I am in the process of designing our retirement home. I want a finished ceiling height of 8 ft in the basement without any bulkheads. To allow room to run the mechanicals I'am trying to decided which construction method is most cost effective; 10 foot basement walls with floor joist above or 8 foot basement walls with floor trusses above. Any thoughts or experiences on either method would be greatly appreciated.
Floor trusses usually come out cheaper than solid joists - in part due to cost of material and but more-so in easier and faster installation. Add in another 2' of basement(all around the basement perimeter and any interior support walls) and it's a no-brainer, go with the trusses. Trusses can also be designed to span a greater area without deflection.
Even beyond that, with the trusses you have an even plane to install a ceiling if you want to. Joists with mechanicals suspended underneath will require extra framing to box them in or make a ceiling.
What is the typical center to center spacing when using floor truss?
It depends on the span. Wherever you get your trusses from will do the engineering work on their truss computer and will recommend proper spacing for the span and size truss you have.
Shorter trusses (height) will have to be spaced closer together than taller trusses. Most common spacing for engineered trusses is 19-3/16" OC. This makes for 5 trusses per 8' run. With a typical 3-1/2" wide top cord of the truss this will leave a true 16" space to span with subfloor.
Next most common spacing is 16" OC (6 trusses per 8' run) or even 12" OC (8 trusses per 8' run). Although you hardly ever see 12" OC as it is more common to go up in truss height instead of adding so many trusses so close together.
Thanks for your help. I am a retired electrical engineer (transmission & distribution) so this is out of my field. I will install 1 1/8" Warmboard as a sub-floor for hydronic heating, so I'am sure this will also have a determining factor on the spacing. Sounds like I need to contact a truss manufacture before I finalize my plans.This message has been edited. Last edited by: MoHawk,
You're welcome. I'm a working General Contractor so this is my area.
Take as much information as you have when you go to the truss shop. A part of the truss buying service is the free use of their engineering capabilities. Bring in any plans that you have and let them know any other information like the heated floors. They can factor all that info in to their truss design to get you what you need. All without hiring a separate engineering service to do the same for hundreds or thousands of dollars.
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