3

   *is that MDF or MDO ?reinforced MDO might do it .. but 50" is a hell of a span with books on it...here's a detail we use to reinforce painted MDO shelves...less than 36"...

1. 
   Mike_Smith | Jun 04, 2001 01:59pm | #4

   *here's the layout for that job...

1. 
   Rich_Beckman | Jun 04, 2001 03:33pm | #5

   *Mike,I don't understand at all what this picture is showing that could be used to "reinforce painted MDO shelves". What am I missing???Nice work though!Rich Beckman

2. 
   Mike_Smith | Jun 04, 2001 04:28pm | #6

   *rich .. the molding in the picture is nailed and glued to the front edge of the MDO.. the real function of the molding is to stiffen the shelf...

3. 
   Jeff_Clarke_ | Jun 04, 2001 07:08pm | #7

   *We use Mike's detail all the time, with different moldings. If the molding is deep enough, you can also glue a flat piece of lath behind it for additional stiffness, although you have to watch the support location. We use 5mm pin insert supports almost exclusively. It is also possible to support the rear of the shelf at the center off the back if it is reinforced, although you may see the shelf support. You can also use invisible supports. I prefer birch ply too.When you are ready to put the books back, put waxed paper under them and live with it for awhile - it will give the paint a chance to harden.Jeff

4. 
   Phill_Giles | Jun 04, 2001 10:38pm | #8

   *I helped assemble a set of shelves for a law library once: they laminated 3/4" architectural foam with a 3/4" x 2" fiberglass box-tube running the width of the shelf in there too (about 1/3 of the depth of the shelf back from the front) between two sheets of 3/8" veneered 5-ply with epoxy and then put moulding across the front and a thin edge down both sides. The box was made by wrapping the glass cloth around a stack of cardboard strips. Those shelves would have been about 40" wide and the cabinet maker who made them said they could hold up a car. The really thick shelves look terrific.

5. 
   Jeff_J._Buck | Jun 05, 2001 01:25am | #9

   *And remember....the stiffening along the back works just as well as along the front......and if both as used......more than twice as strong. .....and ....in the back (i guess in the front too)....the stiffener can extend down....or up. Can even be nailed/glued on the top if it interfers with mounting. Jeff

2. 
   Hershey | Jun 05, 2001 01:25am | #10

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   We are having bookshelves built across a 13.5 foot wall. They will be painted white. The carpenter suggests either MDF or birch plywood for the shelves. Any recommendations for either of these materials, or another? Also, one design shows individual shelves as being 50 inches long. Is this too long for the shelf to support the load of the books without sagging? All advice will be greatly appreciated.