Expanding a too-small kitchen or putting a great room addition on your house can add value and improve living space, but major remodels such as these often require changes to your home's structure_._
Your home has two types of walls; those that support the structure (_load-bearing walls_) and those that do not carry any weight (_partition walls_). You can remove partition walls without compromising your home's structure, but a load-bearing wall cannot be removed without installing a beam capable of supporting the load that was placed on the wall. Removing a load-bearing wall is not a do-it-yourself project. It requires engineering to ensure that the beam can support the load over the span between support members. Proper permits, inspections and the services of a qualified contractor and structural engineer are required.
Replacement Beam Design Factors
Homeowners have two design choices when it comes to replacing a load-bearing wall with a beam. They can:
- Install an exposed beam that extends downward into the room and is typically wrapped or trimmed to make it look as if it belongs there.
- Install a flush beam within the ceiling joists, which is completely hidden from view.
Both options are structurally sound, but it costs more to install a flush beam because the ceiling joists require modification and more labor is involved.
The Design and Engineering Stage
Before removing a load-bearing wall, a thorough analysis is made of the amount of weight the new beam must carry and the best type of material for the beam. This doesn't have to be expensive. The homeowner can take his house plans to a local lumberyard that offers free engineering services. The size and type of beam needed to replace a short wall in a single-story home will be very different from the beam needed to replace a long bearing wall on the first floor of a multiple-story house.
As the beam span and the load it will carry increases, the required size of the beam also increases. Because wood beams suitable for bearing especially heavy loads are so cumbersome, an engineer may opt for a different type of beam. Alternate types include:
- Steel I-beams.
- Structural Composite Lumber (SCL). These relatively new kids on the block offer high structural integrity in a smaller beam than would be necessary with either solid lumber or steel. Depending on the specific project, the engineer might recommend a beam made from laminated veneer lumber (LVL), parallel strand lumber (PSL) or oriented strand lumber (OSL).
The Supporting Posts
The new beam must transfer the weight to bearing points, or vertical posts, on which the beam will rest. The type of posts is up to the engineer, but typical posts are made from multiple wood studs attached to one another, steel poles welded to steel plates and heavy-duty screw-type house jacks that can be adjusted and left in place.
The bearing points for the new beam must transfer the weight all the way to the foundation, which means the engineer might require additional post support in floors beneath the bearing posts. When replacing a basement wall, it might be possible to cut beam "pockets" in the top of the foundation wall to support the new beam.
The Demolition and Replacement Process
Once your contractor has the engineering specs and the beam has arrived, the project can begin. Before tearing out the load-bearing wall, the contractor will construct one or two temporary stud walls to support the joists until the new beam is securely in place.
After removing the existing drywall, mechanical elements, such as wiring or pipes in the wall, are rerouted or terminated. The last part of the demolition is the removal of the studs, along with the floor and ceiling plates, the horizontal members at the top and bottom of the wall frame.
Installing the new beam can be tricky, especially if it's long and heavy, and often requires multiple workers and support jacks. Fitting an exposed beam involves positioning the beam beneath the joists and attaching it to both the joists and the new bearing posts. If you opt for a flush beam, however, the contractor will cut the joists, install the new beam in the ceiling above and install joist hangers to support the joists.