Homeowners often want to create a vaulted ceiling design. In many cases, a vaulted ceiling makes the room feel more open, bringing air and light into a room. It is a substantial remodeling project. It should be approached with care and help from a residential structural engineer. Here are some things to consider.
Most flat ceilings hide gorgeous, open-rafter cathedral ceilings. Substantial structural issues must be taken into consideration before beginning any tear-out project in preparation for constructing a vaulted ceiling.
The cross supports for most flat ceilings have the structural function of providing thrust against which the roof rafters stand. If these horizontal cross supports are removed, then there is a significant risk that the ceiling will sag or fail because of improper support. If you are considering removing a flat ceiling in favor of constructing a vaulted ceiling, first determine how to brace the roof with an alternative method of support for the rafters.
Several options for alternative structural support include placing a very sturdy, strong center roof beam along the roof peak line and attaching all of the rafters to it. If this method is used, then the roof beam will need to be supported at each end by a column that solidly rests against a firm ground surface. Columns can be supported with a concrete footing or be attached to a steel I-beam that supports either the floor or the foundation.
Another alternative structural support which involves substantially more time and effort is to construct entirely new rafters which rise closer to the ceiling. Rafters can be designed so that they provide overall support through a series of smaller cross rafters that are combined into each larger spanning rafter. This structural design not only provides significantly more support, but it also adds overall visual interest to the vaulted ceiling.
With the rafters in place, it is easy to install skylights at desired locations in the vaulted ceiling to allow additional light to filter into the room. Newer skylights can be opened either manually with a crank mechanism or with a small electrical motor to allow ventilation. This feature can be especially attractive if you live in an area with extremely hot summers where accumulated hot air at the top of the ceiling reduces energy efficiency.
Vaulted Ceiling Insulation
There are several options for installing insulation in a vaulted ceiling. Among the easiest options is to install rigid insulation sheets over the rafters, which not only provides insulation, but also the structural function of enclosing the roof. Another type of roof insulation is spray foam insulation, although venting space will need to be included unless newer breathable insulation materials are used.
Finally, traditional fiberglass insulation works well in cathedral ceilings, although a 2-inch breathing space between the insulation and the roof sheathing must be included.
If you decide to construct a vaulted ceiling, check with your local office regarding building permits and consult with an experienced structural engineer to ensure safety throughout the project.