My family’s company, Great Lake Builders, specializes in structural repairs in and around Chicago. Many of the homes we work on are similar to the one shown in this article: wood-frame buildings that have outlived their structural capacity. Some of these suffered damage from badly executed floor-plan changes or from mechanical contractors hacking up the structure to retrofit new systems. And many were underbuilt to begin with. This job suffered from all of the above.
Load-Path Essentials
On this job, most of the structural problems could be traced back to breaks in the load path, which can be devastating to the integrity of a building even if it doesn’t collapse. The effects go beyond plaster or drywall cracks; they manifest in walls and floors that noticeably sag, in floors that bounce and squeak, and in doors that don’t fit their openings and shake the walls when slammed.
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This flush beam in the second floor had no bearing on one end, o…
This flush beam in the second floor had no bearing on one end, only nails loaded in shear into a ledger.
The ledger was partly carried by cripple studs, but the header s…
The ledger was partly carried by cripple studs, but the header supporting these cripples had no support.
No joist hangers supported the joists carried by the flush beam.
Plumbers over the century had done a good job of carving up floo…
Plumbers over the century had done a good job of carving up floor joists.
Very little was left of some joists after the plumber's work…
Very little was left of some joists after the plumber's work.
The span and width of this opening requires a double-LVL beam, b…
The span and width of this opening requires a double-LVL beam, but in a previous renovation o open up the room to the kitchen, remodelers had only used a double 2×12.
From the basement we are looking into a joist bay in the first f…
From the basement we are looking into a joist bay in the first floor. A new steel beam will be installed perpendicular to this basement I-beam girder. The new steel beam will span from this girder to a second basement girder that runs parallel to this one in the background.
A column supporting the existing girder in the basement had almo…
A column supporting the existing girder in the basement had almost no footing.
Loads on a building must be supported by a complete load path that effectively transfers loads “from their point of origin through the load-resisting elements to the foundation,” as it’s described in Chapter 3 of the International Residential Code. In general, the load transfer needs to be continuous from roof through walls and headers, as well as floors, beams, and columns, to the foundation. Rafters and joists should align with studs, and all load-bearing walls and floor loads must be supported by foundation walls and footings or with beams supported by columns to footings. The alignment of structural members is the best way to effectively transfer gravity loads, but the loads are not all from gravity. Lateral loads and uplift forces require connections between members that are tight (wood-to-wood) and tied securely together with fasteners. In our repair work, we hardly ever toenail permanent connections; we rely exclusively on steel clips, corners, and straps fastened with structural screws.
On this job, we were called in to execute an engineer’s design for reinforcing a number of key components in the load path (see “Breaks in the Load Path,” slideshow above). We addressed five critical areas of the structure:
1) Undersized floor joists on the second floor had sagged. In addition, an area of this framing below a second-floor bathroom had been severely chopped up by plumbers.
2) A flush beam in the second floor had no bearing at one end. It was simply toenailed into a ledger that was nailed to cripple studs, and the window header that picked up the loads on these cripples had no support extending to the foundation. In addition, this beam was overloaded on one side and had rolled. The framing predated joist hangers, and the end nails securing the joists to this beam had pulled away.
3) An unsupported bearing wall was failing. It was carrying the other end of the flush beam, as well as a section of the underbuilt second floor, but it had no bearing in the first floor that transferred directly to the two steel girders in the basement.
4) An undermount header that had been retrofit to enlarge a door opening into the kitchen was undersized and unsupported. This beam was in line with the flush beam. For its span and depth, the engineer said it needed to be LVL, but the remodelers who installed it had used dimensional lumber, and one end column did not have bearing that transferred to the basement girders.
5) A steel column that supported one of the basement girders was failing because it had almost no footing.
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Ernesto Bonilla of Great Lake Builders cuts flooring nails so si…
Ernesto Bonilla of Great Lake Builders cuts flooring nails so sister joists will fit tight to the existing ones.
Ernesto and Toby Bonilla roll in sister joists .
A screw in the edge of the sister joist and a hammer help pull t…
A screw in the edge of the sister joist and a hammer help pull the sisters flush to the bottom edge of the existing joists.
Blocking is key to stiffening the floor.
This bearing wall section currently has little support, and will…
This bearing wall section currently has little support, and will bear on the new I-beam to be installed in the basement. The studs in this critical wall section had bowed and required reinforcement with new studs before any jacking could be done.
From the Ground Up
As a rule, you want to approach a load-path repair by starting at the bottom and then lift the structure from a solid foundation. On this job, we began by excavating and pouring a new column footing in the basement, so we would have a stable base to build from once we raised the structure.
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At the top of the wall section described above, the pencil line …
At the top of the wall section described above, the pencil line shows the position of a laser before jacking the beam in the basement. In this phot, the jacking …
… in the basement has begun.
