Recently, our company began what was initially a large kitchen remodel on a turn-of-the-last-century home, but as sometimes happens on a lot of older homes, we encountered some significant structural issues as we started to pull things apart.
There is always pressure to keep costs down, and when unexpected problems arise, that pressure increases. Yet, because these were structural issues, we couldn’t skimp either; we had to ensure solid results. The pull between budget and scope is a common complexity of working on older homes, and while the solution we landed on is very specific to this job, the principles we employed may be useful to readers encountering similar predicaments.
As with many extensive kitchen renovations, we reworked the floor plan, changed stair access, got rid of a narrow hall, opened the kitchen to the dining room, and reworked an adjacent half bath. During the design phase while taking measurements, we noted that not all the surfaces were planing out the way they were supposed to; specifically, something was wrong with the north wall where a window was recessed deeper than it should be. On the exterior, we observed a very subtle outward bow. We recommended the client put $5,000 in contingency, thinking, worst case, we would have to reframe one wall. We figured the problem was probably a combination of an undersized header and some rot.
As we began our demo work, however, we started to uncover layers of crazy: The most glaring discovery was that in one section of the wall the floor joists had become completely disconnected from the rim for no apparent reason. Elsewhere, floor joists had been drilled out and sliced up for mechanicals with no regard for the joists being part of a structural system - we dubbed these “decorative joists.” In one corner, five floor joists had been cut during a past staircase modification, so the corner of the house had effectively been cut loose. The rim joist, now free-floating, was all that was left to support the balloon-framed exterior wall, which had begun to slowly slide off the crumbling foundation. Thankfully, the existing rim joist was an 8x8 beam. If it had been anything less, it would have completely slipped off the foundation and the second floor would have crashed in long ago.
Any one of these conditions would have been manageable on its own, but with all of them facing us at once, two things became immediately clear: We would exceed our contingency, and we needed to bring in a structural engineer. This was not a light decision. Bringing in an engineer ran the very real risk of having to tear out and rebuild a large part of the foundation, or some other equally massive measure that would be excessively expensive for the homeowner. At the same time, we were facing an extreme condition with just too much risk to own the solution ourselves. To navigate through this quagmire, we proposed a solution and brought in the engineer only to verify, and perhaps modify, our approach, rather than open a Pandora’s box for the engineer to develop their own (possibly over-engineered) solution.
Slideshow: Innovative Rim Joist Repair
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The Minneapolis-based design-build firm Otogawa-Anschel recently began a large kitchen remodel, and as often happens when working on older homes, encountered some serious structural issues that couldn't be ignored. This is their solution for fixing the structure while keeping the budget in check.
Play slideshowWe got lucky! The engineer largely agreed with our solution. This was not a foundation failure; only the first two courses of stone had become unstable. The rest, which extended another 8 feet down looked stable. The engineer agreed that if we could grab hold, so to speak, of those top courses of stone, clamp them together and effectively bind them in steel, grout and pin them to the foundation below, we would have a solid structure to which we could reattach the floor framing. On this, we could rebuild the rim and provide solid bearing for the wall. Once we agreed on the proposed this cost effective approach, the engineer specified the exact details for an angle-iron ladder, welded up with angled cross-braces that also functioned as brackets for securing the new rim and joist connections. The ladder spanned the top of the foundation, and included L-brackets to which we attached a new rim beam. Before installing the steel, we had to first clean-up the loose foundation courses—very much like drilling out tooth cavities and removing the loose debris—and then pour reinforced fillings—rebar embedded in non-shrink grout. We were relieved that the engineer agreed that grouted rod would suffice to pin the steel to the rock. Drilling into an old foundation to set epoxy anchors can be very disruptive and we didn’t want our work to cause even more damage.
Slideshow: Buttoning Up the Job
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O-A Design_Build frames in the new floor and dries in the exterior to complete their innovative foundation repair.
Play slideshowAs our engineer described it, the aim of the proposed fix was two-fold: to provide a more stable vertical load path, and to provide a connection for the joists. For this scenario, he specified a triple LVL rim joist. This much beam is needed to support several different loads: It has to tolerate the force of balloon framing, which has floor and roof load coming down in points. That load must be distributed or the rim would twist. We’ve also got the lateral force of the first floor system, pulling inwards on it. It has to distribute force in one direction and be stiff in the other. Not your typical rim joist, but it did the trick at a price the owner could afford.
