Hey folks! I need some advice on whether it's a good idea to modify the trusses in my detached garage/shed, which was built back in the 1930s. The structure is framed with 2x4 lumber and the trusses span about 18 feet. Here's what I have:
- The bottom chord is a single 2x4 that's almost 18 feet long, spanning the building's width.
- The top chords are also 2x4s meeting at a ridge tied into a 1x6 ridge board.
- There's a king post made from 1x6 wood.
- Two web members also made of 1x6, forming a basic triangular shape.
The bottom chord doesn't sit directly on the top plate; it's fastened to the top chords with just two nails on each side. I'm thinking about raising the bottom chord to create more headroom in my garage/shed, but I'm worried that it keeps the walls from bowing out. Thoughts?
2 Answers
Raising the ceiling is doable, but definitely don't just wing it without consulting an engineer. Moving those rafter ties can mess with the forces on your walls and roof, leading to potential collapses. Make sure to get professional advice to ensure everything stays safe.
It sounds like you might have a stick-built roof and ceiling rather than trusses. The way you refer to bottom and top chords is usually for pre-engineered trusses, which weren't common in the 1930s. You can change the framing, but I'd recommend getting a structural engineer involved. They can help design the changes and make sure everything remains stable under load, especially if you have workers on the roof later. The engineer may suggest adding support up to the ridge beam for best results.
Thanks for the insight! I'll definitely consider getting an engineer to help with this.