Copyright 2002 by Leonard G. Barton - rights released for noncommercial use.


Construction of the Fourth Design of a Modified Kenyan Top Bar Hive (KTBH), the CalKenyan (Kenyan hive adapted for California).

Note: this hive (CalKenyan 4) is the latest evolution in a design searies and is the first to be documented with instructions for a builder. I expect to be designing an improved model this Fall (2002) that will combine the best features of previous designs. In particular, I intend to eliminate the bottom screen and bottom board, using one or more continuous narrow and unscreened bottom slots as is now used in a modified CK3. The screened bottom that bees walk on tends to cause a large amount of pollen to be lost while the bottom board (needed to stop drafts) must be regularly cleaned to prevent mold build up and wax moth infestation. The narrow vent on the bottom of CK3 prevents drafts while providing both ventilation and exit for mite fall and wax particles.

Part One.

Note: If you are an experienced user of power tools you will find much more detailed text and pictures concerning tool use and setup than you need. These instructions are to assist a relatively inexperienced person to perform the tasks safely and accurately.

For detailed pictures on working the hive Click Here.

For information on the latest version (CalKenyan 5) Click Here.

There is enough information in that page for an experienced builder to construct the latest version.

Design Evolution and its Effect on Varroa Mite Rejection

The angle of the sides has been steepened from 30 degrees from vertical to 22.5 degrees. Observation of previous hives showed that the bees would build larger cells (for drone brood) as they built downard and that this would collide with the sides. With the steeper sides the bees will have to add additional cells beyond the normal geometry to get closer to the wall. It is expected that this will reduce comb attachment to the walls. I consider comb attachment detrimental to mite rejection in Kenyan (slope sided) hives. Attachment is not much of a problem with comb manipulation if the hive is long enough to allow access to free the last comb with a long knife.- a possible argument in favor of the vertical walled Tanzanian design. Also, frames can be used in Tanzanians, so adheasions would be to the side of the frame rather than to the hive side (see Jackson Long Hive).

For some pictures of a newly developed Tanzanian (vertical sides) see Steve's site at http://www.xscd.com/tbh Of particular note in Steve's hive is the communicating area over the bars, with perforated bars to allow bee access. That hive could also allow easy supering with conventional shallow frame boxes.

Returning to the CalKenyan, the inner wall in this latest design is stabilized with additional woodwork as some buckling has been seen when the polyethylene liner gets warm. Also, the latest hive uses white poly, rather than black, which should also reduce buckling as it absorbs less heat. If you live in a colder climate it will probably be desireable to use black poly on the long side facing the equator (the entrance should face east). In any case your hive should be in a sunny spot but if it gets very hot some overhead shade will help to keep the hive cool at midday.

Effectiveness in Mite Rejection

The second design evolution had a horizontal region that could catch fallen mites that tumbled down the side, with a central area that opening directly to the bottom screen. In this hive, mites on drone brood were observed averaging one per drone (some none, some up to four). When the bees were in this hive various essential oils and sugar dustings were used which increased the mite fall into the bottom tray but appeared to have little effect upon the drone infestation.

After moving the hive to design number 3 (30 degree slope, narrow open bottom slot, no screen), the drone brood was agressively excised for several weeks by cutting and removing drone brood comb. Examination in the later stages of this effort showed greatly reduced mites on this brood, down to one in 20. The drone excision was relaxed and now, although I have a large number of drones, sampling has revealed almost no mites - certainly less than 2%. I attribute this to the steep sides of this third design.

I expect that the mite rejection will be further improved as any mites falling from the central region will now drop directly onto (and presumably through) the bottom screen.


While this hive can be constructed using only hand tools, a power screwdriver/drill will save much time and effort. A portable saw will speed the cutting (but be aware, this is a dangerous tool) but is not required. You will need a hand saw to complete certain cuts. A medium duty stapler is suggested if you are using the corrugated polyproplyne sides and is required if you are making bars of the same material, otherwise you may substitute tacks. Wooden bars can be made from door stop stock and with glued fiberboard webs, but these will be stronger and easier to assemble if you can cut groves for the webs. This can be done by carefully clamping and shiming a portable saw, but in the interests of avoiding responsibility for your safty I leave the details of this to your imagination.

If you do not have a means of ripping stock than a small block plane or rasp and sandpaper may be used to shape certain pieces.

