Beam penetrations
Service holes through beams may be necessary for cabling or plumbing. The positioning of these holes must be carefully considered as they could seriously affect the structural integrity of the beam.
Areas of high stress should be avoided close to the supports where the shear force is at a maximum and also at mid-span where the bending stress is at a maximum. This leaves the zones along the neutral axis and a point of compromise between the mid-span and supports.
Beam penetration
A two-storey house has a rumpus room above the garage. The waste pipe for upstairs must penetrate the floor beams. To ensure the holes are cut within safety limits, use the diagram to calculate the following distances.
The floor beams have a span of 6 m and are 300 mm deep.