Slatted racks: everything you need to know

I was a newbee when my mentor took one look at my overcrowded, bearding colony and said, “I think you need a slatted rack.” And then he left.

Huh? What the heck was he talking about? And later, when I asked around, people who never used one told me they were worthless. After all, they assured me, if you needed one, it would have come with your beginner kit.

I have a tendency (more like a strict rule) not to listen to the overly-self confident, so I bought my first slatted rack and never looked back.

What is a slatted rack?

A slatted rack is an optional piece of beekeeping equipment often used in Langstroth hives. The rack (sometimes called a brood rack) is about two inches high and is placed between the bottom board and the lowest brood box.

The rack has the same outside dimensions as a standard Langstroth hive. The modern version has ten slats that run in the same direction as the frames in the brood box, with space between each one. In addition, it often has a 4-inch wide board that runs parallel to the front of the hive. You frequently see slatted racks in hobby hives but rarely in commercial hives.

What is the purpose of a slatted rack?

The purpose of a slatted rack is to provide dead air space below the brood chamber. This layer of air helps to keep the colony cooler in summer and warmer in winter.

To prevent developing brood from overheating in summer, honey bees are reluctant to accumulate in the nest. Instead, they may beard on the front of the hive or below the hive stand. However, if you add a slatted rack, the adult bees have a place to gather inside the hive without crowding the brood area. In addition, the extra space makes fanning easier and more efficient, which can improve ventilation and promote the curing of your honey.

Some people believe that the purpose of a slatted rack is simply to reduce bearding. But others believe the extra space inside the hive can delay or reduce swarming by relieving overall congestion. Unfortunately, I have no statistics on either of these claims. Still, I love climbing under my hives on a hot day and watching all those bees congregate on the rack. They look happy! (Okay, scratch that, they look like bees.)

In winter, with entrances reduced and varroa boards in place, the slatted rack provides an insulating layer of air between the brood nest and the outside. It also moves the brood nest further from the cold and drafty hive entrance.

Any other advantages?

A queen may resist laying eggs close to the hive entrance, possibly because of fluctuations in air temperature. But by using a slatted rack to move the lowest combs further from the entrance, you can increase the amount of usable brood-raising space.

Is this a new invention?

Absolutely not. Back in 1900, Dr. C. C. Miller came up with the idea of providing a resting place for bees below the brood nest. This idea probably came from observing feral colonies. Bees in the wild attach their first combs to the top of their cavity and build down, adding more and more combs beneath the originals. Often the workers cluster on the very bottom, below the nest, in hot weather. The slatted rack gives hive-dwelling bees a similar opportunity.

Later, in about 1950, Carl Killion added the four-inch board along the front of the rack, apparently to reduce draftiness. But the guy who got all the credit for slatted racks was Richard F. Bovard of Honolulu. Bovard was a woodworker who devised an easy way to construct the rack as a one-piece unit, so for many years, these were known as Bovard racks.

Which way do the slats go?

In the original design, the slats ran perpendicular to the brood frames. In fact, you still see these occasionally, except now we call these “horizontal slatted racks.” However, with the introduction of varroa mites and the common use of screened bottom boards, beekeepers wanted slats that ran parallel to the brood frames so mites could fall freely through the frames and the rack to the screen below.

This modern design is sometimes called a “vertical slatted rack.” You can buy them fully assembled for ten- and eight-frame equipment. My favorite one—no longer made—was a ten-frame version that came unassembled. It was cool because you could put in either 9 or 10 slats, depending on how many frames you used per brood box.

On the other hand, since screened bottom boards are not very good at eliminating varroa from a hive, I don’t think the alignment of slats and frames makes much difference. After all, slatted racks are not designed for varroa control. They are good at what they do but they can’t do everything.

Do all slatted racks have the horizontal board in front?

No. Some of the recent models leave that part out. The purpose of the horizontal board was to reduce turbulence caused by air coming through the entrance. It was also said to reduce the amount of light entering the brood area, which the queen will shy away from.

Apparently, it is cheaper to build a slatted rack without the horizontal board, but if you want the full benefit from having a slatted rack, I would look for one that has all the features.

When do you install the rack?

I always use a slatted rack, and I leave it in place all year long. I install it when I set up a new hive, even a nuc, and never take it out. In fact, some of the modern long Langstroths, such as the Valkyrie long hive, come with the slatted rack built in.

How do you tell the bottom from the top?

Good question. Newer ones are marked with something like “This side up.” That’s because zillions of beekeepers insert them upside down, which causes a horrendous mess when the bees fill it with comb. Unfortunately (I sheepishly admit) I know this from experience.

The top side is the shallow side. There should be bee space (about 3/8 inches) between the bottom of the brood frames and the top of the slats. If there is more space, the bees will fill it with comb, attaching it to the bottom of the brood frames and the inside of the slatted rack. Not good.

While we’re thinking about orientation, don’t forget that the four-inch wide board goes toward the front of the hive, near the opening. Slatted racks can be confusing at first, so pay attention.

Won’t bees build under the slatted rack?

Although I have never seen bees build under the rack, I suppose they could. With bees, things happen, which is why you have a hive tool.

Do you recommend slatted racks for everyone?

As I said earlier, they are optional. They add expense to a hive and they make it both taller and heavier. But I love them and consider them to be part of a standard setup. Some beekeepers think slatted racks should be universally accepted as standard equipment, but sadly, they don’t come close. My recommendation is to try one and see how it works for you.

Build your own

One of my readers, David Manning of Sparta, Missouri, builds his own seriously good-looking slatted racks. If you are so inclined, read his post on How to build a slatted rack. Also, plans by another woodworking artist (and master draftsman), Matthew Waddington of Duvall, Washington, can be found here.

Otherwise, most bee supply companies sell slatted racks fully assembled. I usually paint the outside before placing it above the bottom board, as shown below.

Any questions? Let me know!

Rusty
Honey Bee Suite