Opening a Load-Bearing Wall in an Occupied House
A homeowner wants a 2.4 m wide by 2.1 m high opening cut in the main-floor wall of a two-storey wood-frame house with brick veneer. The wall supports the second-floor joists and the roof, and the joists bear perpendicular to the wall. The drawing shows a steel lintel but no temporary shoring plan. The basement below has a finished ceiling, a concrete floor, and a steel beam 1.2 m from the proposed opening. The contractor proposes to cut the opening in two hours with a reciprocating saw, install the lintel, and 'let the brick above bridge the gap' during the cut. The homeowner wants to stay in the house. The saw operator has not done this before. There is a visible crack in the plaster above the proposed opening, and a nearby door sticks.
1. What is the load path, and what temporary support is needed before any cutting?
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The wall is load-bearing: the second-floor joists and roof bear on it, so the opening removes part of the load path. Before cutting, the loads must be transferred to temporary supports that carry them to the basement floor or steel beam, not to the finished ceiling or an unsupported floor. A typical approach is needle beams through the wall at close spacing, supported by posts on both sides, with the posts bearing on spreader plates or footings over the steel beam or slab. The temporary works must be designed by a qualified engineer because the loads, post spacing, bearing, and slenderness are not guessable. The brick veneer above is not a structural bridge; it is a dead load and a fall hazard.
2. Who must design the shoring, and what sequence should be followed to install the lintel?
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The shoring design must be sealed or signed by a professional engineer, and the contractor must follow it. Sequence: install the temporary supports and pre-load them; verify the load is transferred; monitor the crack; cut the opening in controlled sections; install the steel lintel with the specified bearing length and temporary props; pack or grout the lintel; then remove the temporary supports only after the lintel and masonry have the required support. The saw operator needs instruction and supervision, and the work needs a permit and a check that no services run through the wall. The lintel must bear on solid masonry, not on the veneer alone.
3. What do the crack and the sticking door change about your decision, and how do you communicate this to the homeowner?
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The crack and the sticking door are signs of existing movement or settlement. They change the decision because they may indicate the wall is already distressed or the lintel bearing is inadequate. Before cutting, install crack monitors and take readings; have the engineer review the crack. If movement increases during shoring or cutting, stop work and evacuate the area. Tell the homeowner in writing what will happen, the duration, the temporary supports, the dust and noise, and the egress route. Get a signed scope and the engineer's letter. Do not let the homeowner remain in the room below the work; keep the work area isolated.