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Window Installation Guide     

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1) Pressure Treated Wood Buck 

    Installed Into Concrete  

2) Nail Fin Overlaps Wood

    Window Frame 

  • The nail fin provides the first layer of protection (flashing), over the rough opening. 

  • The nail fin covers the wood buck and gap between the window and frame. 

  • The wood frame is secured to the concrete opening with anchors and construction glue to create a seal.

  • The wood frame provides insulation between the concrete and the window.

  • It is also necessary to secure the window in place.

True North Concrete Cutting installs windows with the upmost consideration for the outside environment. We provide multiple layers of protection and insulation to ensure that your new window performs efficiently in all seasons. Window technology and quality has improved greatly over the years and installing them properly is critical for achieving a gain in energy efficiency and function in relation to the old window. Additionally, a properly installed window will not be prone to leaks that can cause costly damage to the interior of your home. 


Installing a basement window is different than installing a conventional above grade window, in that there is almost never siding to cover the vertical and horizontal junctions between the new window and concrete cutout. We tackle this issue by applying multiple layers of weather barriers over the junctions and by directing water away from the window. These layers include a combination of a caulked vinyl nail fin, BlueSkin flashing, drip cap flashing, caulked PVC trim boards and spray foam. Each of these layers provides a seal at the window junction and prevents air, moisture vapor and water from entering.


All companies are not equal in their installation methodology. Many companies will simply snap the nail fin off and caulk/spray foam the window directly to the concrete - this type of installations is very prone to leaking. While obtaining your quotes for egress windows, always be sure to ask companies about their installation methodology. 

Call us today for a free and no obligation consultation.

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3) Caulking is Applied to Back of 

    Nail Fin on Top and Sides

  • Caulking is applied to the back of the nail fin to provide a water tight barrier between the rough opening and the window. 

  • The bottom is not caulked; this allows water to escape if it enters from another location.


4) BlueSkin Over Nail Fin, 

    Wood Buck and Concrete

  • BlueSkin tape is applied over the nail fin, wood buck and concrete opening. 

  • This provides the second layer of protection (flashing). 

  • BlueSkin is highly effective barrier that is impermeable to air, moisture vapor and water. 

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5) Drip Cap Flashing with End

    Dams Over Window 

  • A drip cap is secured above the window to direct water away from the window.  

  • Drip caps are installed with 1 inch end dams to channel water away from the sides of the window. 

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6) PVC Trim Boards are Installed

    Around the Window

  • PVC trim boards are installed around the window as an added layer of protection. 

  • PVC trim is the preferred material for basement window trim, as they will not degrade as wood trim does.

7) Trims Boards are Caulked and 


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  • This is the final layer of protection on the outer side of the window. 

  • The trim boards are caulked on the inside edge, outside edge and back to provide multiple seals around the window. 

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8) Spray Foam is Injected 

    Between Window and Buck

  • Spray foam is injected around the window to prevent heat loss and as an additional barrier of protection against moisture.

  • Spray foam is a highly expansive material that fills the remaining gaps.   

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