shelf unit in MDF

[lurker]

Lots of questions:

We are having a major bathroom refit. The client & clerk of the works (SWMBO) has commissioned me to make a shelf unit.

The brief is tall (floor to almost ceiling) about 9” deep about 12”- 14” wide with different height open shelves. It has to be free standing as the walls ceiling & floor are to remain unblemished (This is code for “I can chuck it out if I don’t like it”) and gloss white.

I plan to make it in MDF (have only ever used this for jigs etc.) and lip the cut edges in profiled softwood. I have only used the MDF from B&Q before, but I believe there is a better grade?

I was thinking of using almost butt joints in a shallow rebate (a third of the depth) plus glue plus brads: is this a valid technique?

Can anyone suggest further reading? Web preferably

What finish should I use? Compatible with MDF, my poor painting abilities and the wet steamy room? The finish is my biggest worry as I think the build will be fairly straight forward.

 

[Anonymous]

For that sort of spec :roll: you'd do far better buying something off the shelf from a shed.

cheers
Jacob

 

[Alex]

Hi Lurker, I don't know if you get it here but when i was doing shopfitting in S.A you could buy sheets of pre-gloss finished boards of 3/4"mdf, worth looking into cos painting mdf can be nightmare :evil:
With free standing carcase like this book shelf all the strength and rigidness comes from the backboard so don't skimp put in at least 1/2" board rebated and glued. I'd measure the skirting so as to start the back board above this line. Then you'll be able to scribe it to skirting, so the unit can stand against the wall. I'd fix only maybe top middle and bottom shelves the rest just put line of peg holes so the shelf heights are adjustable. For a better asthetic look i'd put in plinth and cornice, 'You know its all about the the trim. '
Alex

 

[lurker]

Hi Jacob,

Welcome back from cyber jail.

Yes, it's something we are considering, except the size ( unknown until the shower is fitted) will be quite specific.

I may well browse IKEA before committing myself.

 

[Anonymous]

Thanks nice to back (I think :lol: ).
As Alex says it's a pipper to paint - you need good primer and lots of coats and sanding to stop it soaking in and get a good finish. And MDF is vulnerable to damp. MFC could be better and would save painting.

cheers

Jacob

 

[George_N]

Moisture resistant (MR) MDF would be best for a bathroom. Not only is it moisture resistant but MR MDF will give a much smoother finish on cut edges than the regular stuff. I've had good results by sealing cut edges with waterproof PVA glue diluted with water (five parts glue, 1 part water). For the paint I have used a water-based system throughout. Prime with a coat of specific MDF primer, undercoat and top coat (B&Q own brand "colours" range). For kitchen cabinet doors I have finished with a couple of coats of Ronseal Diamond Hard acrylic floor varnish (satin). I have been spraying these paints but a brush or foam roller also work ok. Melamine faced chipboard (MFC) is another option for a bathroom as it is pre-finished and easy to clean. However MFC is difficult to cut cleanly without chipping at the edges. Festool users claim good results with the Festool saw and guiderail (expensive) and it is also possible to dress cut edges with a router but the melamine laminate is very hard on tools, even tungsten carbide tipped ones.

 

[jasonB]

For a painted finish I would go with MR MDF as George says, it is a much better board than the contract grade you get from the sheds, look for makes such as Caber or Medite.

I use Dulux Trade quickdrying primer-undercoat (2cts) then an oil undercoat then trade or liquid gloss topcoat (though I prefer eggshell) lay it on with a 4" foam mini roller and lay off with say a 2" brush.

For pre finished then again decent 18mm MFC (not contiboard) and iron on edging. Or for a more durable finish laminate(formica etc) covered ply or MDF is hard to beat if you can find it locally, the ply cores are WBP. This can be finished with iron on edging or an applied timber lipping. If you can't get a decent sawn edge then cut oversize and finish with a router.

Biscuits/dowels and glued butt joints will be fine.

Jason

 

[Racers]

Hi, Lurker

I made a Cd and DVD rack from pine just using butt joints and biscuits the size of a door (it goes behind a door that opens in to the room so it hidden most of the time) for a friend. I made a couple of stainless steel triangular plates let in to a junction between the side and a shelf to fix it to the wall, that stopped any racking and allowed the thickness to be shallow enough to fit behind the door. It was quite stiff with out the fixings, so I think dadoes might be over engineering it a bit for a few towels and scented candles (thats what my wife would use it for :wink: )

Pete

 

[lurker]

Thanks for all your advice, assuming I build it, it will be:

Moisture resistant MDF, then finish as JasonB advises.
I'm going to experiment with the part rebate - my thinking is this will give the shelf edges a "cleaner" profile (and justify a recent spend she has found out about :lol: )
Plinth & corniche to finish off (and hide a few joints!)

I'll also rebate the back to let in the backboard this (I'm told) is to be a contrasting colour.

I don't think I could make an even half decent job using a melamine coated surface - filler and paint are going to disguise the slips!!!

My main concern now is stability, maybe I could put a decorative boulder on the bottom shelf :lol: :lol:

 

[Steve Maskery]

There is another option you could consider, and that is making it out of canary whitewood (aka tulipwood aka american poplar) It's very stable, light, easy to work, widely available and cheap. Best of all it takes a good painted finish. You'll have no edges to lip either.

I made my bathroom cabinet from it, same sort of size, too, and ten years later it's showing no sign of bathroom damage.

Cheers
Steve

 

[Steve Maskery]

By the way, Lurker, I made mayself a new housing jig yesterday, for a bookcase project I'm building. If you are up the motorway, pop in and I'll show you. It's designed for the sort of construction you are planning.
S

 

[WellsWood]

My main concern now is stability, maybe I could put a decorative boulder on the bottom shelf :lol: :lol:

Considering the height of this unit, along with its narrow width, I think you (or rather your project manager) will have to accept that it must be screwed to the wall to achieve this safely. I'd recommend a simple "L" bracket or 2, right on the top where it can't be seen, with a suitable (for the condition of your walls) sized screw in a good fitting rawplug.