Non loadbearing walls- This is an article in a series, where we intend to train homeowners to do basic inspections. Because of the coronavirus pandemic, safety and social distancing is a must. However, that does not mean your construction requirements must be overlooked or paused.
Previously, we discussed how you can identify load-bearing walls from partition walls. That gives you great knowledge into which walls you cannot remove or would need extra measures, and which ones you can remove easily.
But, while partition walls are not bearing any load of the structure, removing them is not that simple as they still contribute to the building’s overall stability. In this post, we are going through the effects that interior walls have on construction in order to learn which ones we can remove, reposition, or where we can add new walls. Bear in mind that you still need to get a city permit, so we need to design for approval.
A load of non-loadbearing walls
Interior walls may not bear any load of the building, but they do have a load of their own. You need to consider the seismic base shear of the wall, particularly when for the upper floors.
As a rule of thumb, the load a floor can endure is 6 psf. With that in mind, you can calculate the weight of the new partition walls you are adding and see if the total weight would exceed the accepted load. For instance, assume your total floor area is 100 feet. That means the floor can endure weights up to 600 pounds, so the total weight of the walls should not exceed 600.
When calculating, we must include both dead load and live load. Dead load is applied to non-movable objects, such as floors and bearing walls while live load applies to movable things such as furniture, people, and interior partition walls.
Preventing ceiling cracks
Added interior walls may partially bend the ceiling of the upper or lower floor, leading to cracks on the finish. Long-span floors are particularly vulnerable to this, caused by added interior walls or foundation settlement.
To offer some protection against such cracks, interior walls should be enhanced with double wood blockings.
Accommodating for lateral load
Buildings sometimes get under pressure from lateral forces, such as wind, seismic forces, or water and earth pressure.
Interior walls have a fair share in improving a building’s lateral resistance, sometimes up to 50%. For that reason, having many partitions in a house is good for the building, as long as it does not exceed the maximum pressure on the floor.
Of course, some design codes (particularly in the United States) prohibit the consideration of the extra resistance interior walls contribute to a building and lean on more conservative calculations. Other design codes allow assuming up to 10% increased resistance from the inclusion of interior walls.
Partition walls help resist deflection as the load on the floor increases. However, many designs omit them entirely, as analysis tools to model complicated 3D structural configurations are not readily available, and including them would increase the cost of the calculations significantly.
In this post, we strived to point out the different loads on a structure, and how non-loadbearing walls still contribute to absorbing some of that load. We learned the limits of how many walls we can add, and where we should not remove them.
Knowing what partition walls do from a structural viewpoint helps you better decisions about your remodeling plans, and what is and what is not possible for your home.