Breaking Down the Costs: What Makes Roof Trusses More Expensive?

Roof trusses are a critical component of modern construction, providing structural support and shaping the roof of a building. Their cost varies widely based on factors like truss design, ceiling height, attic space, and the building's location.

Types of Trusses

The most economical trussed roof is a gable end style with standard heels. This truss uses the least number of pieces to construct the trusses and allows for the most repetition in the fabrication process. 

This style of roof is the most common, and it can be seen on everything from churches to schools, and residences to garages and backyard sheds. With this style, if your building is a rectangle, you will have two parallel walls with gutter and the other two parallel walls will have siding.

The second most popular option is a hip roof. This is a design in which every wall has a gutter line, and the roof slopes up to the peak from every side of the building. Some benefits of a hip roof include lower maintenance costs because there is less painted siding to maintain, and the roof may appear to be less tall, which can help with proportions depending on the overall design of the building. 

The fabrication and installation of a hip roof is more complicated since there will be more individual truss profiles and less repetition in the building process, so you can expect a hip roof to cost a few percent more than a gable roof.

Ceiling Designs 

The typical home built before the 1970’s, with some exceptions, was simple – short walls and flat ceilings. While that was an efficient and economical way to build, it often created a space that felt a little confining. 

In the 1970’s a trend began to add vaulted ceilings to affordable homes, and today most homes have sloped ceilings in at least some of the living spaces. This not only opens the feeling in the home, but also might allow for some views to include sky and transitions into airy outdoor covered living spaces. Like the hip roofs, vaulted trusses are more complex than flat bottom trusses, so they cost a few percent more. 

Another common method to increase the open feeling is to use flat ceiling trusses on taller walls. In this instance the trusses will be more economical, but the wall framing will cost a little more. Either way, it’s an investment in comfort.

Attic Space

Depending on the span and slope of your roof trusses, there is a potential for a lot of empty space! You don’t have to let that space go unused, and it’s a lot easier to make the most of it if you plan ahead with some room-in-attic style trusses. 

Room-in-attic trusses tend to cost 2-3x as much as common trusses for the same size, but the additional usable square footage you gain will be much less expensive than adding a second or third story that is conventionally framed. 

If you would like to use the space but don’t plan to finish it for living in, storage trusses are a good option. They are built with the webs spread out so that you can stack some boxes or other light-weight items in the attic, and their cost tends to be about one and a half times common trusses of the same size.

If you want or need to get more insulation value in your attic, a common solution is the raised heel truss. In this case, the top chord of the truss is held up from the wall so that full depth insulation can be spread to the outside of the attic. Raising the top chord of the truss means more pieces and more fabrication complexity, so it may drive the cost of the truss package up 10% or more.

Another option to achieve this depth of insulation and provide backing for an enclosed soffit is to cantilever the truss overhang. The cost of the cantilevered overhang will be similar to the raised heel method.

If you really want a modern look and want to enjoy the outdoors while still at home, a great option is a low-sloping flat roof that you can use as a deck over your living space below. This is increasingly popular as building lots become more compact, and to get a decent amount of indoor living space there isn’t as much available space for a yard. Since the flat roof trusses will be shallow and have the need to support a higher live load than a typical sloped roof, they will tend to cost 15- 20% more than the typical sloped roof trusses. Like the attic trusses, they are an investment in usable space that would otherwise be lost.

Steepness of Pitch

If you are building with a sloping roof, the steepness of the pitch will affect the cost of the package. A common middle ground is somewhere around a 4/12 to a 6/12 slope. Going either shallower or steeper can increase the price. 

In the case of a shallow roof, the lumber grades and connector plates sizes may need to be increased to meet deflection standards. On the other hand, building with a steep slope may cause additional expense in transportation due to oversize loads.

Any of the styles of roofs described above can be built with standard, raised or cantilevered heels. The standard heel, where the top chord of the truss rests directly on the bottom chord at the outside of the building, is almost always the most economical option. There are the least pieces, and for whatever slope you choose, the standard heel will result in the shortest overall height of the truss. 

Outside Forces

There are a couple of considerations that are outside of our control. In the coastal lowlands of the west, snow depth is low, so the standard load is low – it's often the lowest allowable load per code. 

If you travel up into the hills or mountains and gain some elevation, that potential snow depth becomes greater, and the design load increases along with that depth. The increased load means that the lumber and connector plates in the trusses need to be increased in size and grade to carry that extra weight. 

Bigger lumber and plates will equate to more expensive trusses. This can vary greatly, from as little as a few extra percent to more than doubling the cost of the roof truss package. This is not an area to cut costs, though. The load is what it is, and the safety of your family is worth what it costs to construct a truss package sturdy enough to withstand whatever mother nature will send its way. 

The other load factor that needs to be dealt with is the wind in the local region. Unlike the snow load, wind loading doesn’t typically make a significant difference in the cost of the trusses, but it may impact the cost of the bracing design, materials and installation.

Conclusion

There are a lot of factors that affect the price of the roof truss package. Some of these factors are within our control, others are not. Sometimes spending a little more on the roof trusses is more economical than other ways of accomplishing the similar living space, and other times investing a little more in a vaulted ceiling or raised heels will improve the overall comfort of the structure. 

In the end, a safe budget for roof trusses tends to be about 5-10% of the budget for the building, not including land and permits. For a detailed, accurate price, your roof truss supplier will analyze your building plans, discuss the options with you, and take into consideration your wants, needs and the conditions of the site where you are building.

Thanks for reading this article and please feel free to reach out to your truss supplier with any questions – we love to help!