Building a Modern Shed – Part 11 – Installing the Windows

We’re going to install the windows into our work shed. We’ll go over all the different steps necessary to install windows in general. This article is a mix of step by step instructions and some videos that really helped me get going.

Below is the overview video for installing the windows in our work shed.

Originally, this article is what I used as a reminder for each of the installation steps.  All this is based off the original installation instructions from the manufacturer.  It now includes additional material so you can make informed decisions about your install.  A good start for any project is to do a web search to find the manufacturer’s installation instructions for your windows before starting.

I used this video as a reference for my install.

Rough Opening Verification

Measure the rough opening to make sure it’s at least ½ – ¾ inch larger than the window.

Measuring the Rough Opening Before the Window Install
Measuring the Rough Opening Before the Window Install

Make sure the rough opening is level and plumb.

Do a dry fit to confirm the window will fit.

Test Fitting the Window Before Installation
Test Fitting the Window Before Installation

Preparing the Opening

We’re going to install all the necessary flashing and shims before we install the windows.

Sill Flashing

I’m treating my wall as if it’s a water resistive barrier like a zip wall.  If you’re installing sill flashing on more of a traditional structure and you’re not using a flexible flashing as a sill pan, the video below will help you.

No matter what, if you want to be rock solid on your corners you could use a combination of window flashing corners and flashing tape.

Below is a video on how to use these flashing corners

With all that said, let’s get going on how Pella suggested I install the sill flashing.

Cut a piece of flashing tape so it’s 12 inches longer than the rough opening.  This is so the tape will go up 6 inches on each side of the sill.

Apply the flashing tape so there is at least 2 inches on the exterior and 6 inches up each side of the jambs.

Installing the Sill Pan Flashing
Installing the Sill Pan Flashing

Cut the corner flashing to match the picture below.

Corner Flashing Detail with Water Resistive Barrier
Corner Flashing Detail with Water Resistive Barrier

Jamb Flashing

Cut 2 pieces equal to the height of the opening.

Apply the flashing on each of the sides with at least 2 inches on the exterior.

Installing the Flashing on the Side of the Jamb
Installing the Flashing on the Side of the Jamb

Install the Bottom Shims

These shims are a chance to level the windows if there is any variance in the rough opening.  We’re looking to create a 1/4 – 3/8 inch gap at the bottom of the window.  I’m using a composite shim for this with the hope that if water gets in, they will be less affected by it.

The shims will be placed parallel with the rough opening.

Cut 4 pieces of the shim 1 inch long and 5/8 – 3/4 inch wide.  One set of 2 for each side. When you stack two pieces on top of each other you will get a 1/4 – 3/8 inch gap. In the case of the 4 foot windows, I used 3 sets shims for a little extra support.

Shims Cut to Make a Gap between the Window and Sill
Shims Cut to Make a Gap between the Window and Sill

You’ll shift the shims till they are level.

Shift the Shims until they are Level
Shift the Shims until they are Level

Make sure you leave a little gap in the front of the shims so they won’t touch the window flange.

Checking Level on the Shim on the Window Sill
Checking Level on the Shim on the Window Sill

Use flashing tape to attach the shims to prevent them from moving.

Using Flashing Tape to Hold Down the Level Shims
Using Flashing Tape to Hold Down the Level Shims

Setting the Window In Place

Now we’re going to put the window in place, check that everything is square and plumb and attach the window in place.

The manufacturer’s instruction didn’t mention using a silicon sealant but several references I looked at all used it.  So I decided to make it part of the install.

Apply a bead of silicon sealant on the sides and top of the window opening before setting the window in place. Don’t apply any to the bottom. This will give water a way to get out if for some reason some gets in around the window.

Apply a Bead of Silicon on the Sides and Top Only Before Setting the Window in Place
Apply a Bead of Silicon on the Sides and Top Only Before Setting the Window in Place

Set the window in place. Make sure you place the window on the shim spacers we installed previously.

Placing the Window on Top of the Shims
Placing the Window on Top of the Shims

Go inside the shed and make sure the window is centered side to side in the opening.

Put a screw in each of the top corners to hold the window in place.  Don’t over drive these.  We want to have a little play when plumbing and shimming in the next step.

Putting Screws in the Top Corners to Hold the Window in Place while Shimming
Putting Screws in the Top Corners to Hold the Window in Place while Shimming

The manufacturer suggested using screws with washers.  If you can find screws with a large head like the SPAX powerdrive, it will save you time but cost more.  I went with a #8 2 inch exterior screw and #10 stainless steel washer.

Screws Used for Installing the Windows
Screws Used for Installing the Windows
Stainless Steel Washers used with Screws for Window Installation
Stainless Steel Washers used with Screws for Window Installation

Plumbing and Shimming the Window

The video below really helped me learn how to shim the windows.

Remember to take your time with this.  It will affect how well the window will operate.

Shimming the Windows
Shimming the Windows

Part of shimming is checking to make sure your windows are plumb and square. I found the video below helpful.

Drive 2 more screws into the bottom corners of the nailing fin.

Driving Screws into the Bottom Corners before Final Checks
Driving Screws into the Bottom Corners before Final Checks

Double check the square and plumb one last time.

Finish Driving Fasteners in the Nailing Fin

Now it’s a matter of driving the rest of the screws in.

Driving the Rest of the Screws in After the Final Check
Driving the Rest of the Screws in After the Final Check

Flashing Outside the Window

We’re going to apply flashing on the sides and top of the outside fins of the windows.

Cut 2 pieces of flashing 4 inches longer than the fin sides.

Install the flashing to the sides so it covers the side fin and extends 2 inches above and below the side fin area.

Installing Flashing on the Window Side Fins
Installing Flashing on the Window Side Fins

Cut and install a piece of flashing on the top so it goes past at least 1 inch on both side flashing tape.

Applying Flashing to the Top of the Window Fin
Applying Flashing to the Top of the Window Fin

Sealing with Spray Foam

When you buy your spray foam, make sure it’s for doors and windows.  This foam is designed so it won’t push your doors and windows out of whack.

Applying Spray Foam Insulation
Applying Spray Foam Insulation

Don’t worry if your foam goes a little crazy.  It comes off of the vinyl frame pretty easy.

Scraping Off Excess Spray Foam from the Window
Scraping Off Excess Spray Foam from the Window

Cost

This was one of the most expensive parts of the build, mostly because of the windows I chose.  For example, the front windows are single panel dual pane with argon gas in between.   I could have cut some cost by choosing some different windows, but I’ll spend summers in this structure and I’m hoping the better windows help out.

Window Installation Cost
Window Installation Cost

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