A few years ago, while performing an unrelated renovation, my aunt mentioned that the area surrounding her living room bay window was freezing during the coldest winter months. After pondering the issue for a day or two, I suggested building a structure below the bay window protrusion that was self-contained, to address heat being lost through the floor joists as well as prevent any air movement below the bay window itself. Upon completion, the results were immediate and favourable.
As such, there have been several requests for such a fix, which have been detailed in this column now and again.
Since the start of the pandemic, uncertainty of ongoing work gave way to an influx of renovation requests. There are a few theories as to why this has occurred — in my opinion, having to hunker down at home contributed greatly to a collective desire to focus on home improvements and the elimination of the yearly vacation expense provided the funds to do so. This created a welcome surplus of work within the renovation industry, and it has been greatly appreciated.
An unexpected consequence, however, has made it difficult to cater to everyone in a timely manner. Although it has been my sincerest desire to my best, and many clients have been more than patient awaiting my initial site visit and subsequent quote for the job at hand, there are a few smaller "last-minute" job requests that just won’t fit into an already congested work schedule — this autumn’s "bay window fix" is one of them.
Generally completed in less than a day (provided all the appropriate materials are on site), this project is not complicated, and can be achieved by anyone. It is non-invasive and mimics the contours of the bay window protrusion above. Simply put, it can be a DIYer’s weekend project. All you need are the following materials: an eight-foot-wide roll of thick poly at a bit longer than the length of your bay window, a few 2x4s at eight-foot (six-eight should suffice), a bundle of Rockwool insulation, a sheet of half-inch treated plywood, three-inch ceramic screws, half-inch staples, blue Tuck tape, caulk, a quart of primer and another quart of exterior grade paint tinted to the colour of choice.
Essentially, the area below the bay window protrusion is dug out to a depth of six inches, before the poly is set back against the house footing allowing for an overlap along the front, later. Front and back 2x4 framework set within the poly is constructed with a minimum one-inch setback along the underside of the protrusion. The side frames are then added, making the entire structure rigid, fastened to the underside of the overhang. The cavity is filled with insulation, and the poly is then tightly secured to the front framework encapsulating the cavity and its contents. All poly seams are then sealed with Tuck tape. The front panel, and both side panels are then cut from the half-inch plywood, using the appropriate miters along the edges where two panels meet, as well as along the back adjacent the house footing. Once affixed to the framework, all remaining seams are caulked. The newly built under-structure is then primed and given two coats of paint. Eh voila, the bay window fix is complete, without the need to breach the existing foundation or bay window protrusion. This small project eliminates the flow of air below, and dissipates the extent of heat loss from above.
By all accounts, this simple project has proven invaluable, at a very reasonable cost for materials. My aunt had boasted that pre-bay fix, the living room suffered a 10 C decrease close to the bay window area making it intolerable during the winter. After the bay window fix, the fluctuation improved to a mere 2 C difference, which is generally acceptable when close to any window of the house during the frigid months. I invite all DIYers with a similar bay window issue to take on the challenge. And the time is now, before the temperatures dip down too low — go grab what you need, and "git ‘er done."