How to do your own replacement window installation the easy way

Do your own replacement window installation and save money while adding huge resale value to your property! When thinking of how to make replacement window installation easier think measurements. If you have the exact measurement of the window openings it will make it 10x easier to install. 

How to take the best measurement

To take the best measurement, literally take the measurements and bring them with you. Write them down and also take a photo of the measurement that way you are always certain of the exact measurement. What I mean by this is, literally place the tape measurer in the desired location and snap a photo with the measurer in place. Why? Because it doesn’t get anymore exact than this, and you have the photo in your phone for easy access while at the store. Also, check the store’s inventory by window measurement before driving to the store. Doing this allows you to make sure the windows you need are in stock. This will save you lots of time and energy. When you get to store your replacement window will have a range of measurements specified on the side of the box containing your replacement windows.

How to measure your own window for replacement
How to measure your own window for replacement

 *A tip from experience: 

You may have to drive to several different stores to obtain all the sizes you need. Depending on how old your house is, all window openings may not be the same especially considering bathroom windows. Bathroom windows are almost always smaller than other bedroom and living area windows.

How to get desired replacement window sizes
You may have to go to multiple stores to buy the correct sizes of replacement windows

Another way to make your own DIY installation easier

Be careful as you are moving the old windows. Keep the trim in tack, the window stops, mullions, etc. because these are often reused parts in window installs even by professional window installers.

Carefully remove the trim and the nails in the trim. If you leave the nails in the trim, carefully realign the nails with the nail holes as you wrap up the replacement window install. If you can’t salvage the nails, you can use your nail gun or an old school nail and hammer approach. Just get the right nails so they penetrate the wood enough so the head doesn’t stick out and create an unsightly problem with your install.

How to remove window trim
Remove window trim carefully to reuse it!

Also, before removing the trim and window stops, take a picture of everything. This will help you get things back together accurately.

Setting up your replacement window

Keep your replacement windows near the area where you will install it. That way the replacement window doesn’t have far to travel and you can go from the floor to the frame. Have the rest of your materials on site including your window insulation foam and caulk. 

Have replacement windows and materials near window location
Keep replacement windows and materials near desired install location


Take a picture of the old window
Taking a picture before removing old windows will help with installing replacement windows


Use photos to help with replacement windows
Use photos to help with replacement windows

Once the window is in, insulation applied, screws screwed in, edges caulked, you can prepare to get the window stops and trim back in place. At this point take a photo and high five yourself because you can say you know how to do your own replacement window installation!

Replacement Window Installation Help

DIY Window Flashing

DIY Window Replacement Installation

DIY Window Remodel; Removing an Old Window

My realtor laughed when we said we would renovate ourselves…

DIY window flashing for a clean install

The last post closed with cleaning up the install from the interior; DIY window flashing is all about cleaning up the exterior. On the exterior of a brick house, there is brick moulding around the window. Think of this like the trim or exterior frame around the window.

This moulding is what your storm window frame screws into and there are window stops that keep your window from falling out, just like the interior stops keep your window from falling in.

Why you need to flash your windows

Flashing your windows is necessary to protect your new window, the frame, and the interior walls from moisture and the elements of precipitation. The good news about flashing a window is that it will last 20 plus years. There are 2 options aluminum or vinyl flashing. If you have vinyl siding, go with vinyl flashing. If you chose aluminum flashing it would still work and provide you with a clean install.

Flashing is molding to the specs of the frame of your window and the exterior molding. It is important to have the exact measurements to a T simply because this determines how clean your install will be. 

In the pictures below you will see the before and after and ultimately you will want to go from this:

DIY window flashing mulled window
How to Flash 2 windows or a mulled window

To that:

DIY how to Flash a mulled window or 2 windows
How to Flash 2 windows or a mulled window

Notice how the aluminum flashing covers the top and bottom of the window, the middle and the left and right side of the window. Also the top corners were cut at 45 degree angles to perfectly align.

Should you try Do It Yourself Window Flashing?

If you are looking to save big money on your window install, you want to clean up your install, and you can following directions, then yes! You should certainly try do it yourself window flashing. If you installed your own window, you should definitely flash it, because flashing is much easier. This is a fine detail project that involves measurements, cutting, and precision. The material is literally feather light, so it does not involve heavy lifting.

