I am guessing that this isn’t really the right forum for this but I was hoping you all might be able to help me get pointed in the right direction.
I need to know what the beam span for a triple 2×10 is. I have to span a garage door so I need to go 12′ but I have head clearence plroblems as well.
My garage is in the basement of the house and the deck is also on the front of the house 8′ up from the ground. I am cantilevering the deck by 2′ so if I were to use 2×12 beams and 2×8 joists I would end up with 76″ or 6’4″ of head room. If I can get by with a triple 2×10 beam, 12′ long, with 2×6 joists 12″ on center 10′ long (2′ cantilever, 8′ from the house to the beam) that would save me 4″. Granted not a lot but it would feel like a lot I would think.
Any help in pointing me to the right area would be greatly appreciated, Thanks.
Replies
Probably best to post this in the fine homebuilding board for answers. The breaktime discussion posts at http://forums.taunton.com/tp-breaktime/
Thanks for the heads up gb93433, I posted this question over there as well.
I had this problem some years back. Are you thinking along the lines of a beam on top of two posts and then placing the joists on top of this beam?
You can gain alot of head room by placing your beams on the sides and running the joists between them.
Correct USAnigel, however I do have the wife to contend with hehe. She wants the decking to run parallel to the front of the house and that dictates that the joists sit on the beam.
If I got rid of the cantilever I wouldn't need to worry about head room, but it just would not look right at all.
Edited 4/25/2006 12:15 pm ET by DarrellN
You can use Joist Hangers so that the joists don't have to sit on the beam, but are suspended at the side. They are available in a heavy galvanized form designed for exterior use and contact with the new pressure treated lumber, which is more corrosive than the old. If you are concerned about visibility from the underside, then they could be painted before installation.
How would that work with a cantilever Steve?
Duh. I was thinking about that backwards.
Edited 4/25/2006 2:08 pm ET by SteveSchoene
I would suggest running the decking at 45 degrees, looks great and tightens up the deck bigtime. As a side note around here most townships min joist size is 2x8.
You could also run a beam around the outside of the deck and the run the joists in what ever direction you need.
Here is the plan I have come up with, let me know what you think.
Your plan looks ok but I would use 2x8 in place of the 2x6. And as headroom from the garage is a concern move the beam to the end of the deck and run the joists from the back of it. also add in a couple of cross braces at 45 degrees to keep it all stiff.
By my books, you can use 2x6's on 16 inch centers for the joists and span the 8' dimension comfortably. Going to 12" centers would make a very stiff deck. Putting them on 24" centers would make the deck too springy. The extra 2' cantilevered out past the beam won't affect anything for joist sizing.
For the beam, my charts show that a triple 2x10 will be adequate for a live load of 50 pounds per square foot which you could only achieve by having something like 60 people on the deck all at once.
An alternative would be to use a properly sized steel beam instead of wood, this would gain you another couple of inches of head room.
In choosing the wood for the beams and joists, go through the lumber piles and choose the boards with the straightest grain and smallest knots, it will make the deck stiffer.
Another possibility to consider would be to raise the deck a foot or two and have a couple of steps up to the main part once you stepped outdoors.
John White, Shop Manager, Fine Woodworking Magazine
WOOHOO! John you are awesome, that answers my question. I have the Taunton press book on building decks and didn't see that in there.
The biggest reason I want the 12" centers is a stiff deck and I want to use the Eb-Ty fasteners ever 24", and I will stagger them every other joist. It saves me money!
If you have a link to your book I would be happy to purchase it, especially if it has documentation on those numbers.
My reference was a construction manual that is out of print. I think you could find joist and beam sizing information with an internet search but you might need some engineering background to make sense of the terminology and understand the variables involved
John W..
By the way, these two pictures might help explain things.
I don't think raising the deck would help me unfortunately =(, I am sure I would get a wife veto on that. I already offered to raise the height of the deck over just the garage and it was a no go.
go to your local lumber yard and have them figure you out a gluelam at that length you need as much strength as you can get for your cantilever and a gluelam can hold two to three times as much as a 2x12 with a much smaller depth you may gain more than enough in height by adding a little in width I've used them as ridge beams in cathedral cielings in great rooms and you'd be surprised at what they can hold if engendered correctly, most lumber yards have a program with a specific formula just for that porous .
I was wondering if the triple 2x10 should be glued and carriage bolted together or if nails or screws would be enough. Can Lowes or Home Depot make or get these? If this isn't what you're talking about can you explain it further for me? Thanks
This forum post is now archived. Commenting has been disabled