Skip to Content

Do Ikea Billy Bookcases Sag?

Disclosure: We may get commissions for purchases made through links in this post.

Billy bookcases make excellent home additions and storage options. However, you may have heard that these Ikea products sometimes sag. Well, we have thoroughly done our research so we can answer this question.

Billy bookcases do sometimes sag. However, Ikea says they are constantly improving the shelf strength. How much sag is expected in Billy bookcases is a combination of several factors as listed below.

  • Shelf dimensions
  • Exposure to moisture
  • Weight of items on 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 how to both strengthen and fix Billy bookcase shelves. Further, we answer several questions related to this post.

living room with white bookcase on a white wall, lounge chair. Do Ikea Billy Bookcases Sag

Why do Billy Bookcase Shelves Sag?

Billy bookcases sag because they are made out 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; we explore the ins and outs of what influences the amount and rate of sag in the next several subsections.

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 deciding sag factor is the width. 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 makes Billy bookcases that have a variety of widths. Common ones include 15 3/4 inches and 31 1/2 inches. The moral of the story is that the wider the width, the more likely a shelf will sag. That is to say, Billy bookcases with 31 1/2 inch unsupported width are far more likely to sag than narrower shelves.

Exposure to Moisture

Particle-board (the material in Billy bookcases) is very sensitive to moisture. This does not mean that a quickly cleaned spill with ruin the bookcase immediately. However, prolonged exposure to high humidity will weaken the structure of the particle-board, causing the bookcase to sag.

Moisture content varies based not only on local humidity but also from room to room in a house. Wet humid places like Florida have higher moisture content in the air than dry places like Arizona. Similarly, the bathroom or kitchen has higher moisture content than a living room or office.

To reduce the likelihood that your Billy bookcase will sag, purchase it for a dryer room in your house. Further, be sure to 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 that a Billy bookcase might not be the best place to store a rock collection. However, they are tough enough to handle a relatively heavy load of books in most situations (they are bookcases, after all). If you do notice your bookshelves sagging, you can always reduce the weight on them. 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/different shelves.

Front Edge Support

This is the technique preferred by many contractors for strengthening particle-board but does require a little technical know-how. The idea is to attach a stronger material to the bookshelf's front edge to stop it from sagging. This can be done either to prevent sagging or even to fix minor sagging.

Click here for an easy-to-use rotary saw from Amazon.

Often fir or another common wood is attached to the front of the shelf with glue or nails. This can be done with a table saw, a rotary saw, a tape measure, and a few carpentry skills. Generally, make the scab piece for the front of the shelve about 2-inches by the thickness of the original shelf (or even a quarter-inch thicker than the shelf for more support).

The best time to install front edge support is as soon as possible. Either add these supports when you first purchase a Billy bookcase or as soon as you notice any sag starting. The longer you wait, the more likely there will be irreversible damage.

Back Edge Support

Back-edge support is similar to front-edge but does not require fine carpentry skills and does not produce the same quality of results. This reduction in quality stems from the support location. The support material does not strengthen the "floating" edge of the shelf but rather strengthens the back edge.

There are two main ways to accomplish back-edge support, with wood or with metal U-channels. For wood, cut the piece the length of the shelf and then attach it to the back of the bookcase with glue and nails/screws. Put the support 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.

Click here for a U-Channel product available from Amazon.

The strategy for 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. What you are trying to accomplish is to half the width the shelf goes without support. The downside of this strategy is the reduction in shelving space.

Edge of six cedar two by four wood boards

For neatness and structural integrity, cut the support pieces as close to perfect as possible. 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 it does not solve the problem of failing internal structure. However, but 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 own shelves. However, keep in mind that no shelf is perfectly sturdy, and other materials may sag as well. 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 is not recommended. This leads to decreased stability and can cause serious injury. If you are determined to stack your bookcases anyways, consider attaching both bookcases to the wall to avoid a dangerous situation.

If providing yourself shelving at a higher height is your goal, 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 is a combination of sawdust, wood scraps, and a binding resin. You can identify particle-board because the fine sawdust-like grain is unique. It contrasts to 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 weight of the items on the shelf. We also included a handy guide for how to strengthen a Billy bookcase. Good luck!