Apimaye vs. Primal Bee: Insulation Claims Compared

Updated November 2026. Primal Bee's claims checked on November 5, 2026.

R-50 and R-6.93 measure different things

Primal Bee advertises its EPS foam hive as R-50. Apimaye publishes R-6.93. The two numbers aren't arrived at the same way:

• Apimaye's R-6.93 is a lab result for a 31.3 mm (1.23 in) sample of the polyurethane foam inside Apimaye's walls, tested by an accredited lab to a named standard.
• Primal Bee's R-50 is its own average across the whole hive: the walls, a lid with a 175 mm air chamber, and a bottom board with a 106 mm air chamber. We couldn't find a published lab report verifying R-25 for the side walls or R-50 for the assembled hive.

Primal Bee's comparison page (opens in a new tab) acknowledges the difference, saying its figure is "measured across the top cover, nest walls, and bottom board — not one foam wall." It then sets its R-50 against a "basic insulated example" at about R-7 and marks itself the winner on thermal specification. Its technical guide (opens in a new tab) lists Apimaye at "About R-6.93" in the same table as its own R-50. A fair comparison puts wall against wall, which is what the rest of this page does.

Apimaye: R-6.93

What the number covers

A 31.3 mm sample of the wall foam

Source

TEBAR, an accredited lab (TÜRKAK)

Test standard

EN 12667

Air chambers in the number

None; the sample is solid foam

Lab report published

Yes, you can download it

Primal Bee: R-50 (claimed)

What the number covers

An average across walls, lid and bottom, counting air chambers

Source

Primal Bee's own figure; no independent lab named

Test standard

None named; its patent describes a heat-loss method

Air chambers in the number

Yes, and the totals need far more from them than standard tables allow

Lab report published

None we could find

ClaimedEstimated at R-4.3/in

Side walls (65 mm)

Claimed R-25

Estimated about R-11

Lid

Claimed R-140

Estimated about R-25

Bottom

Claimed R-75

Estimated about R-20

Whole hive

Claimed R-50

Estimated about R-12 to R-13

The claims, and what the foam can actually do

Primal Bee's insulation article (opens in a new tab) lists the parts behind its R-50: side walls of 65 mm EPS, a front wall of 84 to 127 mm, a lid made of two 70 mm foam layers around a 175 mm air chamber, and a 110 mm insulated bottom board with a 106 mm air chamber above it, under the frames. Its getting-started guide (opens in a new tab) says the walls are 30 to 70 mm thick, so parts of the hive are less than half as thick as the 65 mm side walls.

Here's what those thicknesses come to at the ASTM C578 Type XV benchmark of R-4.3 per inch.

Swipe the table sideways to see all columns →

Claimed R-values vs. estimates for the listed foam thickness

Hive part	Claimed	Estimated at R-4.3/in	Foam Primal Bee lists	Foam needed to reach the claim
Side walls	R-25	About R-11	65 mm (2.6 in) EPS	148 mm (5.8 in)
Front wall	R-25	About R-14 to R-22	84 to 127 mm (3.3 to 5 in) EPS	148 mm (5.8 in)
Thinnest walls	Not stated	About R-5	30 mm (1.2 in) EPS
Lid	R-140	About R-25	Two 70 mm EPS layers + 175 mm air chamber	827 mm (32.6 in) of foam
Bottom	R-75	About R-20	110 mm insulated bottom board + 106 mm air chamber	443 mm (17.4 in) of foam
Whole hive	R-50	About R-12 to R-13	All of the above

Foam counted at R-4.3 per inch, the minimum rating for the densest EPS type (Type XV) in ASTM C578. For the bottom, we assume the full 110 mm board thickness is EPS insulation; Primal Bee hasn't published how much of it is foam, so this assumption favors Primal Bee. Each air chamber counted at R-1, our assumption; standard tables put sealed air spaces with ordinary surfaces at about R-0.8 to R-1.6. Whole hive weighted by surface area, explained below. Sources are listed at the bottom of the page.

How the math works

A foam board's R-value is its thickness times its R-value per inch. For EPS foam, the U.S. standard (ASTM C578) lists a minimum of R-4.3 per inch for Type XV, its densest type at 3.0 lb/ft³ (about 48 kg/m³). In the standard, extra density mostly buys strength: going from Type IX at 1.8 lb/ft³ to Type XV at 3.0 lb/ft³ only moves the minimum rating from R-4.2 to R-4.3 per inch.

Primal Bee claims a higher-density formulation, over 90 kg/m³, nearly twice as dense as Type XV. Without a published thermal-conductivity measurement for that specific foam, its exact resistance is unknown. We therefore model performance at R-4.3 per inch and test a more favorable R-5 scenario, with each air chamber counted at R-2. In that scenario the side walls come out at about R-12.8, the lid at R-29.6 and the bottom at R-23.7. Cold weather helps foam a little, about 10% at a 40°F average temperature according to the EPS Industry Alliance. That's still nowhere near R-25, R-140 or R-75.

