A design team agrees on a number before anyone draws a panel. Two thousand square meters of yard, four adults, a silverback, room for the group to break apart. That figure comes from husbandry guidance and from the people who know the animals, and it is the right place to start.
Then the quantity surveyor prices the barrier, and everyone in the room meets the same surprise at the same moment. Nobody sells floor. The supplier sells the skin that wraps the floor, and the skin does not grow at the same rate.
Double the yard and the wall does not double. It grows by about 41%, because a square’s perimeter rises with the square root of its area. Keep the area and stretch the shape instead, and the wall can grow by half again.
Two exhibits with identical floors can carry very different quantities of steel. Three numbers decide which one you get.
Executive Summary
A gorilla enclosure size starts as a husbandry decision in floor area and finishes as a purchase in surface area, and the two do not scale together. Perimeter rises with the square root of area, so doubling the yard adds about 41% to the wall rather than 100%. Shape matters as much as size: at the same floor area, an 80 by 10 m yard needs 59% more wall than a 28 by 28 m yard. Bay length is the third number, because a cable sags with the square of its span and a long bay eventually pushes the frame from posts to masts. Height stays a husbandry choice, since an adult gorilla does not climb. Settle area, shape and bay in that order and the panel, the cable and the fixing line all follow.
Sizing a gorilla exhibit and want the steel quantity before the design freeze?
Send the yard dimensions, the wall height and the group size. We return the mesh surface area, a bay recommendation and a cable diameter, with the fixing line priced separately from the panel.
Quick Answer
Size a gorilla enclosure by the floor area the group can actually use, then check the shape before the headline number. A square yard needs roughly 41% less wall than a long thin yard of double the perimeter, so shape moves the steel quantity more than area does. Set bay spacing last, because it decides whether the panel hangs from posts or from masts.
Key Takeaways
- Floor area is a husbandry number; wall area is a purchasing number, and they scale differently.
- Doubling floor area adds about 41% to the perimeter, not 100%.
- At equal floor area, a long thin yard can need 59% more wall than a square one.
- Bay length drives sag with the square of the span, so it drives cable and frame more than height does.
- Height stays a husbandry decision for gorillas, because adults do not climb.
- Fix area, then shape, then bay, or the panel gets drawn twice.
Size is a husbandry number first
Space standards for great apes talk in floor area and in the chance to leave the group. Both matter, and neither comes from a mesh supplier. A great ape enclosure size that satisfies a regulator can still fail the animals if the group cannot break line of sight, so the usable figure is what remains after the retreat space and the keeper route come out.
That is where space per gorilla turns into a real number rather than a slogan. Four adults in 800 m² works out at 200 m² each on paper and nothing like it in practice, once the service yard, the door apron and the shade structure take their share. Count the area the animals can walk on.
Ethics enters here, long before any material choice. A group that can avoid a dominant animal without leaving the exhibit needs geometry, not just floor: corners, level changes and planting do that work, and the barrier has to make room for them.
None of this changes the panel, and all of it changes the plan the panel follows. The netting is the last decision in the sequence. What we weave as primate enclosure netting runs from a 25 mm to a 100 mm mesh aperture, which spans a juvenile yard and an adult group from one product family.
Then it becomes a surface-area number
A barrier is a surface, and a surface is bought in square meters. That is where a gorilla enclosure dimensions schedule goes wrong first: the floor arrives in one unit, the order goes out in another, and nobody converts between them until the quote lands.
The conversion does not run in a straight line. For any square, the enclosure perimeter equals four times the square root of the area, so the wall grows more slowly than the floor. Double 800 m² to 1,600 m² and the wall runs from 113 m to 160 m, a 41% increase for a 100% increase in space.
Multiply by height and the same ratio holds for mesh surface area, which is why a gorilla enclosure size quoted in floor alone misleads a buyer. At 5 m, those two yards need 566 m² and 800 m² of skin. The larger yard is the better buy per square meter of floor and the better exhibit, which is the rare case where husbandry and budget point the same way.
Shape breaks that agreement. Three yards with the same floor:
| Yard | Floor area | Perimeter | Skin at 5 m | Skin vs square |
| 28 × 28 m | 800 m² | 113 m | 566 m² | baseline |
| 40 × 20 m | 800 m² | 120 m | 600 m² | +6% |
| 80 × 10 m | 800 m² | 180 m | 900 m² | +59% |
Read the third row twice. Same floor, same animals, same husbandry argument, and 59% more steel. The enclosure skin area is a shape decision wearing the clothes of a size decision.
Why the long thin yard costs more
Length carries real husbandry value. A long sightline gives a gorilla somewhere to walk toward, and a tense group uses distance before it uses aggression. That is a genuine argument for a long yard, and it survives scrutiny.
The yard aspect ratio then becomes a trade rather than a mistake. Going from 1:1 to 2:1 costs about 6% more skin. Going to 8:1 costs 59% more and doubles the longest bay as well. Somewhere between those two sits the shape a gorilla outdoor yard can afford.
