The roof is the part nobody counts
Walls are obvious because you can see them from outside. The roof is not, and on any run that is wider than it is tall the roof is the single largest panel of mesh in the job. On the numbers this page opens with — 20 by 10 ft, 6 ft high — the four walls come to 342 sq ft after the door opening is taken out, and the roof is 200. Add a 60 sq ft apron and the roof is 33 percent of the whole job, going somewhere most estimates never look.
The ratio is easy to reason about. Wall area is perimeter times height; roof area is length times width. Make the run wider and the roof grows with the product of both dimensions while the walls grow only with their sum. A 40 by 20 ft run at the same 6 ft has 702 sq ft of wall and 800 sq ft of roof — the roof has overtaken the walls entirely.
Overlap comes off every roll but the first
Two sheets of mesh joined edge to edge are joined by lapping them, and the lapped strip is covered twice. A 4 ft roll with a 4 in lap covers 3 ft 8 in of new width, which is 91.7 percent of what you bought. On the default run it does not change the count — 632 sq ft needed, 183.3 sq ft covered per roll rather than 200, four rolls either way — but it eats most of the slack. Take the wall height to 8 ft for a walk-in aviary and the lap is what pushes it to five rolls while the raw area still says four. The larger the job, the more often the lap is the thing that decides.
| Roll width | Lap | Covered width | Mesh you paid for that is doubled |
|---|---|---|---|
| 2 ft | 4 in | 1 ft 8 in | 16.7% |
| 3 ft | 4 in | 2 ft 8 in | 11.1% |
| 4 ft | 4 in | 3 ft 8 in | 8.3% |
| 5 ft | 4 in | 4 ft 8 in | 6.7% |
That table is the whole argument for buying the widest roll the job can use. A 6 ft wall out of 2 ft mesh is four laps; out of 5 ft mesh it is one. Every lap is doubled material, a line of ties, and a seam that has to be closed properly.
Flat apron or buried apron — same mesh, different weekend
A skirt that stops digging can be laid flat on the ground pointing outward and pinned, or turned down and buried against the base. Either way it is the perimeter times the width, so a 60 ft perimeter with a 12 in apron is 60 sq ft of mesh in both cases. What differs is the work: the flat version is pinned into the sod and disappears under grass in a season, the buried version is a trench all the way round. This page prices the mesh identically and does not tell you which to build, because that depends on the ground, on what is digging, and on how much of the weekend you have.
Fixings add up faster than the mesh
Fastener count is edge length divided by spacing, and edge length is larger than it looks. Top rail and bottom rail all the way round is twice the perimeter. Every post takes a vertical line. If the roof is meshed, its edge is another perimeter. On the default run that is 228 ft of edge, and at 6 in spacing it is 456 fixings before a single seam tie. The seams add 300 more. Buying a box of fifty staples for that job is a category error, and it is a common one.
Where this hands off
The size of the run is not decided here. The chicken coop size calculator takes your own square feet per bird and gives a coop floor, roost length, nest boxes and a run area, and the hutch size calculator does the same job for rabbits and similar. Once you have an area, come back here for the mesh. If the enclosure is built from bought panels rather than framed and meshed, the kennel panel layout calculator handles that instead, and for a plain wire fence line on posts the livestock fence calculator counts posts, rolls and braces.
Questions people ask
How much hardware cloth do I need for a 10 by 20 ft run?
At 6 ft high with a 3 ft door opening and a fully meshed roof, the walls are 342 sq ft and the roof is 200, and a 12 in apron around the 60 ft perimeter is another 60. That is 602 sq ft, or 632 with five percent waste. Buying 4 ft by 50 ft rolls and lapping the seams 4 in, each roll covers 183 sq ft, so it is four rolls. Change any of the height, the roof or the apron and the answer moves a long way, which is why they are all fields.
What gauge and mesh size should I buy?
Not a question this page will answer. Area arithmetic cannot tell you whether a wire holds against a raccoon working a seam for an hour or whether an aperture is small enough to keep a weasel out, and getting that wrong is the failure that actually matters. Ask people keeping the same species in your area, and ask the supplier what their product is rated for. What this page does say is that mesh choice barely changes the roll count for a given roll size, so decide the specification first and cost it afterwards.
Do I really need to mesh the roof?
That depends entirely on what is around, and nothing here has an opinion. What the numbers show is that the roof is not a small add-on: on the default run it is 200 sq ft against 342 sq ft of wall, so it moves the material bill by about a third. If you are undecided, the part-meshed option lets you cost half a roof and see what it does. A run wider than it is tall always has more roof than you expect.
Why is the roll count higher than area divided by roll size?
Two reasons, both in the output. The lap at each seam means a 4 ft roll only covers 3 ft 8 in of new width, so you get 92 percent of the area you paid for. Then the waste percentage adds cut ends and corners on top. Together they typically push the count up by one roll on a small job. The output shows the covered area per roll and the leftover so you can see exactly where it went.
How deep should the apron go?
The depth is your field to fill, and the figure should come from people dealing with whatever digs where you live rather than from a calculator. What this page can tell you is the trade-off: the mesh area is perimeter times width whether it goes down or out, so a 12 in skirt laid flat costs exactly what a 12 in trench costs in material and a great deal less in digging. Going from 12 in to 24 in doubles the apron mesh, which on the default run is 60 sq ft becoming 120 — about a third of a roll.