You will also need two clamps for securing material up to 2 inches thick to your worktable. A sturdy worktable is required (a stout picnic table will do). Take care in your setups so that you do not cut the table.


10 ft of 2x4 for legs - a weather and rot resistant material (cyprus, cedar, or redwood) is recommended, but do not use treated wood. If short pieces are available they should be at least 30 inches long.

An 8 ft length of 1 x 12 board, or shorter pieces of salvage for constructon the hive ends. This is 3/4 inch thick by somewhat more than 11 inches across (11 1/8 to 11/3/4).

16 #8 flathead screws 5/8 inch long for side frame assembly.

12 #12 round head screws 2 inches long, for leg attachment.

12 fender washers, with clearance for the #12 screws. Fender washers have a large diameter relative to the size of the hole.

13 flathead screws 1 1/2 inch long, small diameter (drywall screws are OK here) for landing porch attachment and roof frame assembly

20 2 inch deck screws to join the end walls to the side walls and for fabricating the end walls.

4 2.5 inch deck screws for fabricating the end walls.

12 1 inch wire nails.

30 feet of 1 by 2 pine or fir. Select for straightness and small, tight knots. This is to be cut into 4 pieces the length of the hive (typically 4 ft interior) and 8 pieces about 19 inches long. 4 of these short pieces need only be about 1 inch wide and could be ripped from wider stock.

Wood strips, about 9/16 thick, 1/2 to 3/4 wide, about 2 ft long.

One 4 ft by 8 ft sheet of corugated polyethylene (for a four ft internal hive length). This material (sold under various trade names such as Corroplast) is available from a plastics shop or from a sign frabricator. You have probably seen this material used for those annoying "Work at Home" or "Work from Home" signs, but these are inconviently small for most of this application. Political campaigns can be a rich source of this material, often in full 4 ft by 8 ft sheets - contact the candidate's campaign headquarters or just wait a while after the election. In most juridictions such signs become illegal postings within a few days or a week after the election.

One 36inch by 5 ft sheet of corugated polyethylene if you wish to make a roof from this material, otherwise appropriate plywood and other roofing materials. Additional poly from a full sheet may be used for end covers and rain guards as shown or these may be made from smaller salvage.

Two strips of heavy duty aluminum foil the length of the roof interior. This is required if you make the roof from courrugated poly as even the white poly is somewhat translucent and can act a heat trap. Even with a wood roof it will improve thermal performance in both hot or cold weather.

2 or 3 5 foot lengths and 4 16 inch lengths of 1 by 3 for the roof frame. You may use 2 5 foot lengths and rip one into two pieces for the roof side rails a shown.

One white poly grid made for use as a florescent light diffuser. This is a little less than 2 ft by 4 ft. This is used for an "anti-swarm" grid and also serves to limit the depth of the comb. If you elect to not use this grid then the hive should be built with shallower sides, as deep comb can tear in hot weather.

Carpenter's glue. This need not be waterproof as all glue joints are protected from the weather.

A length of 8 mesh hardware cloth for the bottom screen. As this tends to be irregular across the roll you should cut a strip along the length of the roll. The length should be about two inches longer than the inside length of the hive. The exact width is determined by the width of the completed hull which may vary but a 12 inch wide strip is more than enough if the hive is deep enough to require a hanging grid and can be trimmed down when installed.

Courrugated cardboard for insulating the side walls. This can be salvaged from courrugated shipping boxes.

16 feet of 1 by 3 pine or fir for the roof frame. Material required will vary depending upon the length of the hive.

3/8 inch staples or tacks.

9/16 inch staples or tacks.

Length of the Hive

The smallest practical full size hive would be about 38 inches inside length. The roof can then be close to 48 inches long, a handy size for material. This size may not leave sufficient free end space when the colony has grown, however.

A medium size hive has have 48 inches inside length for economy of materials (the inner and outer sides can be made from a single large sheet of corrugated polyethlyne). This length will require about a 60 inch length for the roof to ensure proper overhang. This is the hive built in the example.

If the side material is plentiful than I recommend a somewhat longer hive as the excess space can be used for storage or internal feeders.

Building the hive hull


The End Walls

Construction of Templates

Cut out a rectangular piece of cardboard 20 inches wide and the same hight as the width of the 1 by 12 board material (this will be between 11 and 11 3/4 inches). This will be cut into two half templates, one for the top part of the end and the other for the lower part.

