I have read many posts reference my question and I am still a little foggy. I have already built a 24 foot by 34 foot ICF basement. The 34 foot side will be a walkout basement. On top of that, I am ready to deck and would like to cantilever four feet over the front of the building (the walkout side). The joists will run along the 24 foot axis and will be 28 feet long to make up the cantilever. I seem to be getting conflicting reports from the manufacturer. On top of this first floor deck, and, on top of the cantilever, I will be putting up SIP walls, an attic deck, and a SIP roof, the peak running the same direction the first floor joists run.
The joists that have been specified for the first floor cantilevered deck are Ilevel 360, 16 inch, 12″ on center, 28 foot joists. I have gone over their installation guide numerous times and still do not completely understand the blocking necessary, especially having to do with the cantilever.
Is this really doable and is there any other resource that I can go to online to see a chart about cantilevering TJI joists and can you build on top of it?
I am building this house largely by myself in Alabama, no inspections are required, but, I want it done right.
Thank you very much if you have anything to add.
Bill
Replies
I believe it is probably doable ------ but, I would contact the manufacturer directly. Ilevel?
As a general rule the manufacturer's are quite helpful with information. I asked a similar question of Louisiana Pacific -- manufacturer of LPI's.
They sent me a written reply to my specific questions and a copy of their "Design Manual" which contains w-a-y more information than the installation guide packed with the I joists.
Incidently, when talking to them - don't call them TJI's -- that is their competition's product.
Jim
Never underestimate the value of a sharp pencil or good light.
I seriously doubt that 16" I-joists would cantilever 4' and carry the loads you described without some sort of reinforcement. And standard load charts for the I-joists aren't gonna go that far.
The only way I can see that you can get a definitive answer is from the engineering department of the manufacturer. If they're giving you conflicting reports, keep on their butts until they give you a definite answer.
What Boss said. FKA Blue (eyeddevil)
On a cantaleiver I did a few years back they wanted an LVL so often in the layout instead of a joist, corners and every 6 ft after that.
Then the plans called for 3/4" plywood nailed to both sides of each joist. Starting from the rim joist and back over the cantaleiver 8'.
You might be able to do it if you have it engineered for it.
Matt- Woods favorite carpenter.
48" isn't common but can be done. Ilevel or their subsidiaries engineering department should be able to come up with a design for this. You may end up using microlams or a combination microlam/I joist for this. The back span is what is critical here, as the amount of weight from the cant. will want to "pick up" the floor at the endspan of the joists (on interior/inside). These should be tied down at bearing (probably at least 10' back of your walkout wall over bearing). Also, consider moisture content on the outside spans, you may need a treated material which will affect what is used here).
Thanks all for your quick responses. I am on my way to the supplier now and I believe in the interest of conservatism, I will pull the cantilever back to two feet if he can't give me a definitive answer.
Again, I appreciate all the help.
Bill
Bill,If you really want the 4' cantilever, you can ask about using 3-1/2" x 16" or 5-1/4" x 16" microlams for that section.Joe Carola
Edited 11/2/2007 9:28 am ET by Framer
Thanks Joe,
I think I will have plenty of room with the two feet, I was being greedy:) It is a lake house after all and we will only be sleeping in this part anyway. Thanks again for the help.
Bill
Have you read and understood the tech info available from I-Level as downloads from their site?
Cantilevered spans, loadings, and details are presented there.
I am surprised you would ask here, in a forum of mostly words, spoken by strangers with unknown qualifications.
You need drawings, tables, charts, and specs. All are available from I-Level.
Gene stop it.You prefer charts, I prefer seat of the pants engineering. Of course, I've been involved in some serious fixes of engineering that was scientifically done and screwed up royal.
FKA Blue (eyeddevil)
I don't find them the easiest to understand, and yes, I have downloaded and studied them all. But hey, I'm only an airline pilot:) I'm going with the 2 foot cant. and hoping for the best. Well, with my architects blessing.
Bill