With their continuous insulation, ICF walls provide a more secure building envelope. However, window openings present the potential for air and moisture to escape or enter the structure. Our Gorilla Buck helps create a more secure and sealed window opening. Proper flashing also creates reliable seals around windows. This post is a guide to help with ICF window flashing.
A Simple Guide to ICF Window Flashing
Before installing window flashing on ICF walls, consider why it is essential. Window flashing ensures durable walls and an energy-efficient structure regardless of construction method. By directing water away from the opening, flashing maintains a watertight seal around the window, preventing water ingress and protecting the structure from damage caused by leaks, mold, and rot. Flashing also prevents air leaks that impact comfort or reduce the efficiency of heating and cooling systems.
Now, let’s cover the basics of installing it on windows in ICF walls.
Flashing Tools and Materials
Flashing installation is part of installing windows. It occurs after the concrete cures. Once the wall is ready, you must gather your tools and materials for flashing windows in ICF walls. The following are some of the basic tools and materials you’ll need:
- Measuring Tape: This is used to measure openings and the flashing membrane before cutting.
- Utility Knife: cuts the waterproof membrane.
- Caulk Gun: It applies polyurethane sealant. You’ll also need the sealant to use in the caulk gun.
- Rasp Tool: It prepares the window opening.
- Fastening Tools: These are used to install the window assembly.
- Waterproof Membrane: This is the flashing material you’ll use for the window opening. It may be self-adhering or liquid-applied.
- EPS Spray Foam: It fills gaps around the window opening.
- Fasteners: These are for safely holding the window in place.
- Safety Gear: Wear gloves, eye protection, and other safety gear.
It is important to note that this is a list of basic tools and materials. Additional tools and materials may be necessary depending on the window or ICF manufacturer. Installers should consult the relevant manuals and other resources when preparing for the job.
With tools and materials out of the way, let’s move on to the steps for flashing windows in ICF walls.
Inspect and Prepare the Window Opening
The first step in installing window flashing is to inspect the opening and prepare it for installation. Begin by removing any loose debris, dirt, and dust from around the opening’s surface. Having a clean surface is important because dust and dirt can compromise the flashing membrane’s adhesion.
Examine the area around the opening for gaps or holes. If any exist, fill them with spray foam to prevent paths for water intrusion. After that, use your rasp tool to level the foam around the opening. Along with eliminating imperfections and leveling the foam, it prepares it for applying the flashing material. The rougher surface will help the adhesive bond with the foam.
Sealing the Seams
Sealing the seams around the window opening ensures a watertight and reliable installation. Use a high-quality polyurethane sealant to fill the seams and gaps around the window opening. Apply the sealant, ensuring it extends slightly beyond the area where the flashing will stop.
Seal horizontal and vertical seams and continue until you reach the concrete surface. These seams are common weak points; proper sealing prevents water and air infiltration. If necessary, smooth the sealant with a caulk tool to ensure a continuous, even application.
Installing the Sill Flashing
When installing window flashing on ICF walls, you should always start at the bottom and work your way upward. That way, the higher pieces overlap the lower pieces to ensure proper water drainage. You’ll install the first piece of flashing for the sill.
Start by cutting bowtie-shaped pieces and installing them at the corners of the sill. Since the corners are vulnerable, the bowties ensure a proper seal and prevent water intrusion.
After that, you can measure and cut the sill piece for your window flashing. Cut it to ensure it extends at least three inches beyond the window opening on both sides. Cut and fold flaps for a seamless installation around the corners. Position the membrane on the prepared sill and follow the instructions to ensure it adheres to the surface.
Installing Flashing on the Sides
After completing the sill flashing, the next step is to install the side flashing. Ensure it overlaps the sill flashing. Begin by measuring and cutting the flashing membrane for each side of the window. It should extend to cover the flap from the sill piece and a few inches beyond the top of the opening.
Carefully align each piece of side flashing with the side of the window opening. Apply the flashing to the wall. Remember to cut flaps to fold the flashing over the opening and around the top. You also must ensure the sill piece creates a watertight seal over the sill piece.
Installing Flashing at the Top
With flashing on the sides, it’s time to install flashing at the opening’s top. Like with the sill, you’ll need to cut bowtie-shaped pieces to fit at the corner. Once you’ve cut and placed those pieces, you can cut the flashing to fit at the top. Remember, the flashing should extend a few inches beyond the opening on each side.
Align the flashing with the top of the window and ensure it overlaps the pieces for the sides. Remember to cut flaps to fold the membrane in and around the edges like with the other pieces. Once you have it placed, press it firmly to ensure adhesion.
Seal and Install Window
With the waterproof membrane on all four sides, it’s time to seal around the flashing. Grab your caulk gun and polyurethane sealant to seal around the top and sides. Use the sealant to create an upside-down “U” shape around the window. After you’ve sealed the flashing, you can install the window assembly.
Flash and Seal the Window
Once the window is in place, apply flashing material over the flange at the top and sides. As you did before, you want the top flashing to overlap the sides. It is also important that the pieces extend beyond the opening. After the flashing is in place, use your caulk gun to seal around the edges. With that, you have the final waterproof barrier around the window.
These are basic steps to installing flashing for a window in an ICF wall. However, some steps may vary depending on the ICF manufacturer and the window design. Installers may need to contact ICF and window manufacturers for more information.
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