Window Flashing

Window Flashing for a newly built home
Newly Built Home With Window Flashing

I’m sure you would have come across window flashing in the exterior of houses. Window flashing helps to prevent water from getting into your house by making a window airtight. It also makes window installation easier and reduces energy loss. The window flashing is the part that’s exposed to the elements (mainly rain) so it needs to be sturdy enough to face harsh weather conditions for several decades.

Window flashings are usually made of either aluminum or rubber, both materials are inert (they don’t rust or corrode easily). However, rubber window flashings possess better pliability compared with aluminum ones thus creating an effective seal along uneven surfaces like brickwork and stucco. They are an ideal choice in areas with high humidity.

Aluminum window flashings are more rigid, lighter, and corrosion-resistant compared to rubber window flashing thus making them perfect for most types of installations. They are also cheaper than rubber window flashes.

The Rubber window flashing is generally long-lasting but you need to check out the warranty period when buying one as it might not be long enough to cover your needs especially in places with harsh weather conditions. That is why either aluminum or rubber window flashing is extensively used today for sealing window joints successfully in all kinds of window designs.

However, both aluminum window flashes and rubber window flashes have their pros and cons so let’s look at them closely before deciding which one will best suit your purpose:


Window flashing assembled with aluminum on the window frame, house wall, and window sill before the window is installed.


– Corrosion-resistant; works great in severe weather conditions like heavy rains and winds.

– Low maintenance; doesn’t require re-painting or sealing after installation of window (if it’s left exposed).

 – Lightweight; easier to install compared to rubber window flashes thus helping you save on time and money.

 – Can be easily cut to size during installation making it easier for you to fit around tricky areas like window panes, locks, etc.


– Requires professional help when installing window flashing thus increasing window installation costs.   

– Higher in price compared to rubber window flashes.


Rubber window gasket window flashing in action at the window panes where it completes an airtight seal.


– Creates an effective seal when installed tightly thus preventing water leakage into your home. – High pliability makes it easier to form around different surfaces easily making installation much simpler and faster. – It’s easy for you to cut rubber window flashings during installation providing you with more freedom when fitting around tricky areas like window panes, locks, etc…


– Requires professional help for installation. – Check the warranty period carefully to determine whether the window flashing will last a good number of years before requiring replacement.

Choosing window flashings is a big decision especially if you have chosen to have a window installed in your home so take your time and do some research on window flashings, compare different window installation materials and sealants available thus making it easier for you to come up with the perfect one that suits your needs.

window flashing for a client
Window Flashing

How do you install window flashing?

There are different window flashing installation methods you can use but the easiest one is to place window flashing over window panes with one side exposed to the window frame thus creating an airtight seal. The exposed part of window flashing is held in position using either screws or nails. Let’s look at how you install window gasket rubber window flashing:

Step 1: Determine the right size for your window exposure like a window sill, window frame, and window head (if it’s exposed.) To do this, measure your windows by determining the width and height of each exposure then add up these measurements together to help you determine the right size. For instance, if you want 16″ by 11″ window exposure rubber flashings, remember that adding up all window measurements together will not always mean that you need window flashings of the same size.

Step 2: Next, cut window flashings to fit all window exposures where rubber window flashing requires a zigzag patterned cut along the window sill and window frame edges thus giving your window panes an airtight seal around them. You can use a sharp knife or razor blade for cutting rubber window flashings but ensure that you cut within the lines to avoid unnecessary damage to your window flashings.

window flashing
Window Flashing

Step 3: Secure one end of the rubber window gasket by tucking it into the side-channel groove then push it up against the windowpane till it is fitted tightly before securing it with nails using a hammer. 

Step 4: Repeat these window flashing installation steps on the window head and window sill thus completing window flashing installation.

To make window flashing installation much simpler, you can use a self-adhering window gasket which involves sticking rubber window flashings in place before installing window panes to the window frame with nails. 

When using a self-adhering window gasket for your home windows, ensure that you have a clear understanding of all its properties before use including its warranty period since most manufacturers will only allow the replacing of their products within specified periods.

So what’s the best way to install window flashings?

Well, this depends mainly on your preferences and your budget but if you are looking for professional help for installing window flashings at your home or workplace consider window flashing installation specialists from Commercial Roofing Chicago Hub who will come to your rescue within the shortest possible time.

By reading this article you are now more informed on window flashings thus helping you make better window gasket purchase decisions since window installation cannot be complete without window flashings, they are meant for each other!