When the new beam in the basement is level, the wall has been ra…
When the new beam in the basement is level, the wall has been raised more than an inch.
Steel shims are placed between the new beam and the old basement…
Steel shims are placed between the new beam and the old basement girders
The existing column supports for the basement girder were replac…
The existing column supports for the basement girder were replaced. Here the footing is being prepped with rebar and anchors.
Ernesto Bonilla finishes off the new footings
Reinforcements needed. Before jacking anything up, we first needed to sister the undersized floor joists in the second floor (see “Sister Support,” slideshow at left). We wanted to create a flat floor system so that when we started to lift the structure from the basement, the floor would rise uniformly and we would be able to accurately measure our progress. This would have been impossible with the extent to which the existing floor sagged.
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Undermount beam. Prior to removing the old undermount beam, the …
Undermount beam. Prior to removing the old undermount beam, the crew erects shoring on each side of the opening.
Undermount beam. The author joins the two LVLs with structural s…
Undermount beam. The author joins the two LVLs with structural screws
Undermount beam. To ensure bearing on both plies, the author pla…
Undermount beam. To ensure bearing on both plies, the author planes the top edge of the assembled beam.
Undermount beam. Ernesto and Toby lift the beam into place, and …
Undermount beam. Ernesto and Toby lift the beam into place, and snug up the shoring to hold it in place.
Undermount beam. It extends beyond the corner so the end column …
Undermount beam. It extends beyond the corner so the end column (new framing in foreground) bears directly on the new basement beam.
Flush beam. In preparation fro replacing the flush-framed beam, …
Flush beam. In preparation fro replacing the flush-framed beam, the crew erects shoring to hold up the joists.
Flush beam. After removing the old beam, they cut through the le…
Flush beam. After removing the old beam, they cut through the ledger so the new flush beam will extend over the window, and a new header will be installed beneath it, supported by full length jack posts that extend to the foundation wall to complete the load path.
Flush beam. As a measure of added protection. the crew has neatl…
Flush beam. As a measure of added protection. the crew has neatly wrapped the end of the beam that pockets into the exterior wall with a peel-and-stick flashing membrane.
Flush beam. Ernesto and Toby use shoring to lift the new beam in…
Flush beam. Ernesto and Toby use shoring to lift the new beam into place.
Flush beam. With the beam raised into place, the joists are secu…
Flush beam. With the beam raised into place, the joists are secured with joist hangers.
Flush beam. The other end of the new beam is supported by a new …
Flush beam. The other end of the new beam is supported by a new LVL header, which is supported by full length jacks on both sides of the window opening.
Flush beam. Framing completed at the exterior end of the beam.
Flush beam. A built-up column provides full bearing for one end…
Flush beam. A built-up column provides full bearing for one end of the flush beam. The base of the column bears on the new beam that was installed in the basement, which in turn is carried by the main girders.
Flush beam. Framing completed at the interior end of the beam.
We also strengthened the unsupported bearing wall section mentioned above. The top and bottom wall plates had sagged at each stud, and the studs themselves were bowed. By reinforcing the wall with additional, plumb studs, we could reliably lift from below, knowing that everything would stay straight and the lifting force would be effectively transferred, raising the structure as a whole.
Basement I- beam. Before lifting, we installed a new steel I-beam spanning between the two existing basement girders. This new steel beam was positioned directly under the previously unsupported wall section; it would support the corner column at one end of the flush beam as well as the column at one end of the undermount beam. Jacking up this new beam to level straightened the wall plates and lifted the reinforced second floor as well.
Two new LVL beams. Once the main floor elevation was established, we could install a new flush beam, built up from four LVL plies, and a new undermount beam, made from two LVL plies (see “Two New LVL Beams,” slideshow above).
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To complete the job of reinforcing the floor system, the joists…
To complete the job of reinforcing the floor system, the joists hacked up by plumbers had to be headed off.
Ernest secures metal clips to the new header using structural sc…
Ernest secures metal clips to the new header using structural screws made by Simpson Strong Tie.
The completed framing transfers the floor load around an existin…
The completed framing transfers the floor load around an existing drain pipe.
Framing as a system: The completed framing repairs result in a f…
Framing as a system: The completed framing repairs result in a flat, level floor/ceiling assembly with all loads transferred effectively to the foundation.
The final step on this project was to rebuild the floor where the plumbers had hacked it up. This required adding headers across joists to carry the loads around the plumbing so we could remove the cut-up joists. It was painstaking work, as it’s difficult to screw off framing hardware in such tight spaces. Nevertheless, it’s critical to follow through with tight joints and all holes in the hardware filled with screws.
JLC contributing editor Jake Lewandowski is a construction manager with his family’s business, Great Lakes Builders (greatlakesbuildersinc.com), which specializes in structural repairs in Greater Chicago. Follow him on Instagram: @jakemlewandowski