Window Installation Problem

By Robert Robillard on Uncategorized

To many times I run in to water infiltration issues due to poor window and door installations with incorrect flashing details or no flashing at all.

Window Installations and Water Infiltration

The days of throwing a window in a opening. Plumb, level, square are over.

Rough opening window and door  flashing has been ignored for years. Here is one example below. Because of the lack of flashing, this window leaked.  Water leakage lead to ant infestation, wet insulation and rotted sheathing.

After the necessary framing, insulation and sheathing repairs we begin the proper flashing techniques

In this instance we used Grace Vicor Plus and Vicorners for the sill panning and rough opening flashing. Prefab sill pans can also be bought at any lumber yard.

It is also important to bridge the continuous joint between the window casing and the siding. Being a retrofit this was a achieved by sliding metal flashing behind the siding prior to installing the casing. This saved a lot clap board replacement which the client was happy about. Note all flashing should be installed in a water boarding fashion.  Meaning that the flashing should drain onto a clapboard and out and away from the house sheathing.

After the window is installed as specified by the manufacturer, we covered the nailing flanges with 3” strips of Vicor. The interior was insulated using low expanding foam insulation.

Finish the interior as you normally would. Prior to installing the exterior casing I like to blind caulk the siding joist as added protection, Also don’t forget the primary trim flashing (window cap)at the exterior head casing.

Now here is a window installed that wont leak.

This article was written by Joshua West, Manager of Joshua C P West LLC Renovation and Construction. Joshua West has been in the construction industry since 1985 working in the fields of House Building Masonry, Home Renovation and Finish Carpentry. Josh West started his business in 1995, working mainly on residential renovation projects through-out the Metro Boston area. Joshua is also a family man w/ 4 children and wife. He enjoys the outdoors, target shooting, boxing training, and spending time fishing with kids. Come visit his Web Site at

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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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