Set the material in front of you with the long part from side to side.

Mark a rectangle to be cut out at the upper left corner of the material, 3/8 inch wide and 1 1/2 inch vertically. Measure from the lower right corner across 4 1/2 inches and mark.

Measure from the upper right corner across 9 1/4 inches and mark.

Draw a construction line between the two marks. This should form a line tilted away from the right edge at approximately 22.5 degrees.

From the upper edge, measure down along the construction line 2 1/4 inches and mark the point. Below this point mark the construction line as a cutting line.

Place a straightedge at the upper left corner of the material and move the right end of the straightege until it intersects the construction line at the marked point. Mark a line between the corner and the point as a cutting line.

Measure 14 inches from the upper right corner of the material along the upper edge and mark a cutting line, parallel to the first cutting line and terminating at the second. This shortens the long narrow spur that is part of the smaller template.

The piece at the lower left (the larger piece) is a half template for the upper part. The small rectangular cutout is to recieve the ridge part of the roof assembly.

The other large piece is a half template for the bottom part. Cut out at the cutting lines. You should have a small rectanglular scrap, a narrow trianglular scrap, and two half templates.

Selection of Materials

Most low cost pine has knots. Tight knots in well dried material will not be a problem, but you should avoid having them at the cut edges of your components. The half templates may be used to select your material to ensure that no significant knots are at the edges, so take them with you to your supplier. Avoid damp wood or wood with warps or cracks.

Material Cutting Pattern and Layout of Cutting Lines

Starting at the left end of the board, place the large template with the ridge cutout to the upper right and match the lower left corner of the template to the material while alighing the lower edges. Mark the cut lines and the centerline. Flip the template over across the centerline and mark the cut lines.

Place the smaller template for the lower part with its upper edge aligned with the upper edge of the material. The edge of the template should align with the two of the previous cut lines. Mark the short cut line and the centerline. Flip the template across the centerline and mark the cut lines.

Continue alternating and flipping templates until you have two large top pieces and two smaller bottom pieces marked.

Cutting the End Pieces

In this case these were cut from smaller pieces salvaged from a bookcase, but you would procede in a similar manner if working from a larger board. Clamp the stock to a sturdy table.


Rough cut to the intersection of the cutting lines.


Finish the cut with a hand saw while supporting the material.


Drilling the Lower End Parts

Select screws that are long enough. (These go in the opposite way, actually) [Deck_Screws]

Drill holes large enough so the screws do not bind.


Insets for the heads ensure that the screws will project into the material.


Assembling the Ends

Having marked the centers of the mating edges, glue the edges and align the marks. Tighten the screws, being sure that the pieces are in alignment to form a single flat piece. Take care to not overtighten - that could crack the wood.


Upper Vents and Entrance

Route slots or drill 1/2 inch holes in the areas shown. when marking for the upper vent slots allow 3/16 from the frame mark for the inner liner.


The entrance should be between the areas supported by the end walls, rather than lower down where the structure is weaker.


The Side Walls

Cutting the Side Frames

The outer part of the frame uses half lap joints. You may use other types of joints if you do not have the tools to make the joint as the rigidity of the frame is enhanced by the inner and outer liners. One alternative method would be to use thin plywood or fiberboard triangular gussets on the outside face of the frame. (We will attach the outer skin before assembling the hull to make sure it is strong.)

If you are using the half lap joints, the length of the perimeter pieces are the same as the dimensions of the side panels, about 19 inches high and (in this case) 48 inches long, the interior length of the hull. Cut four long pieces and two short pieces. You should have enough material left to fit inside across the rectangular frame, dividing it into two open panels. These will be cut to size later after the basic frame is finished. Using a table saw, cut the half laps. The distance from the end is equal to the width of the material used for the side frame and the depth is half of the thickness of the material.

You can set the correct depth by making cuts in from both sides of some scrap material of the same thickness, adjusting the saw upward until you cut through.


With the fence well clear, mark and make the first lap joint.


