The effects of a single opening size and location on diaphragm shear, chord forces and framing member forces were investigated for a typical wood diaphragm. In conclusion, the maximum shear in the diaphragm with opening is greater than that in the diaphragm without opening. Increasing the distance between the edges of opening and diaphragm can reduce this increase in maximum shear significantly. When the dimension of the opening is no greater than 15% of the corresponding dimension of the diaphragm in both directions, and the distance of opening edge from diaphragm edge is no less than 3 times the larger dimension of the opening and that the portion of diaphragm alongside the opening satisfies the maximum aspect ratio requirement, the increase in maximum shear is less than 10%.