A truss is the hardest surface in this whole set to protect, and the honest answer is usually not spikes. Hundreds of angled members, node points every few metres, thirty feet in the air. Here is why netting below the structure is the right call, and when it is not.
At a Glance
Birds use trusses because a truss offers exactly what a cliff ledge offers: a flat horizontal member to stand on, a vertical behind it, and cover overhead from the roof sheet. The node points — where diagonal members meet the bottom chord — are the prize. They form a small sheltered platform with support on three sides, and that is where the nests go.
Everything below then receives what happens up there: stock, machinery, floors, people.
We sell spikes. This is not the surface for them.
A single truss has a bottom chord, a top chord, and a dozen or more diagonal members, with a node point every two to three metres. A shed has a truss every four or five metres. Protecting all of that surface individually means hundreds of small pieces, each one fixed at height, at awkward angles, on galvanised steel that adhesive does not like.
Even done perfectly it leaves the purlins, and the birds move to those. The cost of the access alone — scaffold or boom, for days — usually exceeds the cost of netting the entire span once.
There are two exceptions, and they are worth knowing:
A horizontal net stretched below the bottom chord separates the roof void from everything under it. Birds may still get into the void. Nothing they do there reaches the floor.
| Spiking every member | Horizontal net below | |
|---|---|---|
| Surfaces covered | Only the ones you reach | All of them, including the ones you cannot see |
| Purlins | Still available to birds | Above the net — irrelevant |
| Access time | Days at height, member by member | Installed line by line, far quicker per square metre |
| Later roof work | Unaffected | Needs planning — net has to be worked around |
| Cost driver | Access, overwhelmingly | Material and span |
| What still gets fouled | Anything you missed | The net itself, which is the point of it |
You do not have to net the whole shed
Net the bays that carry product or people — racking, packing, the line, the inspection area. A partial installation over the zone that matters costs a fraction of the full footprint and removes the same contamination risk. This is the single biggest saving available on a truss job and it is rarely suggested.
| Location | Used for |
|---|---|
| Node points on the bottom chord | Nesting. Sheltered on three sides — the prime site. |
| Bottom chord runs | Perching along the length. |
| Purlins | Continuous perch running the whole building. |
| Gusset plates | Flat platforms at the joints. |
| Apex and ridge | Highest point, sheltered, favoured for roosting. |
| Bracing angles | Perch, and material collects on them. |
Neither spikes nor net achieve much while the birds are still flying in freely. Before specifying anything, find the route in.
The lights-off test
Stand inside in daytime with the lights off. Every gap in the envelope shows as a line of daylight. Five minutes, no equipment, and it tells you more than watching the birds for a week.
The primary answer here. Horizontally below the truss line to separate the void from the floor, and vertically at ventilators, eaves gaps and gable louvres to stop entry.
Fits: full or partial span exclusion, ventilators, eaves, gable openings
For the exceptions: a single member over a critical bench, wide gusset plates, and the flat-topped items nearby — light fittings, cable trays, racking tops.
Uncommon, but sloping-roof houses, farmhouses and covered parking with an exposed truss have exactly the same problem at a smaller scale.
Malls, showrooms, atriums and covered markets, where the truss is visible and appearance constrains what can be installed.
The main case. Sheds, factories and warehouses, where the span is large and the quantities run to thousands of square metres.
Physically yes, practically no. A truss has hundreds of members and node points, all at height and at angles, and even a complete job leaves the purlins. The access cost alone usually exceeds netting the span once.
Close the entry points in the building envelope, then net horizontally below the truss line so the roof void is separated from the floor. Spikes are for the specific exceptions, not the structure.
No, and this is where most of the saving is. Netting only the bays over racking, packing or the production line removes the contamination risk at a fraction of the full-footprint cost.
Node points — where the diagonals meet the bottom chord — give shelter on three sides and a flat base. It is the closest thing in a steel building to a natural ledge, which is why every truss in the shed is used at the same spots.
It has to be planned around them. Send photographs showing the services below the truss line and the net can be set at a level that clears them.
Not while there are eggs or chicks — most wild birds in India are protected under the Wildlife Protection Act, 1972. Plan the access for after they fledge and install immediately, while the structure is empty.
By the square metres of net for the area being covered, plus any spikes for the exceptions. Send the bay dimensions and how many bays need protecting.
Send photographs of the truss line and of the entry points — ventilators, eaves, gable louvres — along with the bay dimensions. We will tell you what area actually needs covering, which is usually less than people expect.