Venetian blinds are a classic for a reason—they offer the best light and airflow control of almost any window covering. However, because they are made of many individual horizontal slats, they require high precision. One wrong measurement or material choice can lead to a blind that clatters, sags, or simply doesn’t fit the window’s depth.
Avoid these five common pitfalls to ensure your DIY Venetian project is a success.
1. Choosing the Wrong Material for the Room
The biggest mistake is choosing a material based on looks alone while ignoring the environment.
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The Mistake: Putting natural Timber Venetians in a bathroom or above a kitchen sink. The steam and humidity will eventually cause the wood to warp, swell, or develop mould.
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The Fix: Match the material to the “zone.“
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Bathrooms/Kitchens: Use PVC (Faux Wood). It looks like timber but is 100% moisture resistant.
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Lounge/Bedrooms: Use Natural Timber for its superior insulation and lightweight feel.
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Home Offices: Aluminium is excellent for reflecting screen glare and fitting into slim recesses.
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2. Ignoring “Recess Depth” (The Protrusion Problem)
A Venetian blind needs space to “tilt” its slats. If your window frame is shallow, the blind might stick out into the room.
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The Mistake: Ordering a 63mm wide slat for a window with only 50mm of depth. The blind will hang past the architrave, looking unfinished and letting light leak in through the sides.
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The Fix: Measure your recess depth (the space from the glass to the edge of the frame).
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If you have a shallow recess, opt for a 50mm slat or even a slimline Aluminium Venetian.
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If you want the chunky, shutter-style look of 63mm slats, ensure you have at least 70mm of depth or choose a Face Fit mount.
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3. The “Cloth Tape” Accuracy Error
Venetians are unforgiving. If a roller blind is 5mm too narrow, you might not notice. If a Venetian is 5mm too wide, it simply will not fit inside the window frame.
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The Mistake: Using a flexible sewing tape or a laser measurer. Fabric tapes stretch over time, and lasers can be tricky on glass.
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The Fix: Always use a steel tape measure. Measure the width at the top, middle, and bottom. For an inside mount, use the smallest width of the three. This ensures the blind won’t jam against the window casing as it’s raised or lowered.
4. Forgetting about “Stack Height”
When you pull a Venetian blind all the way up, the slats “stack” at the top. The more slats there are (especially with timber), the thicker that stack becomes.
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The Mistake: Installing a Venetian on a door or a low window without checking the stack height. You may find that when the blind is “open,” it still covers the top 20cm of your view or hits your head as you walk through a door.
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The Fix: If you have a beautiful view you don’t want to block, consider a Face Fit mount above the window. This allows the blind to stack onto the wall, leaving the glass completely clear when the blind is raised.
5. Neglecting Window Obstructions
Horizontal slats need a clear path to move up and down.
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The Mistake: Forgetting to account for window winders, handles, or security sensors that stick out. If the slats hit these on the way down, the blind will sit crooked and the slats can become bent or damaged.
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The Fix: Check for any hardware that protrudes from the window. If you have winders, you may need to Face Fit the blind so it clears the obstructions, or choose a narrower slat that can sit in front of the handle.
Feature What to Check Why it Matters Moisture Is it a “Wet Area”? Prevents warping/mould in bathrooms. Depth Slat width vs. Frame depth Ensures the blind sits flush and looks professional. Width Smallest of 3 measurements Guarantees the blind won’t jam in the frame. Hardware Protruding handles/winders Prevents slats from bending or sitting unevenly. Weight Timber vs. PVC Large PVC blinds can be heavy; Timber is lighter for big windows. Get the “Designer Look” for Less
Venetian blinds are a fantastic way to add value to your home, provided the fit is perfect. By taking a few extra minutes to check your depths and obstructions, you can avoid the costly “return and replace” cycle and enjoy a high-end finish.
