Roof trusses are the literal backbone of your roofing system, and replacing one can get costly. Use this roof truss cost guide to set your budget properly.
Roof Truss Calculator: How Many Trusses Do I Need?
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A roof truss calculator helps you determine how many trusses your roof needs based on your roof's length and standard 24-inch on-center spacing.
Expect to pay $13,000 to $22,200 for professional roof framing, while building your own trusses can save $70 to $560 per truss in materials.
You can calculate the number of trusses by multiplying your roof's length in feet by 12, dividing by 24, and adding one extra truss.
Hiring a local home building professional keeps measurements accurate and installation safe, especially when working at tall heights and following local building codes.
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If you’re building or remodeling a truss-supported roof, one of the many things you’ll have to consider is how many trusses you need. Thankfully, there’s an easy way to calculate this—as long as you know the length of your roof and the amount of spacing between trusses. Here’s how to figure it out.
How Many Trusses Do I Need for My Roof?
In residential construction, there’s usually 24 inches of on-center spacing between roof trusses. Using that as a guideline, here’s how many trusses you would need for your home, depending on the length of your roof:
| Roof Feet in Length | Number of Trusses Needed |
|---|---|
| 20 | 11 |
| 30 | 16 |
| 40 | 21 |
| 50 | 26 |
| 60 | 31 |
| 70 | 36 |
| 80 | 41 |
How to Calculate the Right Number of Roof Trusses
If you’re replacing trusses in an existing home, you can determine how many new ones you need simply by counting the old ones. However, if you’re building a new house, you can use a formula to figure out how many trusses you need.
Assuming you leave the standard 24 inches of space between trusses, your roof’s length is the only measurement you need to calculate the right number of trusses for your home. When you have that, you can plug it into this formula:
Number of Trusses = [Roof Length (in feet) x 12] / 24 + 1
For example, if your roof is 40 feet long, you’d need 21 trusses. Adding the extra truss at the end ensures you’ll have one truss at the front of your roof, then another truss for every 24 inches of roof length, and one more truss at the back of your roof.
How to Measure Your Roof for Trusses
Measuring your roof for trusses isn’t something you should do alone. Instead, you’ll need to work with a home builder near you or pay for the cost to hire a structural engineer to find your roof’s measurements, calculate the right number of trusses, and pull the necessary building permits. During that process, these professionals will provide all the guidance you need for measuring and installing trusses.
Who to Hire to Install Roof Trusses
Photo: RyanJLane / E+ / Getty Images
If you have carpentry experience, you could build your own roof trusses instead of ordering them from a truss manufacturer. By doing so, you could save $70 to $560 per truss in material costs (not including labor), depending on the truss size.
However, when it comes to installing trusses, it’s far safer and easier to hire a professional. This is a job that requires you to follow local building codes, pull permits, work at tall heights, and lift heavy objects.
Plus, trusses are a vital part of your home’s framework—and if you make a mistake during installation, it could affect the structural integrity of your house. On average, hiring a pro to frame a roof costs $13,000 to $22,200.
Frequently Asked Questions
Roofing services reviews from real Angi homeowners in Columbus, OH
4.3★ avg. • 120 total reviews
- Chance R.
D1 Roofing delivers outstanding service from beginning to end, backed by a strong warranty and expert teams. I highly recommend them for their excellence in meeting and surpassing expectations with unmatched communication. Choosing D1 Roofing was flawless decision
Division 1 Roofing LLC - Jeremy P.
This place took $25,000 for a flat roof job with a five-year warranty and never returned to fix the leaks that were caused by their work. These people are not professionals and should not be doing this type of work. They incorrectly changed the pitch of the roof, and caused more damage than...
- David B.
The technician was very professional and friendly. He answered all my questions and was very thorough. He left the fireplace area very clean . He inspected from the roof and advised me as to other work that might need to be done. There was no pressure there. I was very satisfied with the...
Supreme brick & chimney - Kevin S.
I am really impressed with their timeliness and turnaround. Mitchell came out, and we decided to move forward with their pricing. Our roof was on within a week, and we could not be happier with their team! Amazing company, great prices and honest, dependable craftsmanship. I highly recommend...
Window Depot USA of Central Ohio - Rob B.
Manuel Calvillo is the best option in the area for roofing and you won't be disappointed.
- Julie K.
They damaged multiple items on my property, including a marble slab used as a table top, tried to hide it, and refused to pay or replace. Arrived day one without a ladder to access roof & delayed a day. Left a mess in back yard; didn't wear face masks; no show by owner to property to see damages
Grants Tree Service - Marcia L.
I've hired Gary/Cherokee Roofing for two different homes, work quality, responsiveness, and completion have been great both times. And the prices quoted were very competitive. I would definitely hire again.
- Paul F.
Lyle did a great job removing asbestos shingles from our front porch roof. They worked together with our roofer to make sure that the new roof was able to be installed on the same day that Lyle removed the asbestos shingles.
Lyle Environmental - Paul F.
Bradley Builders did a good job replacing the roof on our front porch. They color-matched the existing shingles on the rest of the house and installed a metal ridge roll since we live in a historical neighborhood. They did the job while we were out of town. When we got back, everything was...
Bradley Builders, Inc. - Madison B.
I would absolutely recommend this business. They offer a variety of services, including: painting, roofing, and refinishing wood flooring. I hired them to refinish the original hardwood flooring in my home built in 1874. The job was quite challenging, as the floors were extremely aged and...
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