Knock-Down Frames and Parts

A flat-pack frame is a wooden hive frame made up of a top bar, two side bars and a bottom bar, which is sent to the beekeeper in parts and assembled by the beekeeper with glue and nails. It is cheaper, takes up little space and can be assembled as needed; however, its dimensions must be correct, the wood dry and the assembly square. On this page you will find the parts of a frame, what to look for when choosing, step-by-step assembly and maintenance.

What is a flat-pack frame and why choose one?

“Flat-pack” means the frame arrives from the factory unassembled, in parts. The beekeeper assembles the frames in the winter months, before the season. Once glued and nailed, a frame is no longer something to be taken apart and put back together; it works in the hive as a single unit for years.

• Economy: Because the assembly work is left to the beekeeper, it is usually cheaper than an assembled frame.
• Transport and storage: The parts come in bundles and take up far less space than assembled frames.
• Flexibility: The beekeeper assembles only as many frames as needed; a spare for a broken bar can be obtained separately.
• Quality control: Because you do the assembly yourself, you also decide on the quality of the gluing, nailing and squaring.

What are the parts of a frame?

Top bar

This is the thickest part of the frame and bears the most weight. The lugs at each end hang the frame on the rebate along the inside edge of the hive body. On its underside there is a groove in which the foundation sits, or a removable wedge; the wedge clamps the top edge of the foundation against the top bar.

Side bars

The side bars have wire holes for the wire to pass through. Common Hoffmann-type side bars are widened at the top; when the frames are pushed together, these wide sections butt against each other and the correct spacing between frames forms by itself. On frames with straight side bars, this spacing is provided by spacing nails, plastic spacers or castellated spacers in the hive body.

Bottom bar

There are one-piece, grooved and split types (made of two thin bars). The bottom edge of the foundation should not rest on the bottom bar; a gap of a few millimetres should be left between them.

Why do bee space and frame size matter?

Bees leave gaps of about 6–9 mm open as passageways; they seal narrower gaps with propolis and build comb in wider ones. This principle of bee space determines the distance of the frame from the walls of the hive body, from the floor and from the neighbouring frame. In the brood area, the distance between frame centres is usually around 35 mm.

• The frame size must match your hive type (Langstroth, Dadant, etc.) exactly. An error of a few millimetres means brace comb and frames glued in place with propolis.
• Using a single frame size in an apiary means frames can be swapped between hives.
• Do not mix up brood (deep) and honey (shallow) frames.

What should you look for when choosing flat-pack frames?

• Wood quality: Dry, straight-grained bars free of knots and cracks. Damp wood warps after assembly.
• Dimensional accuracy: The bars in the same pack must be identical in length and in their joints.
• Type of joint: The parts should fit together tightly with no play; a loose joint stays weak even with glue and nails.
• Pre-drilled side bars: Ready-drilled wire holes make assembly easier; the holes should be at the same height on both side bars.
• Hive compatibility: The top bar length, lug thickness and frame depth must suit your hive body.

One-piece plastic frames need no assembly; however, a broken part cannot be repaired, and some beekeepers feel that bees accept wooden frames more readily.

How do you assemble a flat-pack frame?

1. Do a dry run: Put one frame together without glue and check that the parts fit exactly.
2. Apply glue: Apply a weatherproof, water-resistant wood glue to the joint surfaces. Glue noticeably extends the life of the frame.
3. Assemble: Fit the side bars into the joints of the top bar, and the bottom bar onto the side bars. An assembly jig lets you put together many frames neatly at the same time.
4. Nail: Use thin nails or staples of a suitable length. Nailing the top bar to the side bar from two directions stops the lugs and the corner from coming apart. Take care that the nail does not split the bar.
5. Check it is square: Before the glue dries, check that the corners are square; a skewed frame rubs in the hive.
6. Wire: Once the glue has dried, wire the frame (see the “Frame Wire and Frame Wiring” page).

Frame maintenance, cleaning and reuse

A well-assembled wooden frame can be used for many years. Once the old comb has been cut out, the frame is cleaned, rewired and goes back into the hive with new foundation.

• Scraping: Propolis and wax residues are scraped off with a hive tool; the lugs and the bearing surfaces of the side bars in particular should be clean.
• Washing: Very dirty frames can be washed in hot soda water. This solution is caustic; safety goggles and gloves are essential, and the frames are rinsed thoroughly with water afterwards.
• Hygiene: Frames from a diseased or dead colony must be cleaned before being given to another hive. If you suspect a notifiable disease such as American foulbrood, do not move the frames; report to the official veterinary service / local agriculture authority.
• Repair: A frame with a broken or loose lug is repaired or set aside; a loose frame can fall apart in the extractor.

Common mistakes with flat-pack frames

• Assembling with nails only and no glue: the frame loosens over time and falls apart in the extractor.
• Splitting the bar with a thick nail, or driving a nail over a wire hole.
• Not checking for square; a skewed frame jams in the hive.
• Mixing bars from different manufacturers; the spacing is thrown off by differences in size.
• Storing assembled frames somewhere damp and open to wax moths and rodents.