Once you have made the first joint you can set the fence to use with a gauge block (do not use the fence as a gauge directly as the workpiece can then bind against the saw and kick back). With the first piece against the saw, put a gauge block (a wood scrap that you can align and position easilly) at the end. Adjust the fence against this. You can now position the block against the fence at the edge toward you, and with the workpiece on the miter gauge (set to 90 degrees), slide the workpiece against the gauge. Clamp the workpiece to the miter gauge with your hand and remove the gauge block. You may now procede to make the first cut, with subsequent cuts as you move the workpiece further from the fence to form the half lap. The laps at each end are made on the same side of each piece.

Finish the lap by block sanding the high spots off.

Predrilling the Side Frames

Make sure that all corresponding pieces are cut to identical lengths and that the half laps are the correct depth and width.


Assembling the Side Frames

Starting at one corner clamp the pieces (using a square for alignment) and predrill countersinks using a combination drill and countersink for flat head screws. Arrange the position of the countersink on the drill to ensure that you create a shallow pilot hole in the lower piece. Each corner should use two screws. Once the holes are drilled, mark the mating pieces distinctly as they cannot be re-arranged. Unclamp the joint and redrill a clearance hole for the screw in the upper piece.


Being sure to keep the marked matching ends together, assemble the frame by gluing the joint, clamping in square alignment, and attach with screws, #8 flathead, 5/8 inch long.

The Inner Cross Pieces

For each frame, cut two pieces to go across the narrow dimension on the inside. These will serve to keep the skin from buckling when heated and do not even need to be attached to the frame. They can be simply stapled in place when the outer skin is attached, although I glued mine in place without nails or screws.


The Outer Skin and Skin Extension

Cut the outer skin piece to match the length of the frame, but long enough so that it will extend an inch beyond the bottom of the ends which is already well below the bottom edge of the frame. This dimension will be between 21 and 22 1/2 inches, depending on the width of the boards used to construct the ends.

Trial fit the skin to make certain that it does not extend beyond the frames at the front and back ends as we need to have the wood of the frame contacting the end pieces.

Using the stapler, attach the outer skin to the frame, making sure that it aligns with the top and side edges and extends beyond the bottom edge.

Assembling the Outer Hull

Predrilling the Ends for Side Frame Attachment

Having well marked the postions of the side panels on the inside of the end pieces, predrill from the inside for deck screws, making certain that the screw to be used does not bind in the hole. The upper and lower screw holes should be at least an inch inside of the half laps. If you need to be able to completely dismantle the hive for shipping, use four screws, otherwise we will use glue and three should suffice.

[Picture to be provided here]

Attaching the Ends

Assembly will easier and more accurate if you attach temporary cleats to the inside faces of the end panels. These should be made from 2 x 2 stock. Use screws that will go into but not through the end panels.

[Picture to be provided here]

As each joint is made it is first glued then placed in the marked position on the end and screwed.

For the first side attachment you can place one side flat on the table with the outer skin down and the short edge parallel to and slightly beyond the edge of the table. Next, add glue to the joint and place an end piece on this side - the temporary cleat will hold it from falling. Slide the end to align with the positioning marks. Using a square to keep a 90 degree angle, attach the end to the side frame with screws.

[Picture to be provided here]

You may then place the end on the table with the side vertical. Take care not to stress the joint you just made. The part of the side for the next joint should overhang the table so that you may drive the screws from the bottom

Glue and position the second side. You may place the other prepared end atop the assembly to stabilize it. You may also staple a scrap of cardboard or poly across either opening to hold it in place.

Working from the bottom at the edge of the table attach the second side to the face.

[Picture to be provided here]

You may then place the unit on the floor and glue and screw the other end on. As you make the last attachment make certain that the assembly is not twisted. This can be checked by placing a straightedge across the large opening at each end and sighting on them.

[Picture to be provided here]

The hull may now be placed on the table inverteds for attaching the mite screen.

Fabricating the Mite Screen


The long dimension of the screen should come from the long dimension of the material - allong the roll rather than across it, as this dimension will have straight wires.

Cut the screen to a little less than the width of the outer edges of the frames at the bottom.

Cut the screen 2 inches longer than the interior length. Fold the corners down, then fold the ends up.

Attaching the Mite Screen


Staple one end in place. Stretch the screen and staple the other end, adjusting the fold if necessary. Then staple along the bottoms of the side frames.

The screen is permanently attached as by closing the hull on three sides it becomes much more resistant to twisting. The bees do an excelent job of keeping the hive interior clean and the upper surface remains accessable from the top when the top bars and hanging grid are removed.

