I’m planning out a built in shelf, and am wondering if 1″ mdf will span 64″ at either 12″ or 10″ wide with no centre supports. or should I expect it to sag without the extra support? I was planning to have no facing.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Skim-coating with joint compound covers texture, renews old drywall and plaster, and leaves smooth surfaces ready to paint.
Featured Video
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Fine Homebuilding Magazine
Fine Home Building
Follow
-
Fine Homebuilding
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial Now -
GBA Prime
Get instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
I wouldn't go over 36" with mdf. You can stretch it to 48" if you glue/nail a 1" piece of poplar to the exposed edge.
The max I go with any material is 48" with or without facing.
--------------------------
It's only satisfying if you eat it.
Somewhat on topic:
I need to build built-in bookcases on either side of our fireplace in phase2 of our addition/remodel. Each will be 36" wide. Do you think MDF is a poor choice of material for the shelves in a book case? What about the carcasses? We're talking paintgrade here. Also, what is an appropriate depth? 12"? What would you recommend as an alternative material for paint grade bookshelves?View Image
Depends.
Are you going to keep books in the cases(thinking about the weight)? Do you want the shelves adjustable?
12" is a standard over all depth, just to make sheet goods work. With the carcass at 12" the shelves generally end up 10 1/2" or so.
If you are going to paint it, I would consider cabinet grade birch plywood(atleast 5 ply). 1" poplar nosing on the shelves, and a 1 1/4" face frame on the carcass.
MDF would work, it makes a hell of mess machining it, so I try to avoid it.--------------------------
It's only satisfying if you eat it.
Cool, thank you. Don't plan on making the shelves adjustable. I'll probably go with the ply then. MDF makes me sneeze like crazy.View Image
I will be cutting lots of mdf. am planning on wearing a respirator. what have you worn in the past? I know that dust can get pretty nasty.
brian.. i like MDO for paint grade with poplar facings...
i went back and found an old thread i did on paintgrade MDO
***Bookcases I have known **** take a lookseeMike Smith Rhode Island : Design / Build / Repair / Restore
Found it.... thanks Mike.View Image
Since it will be painted ... HD and Lowes now carry a 9 or 11 ply 3/4" plywood with a nice face, and it's about $35 a sheet. I would use that rather than mdf, and add an applied nosing both for strength and to make the shelf look little thicker.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
As much as I dislike MDF it does paint quite well with the right primer. We've built a bunch of paint grade cabinets/built ins with various combinations of MDF and birch AC ply and most of the carpenters would agree that the birch cabinets are the way to go.
MDF has it's place as it's so inexpensive and can leave a super flat surface if treated with care, but if it weren't for it's low price it wouldn't be as popular as it is on it's own merits.
Beer was created so carpenters wouldn't rule the world.
TY...built ins are new territory for me.
I missed the 1" MDF the first time around.
I never worked with 1" MDF shelving, so this is all conjecture, but 48" would be safe without nosing. You may be able to stretch to 64", but I'd be leary.--------------------------
It's only satisfying if you eat it.
Even at 1" I would not go over 48"36" is plenty unless the nosing is designed to take up some load
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
i would bet that even 1' mdf ( never mind 3/4 ) would sag of it's own weight over 64"
i would break that span in half or figure out how to bury some small steel angle in the front edge.... 64" is a LOOONGGGG span for any kind of shelf materials... books , plates, glassware... nope.. sag city
Mike,
Can you post of picture of that white bookshelf/cabinet you did a while back? IIRC, it had built in lighting and wrapped around and inside corner. I'd like to save the pic and try to steal a bit from it if you don't mind. What did you use for materials on that one?View Image
MDF along with chipboard is prone to sagging even under its own weight without additional load. If you intend to load shelves with significant weight, e.g., books, then expect books to typically weigh between about 18 and 25 lbs., per linear foot.
There's an online calculator called the Sagulator that you can punch numbers into to give you an idea of shelf deflection under load, http://www.woodworkersweb.com/sagulator.htm I punched in 1" MDF over 60" length and 10" deep with 20 lbs per linear foot and came up with a deflection of about 1-3/16" which is very noticeable to the eye-- it looks like something you'd see in a skateboard park. Even if you use this calculator it only tells part of the story for shelves continue to deform to some extent under the same load as time progresses, particularly MDF and chipboard-- we're getting into elements of Hooke's Law, strain, stress, modulus of elasticity and proportional limits.
Plywood carries loads better than either MDF or chipboard and the same thickness of ply over the same length will deflect less under the same load. Solid woods, especially stiff ones like the white oaks carry loads even better-- and oak shelves seem to paint up pretty well too. Slainte.
Richard Jones Furniture
Edited 1/31/2006 5:26 pm by SgianDubh
Richard ... how are things across the pond? Do you miss Houston yet?
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Two years plus since I moved home to the UK Eddie. I miss the Houston climate like I miss a hole in the head, although the weather at this time of year was always pleasant, even if the rest of the year was pure misery, ha, ha. Slainte.Richard Jones Furniture
Interesting choice of names. Scottish?
Don K.
EJG Homes Renovations - New Construction - Rentals
Something like that, ha, ha. Slainte.Richard Jones Furniture
Richard was a long time participant at Knots. Check his web site ... he does some kick-a$$ furniture. Awesome.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I still contribute to Knots on a fairly regular basis Eddie. I used to get into Breaktime quite often too, but mostly just for exchanging banter and tall tales in the Tavern. I've got very little useful information to pass on to concrete encrusted, hairy arsed, hammer swinging builders, ha, ha.
Since I moved back to home the UK a couple of years ago I've found myself too busy really to spend much time in forums that aren't core to my furniture interests. But I do seem to be drifting back more often into BT again. Whether I'll say anything useful in a thread might be a different story, but I've always enjoyed the craic over here.
Anyway, take care. Slainte.
Richard Jones Furniture
Edited 2/12/2006 2:06 pm by SgianDubh
richard.. how does NY sound in August ?Mike Smith Rhode Island : Design / Build / Repair / Restore
You mean the TipiFest Mike? I'd love to catch up with you all again, but I suspect I won't be able to make it unlesss I end up visiting family and friends in TX at the last minute.
Gulf Coast Texas is so refreshingly mild and pleasant in August I find. It was always my favourite month when I lived there. Slainte.Richard Jones Furniture
Gulf Coast Texas is so refreshingly mild and pleasant in August I find. It was always my favourite month when I lived there
You're full of Bs too.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Using the Sagulator (http://www.woodbin.com/calcs/sagulator.htm)
With MD MDF, 64" wide, 12" deep, 1" thick, 400# loading (which is high, but not so much for encyclopedias or he like), the deflection comes back as 3.7"
Bumping up to HD MDF, going down to 200# still is 1.37" (that 200# is only 3.84psi, too--high for one china plate, low for an encylcopedia).
Hmm, may take some more ciphering.