The rising popularity of engineered-wood products, such as glued-laminated timber (glulam), as analternative to traditional sawn lumber encourages to fabricate glulam built-up sections that can expand the horizon of the use of this sustainable material in the construction of mid- and high-rise timber buildings. As a pilot investigation into the subject, five full-size built-up glulam box-section beam assemblies were experimentally examined under four-point flexural bending. Self-tapping screws were used in different patterns to form three beam assembly configurations. Each beam built-up section was made of four glulam panels, each of 44-mm thickness except the bottom flange panel that had 86-mm thickness. Experimental testing showed that reducing the spacing from 800 mm to 200 mm of the screws connecting the built-up section’s top and bottom flange panels to the web panels increased the beam flexural bending strength by about 45%. While reducing the spacing from 200 mm to 100 mm only for the screws connecting the bottom flange to the web panels over a distance equal to one-third beam span length from each support, where the maximum shear stresses existed, increased the beam flexural bending strength by an additional 10%.