Billy bookcases are great for home storage, but you’ve probably heard they can sag. We’ve done the research to give you the real scoop.
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Billy bookcases sometimes sag. However, Ikea says they are constantly improving thee shelf strength. The amount of sag expected in Billy bookcases depends on several factors, as listed below.
- Shelf dimensions
- Exposure to moisture
- Weight of items on the shelf
Keep reading the rest of this post for a detailed answer on why and how Billy bookcases sag.
We also include a handy guide on strengthening and fixing Billy bookcase shelves. Further, we answer several questions related to this post
Why do Billy Bookcase Shelves Sag?
Billy bookcases sag because they are made of particle board. This material, while cheap, is not as durable as pure wood or other shelf materials.
Not all Billy bookcase shelves will sag equally; in the next several subsections, we explore what influences the amount and rate of sag.
For more information on what materials Ikea uses for their furniture, please visit this article, “What Is Ikea Furniture Made Of? Is It Real Wood?“.
Shelf Dimensions
The length and the width combine to determine how much open space a shelf has without support. This open space is where the bookcase shelves have to rely on internal strength. When that internal structure fails, sag begins.
Since all Billy bookcases have shelves with a depth of 11 inches, the width is the deciding sag factor.
For purposes of sag, the total width of the bookcase does not matter. Instead, we are interested in how long a shelf goes without support.
Click here for a Billy bookcase from Amazon with a shelf width of 31 1/2 inches.
Ikea’s Billy bookcases come in various widths, like 15 3/4 inches and 31 1/2 inches. The takeaway? Wider shelves, like the 31 1/2-inch ones, are more likely to sag.
Exposure to Moisture
Billy bookcases are made of particle board, which is sensitive to moisture. A quick spill won’t ruin them, but long-term humidity can weaken the structure and cause sagging.
Humidity varies by location and room. For example, Florida is more humid than Arizona, and bathrooms or kitchens are more humid than living rooms or offices.
Purchase your Billy bookcase for a dryer room in your house to reduce the likelihood of it sagging. Also, clean up any moisture spills as soon as possible.
Weight of Item on Shelf
This factor combines with width and moisture exposure and leads to sagging shelves. Wide shelves in relatively high moisture may never sag unless they are also burdened.
The consideration here is that lighter loads are less likely to cause the shelves to fail and start to sag.
Click here for a Billy bookcase from Amazon with narrower shelves.
This means a Billy bookcase isn’t ideal for storing a rock collection, but it can handle a good amount of books (it is a bookcase, after all).
If you notice your bookshelves sagging, you can always reduce their weight. For heavier shelf items, opt for a Billy bookcase with shorter shelves.
How to Strengthen and Fix Billy Bookcase Shelves?
There are four main techniques for fixing a sagging Billy bookcase shelf. In this section, we will go over each method in general terms to get you started.
The strategies are front edge support, midline support, back edge support, simply flipping the shelves, and buying new or different shelves.
Front Edge Support
Many contractors prefer this technique for strengthening particle boards, but it requires a little technical know-how.
The idea is to attach a stronger material to the bookshelf’s front edge to prevent sagging or fix minor sagging.
Often, fir or another common wood is attached to the front of the shelf with glue or nails.
You’ll need a table saw, rotary saw, tape measure, and some basic carpentry skills. Make the front piece about 2 inches by the shelf’s thickness (or a bit thicker for extra support).
Install these supports as soon as possible, either when you get the bookcase or at the first sign of sagging. Waiting too long can cause irreversible damage.
Back Edge Support
Back-edge support is easier to install than front-edge support but isn’t as effective. It strengthens the back edge, not the “floating” front edge.
To add back-edge support, use either wood or metal U-channels. For wood, cut a piece the length of the shelf and attach it to the back of the bookcase with glue and nails or screws just under the shelf.
Make sure it isn’t so big as to make the shelf unusable. This provides lengthwise support and will slow the sag of the particle board.
The strategy for the U-channel is similar.
Purchase a U-channel that fits over the shelves, cut the channel to length, and then attach to the bookcase’s back with screws and slide the shelf into the channel.
This also provides support lengthwise and will slow sag.
Midline Support
Of the techniques requiring some do-it-yourself skills, this is the easiest.
All you need is to cut a 2 x 4 or other board to fit between the shelves from the ground to the top shelf. This halves the shelf’s unsupported width. The downside? It reduces your shelving space.
Cut the support pieces as close to perfect as possible for neatness and structural integrity. Since the weight of the shelves naturally sags – if you cut well, you might not even need to attach the pieces.
If you need to attach the pieces, keep in mind that you might want to remove the shelves later, so maybe use screws.
Flip the Shelves
This trick is simple. Just take the sagging side and point it up! The issue with this strategy is that it does not solve the problem of a failing internal structure.
However, by flipping shelves back and forth, you can get a lot of additional time out of your Billy bookcase with almost no extra work.
Buy New Shelves
You can buy shelves from Ikea or elsewhere to fit the space in your Billy bookcase. If you want, you can even make your shelves.
However, keep in mind that no shelf is perfectly sturdy, and other materials may also sag. Also, the exact dimensions of Billy bookcase shelves have changed over time.
How Much Weight Can Billy Bookcases Hold?
Historically, Ikea Billy Bookcase shelves are designed to hold approximately 30 kilograms or about 66 pounds. This is a lot of weight and usually much more than you will want to place on a Billy Bookcase shelf.
However, many experience sagging even at weights less than this, especially with moisture exposure.
How Long Do Billy Bookcases Last?
Billy bookcases can last as long as 20 years. However, you can only expect a long life out of them if you treat them gently and do not let them get wet.
The easier the life of your Billy bookcase, the longer you can expect it to last.
Can You Stack Ikea Billy Bookcases?
Stacking Billy bookcases isn’t recommended—it can make them unstable and dangerous. If you really want to stack them, attach both to the wall for safety.
If you want to provide yourself with shelving at a higher height, you can always consider wall-mounting your bookcases. It is safest to wall mount all bookcases, no matter what.
Visit this fantastic article to learn how to wall mount Ikea Billy bookcases, “Can An Ikea Billy bookcase Be Wall-Mounted?“.
What Are Ikea Billy Bookcases Made Of?
Billy bookcases are made of particle board. This material combines sawdust, wood scraps, and a binding resin.
You can identify particle-board because the fine sawdust-like grain is unique. It contrasts with real wood, which has long wood-like grain.
In Closing
This article has answered, yes, Billy bookcases can sag. However, whether or not a Billy bookcase sags depends on shelf dimensions, moisture exposure, and the items’ weight.
We also included a handy guide for how to strengthen a Billy bookcase. Good luck!
