Safety During Demolition, Construction

brainditch wrote:

Rivernile- I didn't quite get around to trying to answer your question. What size lumber are your joists? Are they oriented so that they are running across the 13' direction (I would hope they are, otherwise they'd have to be very large to span the 17' without deflection). When you are in your studio, can you visibly see movement in your celing when someone walks on the floor above? Is there any visible signs of sagging? Did you have to move or remove any walls prior to dong your build? I'll go check some more pictures of your build that you put into the Firestop thread to try and see if there is anything I can learn from them. Brainditch

My first floor is supported by the regular truss system as you explain with the metal plates at sertain points holing the pieces of 2X4's togather. Now i know these are made to deflect under presure so my inner ceiling is a few inches below the bottom chord of the truss. In between the top chord is where i installed two layers of 5/8'' with green glue and caulk.no aditional gyp board to the bottom of the truss just my new independent ceiling. No i cannot see anything move its just wenthe family is in the kitchen and moving around you kinda feel the slight deflection not a big amount just something to remind me that the floors do deflect.other than the island in the middle of the kitchen(with fridge) and some leather sofa in family room i dont have alot of additional weight except the family which is 4 of us at about 170lb each.The trusses run accros the 13'' and rest on the outside walls and no i did not move any walls. It just remind me everytime and i guest i am still concerned because i did not hire i engineer. Thanks for the compliments on the room. Its almost finished i will post some better pics soon.

"They are most often found in attic spaces, holding the roof up." They are in all aspects of the build, floor and ceiling, roof included. In a basement footprint, the trusses would be spanning the basement.

Sorry for the confusion Rivernile and xSpace, I guess I'm used to the Pacific Northwest construction lingo, which is I guess closer to the architectural definition - such as: truss, in architecture and engineering, a supporting structure or framework composed of beams, girders, or rods commonly of steel or wood lying in a single plane. A truss usually takes the form of a triangle or combination of triangles, since this design ensures the greatest rigidity. Trusses are used for large spans and heavy loads, especially in bridges and roofs. Their open construction is lighter than, yet just as strong as, a beam with a solid web between upper and lower lines. The members are known as tie-beams, posts, rafters, and struts; the distance over which the truss extends is called the span. The upper and lower lines or beams are connected by web members. The Columbia Electronic Encyclopedia® Copyright © 2007, Whereas I think you folks may refer to any horizontal member without full length support from underneath (such as a joist) as a truss. It's cool, just as a "rose by any other name...." By the way Rivernile thanks for your last post, I didn't realize that you had built a full "room within a room" with a seperate ceiling. That takes some worry out of your situation, cause your house joists (or truss, as you folks call it) weren't having to take the full load of (nearly) 10 PSF of 5/8" sheetrock. You're probably OK with the 5 PSF of sheetrock that you used for beefing up the original decking/floor underside, just keep an ear open for any extra creaking sounds, especially if the upstairs kitchen flooring already feels a little "spongy". Brainditch

Sorry guys, I've been working on too many older houses recently. Yes, they have had Floor Truss systems for quite a few years now, and it's becoming more and more common in newer construction, rather than relying on the older solid 2 X 12 joist and beam system. So yeah, Rivernile you probably do have true trusses underneath your kitchen. This might explain a little bit more of my confusion. Unless I'm mistaken (which wouldn't be the first time) no matter which system your house is built with it still follows the L/360, L/240 system for allowable flex, as that's been a part of the building codes for a while. So if you get worried about it Rivernile, one way to check it might be to measure the length of the span for those trusses (in inches) and divide that by 360 (let's say). If the sag in the truss is getting close to the number (in inches or fractions of an inch) that you came up with, you might want to take a deeper look, otherwise--enjoy your beatiful build, man! Brainditch