Why Roof Window Recesses Vary – And What to Do About Gaps Around Your Blinds
When you're measuring for made-to-measure roof lantern blinds, it's not uncommon to notice slight variations in width or height. You might measure one side of the recess at 172.5 cm and the other at 173.5 cm. Don’t worry—this is totally normal.
Why Do Roof Recess Sizes Vary
- Plasterwork isn’t always uniform, especially in older homes.
- Ceilings and walls may bow or dip, causing a shift of a few millimetres.
- Skews in building materials can occur over time due to settling or expansion/contraction.
These variations can result in noticeable gaps when you fit a roof lantern blind that was made to measure.
How We Handle Recess Variation When Making Blinds
To ensure your blind fits smoothly and doesn’t catch on the sides, we always recommend:
- Measuring at three points across the width and length.
- We then use the smallest measurement you have provided us and deduct 5 mm.
This prevents scraping—but it can leave small gaps around the edges. There are 2 options to deal with these gaps.
Option 1: Seal the Gaps with Caulk
For most customers, a neat bead of decorator’s caulk is enough to fill the narrow space between the edge of the blind and the recessed wall. It’s cheap, easy to apply and paintable to match your décor
Option 2: Cover with a Flexible Angle Trim
Flexible angle trim is a white uPVC strip that bends easily to fit around corners. It’s:
- Fully flexible from 0° to 180°, so it moulds to your window recess shape
- Supplied in 5 metre lengths, easy to cut to size
- Typically 25mm x 25mm when folded, and 2mm thick
- Adhesive-friendly—sticks with silicone, super glue or no nails
You can find them at DIY stores like B&Q.
When Should I Use Flexible Trim Instead of Caulk
- If the recess is visibly uneven and the gap exceeds 5–8 mm
- If you want a tidy, framed look around your blinds
- In water-prone areas like kitchens or bathrooms
Gaps around your blinds don’t mean you measured incorrectly—they just mean your window isn’t perfectly square. By understanding how we handle recess size variation, and knowing your options—caulk for small gaps, or a flexible uPVC trim for larger ones—you can get a stunning finish every time.
Need help? Explore our made-to-measure blind solutions or get in touch for support.
