How to Choose the Right Size Full Cassette Awning for Your Patio or Deck

To choose the right size full cassette awning, measure your patio width, add 6 to 12 inches of overlap on each side, and select a projection (how far the awning extends outward) based on sun angle and how you use the space. Standard widths range from 10 to 20 feet with projections of 8 to 13 feet. Most residential patios pair well with a 12-to-16-foot-wide awning and a 10-to-11-foot projection.

I've measured a lot of patios over the years, and the number one mistake is ordering an awning exactly as wide as the patio. Here's how to get it right.

Step 1: Measure Your Patio Width
Grab a tape measure. Measure the full width you want shaded — from the wall where the awning will mount, across to the outer edge of your patio. Write that number down.

Now add 12 to 24 inches. That's your target awning width. Why? Because the sun moves. At midday, shade falls almost directly below the awning. But in late afternoon, when the sun drops lower, light creeps in from the sides. Extra width blocks that lateral light and keeps your seating area shaded.

If your patio is 12 feet wide, a 14-foot awning gives you a foot of overlap on each side. That's the minimum I'd recommend. For west-facing patios, go closer to 12 inches per side.

One caveat: the cassette needs solid mounting surface — brick, concrete, or a structural beam. Vinyl siding alone won't hold it.

Step 2: Figure Out Your Projection
Projection is how far the awning sticks out from the wall. A 10-foot projection covers a 10-foot-deep portion of your patio. Standard projections range from 8 to 13 feet:

8 to 9 feet: Narrow patios, walkways, small seating areas. Covers a bistro table and two chairs.
10 to 11 feet: The sweet spot for most patios. Covers a dining table for six with room to walk behind chairs.
12 to 13 feet: Large decks where you want a full outdoor living room — sofa, chairs, coffee table, and dining area.

 
The kicker is sun angle. In summer, the sun is high and a 10-foot projection shades most of a standard patio. In spring and fall, when the sun sits lower, that same projection leaves the outer edge in full sun. If you want shade in September at 4 PM, you need more projection.

Step 3: Wall Height and Cassette Size
A 16-foot-wide awning has a cassette roughly 16 feet long and 8 to 10 inches square in cross-section. That's a substantial box on your wall. You need at least 8 feet of clearance from the patio floor to the bottom of the cassette (7 feet 6 inches absolute minimum, but people will hit their heads).

The cassette typically mounts 9 to 10 feet up, giving enough headroom and allowing the fabric to slope slightly downward (about 15 to 25 degrees) so rain runs off instead of pooling.

Step 4: Match the Awning to How You Use the Space
Picture this: you're sitting on your patio at 3 PM in July. Where exactly are you sitting? Walk out there and look at where shade falls now versus where you want it.

A dining area needs the awning to cover the table plus 3 feet per side for chair clearance. A lounge area needs coverage for the full seating group. If you have both, size for the larger area.

Don't forget the grill. Greasy smoke near acrylic fabric stains and holds odors. Let the grill sit just outside the shaded zone.

Cost by Size
Full cassette awnings scale in price with width. A 10-foot-wide unit with motor and acrylic fabric runs 1,800to2,500. A 16-foot version runs 3,000to4,000. A 20-foot premium model (Markilux, Weinor) can hit 5,000to6,000. Going from 10-foot to 13-foot projection typically adds 400to800.

Quick reference: 10x8 foot for a small bistro setup (1,800to2,500). 12x10 foot for a standard patio with dining table (2,500to3,200). 16x11 foot for a full seating area (3,200to4,500). 20x13 foot for a large outdoor living room (4,500to6,000+).

FAQ
Q: How much overlap should a full cassette awning have beyond the patio edge? A: Aim for 6 to 12 inches per side. More overlap is better for west-facing patios where afternoon sun angles in from the sides. Less overlap works fine for east-facing patios used mainly in the morning.

Q: Can a full cassette awning be too big for my space? A: Yes. A 20-foot awning on a 12-foot patio looks disproportionate and wastes money on shade you don't use. It also puts extra load on your wall mounting. Size to your actual patio.

Q: What if my patio is wider than 20 feet? A: Use two awnings side by side with a small gap, or look into custom oversized units from brands like Weinor or Markilux that go up to 23 feet. For very wide spaces, a pergola system may be more practical.