Optimizing the Pitch of a Roof, Building Width, and Overhang for Efficient Roof Sheathing Costs

Many builders, especially smaller ones, might not regularly consider this, but the giants in the home building industry have been implementing it for years.

It concerns the substantial cost implications of roof sheathing, which can result in considerable expenditure in terms of time and resources if not done correctly. I'm proposing a simple measure that could lead to significant savings in your projects.

Measuring for Roof Sheathing

The first step is to assess the required sheathing area for your project accurately. This requires careful consideration of several aspects, such as the roof's pitch or slope, the building's width, the roof design (hip, shed, or gable), and the roof overhang. For instance, let's look at a standard gable roof.

A typical gable roof may need one four-foot sheet of plywood and an additional piece of one foot three and a quarter inches. The latter isn't much of a concern as this dimension is slightly less than 16 inches, suggesting we can derive three pieces for this section from one plywood sheet with minimal waste. Alternatively, adding an overhang to the building would enable us to accommodate two full plywood sheets or one full and another slightly smaller sheet, depending on the design.

Adjustments for Efficiency

If these options don't suit your design, you can always modify the roof's pitch, alter the building's dimensions (wider, shorter), or tweak the overhang's length. For instance, let's consider a 10-foot comprehensive structure with an 8:12 roof pitch. For a gable roof to meet engineering standards (with proper perimeter nailing), we would need a full four-foot-wide plywood sheet, a small gap, and another two-foot piece.

Adjusting the overhang length could make two full four-foot sheets fit perfectly. This concept might be tricky, but it gets easier with time.

Advanced Adjustments

Let's take another step and widen the building to 14 feet, altering the slope to 5:12. The result is seven foot seven inches, slightly shorter than two plywood sheets. However, the waste would only be about five inches. A roof overhang requiring larger than 24 inches can pose issues, especially considering the necessity of perimeter nailing.

Considering the bigger picture, a slight increase in waste is tolerable in such scenarios. However, more substantial waste, such as requiring a 2-foot 5-inch wide piece resulting in a non-usable piece of scrap, should be avoided. These challenges can be addressed by reducing the overhang length or repositioning the sheathing.

Real-world Challenges

The most common issue encountered in the field is dealing with small pieces. For instance, consider an 8:12 roof on a 14-foot span building. The optimal solution would be a whole piece and a minimum two-foot piece. Anything smaller than two feet could be problematic in some projects, leading to wastage.

We could avoid this wastage by including an overhang. It is essential to remember that saving on roof sheathing should not result in additional expenses for roof framing due to more extended rafters or other materials.

Lastly, a proven tactic used by truss manufacturers for years is to work with fractions. For instance, a 5.75-inch or 6.25-inch measurement could be more efficient. Don't hesitate to adjust these figures as necessary, as long as it aligns with your local building regulations.

The primary aim of this article is to emphasize the importance of optimal planning and precise calculations in roof sheathing, which can lead to high cost and resource savings in your projects.