It is difficult to recommend a type of shelf material and be specific about the thickness and the spacing between supports as they depends so much on the weight being placed upon them and the grade of the material used.
The comments below are for comparison purposes only and advice should, where possible, be obtained from the manufacturer or supplier of the shelf material.
This page only deals with the shelf material, see our other page for methods of supporting shelves.
For the comparison below:
● A light load is considered to be small plants, vases, trinkets etc.
● A medium load is considered to be paperback books.
● A heavy load is considers to be large hardcover books, large plants etc.
The actual classification of an intended load must be 'common-sense', if in doubt, build stronger.
Always remember what a shelf was originally designed for before suddenly putting a heavy item on a shelf intended for only light objects.
The overhangs at each end beyond the brackets should always be kept to a minimum, generally no greater than 20% of the distance between the support brackets.
timber - pine board - chipboard - MDF - blockboard - plywood -glass
shelf stiffener - timber edging
Solid timber
Solid wood is strong and available in a variety of planed widths to suit most shelving needs - where the required width cannot be obtained, tongued and grooved board can be used to avoid the separate planks from warping open - alternatively the separate planks could be joined using dowels or other means.
Timber is easy to work and can be finished using polishes, varnish or paint.
The thickness required to avoid sagging will depend upon the weight being placed on the shelf and also the distance between the supports. Use 18mm thick timber as a minimum and support the shelf at no greater than 700mm centres or 25mm timber with supports no greater than 900mm.
Slatted timber - an alternative for wide shelves is to make a slatted shelf using a number of strips of timber fixed to battens underneath - the under battens then being secured to the support brackets.
Edge laminated softwood board
Edge laminated softwood board (pine board etc) - made up of strips of softwood (typically 25 to 100mm wide) glued edge to edge to achieve finished boards upto 600mm wide.
This is typically as strong as solid timber and often looks as good except at very close up - some boards may be found to incorporate a lot of filler to build the surface up to a smooth finish, this can have a detrimental affect on clear finishes.
Use the support spacings as above for solid timber.
Chipboard
Plain chipboard - unlaminated chipboard is the cheapest and weakest material. It is generally unsuitable for shelving as the finish is poor.
Laminated chipboard - laminated chipboard is cheaper than solid timber and comes in a number of different types of veneer. It is not so strong as solid timber and will tend to sag except under a very light load. Use 12mm chipboard as a minimum and support the shelf at no greater than 300mm centres for all but the lightest of loads. Or 18mm chipboard with supports no greater than 700mm apart.
MDF
MDF (Medium Density Fibreboard) is stronger than chipboard. Care needs to be taken when when working with MDF as it is manufactured using urea-formaldehyde resin which can be harmful. Adequate ventilation and wearing a face mask to avoid breathing in the dust when machining it are essential.
Formaldehyde can also be released over time in low concentrations; not everyone is affected but some people can be adversely affected by just having a piece of MDF in a room.
MDF can be finished using paint to suit the decor or just sealed with a varnish. Use 18mm MDF as a minimum and support the shelf at no greater than 500mm centres for all but the lightest of loads. Or 25mm MDF with supports no greater than 700mm apart.
Blockboard
Blockboard (with the core running lengthways) is stronger than chipboard and is less likely to sag. It is easy to work with and can be finished using paint, the edges will probably need to be covered with a trim to hide the different strips. Use 18mm thickness as a minimum and support the shelf at no greater than 700mm centres for all but the lightest of loads.
Plywood
Plywood is stronger than laminated chipboard and is less likely to sag. It is easy to work with and can be finished using paint, the edges will probably need to be covered with a trim to hide the different layers. Use 18mm thickness as a minimum and support the shelf at no greater than 700mm centres for all but the lightest of loads.
Glass
Glass can be an attractive shelving for light loading and many DIY stores stock pre-cut glass shelving either on its own or as part of a complete shelving kit - special brackets are available for glass shelving, they have clips and lips to hold the glass in place. The glass is specially toughened so cannot be cut to size, if 'non-standard' sizes are required, go to a glazing merchant where it can be cut to size and then toughened. Never use ordinary window glass.
Shelf stiffener
Any shelf material can be stiffened to increase the load it will carry and the distance required between supports. Screw and glue the batten to the underside. A batten fixed to the wall and supporting the rear of the shelf can be used instead or as well.
Timber edging
When chipboard, plywood or blockboard has been cut, the exposed edges may be unattractive. A hardwood edging trim, cut with corner mitres, can easily be glued and pined to the edges to hide the cut edges.
