What material for fitted office upright dividers?

[farlsborough]

I'm taking on probably the biggest cabinetry project I've done so far, partly the fault of Peter Millard (!) and partly the astronomical cost of any trade work at the moment!

It will be a whole wall's worth, divided into 3 sections of nearly equal width - left side, bookshelves (18mm ply on timber frames), and middle and right side an integrated desk and office shelves respectively, with these two sections including 6 wall-mounted 18mm MRMDF cabinets above (3x for mid section, 3x left side).

Between the sections will be (two) full lengths that run from floor to top of cabinets, that will give the whole thing some structure, and will be sandwiched between the cabinets at the top where the middle and right sections join, and between the desk area/cabinets and bookshelves where the middle and left sections join (see picture). I imagine they'll be 400mm deep approx.

My question is - what should these be made of?
They will be standing on end so shouldn't be under that much bending force. The cabinets will be secured to the walls so they wouldn't be carrying much if any weight from these. However, they do need to be able to support one end of the book shelves, although worth noting again that each shelf will supported by a batten fixed into the wall along its length. It will also have battens screwed to it to support the ends of the desk (lightweight material), also supported at the back by a batten fixed to the wall.

My original plan was MDF - for cost and ease of finishing lots of visible edging. But if so, how thick? Will 18mm be enough or does it need to be thicker? (Hoping to avoid thicker as I would like the cabinets to be "framed" with 18mm MDF round all edges in 2x blocked of 3 cabinets, so thicker will spoil that effect).
Or, will MRMDF not cut it and should I be biting the bullet and using ply, and just dedicating an afternoon to filling and sanding the edges?
Or, neither - look into getting some machined pine boards?

Thanks for any opinions, problems you can foresee etc.
And yes, those will be MDF shaker panel doors, thank you Peter...

 

[Droogs]

18mm MDF will be fine. Are you intending to paint or are you looking to have a wood finish. If painting then a bit of car body filler on the edges and then sanded will be good enough to give a clean face under the paint. If going with wood finish then edge the mdf boards with 20x18mm solid in the same wood or using a dark veneer mdf go with a light wood edging or visa verca and then give a finish to a shine of choice.

 

[martin.pearson]

Can't really comment as it's not my thing but when was the last time you checked prices? There was a post on here fairly recently where someone said that plywood was actually cheaper than MDF just now lol

 

[Ollie78]

If I were you I would just make it all with birch ply, apart from the doors. At the moment decent MR mdf is not far off Birch ply prices anyway. 18mm birch is about £80 a sheet at Lavers you can probably screw them down if you get a few.
Decent ply should have very few voids and will actually finish nicer than MDF it is lighter and less likely to sag. If its being painted then a tulipwood lipping works a treat and is cheap and easy.
Pine boards are not normally made out of good stuff and will move more than ply or mdf so I would not suggest this as a method.

Ollie

 

[farlsborough]

Thanks all, especially tip off re. birch ply. It will all be painted.