WBP plywood for built in bookcase?

[jmc67]

First post from a newbie.... I wanting to tackle a built in bookcase, which will be painted. The idea is to fill approx a 9 foot space, floor to ceiling, and have shelves 18-24 inch across (10 inch depth). I've been looking around for advice on the right materials, and am split between 18mm mdf and 18mm ply. Originally I was looking for Birch ply, which was about £60 per sheet, but I've found somewhere offering WBP ply for less than half that.

Question is, is WBP ply good enough/suitable for making bookcases?

Any advice would be great.

 

[big-all]

i have made this exact item made mine from pine in six sections the
bottom sections are bigger at 12" deep
the sections being a 4" plinth to clear the skirting so you can cut the skirting in
then somthing like a 14+12" giving the base unit a height off about 31"
the top is 22-25mm bigger than the sides and overhangs on the rhs so the top goes to the wall and at the outer end it overhangs to finnish unit

the top part off the units made from 6x1" stopping 1" below the picture rail height
shelves spaced fo books dvds ect
top replicating the base top
all screwed together as one unit with a nice overhang all the way round the top and the same on top off the base

all backs are 9mm tounge and groove boards

 

[jmc67]

Thanks for the info. So was that with pine, or pine faced plywood big-all? I'd be happier working with ply or even mdf given my relative inexperience, hence the q about WBP ply for this.

 

[big-all]

ply you need to finnish the exposed edges
mdf can split unless you pilot and are very carefull although 18mm is less likley to
timberboard would be fine with 12" you need to glue 2 boards together anyway

if your set on ply or mdf i would go for mdf but idealy you need support every 24" or so to save sag
on the height if your going closer than 3" off the ceiling your unit needs to be in 2 halves then you only need around 12mm clearance

what is the exact width and height and how much off that space do you want to fill!!

 

[jmc67]

Exact size a good question - I haven't even moved in yet, so only have the details from the drawing of the house, hence me being a bit vague. I was thinking front edging anyway on the ply (or mdf for additional strength), however as you say with using proper timber that wouldn't be needed.

I'd read about sag with mdf, and hence was thinking 18-24" shelves to minimise that. That was when I got to thinking ply as it is much more sag resistant.

Out of interest, any idea of approximate cost implication of, for want of a better term, 'proper timber' for this type of build in relation to ply. Much more or less per square meter? Is there more work needed to ensure the boards are flat, don't warp over time etc? Newbie, so hence the newbie questions.

 

[big-all]

sorry i thought you said 9x9ft lol
thats why i said 6 units
you could be wider with a central divider 40" for example

not only is it easier to make in 2 halves its also more economical as theres fewer bits requiring a full board for them to fit

 

[jmc67]

I was actually thinking 4 or 5 individual units, as they should be easier for me to move around and less likely to sag.

 

[big-all]

20" wide will be perfect just remember with your calculations you need to deduct clearences for skirtings allow for walls out off true and most importantly allow /deduct material thicknesses from your calculations a 20" shelve unit will only have 18.5" shelves if you use 18mm mdf or 19" if 12mm is used

if your painting mdf is the way to go if you keep it down to 20" you wont have to front the shelves so save on construction time
after planning stage i would cut and make a butt screw and glued joined shelve unit 20"x 96" 12" lower half and 6" upper halve fill mould and undercoat in about 2 hrs
i would expect you to take 2 days

but a word off advice cut all components the same size at the same time
if you are say planning 3 bottom and 3 top or just 1 bottom and one top
if you cut all shelves at the same time you units are almost gaurenteed to be parralel sides

for the back panels you only need 6mm mdf/ply 9mm txg cladding MAMIMUM

 

[jmc67]

Cool, thanks. With regards to the width, I was thinking 18-20" but want to make sure there is no sag (even with magazines on the shelves). You reckon that will be fine then with 18mm mdf?

 

[big-all]

without edging the sagulator says you can load up to 49pounds a foot
http://www.woodbin.com/calcs/sagulator.htm

12" deep 19" wide 3/4" mdf[m] fixed