Measuring Made Simple with the Cills App
Forget the complicated setups and multiple tools. Measuring your window cills has never been easier. All you need is:
A tape measure – any standard tape measure will do
An account with Cills.ie – takes 30 seconds to create
That's it. No spirit levels, laser measures, or complicated spreadsheets. The app guides you through everything.
How It Works
Step 1: Download the Cills App
Head to the App Store or Google Play and download the Cills app. It's completely free.
Step 2: Create Your Account
Sign up at Cills.ie or directly through the app. You'll need an email address and a password. Takes less than a minute.
Step 3: Create Your Project
Open the app and tap "New Project". Give it a name – something like "Front Extension" or "House Retrofit" – and you're ready to start measuring.
Step 4: Add Your Measurements
The app walks you through each dimension step by step:
A (Upstand Height): The back edge that sits behind the window frame. Usually 20mm to 30mm for standard installations
B (Projection Depth): How far the cill sticks out from the wall face. Measure from the window frame to where you want the drip edge to end.
C (Internal Profile): The measurement for the cill profile itself, slop.
DE (Thickness): The combined thickness of the cill body.
F (Front Lip Width): The visible front fascia that you see from the ground.
G (Main Sill Width): The width that matches your actual window opening.
J (Wing/Side Lip): The return dimension on each side of the cill.
K (Profile Measurement): Additional measurement for complex configurations, this is the same as DE - thickness.
H (Overall Length): The total length including all returns and wings.
The app shows you exactly where to measure with clear diagrams. No guesswork.
Why the App Makes It Easier
Visual Guides
Each measurement has a diagram showing exactly where to place your tape. Hold your phone in one hand, tape in the other, and follow along.
Built-in Validation
Enter a measurement that doesn't make sense? The app flags it immediately. Catch mistakes before they become expensive.
Photo Attachments
Snap a photo of each window and attach it to the measurement. When your cills arrive, you'll know exactly which one goes where.
Instant Quotes
As you add measurements, the app calculates pricing in real time. No waiting for quotes or back and forth emails.
Save and Continue
Measure the ground floor today, first floor tomorrow. Your project saves automatically and syncs across devices.
“Never be limited by other people’s limited imaginations.”
The Key Dimensions Explained
Every window cill needs these measurements:
G (Opening Width): The actual window opening at the bottom. Measure between the internal reveals.
H (Overall Length): Total length including returns or overhangs past the opening.
B (Projection): How far the cill projects from the wall. For external insulation projects, this covers insulation depth plus render plus overhang.
A (Upstand Height): The back edge that tucks behind the window frame to prevent water ingress.
J (End Returns): The dimension of turned down ends at each side.
DE (Drip Edge): The front edge that throws water clear of the building.
F (Fascia Depth): The vertical face at the front of the cill.
Step by step Guide
When every measurement is precise and every step is clear, ordering perfect-fit aluminium cills becomes effortless.
Daniel Ganea
Window Cills Guide
Trusted & Used By Professionals From
Start Ordering Aluminium Window Cills Today
Cills.ie makes it easy to measure, customise, and order aluminium cills, flashings, trims, and cappings — all online, with engineer support included.
