Thread: Chipboard vs. MDF for Large Desk with top Shelves

4" screws is waaaaaay overkill, 2" is fine.
Nothing wrong with using MDF, it should be a bit stronger than chipboard because there's more "stuff" in it, but it'll also be heavier. Just make sure all your screws are pre-bored and countersunk. Also keep screws back at least 40mm from the edges, any closer and they can split the board even with pre-boring.

I'd recommend a back in the shelf section to prevent sideways pressure from twisting it and also so you can screw into the middle of the shelves for extra support. It doesn't need to be as thick as the rest, a bit of 6mm MDF is all that's needed.

I would probably be more worried about sagging then joint strength - especially for the long span which is the desktop.

MDF is not as stiff as particalboard so it will sag more.

There is a 'sagulator' on the web somewhere which will tell you whether the products you use are in any danger of sagging.

There are also some really good guides on the correct way to join with screws, for both mdf and particleboard, put out by the manufacturers.

You can also buy various specialised joining components from suppliers such as Hafele and Nova which are probably a better way then screws to join either product.

And yep, mdf is a bit more inclined to split then pineboard. I always predrill mdf but never particleboard.

Read the guides and stick to them and you should still end up with an acceptably rigid structure.

When drilling into the "end grain" of mdf make very sure that the hole is nearly as big as the threads on the screw - you should only need the screw to be ½mm bigger than the hole - MDF just LOVES to split when screwed into the end. If you are worried about the strength of the screw in that size hole then screw and glue in the hole. You can use PVA glue for that but Polyurethane glue would be better for adhesion to the screw.

Originally Posted by Arron

I would probably be more worried about sagging then joint strength - especially for the long span which is the desktop.

MDF is not as stiff as particalboard so it will sag more.

The best way to avoid the sag is through design. For example, for the type of desk described, there is usually a panel say 200 - 300 mm wide panel installed between the leg panels and perpendicular to the top. The panel is usually set towards the back of the desk, where it can't be seen, and sometimes a smaller, 50-100 mm panel is installed towards the front of the desk. These add enormous flexural rigidity to the whole structure, and keep everything square.

I made a couple of desks with a sort of similar design for two nieces some time ago. With most desk designs made from veneered MDF, the back section usually has a strengthening piece running along the rear between the two upright sections and somehow screwed, or whatever, into the side and top.

To make the overhead section, I ran a piece of material that ran from underneath, about 250mm from memory, which then was raised above the desktop by about another 250mm. This top was/is used to hold a clip on light and they blue-tack all sorts of things to the rear face board.

I screwed the rear board directly into the side uprights, and desktop itself, from the rear. You should be able to see the rear lower section. Essentially it was probably a 500mm wide piece that was cut to size. This desk, and her sister’s, was made entirely from nature strip pick-ups.

Main material was/is 16mm thick, I used 40mm MDF Aldi screws. Pre-drilling was with a tapered drill countersink combined unit, something that is almost a pre-requisite for this kind of pre-drilling as far as my experience with MDF is concerned.

The desk doesn’t move. I was later told, little madam and her older sister, did a few dances on their new desks before their parents found out; the desks passed with flying colours and are used every day.

What I’m suggesting is that you run your overhead unit downwards at the rear, and, attach it in a like manner to what I did. Having used MDF and chipboard for various similar projects, I have found this design feature this usually gives great structural integrity when building something like this.

Tanya's new desk_2_2.jpgTapered_countersink_drill_bits.jpg

Mick.

Originally Posted by Optimark

I made a couple of desks with a sort of similar design for two nieces some time ago. With most desk designs made from veneered MDF, the back section usually has a strengthening piece running along the rear between the two upright sections and somehow screwed, or whatever, into the side and top.

Main material was/is 16mm thick, I used 40mm MDF Aldi screws. Pre-drilling was with a tapered drill countersink combined unit, something that is almost a pre-requisite for this kind of pre-drilling as far as my experience with MDF is concerned.

What I’m suggesting is that you run your overhead unit downwards at the rear, and, attach it in a like manner to what I did. Having used MDF and chipboard for various similar projects, I have found this design feature this usually gives great structural integrity when building something like this.


Mick.

This is great advice from Mick... which answers the original question pretty much in full. My own bit of advice is spend a bit of time (as Mick has) with the design. With the inclusion of strengthening structural elements, 16 - 19 mm laminated MDF is cheap, easy to work with, will result in a strong - fit for purpose and great looking desk.

Horses for causes... The end result will look like so much of the inexpensive prefab furniture that is readily available - but there is nothing wrong with that, as long as that is what you want, and low cost and ease of build are a priority.

As for the original question, I have a feeling that laminated MDF is more readily available these days, but white melamine chip board is the staple of kitchen cabinets. I tend to prefer chip board myself, but I can't give you a very good reason for the preference.