One working rule: hold the long side under three times the short side unless the brief demands a running line. A gorilla exhibit size that reads as generous on a plan can still be a bargain or a budget problem, and the ratio tells you which before the drawing is fixed.
The bay is the third number
Bay is the distance between the posts or masts that hold a panel. It appears on no husbandry list, and it moves more of the cost than height does.
A cable sags with the square of its span at a given tension. Move from a 6 m bay to a 10 m bay and the same cable sags about 2.8 times as far. Nobody accepts that much movement in a barrier a gorilla leans on, so the answer is more tension, a heavier wire rope diameter, or a mid-rail.
Panel bay spacing also sets the panel count, the number of edge cables and the number of terminations, and terminations are where a hand-woven panel gives up first. Fewer, longer bays mean fewer parts and more load in each one. The optimum usually sits between 6 and 10 m for a 5 m wall.
When posts stop working
Past about 10 m, a cantilever post holding a 5 m panel starts to behave like a mast, and a mast needs a back-stay. That is the point where the barrier becomes a catenary mesh: masts at 20 to 30 m, a perimeter cable, and stainless steel rope mesh tensioned between them.
A mast and cable net suits a big yard because it puts steel where steel is cheap, in the ground and in a few tall members, instead of in a post every 6 m. It also clears the sightline, which the husbandry argument wanted in the first place.
Welfare guidance makes the same point from the animal side. WOAH animal welfare standards treat space, shelter and the chance to withdraw as one requirement rather than three, which is why the shape of a yard belongs in the welfare conversation and not only in the cost one.
Whatever the bay, the unit that ships is a panel. This guide to the standard panel covers how panel size, edge cable and swage ferrule count interact, and here the only question is how many of them the bay demands.
Height is a husbandry number, not a structural one
An adult gorilla does not climb and cannot jump. That single fact removes most of the structural case for height, and it explains why a gorilla enclosure roof often stays off the drawing.
Height then answers to regulation and to behavior. A wall tall enough to beat a standing reach, with a top detail that offers nothing to grip, does the work. Five meters is a common working height, and that figure is a policy choice rather than an engineering one.
Open top or closed
An open top gorilla yard is the norm, and it holds up. The exception is the juvenile, which climbs, and a juvenile that reaches the top of a 5 m wall has found the one path the design ignored.
Two details close that path without a lid. A smooth top rail set inboard, and a return that leans the top of the panel inward. Where the brief wants a closed volume, because of a mixed exhibit, a bird strike problem or a public bridge overhead, the roof becomes a mesh surface and joins the skin calculation.
This is the same problem climb-proof primate design answers with geometry rather than height, and for gorillas the answer looks the same.
The size decision in six numbers
Write these down before anyone draws a panel.
- Floor area the group can use, after retreat space and keeper routes.
- Group size, and how many animals can reach the same panel at once.
- Perimeter, taken from the shape you chose rather than the area you were given.
- Skin area: perimeter times height, plus any roof.
- Bay spacing, and whether that spacing needs a mid-rail or a mast.
- The fixing line, and what the horizontal load at 2 kN per adult in the bottom 1.5 m goes into.
Two of those numbers are husbandry, three are geometry, and one is structural. A gorilla enclosure size that stops at the first is a plan; one that carries all six is an order.
The panel is the least interesting item on that list and the one most buyers reach for first. Hand-woven stainless steel mesh does what the drawing asks, provided the corrosion resistance matches the site and the washdown regime. The drawing decides whether the yard works.
For the group side of the same problem, this guide to gorilla nets sets out how a bachelor group and a family group load a panel differently.
FAQ
Start from the space standard your regulator or accrediting body publishes, then add the retreat space the group needs to separate. A floor area that meets the minimum but leaves no line of sight break tends to produce the behavior problems the extra space was meant to prevent.
No, and the difference is large. Doubling the floor area adds about 41% to the perimeter and therefore to the wall, because perimeter follows the square root of area. What does cost proportionally more is a change of shape, which can add 59% to the skin at the same floor area.
On paper yes, by about 11% at 800 m², because a circle carries the least perimeter for any given area. In practice the saving usually disappears in curved panel fabrication, radial posts and a sightline that curves away from the visitor, so most yards stay rectangular.
Not normally, because an adult gorilla does not climb or jump. The cases that do need one are a juvenile group, an exhibit crossed by a public bridge or an overhead path, and any yard where birds or debris create a separate problem the mesh has to solve.
Between 6 and 10 m for a 5 m wall, with the longer end needing a mid-rail or heavier cable to hold panel deflection. Past about 10 m the frame stops behaving like posts and starts behaving like masts, and the system changes with it.
Get the surface area before the design freeze, not after.
Send the yard plan and the group composition. We will return the skin area, a bay recommendation and the cable diameter for the group, so the quantity lands in the budget while the shape can still move.