When is it permissible to use a single top plate in a wood stud wall?

Using a single top plate in a wood stud wall is permissible when rafters are within 1 inch of the studs. This condition allows for a strong and effective connection between the roof framing and the wall framing. Essentially, having the rafters closely aligned with the studs helps to ensure that there is enough structural support and load transfer through the wall system, thereby maintaining the overall integrity of the structure.

The involvement of rafters close to the studs when using a single top plate allows for better lateral stability and helps resist lateral forces, such as those caused by wind. Therefore, the connection is crucial in maintaining the wall's and structure's performance, ensuring safety and adherence to building codes.

Other scenarios, such as having no ceiling present or setting specific height restrictions, do not inherently provide the necessary structural integrity that a close alignment of rafters and studs does. Similarly, while wind exposure may be an important consideration in building design, it doesn’t specifically justify the use of a single top plate without the support of properly aligned rafters.