Trickle vents are a simple yet effective way to improve airflow, reduce condensation, and maintain a comfortable indoor environment. In this guide, we’ll show you exactly how to install trickle vents yourself - with a full list of what you’ll need and step-by-step instructions to get the job done right.
Why Install a Trickle Vent?
A trickle vent is a small device fitted to a window or door frame that allows a controlled amount of fresh air into the room, even when the window is closed. It helps reduce moisture build-up and condensation, supports good indoor air quality, and improves ventilation without causing significant heat loss. In many newer homes and window replacements, trickle vents are recommended or required to meet ventilation standards.
What You Will Need
Drill
Drill bits suitable for your window frame (usually 8–10 mm for uPVC or metal)
Screwdriver or driver bit for the vent screws
Fine sandpaper or cloth to smooth edges
Masking tape (optional, for marking drill depth
Step-by-Step Installation Guide
Step 1: Choose the Right Vent and Location
Select a trickle vent that suits your window type (uPVC, aluminium, or timber).
The vent should be fitted at the top of the window frame to allow warm, moist air to escape efficiently.
Check the vent colour and finish to match your window.
Step 2: Mark the Position
Measure and mark the centre line at the top of the window where the vent will go.
Use the vent as a guide to mark the fixing holes.
Make sure the markings line up on both the inside and outside of the frame.
Step 3: Prepare for Drilling
If your frame has metal reinforcement, mark the drill bit with tape to avoid drilling too deep.
Use the correct drill bit for your frame material and check the vent manufacturer’s guidance for hole size and spacing.
Step 4: Add the Ventilation Holes
Before you fix the vent covers, you’ll need to create the airflow path through the window frame.
Measure and mark the slot area where the air will pass through. The slot should be positioned directly behind the vent openings.
Drill a series of holes along this line, keeping them close together. Use a small bit (around 5–6 mm) to start.
Smooth any rough edges with sandpaper to ensure clean airflow and a flush fit for the vent.
Step 5: Drill the Fixing Holes
Drill at the marked points, starting with a small pilot hole before increasing to the final diameter.
Keep the drill steady and perpendicular to the frame so the holes align properly on both sides.
Work slowly if you hit metal reinforcement inside the frame.
Step 5: Clean and Smooth the Holes
After drilling, remove any burrs or rough edges so the vent sits flush.
Wipe away any dust or debris with a cloth or use a small vacuum to clean the area.
Step 6: Fit the Internal and External Vent Covers
From inside the room, position the internal vent cover over the drilled holes and fix it in place with the screws provided. Avoid overtightening to prevent cracking the vent casing.
Then, from outside, align the external cover (often fitted with a bug guard) with the holes and secure it.
Make sure the external grill faces outward correctly.
Step 7: Test and Finish
Open and close the vent to ensure it operates smoothly.
Check that the vent sits neatly and that there are no gaps around the edges.
Clean the surrounding frame and remove any pencil marks.
Pro Tips
The small airflow from a trickle vent helps prevent condensation and improves air quality with minimal heat loss.
If your frame contains steel reinforcement or you’re unsure about drilling, consider getting professional advice.
Make sure the vent doesn’t interfere with the window’s operation.
For best results, keep trickle vents open year-round to maintain air circulation.