The Legs

You can cut four legs from a single 10 foot piece of 2 x 4.

Cutting the Legs

The leg fits into the triangle formed by the end and the side. Cut the end at an angle so that the outer edge of the leg aligns with the outer edge of the upper part of the end and the inner end fits against the side. [Leg_Fit_Up]

This should be a 45 degree cut


The foot base is cut at 67.5 degrees.


Additional cuts are used to shape the leg. The vertical foot will then fit inside of a cat food can which can be filled with sand and oil or with water (which must be replenished daily). This is to foil ants.


The foot may be shaped with a rasp or sander and finshed to form a more pleasing shape.


Attaching the Legs

Each leg is attached with three #12 screws, 2 inches long, with fender washers. The clearance drill is 7/32 inch. One screw is at the top, near the apex of the triangle. The other two are near the bottom edge of the top part of the face, but not on an exactly horizontal line - they should not be on the same grain lines.

Fanning Area Rim

Cut some scrap down to about 9/16 inch thick and make three pieces long enough to enclose the entrance and vents. Clamp a temporary cleat horizontal and slightly under the routed bottom entrance. This will be a guide for placing the rim parts. The rim parts will in turn guide the placement of the landing porch.

Using 1 inch wire nails, affix the rim as shown. [Refined_Foot]

The Landing Porch

Fabricating the Landing Porch

Cut a piece of board that will span the hive face just below the entrance slot. This should be about three inches long and the grain should run away from the hive face. The edge that goes against the face should be cut at a slight angle (about 2 degrees) so that the porch will slope away from the entrance. Cut another smaller board as a support for this. Glue the boards together, aligning the edges that will go against the hive face. [Clamping_Porch]

Installing the Landing Porch

Hold the porch against the face and mark its position. Remove the porch and mark the position for several holes for screws to attach the face. These should be above and below the surface of the mite screeen and should not enter the join between the top and bottom porch components.


Drill through with clearance holes for the screws (some of these will penetrate the folded end of the mite screen). Attach the porch using glue and screws from this inside of the hive above and below the screen.

The Interior Ramp

The bottom of the entrance is a bit above the surface of the mite screen. To make it easy for the houskeeping bees to drag detrius from the hive, add a ramp inside of the entrance. Rip or plane a wedge. The ends of the wedge are cut to match the inside of the hive at 22.5 degrees. [Interior_Ramp]

Cut clearance for any protruding screwheads used to attach the porch and glue the wedge in place. After the glue is dry a few short staples may be used to secure the screen to the wedge. [Ramp_Bottom_View]

Finishing the Hive Interior

Cardboard Insulation

Using sections of cardboard box, insulate the rectangular voids. Use enough layers (four) to fill the void completely. Do not use glossy printed cardboard, rather just the plain brown stuff.


The cardboard is retained by stapling across the edge.


The Interior Liner

Prepare a piece of corrugated polyethelyne sheet the appropriate length (48 inches in this case) and 22 inches wide. Lightly sand the interior face so the bees can get a grip on it. Mark the position of the intermediate pieces in the frame so that you will be able to staple into it even though you cannot see these with the liner on.

Cut away one corner for clearance at the interior ramp


Set the bottom edge of the liner on the mite screen and staple the liner onto the frame. Be sure that the top staples are not at the upper edge of the frame, but rather at least 3/4 inch below this edge.

Fold the excess over the edge, but do not staple yet.

Cut a piece of scrap lath 22 inches long to form an inner bar gauge. Set this into the hull so that it is parallel with a line across the width of the hive. The bottom of the gauge should be about 1/2 to 3/4 inch below the top edge of the hive.

The Rolled Edge

Crease the poly below the fold you just made at the point indicated by the inner bar gauge. Use something blunt so that you do not cut the material.

Push the edge toward the center so that the portion of liner between the crease and the first fold will be vertical when the hive is in place. The horizontal distance between these vertical portions should be 22 inches, the same as the length of the inner bar gauge.

This little ledge will keep the bars from poping up if they are side loaded when you handle them. This is not a problem when they are full of comb, just when they are empty).

Maintaining this ledge staple along the top edge of the frame on both sides.

The Edge Extension

The excess material should extend beyond the edge of the frame a bit.

Click Here for Part 2

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