For scale: a 65 mm wall at R-25 would need foam conducting heat about 40% less than still air, a level reached by vacuum panels and aerogels, not air-filled foams like EPS.

Put another way: to reach R-25, a foam wall needs about 5 to 6 inches of EPS. To reach R-140, a lid would need 28 to 33 inches of solid foam.

Foam the hive hasFoam the claim needs

65 mm

148 mm

Side walls

110 mm

443 mm

Bottom

140 mm

827 mm

Lid

EPS at R-4.3 per inch. Air chambers aren't drawn; we count each at about R-1.

What the air chambers can add

The two biggest numbers, the R-140 lid and the R-75 bottom, lean on air chambers. Counting a sealed air space is standard engineering practice. What it's worth depends on which way heat flows through it, the temperature, and whether its surfaces are reflective. For sealed air spaces up to 3.5 inches deep with ordinary, non-reflective surfaces like foam, the ASHRAE Handbook's table gives about R-0.8 to R-1.0 when heat flows up, as it does through a lid, and about R-1.0 to R-1.6 when heat flows down, as it does into a bottom chamber.

A deeper gap doesn't add much. When heat flows up, the air circulates and carries heat across. Even when the air stays still, heat radiates straight across the gap, which keeps an air space with ordinary surfaces to roughly R-2 or less, however deep it is. Only shiny, foil-faced air spaces go much higher, and we found no mention of reflective surfaces in Primal Bee's description of its hive.

We counted each air chamber at R-1, and at R-2 as a generous check. Either way, the shortfall is huge. For the lid to reach R-140, its air chamber would have to supply about R-116, because the foam only gives about R-24. For the bottom to reach R-75, its air chamber would have to supply about R-56.

Primal Bee describes the bottom air chamber as the space between the varroa tray and the bottom of the frames, and the hive has a screened bottom board for ventilation. If that space is open to the airflow, it's worth less than a sealed air space, so our count is generous.

The averaging problem

A single whole-hive R-value sounds scientific, but heat doesn't average that way. Heat leaves through every square inch of the hive, and the walls are most of the surface: on a hive 15.7 × 23.4 × 58.2 inches, the four sides make up about 86% of the outside area. A very thick lid can't make up for walls that let heat through.

Engineers average heat loss, not R-values. Done that way with Primal Bee's own numbers (R-25 walls, R-140 lid, R-75 bottom), the whole hive comes out around R-28, not R-50. With our estimates for the foam listed, it's about R-12 to R-13, or about R-14.4 even if the back wall is as thick as the front. That's an estimate from published dimensions, not a measurement, and it would be lower where walls are as thin as 30 mm. It also counts only heat passing through the walls, lid and bottom. A real hive loses more through the entrance, ventilation and gaps between boxes, so an assembled hive would do worse, not better. The full calculation is under Whole-hive calculation, in How we checked. A plain average of R-25, R-140 and R-75 is R-80, so it isn't clear how R-50 was calculated.

Red flags to watch for

• No lab report, and no method shown. A measured R-value should come with a lab report naming the test standard, the sample and the conditions. A calculated R-value can be legitimate too, but the maker should show its assumptions and math. Primal Bee's science page (opens in a new tab) describes its own thermal-camera photo as "not one shared laboratory R-value test," and we couldn't find how its R-50 was calculated.
• One whole-hive "average". A single big number can hide thin walls behind a thick lid.
• Big numbers for air chambers. Counting an air space is normal, but with ordinary surfaces it's worth about R-1 to R-2. A total that needs far more than that from the air deserves a question.
• Numbers that change from page to page. Its technical guide (opens in a new tab) lists the nest side walls at "about R-25" in a table, then says in its FAQ that "the nest walls average about R-50." Its getting-started guide (opens in a new tab) says "the average R-value of the walls is around 50" and that "the outer lid exceeds R-125," while its insulation article gives R-25 walls and an R-140 lid. The same article calls the air space under the nest a "90mm air cushion" in one place and a 106 mm air chamber in another. Wall thickness is "30 to 70 mm" on one page and up to 127 mm on another.
• A patent offered as proof. Primal Bee's U.S. patent (opens in a new tab) describes a whole-hive heat-loss test, with a heater standing in for the colony, and that's a reasonable way to compare hives. But a patent protects an invention; it isn't a performance test. The patent office doesn't test or certify a hive's R-value, and we found no R-values in the patent.

An open offer: if any hive maker publishes an accredited lab report for its R-values, send it to support@apimaye-usa.com and we'll update this page.

