1. High wind pressure

2. Wind-driven rain

3. Pressure cycles (wind pushing and pulling the window many times).

In technical terms, the window will have a design pressure rating (DP) or a similar value. For example, you might see something like DP50. 

You can think of this like a stress score that tells you how much wind load the window is designed to handle. Higher number = stronger window.

In many coastal or hurricane-prone areas, the local building code requires this type of window for new projects. So when someone in Florida or a Caribbean island says “hurricane window”, they often mean “a window that meets our local hurricane code”.

Now let’s look at impact windows.

When people say impact window, they are focusing more on resistance to flying objects. During a hurricane, debris like roof tiles, branches, and pieces of wood can hit the glass at high speed.

The job of an impact window is: to handle that hit, and if the glass breaks, it should crack but stay in place, not fall out and leave a big hole. To do this, impact windows almost always use laminated glass:

1. Two panes of glass (for example, 5 mm + 5 mm or 6 mm + 6 mm),
2. With a strong plastic interlayer in the middle (often 0.76–1.52 mm of PVB or SGP).

So you might see a spec like 5 + 0.76 PVB + 5 mm. That means: glass – plastic – glass. If something hits the window during a storm, the glass may break, but the plastic layer holds the pieces together—just like a car windshield.

Hurricane windows look at how the whole window system behaves in a storm. Impact windows look at how the glass and window behave when hit by flying objects.

In serious storm zones, a good hurricane window is usually also impact-rated. That’s why one product can be both. This is also why the names can be confusing.

For you as a buyer, the key question is not “Is it called hurricane or impact?” but: What has this window been tested for, and does it match the risk in my area?

How These Windows Are Built and How They Work

To understand the difference a bit deeper, let’s look at how these windows are put together—without going too crazy on the technical side.

1. The glass: first line of defense

For hurricane/impact systems, we normally use: Laminated glass. For example two glass panes (for example: 5 mm + 5 mm, 6 mm + 6 mm), one interlayer in between (0.38 / 0.76 / 1.52 mm, depending on the protection level).

Sometimes we also combine this with insulating glass (double glazing). For example: outside: 6 mm glass, air gap: 12 mm, inside: 6 + 0.76 PVB + 6 mm laminated.

This kind of build gives you impact resistance, better sound insulation, and better energy performance.

In impact testing, the glass unit is hit by a standard “missile”—often a piece of wood (like a 2×4) fired at a set speed. The goal is the glass may crack, but the opening must stay closed, and the glass must not blow out of the frame.

2. The frame: the skeleton holding it all together

The frame is just as important as the glass. For hurricane/impact windows, we usually use thicker aluminum profiles with internal chambers or reinforcements, or uPVC profiles with steel reinforcement.

On the technical side, we look at wall thickness of the profile, how the corners are joined (screwed, crimped, welded), and how the glass is fixed into the frame (glazing beads, structural sealant, gaskets).

Why does this matter?
Because during a storm, wind pressure can be very high. The frame has to: hold the glass in place, stay anchored to the wall, and work together with heavy-duty hardware (locks, hinges, rollers) so the sash doesn’t twist or open by accident.

3. The whole window system: tested like in a real storm

For a hurricane window, the complete unit is tested for: Structural performance – how much pressure it can take before it deforms too much. Water penetration – how much water gets in at a certain pressure. In simple terms, good systems will handle heavy rain plus strong wind without obvious leaks.

Air infiltration – how much air can pass through the window when there is a pressure difference. Lower numbers = less draft and better energy efficiency.

Pressure cycles – repeated positive and negative pressure to simulate real storm gusts.