Fitting bird spikes to a fence is straightforward: measure the run, cut the strips to length, then fix them to the top of each panel or post using screws, cable ties, or waterproof adhesive pads depending on your surface. Done right, a fence-top installation takes under an hour and lasts several years without maintenance.
What you need before you start
Before you touch a strip, collect these:
- A tape measure
- A pencil or chalk line
- A cordless drill with a suitable bit (wood, masonry, or metal depending on your fence)
- Cable ties or screws (both are included in every ThornGuard pack)
- A pair of scissors or a craft knife
- Waterproof adhesive pads if you cannot drill — for example on uPVC capping rails or rendered brick
Work out the total linear run of fence you want to protect. If the top is less than 50 mm wide, a single row of spikes down the centre is enough. If the capping is wider, you may need two rows side by side, or strips folded to wrap the edge.
How much strip do you actually need?
This is where most people miscalculate. Spike strips are sold by their flat length, but you have three options for how you deploy that length:
Laid flat along the top — one strip covers its stated length. A 4 m pack covers roughly 4 m of fence top.
Split lengthways down the middle — each strip becomes two narrower rows. A 4 m pack suddenly covers up to 12 m of fence top in a single row. This works well on narrow capping rails where you only need a thin band of spikes.
Folded to wrap a post or rail on three sides — you use more strip per metre of fence, but you cover the front face, top, and back face of a post in one pass, which stops animals that approach from the garden side as well as the outside.
Measure your run, decide which layout suits your fence profile, then buy accordingly. If in doubt, buy the larger pack — offcuts are always useful on gate posts and shed edges.
Step 1 — Mark the fixing line
Snap a chalk line or run a piece of masking tape along the centre of the fence top. This gives you a straight reference when you fix the first strip, and avoids the slightly wonky look that comes from eyeballing each panel separately.
On a close-board fence, the capping rail is usually the right place — it sits above the boards and is the natural landing point for pigeons and squirrels alike.
Step 2 — Cut strips to fit panels
Most fence panels come in 1.83 m (6 ft) widths, but fence runs rarely divide evenly. Cut strips across the four moulded cut lines on each section. You do not need anything more than scissors — the polypropylene cuts cleanly without cracking.
If you are splitting a strip lengthways to cover a narrow rail, run the scissors or a craft knife along the centreline. The two halves each keep their spike rows and fix independently.
Step 3 — Choose your fixing method
Screws into timber
This is the most permanent option and takes about 30 seconds per strip. Pre-drill a small pilot hole through the mounting foot of the strip, then drive in the supplied screws. On a soft wood capping rail, you can often skip the pilot hole entirely. Space fixings roughly every 400–500 mm along the strip.
Cable ties through trellis or slatted rail
If your fence has a trellis topper, slatted rail, or any section you cannot screw into directly, loop cable ties through the gaps in the spike base and around the rail. Pull them tight, trim the tails flush. This is also the method to use on metal railings.
Adhesive pads on uPVC, render, or stone
Where you genuinely cannot drill — a uPVC capping rail, a painted rendered wall, or a stone coping — waterproof adhesive pads are the right fix. Clean the surface thoroughly with isopropyl alcohol and let it dry completely. Press the pad firmly to the underside of the spike strip, peel the backing, and hold it down for 30 seconds. Allow 24 hours before the bond is fully cured, and avoid fitting in temperatures below 5 °C.
Step 4 — Handle posts and corners
Fence posts are the most-overlooked gap in any spike installation. A squirrel or cat that cannot land on the panel top will simply land on the post instead and use it as a stepping stone. There are two approaches:
Fold a strip around the post on three sides. ThornGuard strips fold along their length, so a single strip can wrap the top face and both side faces of a standard post. Fix it with cable ties pulled around the whole post, or screws into each face.
Use an offcut to cap the post end. If the post has a flat cap, a small offcut cut to size and screwed or adhesive-padded on top is enough.
At corners where two fence runs meet, mitre the end of each strip at 45° with scissors so they butt together neatly without a gap.
Why flat single-height spikes often fail on climbing animals
Standard flat spikes — the kind with all the pins at the same height — stop birds from landing because birds need a clear, flat surface to touch down on. But squirrels, foxes, and cats do not land: they climb. A uniform row of short pins is something they step between or press down on without discomfort.
The reason ThornGuard's irregular three-height design (12 mm, 22 mm, and 36 mm pins in a staggered pattern) works on climbers as well as flyers is that there is no predictable gap to step through. A squirrel pressing down with a paw hits a spike at a different height whichever angle it approaches from. This is also why wrapping the post — not just the panel top — matters: a climbing animal has to grip the post face, and that is where the taller spikes do their job.
If you have had cheap flat spikes that squirrels simply walk over, this is the specific problem they were not designed to solve.
What to do if the fence top is uneven
Old timber fences often have capping rails that have bowed, cupped, or been replaced with mismatched boards. In those cases:
- Use screws rather than adhesive — they pull the strip down onto the surface even where there is a slight gap
- Cut strips at the low points and start a new strip at the high points rather than trying to span a step
- On very rough stone or brick coping, pack the fixing point with a small wedge of treated timber and screw through both
How long does installation take?
A typical 15 m garden fence — three panels each side plus gate posts — takes between 45 minutes and 90 minutes for one person working alone. The time is mostly spent measuring and cutting; the actual fixing is fast. If you are using adhesive pads, add time for surface preparation and allow an overnight cure before the fence is fully protected.
For a full illustrated walkthrough with photos of each fixing method, see our fitting guide.
Common questions
Do bird spikes actually work on squirrels, or just birds?
Standard flat single-height spikes generally do not deter squirrels — they climb between or over the pins without difficulty. Spikes with an irregular three-height design, like ThornGuard, are specifically built to stop climbers as well as perching birds, because the unpredictable pin heights prevent squirrels from finding a comfortable foothold.
Can you put spikes on a garden wall as well as a fence?
Yes — spikes can be fixed to brick or stone coping using masonry screws (drill and plug first), cable ties anchored to vine eyes, or waterproof adhesive pads on smooth stone. Check that your wall is your own property boundary before fitting, and never fit spikes in a way that could injure a person who might reasonably lean on or reach over the wall.
Are bird spikes legal in the UK?
Bird deterrent spikes are completely legal in the UK for use on your own property. There are no restrictions on fitting them to fences, walls, gutters, ledges, or roofs. The one important exception is timing: you must not disturb an active bird nest during the nesting season (roughly February to August). Fit spikes before birds settle, or after they have left — never while eggs or chicks are present.
Originally published at ThornGuard
