If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them.”
— Henry David Thoreau
Now that the small three-season porch at the back of our bungalow had been removed, it was finally time to build up and onto our home. But first things first.
Foundation investigation
We always knew the century-old brick foundation of our home would need a thorough evaluation to confirm whether it could safely support the added weight of a new second story. In the early days of our project, when the design was a twinkle in our eyes, test holes were excavated at several points around the perimeter to check the depth and condition of both the existing foundation and the footing, which is the part of the structure that sits directly on the soil and spreads the building’s load over a wider area.
Test holes dug under the original foundation.
The investigation showed that the main structure sat on an 8-inch brick foundation that flared to nearly 16 inches at the base. After consulting with a structural engineer, we underpinned the existing foundation to create a more robust base before proceeding with the second-floor addition.
Concrete connect-the-dots
The underpinning process involved excavating beneath the existing brick footing in select locations and pouring a new footing to increase the foundation’s height and width. Each concrete pour was reinforced with rebar so that, once complete, a continuous concrete footing would support the added load and help prevent future settling.
The original brick foundation sees the light of day for the first time in over 100 years (left), and pouring the new foundation (right).
Because the new concrete had to be placed under the old foundation, the work was done in short segments — almost like a concrete connect-the-dots. Short, deep trenches were dug at intervals along each side of the existing footing, with forms set for the new concrete. As each section was poured and cured, the crew moved to the next, working methodically around the entire house. The added cost was also offset by the increased value of a larger addition with a full basement.
A small setback leads to big improvements
In 1927, a three-season porch had been added to the original home, and the initial plan was to extend the new primary bedroom suite over this part of the first floor. When the investigation showed that the porch foundation could not safely support additional weight, it became clear that a brand-new foundation would be needed for the rear addition instead. Although this change added some cost, it ultimately strengthened the project by opening up better options for the second-floor layout.
The three-season porch (above right), added in 1927, had a crawl space beneath but lacked a sturdy foundation.
Excavation time
With the new design in place, it was time to excavate the backyard for the foundation of the two-story addition — the first entirely new piece of the project. During the basement dig, the crew unearthed a massive boulder, likely carried and dropped in place by retreating glaciers during the last Ice Age! A 3-inch layer of crushed rock was then laid to keep the site from turning into a mud pit while the footings were formed.
(Clockwise from upper left) Nate welcomes you to the new basement, preparing the foundation floor,
the basement walls are in, and backfilling the foundation.
The new footings were laid out and poured, with rebar drilled in and the foundation wall framing set on top. Once the walls were poured, anchor bolts were installed, window wells were placed, and the perimeter drainage was added, setting the stage for the concrete floor of what would become a music room.
With a solid new foundation in place, the house was ready for framing.
Next up in the series, Our Little House Grows Up: A Peek Inside a 100-Year-Old Home Addition – Walls Up!
