Note that not all rebar caps protect against impalement. Make sure they're OSHA approved.
--Keith
Last edited by sharward on Thu Jul 12, 2007 7:00 am, edited 1 time in total.
"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006
The 10 foot model is at Lowe's (not yet on their Web site though... ) for about $240 and worth every last penny. It's extremely well made and rated at 250 pounds!!
I HIGHLY recommend this product! They make an 8 foot model too... And they're fully adjustable for various heights up to 10' 3" (ceiling to floor).
--Keith
"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006
I every dwelling I have ever lived in, the attic access door had no built-in ladder for access. What makes this product so cool is that it works for small openings (as small as 22½" x 22½") and its telescoping design requires very little space to expand.
--Keith
"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006
Ro wrote:hmm, is that like a "standard" product use for attics anyway? Here in the Netherlands it's quite common to 'ave such. Oh well, better save than sorry.
Typically, in New England anyway, the attic either has a larger opening (about 2' x 4') with a 3-section fold-down staircase, or a smaller opening with no built-in ladder at all. This product is cool in the way it addresses the smaller-opening situation.
sharward wrote:Be sure not to overload your joists. Adding just one layer of gypsum to your ceiling could transform an otherwise safe ceiling to one that can kill.
This span calculator (courtesy the American Wood Council) is helpful in determining the maximum span of a joist under a variety of weight parameters.
For more information about loads and span tables, see Understanding Loads and Using Span Tables by Paul Fisette, as it appears on the American Wood Council Web site.
When in doubt, consult a professional structural engineer.
Ditto, and especially if your ceiling/roof system includes trusses! The danger here is that it far more difficult to determine the load capacity of a truss system than consulting a Load Span Table! If you see an open span (no columns or support walls) in a room of more than 12 feet in width or height, verify what is supporting the ceiling before adding more drywall. If a 1 pound hammer falling off the top of a ladder can kill you, think about what that several hundred pounds of 5/8" drywall you are about to hang, not to mention the several thousand pounds of an entire roof truss system could do to you. When truss systems do fail, they can fail spectacularly.
Brainditch
I too have joist system for my kitchen and family room floors and the span accross is 13' to 14' in some areas.
I haded 2 layers of 5/8'' drywall between the joist from the basement and then i build my room within a room with tottally new ceiling.
I spoke to someone at one of the truss company and the said 2 layers would be ok but i did not hire a engineer.
Now from time to time when me and my family are in the kichen and i feel the slight deflection of the floor my mind always go on that.
I know its late ask now but from what i explain do you guys think i should worry?
Hey Rivernile,
Just to be clear, a ceiling that uses joists above it is different than a ceiling that has a truss system above it. Joist systems are supported underneath by beams, load bearing walls, and posts or columns. Their strength can sometimes be enhanced by adding these same elements in the middle of their spans, or in some cases by "sistering" same sized joists together. Joist systems are usually found in multi-storied houses, and is usually a situation where the ceiling of the lower floor and the floor of the upper floor are carried by the same set of boards (oriented with their thinner edges up) called joists.
A wooden truss system is usually made up of narrower boards made into the shape of a large triangle made up of smaller triangles, and is usually held together by flat metal plates with "teeth" punched into them. They are most often found in attic spaces, holding the roof up. As an assembly, trusses are very strong for their weight (in certain planes of force), but cannot be made stronger by adding support arbitrarily underneath them. The should never be cut into or otherwise modified without specific engineering approval, because a failure or weakening of one of the boards that make them up could cause a complete failure of the entire truss, and it and everything above it could come crashing down.
Adding ceiling mass without considering the load bearing capacity of the supporting structure should never be done. In many cases with joist systems, there is reserve load bearing capacity built into the system, and a competent builder can assess if that capacity is close to being exceded by consulting Load Span Tables and adding up the weights that are already being supported. Sometimes an engineer would need to be consulted (never a bad idea, just more expensive).
But with truss systems, it is are inherently difficult to calculate the load bearing capacities for them, and should usually involve consulting with an engineer. The part of a truss (the horizontal board) that you would support a normal ceiling with is called a Bottom Chord, and they are very often the weakest part of the truss. Seldom are they designed for more than the expected load of a single layer of 1/2" or 5/8" drywall. Keep in mind that two layers of 5/8" drywall adds up to about 5 pounds per square foot (PSF) of load, and many roof trusses made of 2"X4" members spec the Bottom Chord at 10 lbs. P.S.F. maximum!
All this is not meant to scare you off, just find out what is supporting your ceiling, please!
P.S. - Man that's a very cool build you've got going there for River Nile Productions, and the Router-cut logo into your bass trap fronts is frickin' awesome!
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
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.
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.
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".
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!
)
) for about $240 and worth every last penny. It's extremely well made and rated at 250 pounds!! 