My experience with flashing

As I mention later, I could not find much reliable or helpful information on flashing windows. I pulled from everywhere including professional window installers, Home Depot & Lowes’ employees, YouTube, This Old House, and more. What I heard was, “you need some window casing,” “you need some window molding,” “you need to get someone to wrap your windows in aluminum,” or “you need to have your window capped.” These are all the things you may read or hear as you look for how to get your windows flashed or wrapped in vinyl or aluminum. Either way, when it comes to DIY window flashing these terms may be used interchangeably. (Please note I am not saying they should be, because the process was much more confusing because of that.)

Cutting the flashing

So truth be told, there is very limited DIY information available on flashing windows. For weeks, I’d go to work. Watch YouTube before driving home. Then stop at Home Depot and Lowes on my way home to look at aluminum, aluminum rolls, chimney flashing, etc. I had no clue what I was looking at and the YouTube videos were only How Tos not really “What to buy and from where”. And when I thought I found a good video, it was just a guy using a Brake to bend aluminum to make flashing for his own windows. More or less him bragging out how he was able to flash his windows. 

Where to buy Window Flashing

If you are DIYer on a budget like me, then you want to always keep quality and budget in mind. Moving forward, I finally found 1 video where the guy was talking about

He went on to show how simple it was to install flashing ordered from Trimbender if you can provide the exact measurements of the window. He even instructed on how to measure. The rest was history.

Trim bender refers to it as window trim (see image below). This is what you need to order.

DIY window flashing brick mold trim
DIY window flashing trim from

I measure every single window, I placed my order through their website and I paid their outrageous standard shipping fee of $69. Being on a budget and uncertain if this would even work I placed a small order for about 5 windows. Let’s just say Trimbender makes it very easy for you to get the flashing you need! They literally make it to the specifications and all you have to do is cut it because it comes in 6ft and 9ft lengths. You can even order the nails through them as well. Most important your order arrives in 7 days max.

Cutting your flashing

As mentioned earlier, if you buy an aluminum roll, you can cut it using a Brake. A Brake is a $1,500 piece of equipment that will cut your aluminum to size. It is about 6+ ft. long. Ever see those window installer guys with their trailers? They have a Brake in there! But if you are a do it yourself on a budget, don’t buy a brake. Just go to trim bender and save the hassle. Now that you have your order and it is time to unbox and install.

You are going to need a multi angle miter cuter tool. I bought mines on Amazon for $15. Also, you will need Tin Snips, which in my opinion worked better for me. You are going to measure the angle you need, 45 degrees in most cases and cut the corners. You are also going to cut the length and width of your windows to cut the flashing to those specifications.

Purchase Tins Snips for $23.99 at Amazon see below

DIY Tin Snip Aluminum Flashing Tool
DIY Tin Snip Aluminum Flashing Cutting Tool


One last tip about cutting. After I did the 45 degree cuts, I noticed driving around and visiting my parents, a lot of houses don’t have 45 degree cuts on their flashing. Their installers kept it square and it just overlaps and still maintains a clean look. Much simpler if you ask me because it is a pain standing outside in the winter cutting aluminum.

You can experiment, you may choose to keep it square. To do so, just account for the cut in your measurements. 

Either way, when flashing make sure you overlap the sides of the flashing on top of your bottom at the points where the sides and bottom meet, and overlap the top with the side at the points where the top meets the sides. This creates a protective barrier from moisture getting behind your flashing and becoming trapped. When I say the bottom, I am talking about the window sill flashing.

Congratulations you just finished learning how to prepare and complete DIY Window Flashing!

Other helpful links

DIY Window Replacement Installation

DIY Window Remodel & Removing an Old Window

This the Miter Tool I used from Amazon for $28.99

DIY Window Aluminum Wrap Trim cutting tool
DIY Installing Aluminum Window Wrap Trim Miter Cutter tool


DIY replace windows

DIY Replacement Window Installation

A DIY replacement window installation is the way to go if you want to save some serious money, I’m talking about thousands. So in the last post we talked about doing a DIY Window Removal. The most essential take away was the simple fact that you have to get to the window sashes. In my experience there weren’t any straight forward videos or How Tos that were available for our specific window design, window stop configuration, etc.