Where a thicker foam wall does beat Apimaye

Here's the part most comparison pages leave out: thickness matters. A 65 mm EPS wall, estimated at about R-11, should insulate better than an Apimaye side wall at our lab-tested R-6.93.

Inch for inch, Apimaye's polyurethane foam measured R-5.6 per inch in the lab. Against the ASTM C578 minimum for the densest EPS, adjusted to the same test temperature, that's roughly 20% better per inch. Primal Bee hasn't published a conductivity measurement for its own foam, so we can't give an exact head-to-head figure, but even at R-5 per inch, better than any EPS type in the standard, Primal Bee's foam would still trail Apimaye's measured R-5.6. The EPS wall is simply about twice as thick. We'd rather tell you that than pretend otherwise.

Apimaye polyurethane foam (lab-tested)

R-5.6 per inch

ASTM C578 Type XV EPS (minimum rating)

R-4.3 per inch

Pine wood

About R-1.2 per inch

Wood ranges from about R-1.0 to R-1.4 per inch.

Here's what you get with Apimaye:

• A number you can check. R-6.93, measured by an accredited lab, with the full report published.
• A hard plastic shell. The foam is sealed inside UV-stabilized, food-grade plastic. Bare EPS hives are foam on the outside, and Primal Bee includes instructions for painting its hive. See how bare foam holds up.
• Standard frames. Ergo brood boxes take standard 10-frame Langstroth frames, and 10-frame wooden boxes stack on top. Primal Bee's hive uses its own brood frames, and Primal Bee says standard Langstroth frames don't fit the nest.
• 6 to 7 times the insulation of a wooden hive. Softwood lumber is about R-1.0 to R-1.4 per inch, so a 3/4-inch pine wall is roughly R-1.

Insulation is only part of the picture. Foam hives also have to stand up to wax moths, mice, sun and hive tools. See hard plastic vs. foam (EPS) beehives, with photos of wax moth damage.

How much does the extra R-value matter?

Insulation has diminishing returns. Heat loss through a wall is proportional to 1 divided by its R-value, so the first few R-values do most of the work.

Wooden hive wall (about R-1)

100%

Apimaye wall (R-6.93)

About 14%

65 mm EPS wall (estimated R-11)

About 9%

Going from a wooden wall to Apimaye's R-6.93 cuts the heat lost through the walls by about 86%. A 65 mm EPS wall cuts it by about 91%. The extra 5 points are real, but small.

The walls also aren't the only way heat escapes. The entrance, ventilation, the bottom board and the joints between boxes don't change when the walls get thicker, so the whole hive gains even less. In measurements of complete hives (Mitchell, 2016), wooden hives lost heat at about 2.6 W/K and EPS foam hives at about 0.9 to 1.3 W/K. That's 2 to 3 times better than wood, less than the difference in their wall insulation would suggest.

What the research shows: a 2026 USDA-ARS study found polyurethane-insulated hives warmer and drier than wooden ones, and over the season the wooden hives lost 4.8 kg while the polyurethane hives lost 0.8 kg. We haven't found any study that compares insulated hives at R-6 and R-11, so there's no published evidence that colonies do better at one than the other. The big step is from wood to a well-insulated hive.

Apimaye's lab test

Apimaye wall insulation lab test details, transcribed from TEBAR test report No. R1600463

Laboratory	TEBAR Test Certification R&D Inc., Istanbul, accredited by TÜRKAK, the Turkish Accreditation Agency (No. AB-0302-T)
Test standard	EN 12667, the European standard for measuring the thermal resistance of insulation (heat flow meter method). Thickness measured to EN 12085.
What was tested	The polyurethane foam (PUR) used as the core insulation between Apimaye hive walls, brand name Apimaye, made in 2016. One 297 × 297 mm specimen (No. N1600254), 31.3 mm (1.23 in) thick, sent to the lab by the manufacturer, Yıldırım Plastik of Istanbul.
Test conditions	10°C (50°F) mean temperature, 20°C difference across the sample, heat flow of 16.4 W/m². Sample density 60.55 kg/m³, conditioned at 23 ± 5°C. No change in thickness, length or width during the test.
Result	Thermal resistance 1.22 m²·K/W = R-6.93 (US units). Thermal conductivity 0.0257 ± 0.001 W/m·K (95% confidence).
Report	No. R1600463, 5 pages. Tested June 22–23, 2016, issued June 24, 2016. Signed by K. Çatkın, laboratory technician, and E. Kara, head of the testing laboratory.

To be clear about what this covers: the lab tested the wall insulation itself, not an assembled hive, and that's the number we publish. We don't add air spaces or average it across the lid and floor to make it bigger. More about the test or download the report (PDF). The PDF is a scanned image without selectable text; the table above transcribes its key details.