Taking off from where we left off last post, at this point you should have a clear windowless window frame. Use a shop vacuum or a vacuum with a dust filter to clean any excess dust and debris. You can also you use hand broom (you know the little one that comes with a dust pan) if you have one. Before I go any further, let me say getting to the removal step and pre installation, we are assuming you already measured your window frame from left to right and top to bottom. And bought the replacement window.

DIY replace windows
DIY Replace windows yourself

What is a replacement window?

A replacement window is just that, a replacement. It will fit right into the same opening you removed the old window from assuming you have accurate measurements that are accurate within .5 inches. As you will see when you buy the replacement, it will give you a range i.e., fits openings 29.5-30.5″.


What is a New Construction Window?

The other alternative is a new construction window. These windows are designed for a rough tear out where you have literally removed everything to the bare bones even the window sill. New Construction windows come with a nail fin and are install from the outside of the house.

DIY Replacement Window Installation Materials

Drill (Preferably Ryobi)

Pack of Window Shims

Caulk (white so it blends in with your new vinyl window)

Spray Foam (Use low expanding for windows)

Shoe stops

Inside window stop or Interior Casing/Trim (to clean up the install)

Install that new window

First, check the specs on  your window and measure it a final time before preparing to install. This ensures that it will fit. Let’s just say I learned the hard way last January in freezing temps buying a window right before Home Depot closed, which meant I couldn’t return it that night. I didn’t realize the size was off until I tore out the old window (yikes).

After you have confirmed the measurements. Get your drill ready, your window can now be placed into the frame. Use window shims to make the distance where the window is not touching the frame. These shims can be applied on the bottom and left and right sides of your window. Once they are in a good position where you can let your window go and it won’t fall in or out, you are ready to check the leveling using a leveler.

Level the new window

Place the leveler on the top of the bottom sash in between the window locks. Once the indication shows level. Get the drill and the screws to the screws into to the frame. I suggest going left to right. Top left and bottom right and vice versa to keep everything balanced. You don’t want to screw in an entire side and then everything is off as you go to the next side.

After you have your screws in, check for plume. Making sure you window is level and can open and close properly. Keep in mind depending on the material your window is made of you have to be mindful of temperature functions and humidity that may allow the window to close easier or not.

Insulate that new window

Here is the messy part, the DIY replacement window insulation. Now it is time to go in between the window shims or any cracks between the frame and the window and using the small nozzle on your spray foam. To do this insert the spray foam (straw) into these cracks, and pull the trigger to spray a good amount of foam. It is important to use low expanding foam because if you use a high expanding foam, there is a chance that you can spray way too much and literally move the window even though it is screwed into the frame.

Please note that spray foam gets very messy because it is very sticky and difficult to remove. I’m not saying it can’t be removed but trust me you will see what I mean if you get it on your hands or clothes. If it gets on your clothes, toss it, from my experience it doesn’t come out.

DIY replacement window insulation

DIY replacement window insulation with spray foam


Where to put the spray foam

The spray foam goes around the perimeter of the window. Don’t worry if you spray too much. At least your window is insulated. No bugs are getting through. More importantly cold air won’t be seeping in or warm air escaping. Keep in mind that some brands offer window head expanders and sill extenders. These are designed to help fill the gap between the top and bottom of the window and frame. It is ideal to spray foam inside the head expander and behind the sill extender. This helps ensure no gaps for air to come in or heat to escape your home. Also, when you spray too much foam, don’t worry. Take a very sharp utility knife or razor blade and make a straight cut to remove the excess.

Depending on how much excess, you might decided to push it back in the cracks. To do this, use a painters tool or putty knife. Ultimately, you will cover it all up with interior trim, window molding or interior window stops. This depends on what Home Depot has in stock when you go pick up your materials.

Cleaning up the Window install

After the spray foam around the windows dries, use caulk on small cracks. Do not try to cover a .25 inch or .5 inch crack with caulk. This is where shoe stops, interior stops, or interior trim come in. They take this:

DIY replacement Window Molding interior trim install
DIY Window replacement including Molding and Interior Trim

Congratulations on your first DIY replacement window install

And that should do it folks! You have successfully completed your DIY replacement window installation.

Now go enjoy your favorite cigar, glass of bourbon, IPA, coffee, or tea!

Other Helpful Resources

DIY Window Remodel  Removing an Old Window
We are all DIYers
How my wife and I became DIYers