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
I think my head just exploded trying to picture that setup...
The garage door will be under the deck?
Justin Fink - FHB Editorial
ROFL!
Here is a quick 3d drawing of it.
In Ontario, Canada, with 1&2 grade SPF lumber, and a joist span of =< 8'-0", this beam can have an open span of 13'-0".
I have 0 idea what you are trying to say however. Are you spanning the garage opening? In this case your talking about a header/lintle not a beam per se. If this is an internal structural member maybe consider an engineered lumber product or structural steel beam.
If you are cantilevering, are these the same joists as your internal floor joists? Are they all spanning in the same direction or are they headed? If they're headed, how far back are you going? Cantelivers are an engineered option that require serious design considerations for both evelope conditions and load transfer. Take your time to examining all your options.
Good luck, Glen in Canada
Might be wrong here ...
Sounds like he has a split-level house, or on a slight incline so the garage & drive are below the first floor level. So he wants to build a deck out from the kitchen and over part of the driveway, right in front of the garage door.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Just re-read your question, I think I get it now...
So, you're going to have posts @8' out from your house, in the driveway? O.k., but for the love of liability insurance premiums don't load up the deck and have cars going in and out, or a disaster is waiting to happen! Not a great design.
Glen in Canada
LOL, you should see the deck as is! It is horrid! I am posting a photo of the house, hope this helps.
The beam is for the deck in front of the two garage doors, I will be using 6x6 posts and the posts will be sunk into the concrete footings.
The garage doors are 8' wide so I really need the 12' span, 2' on either side. The wife wouldn't feel comfortable with less. As it is it is wider then 12' now.
The plan is to put 2 6x6 posts in between the two garage doors about 2' on center apart from each other, that would then mean that the other posts would be 12' on center from there and would be centered on the garage doors.
Hope that helps.
Edited 4/25/2006 2:36 pm ET by DarrellN
Still not crazy about the design but I can see why it would be a nice deck with that exposure.
Do not sink the posts into the concrete, this is prone to rotting quickly. Instead dig pier footings down below the frostline, make sure it has an adfreeze barrier (often a plastic slip cover), then run it 8" above grade and attach the post from there. I would hate to see you set yourself up for years of frustration just to avoid a days hard labour.
Good luck, Glen in Canada
Actually, you described exactly what I want to have done, however their are two reasons not to.
Reason 1 - If the posts are sunk into the concrete and then the posts are hit by a car, at low speed <g>, the likelyhood of the post breaking is very low.
Reason 2 - (the more important of the 2) For some reason I don't understand, the building inspector likes it better that way <shrugs>.
By the way, the deck looks over the Mississppi river, nice view. Also, I am open to other deck designs if anyone has an idea.
Basically the strength of the post surviving a "hit" will be limited by the weakest connection. I suspect you are looking to either sadle and bolt the post to the beam or ledge and bolt the post to the beam. If your connection point at the base is equally strong... all is equal. Also, if the post begins to rot in the concrete, this WILL be the weak point, and I assure you it will be far weaker than a double 1/2" galv. carriage bolt connection!
As for the building inspector...a daily hazard of the job for a builder. My solution is know the code, know the reason for the code, and prove your deviation addresses the reason behind the code. A good working relationship combined with sound building sciencce knowledge is the secret to using non standard building practices. I personally wouldn't budge on this one. Too much time and money at risk. This is a structural concern, as such, priority one to do right.
Good Luck, Glen in Canada
In our area, your method of construction is not allowed, but proper post base supports are. They are just as strong and more able to survive a hit than just wood in the concrete. I am pretty sure there is some miscommunication either in the whole concept or the bases the inspector thinks you want to use. Go to Simpson.com and check out their catalog. You can download the specs and show to your inspector.Posts set in concrete weaken rapidly and then are much tougher to remove and replace, should they ever be damaged.You may have to install concrete filled barriers around the pipes as they are in a very vulnerable location.
Great information! I am checking it out now.
Still, any idea where I can find info on the beam span of a triple 2x10? Glen in Canada said that it would span 13' with a joist length of no more then 8'. But does that pertain to me?
My joists are going to be 10' long but hit the beam at 8' for a 2' cantilever and my span is 12'.
Does it sound like I should be going to 2x8 joists or 2x12 beams or a combination? I don't want this to be minimum code, I want the deck to feel solid with very little bounce but head clearence is also an issue, underneath the deck.
However, head room is secondary to a solid deck.
There are beam span tables published for the various types of wood. Just do a google search and make sure they are talking about the wood you are using. Basically you are doing an 8 foot span and then a 2 foot cantalever. The way the joists attach back at the garage will be a big consideration.I would suggest having it enginneered as there is a lot of liability here.
I have found all kinds of tables but nothing that really covers triple 2x's, that's why I came looking for help =).
I thought that a ledger board on the house that was carriage bolted or lagged appropriately would be fine, then use joist hangers, is that right?
1)
I would use as deep a joist as I could so the cantilevered part of the deck doesn't feel 'spongy'. Looks like folks would congregate there.2)
Perhaps you could kill 2 birds with one stone and have the concrete piers come up a good 1 1/2' -2' above ground. This eliminates the posts rotting in the ground, and some rebar in the piers will take an errant bumper hit better than any old 6x6.3)
If the link works there's a beam chart for decks at the web site below
http://www.barronslumber.com/deck/hdeckguide.htmLet's not confuse the issue with facts!
In Ontario Canada the max. span would be 11'-7" for the 10'-0 joist. As for the 2x6 vs. 2x8. 10' is a big clear span, too big for 2x6's. They would not fail (likely) on a 12" o.c., but deflection would be an issue, especially if you were to load up the deck. 2x8's would be my min. recommendation. Typically deeper is cheaper, so going 2x10 @ 16" o.c. will actually give you more rigidity for less cost. As the joists are now too deep you could notch each one at the beam, then ledger on either side of the beam to take load at the edges of the notched joists. This will effectively provide you with all the strength f a 2x10, while reducing its effective height. The risk is that the building inspector will be uncomfortable with this arrangement, but if the ledger was a 2x6, and properly nailed to the beam, ( I would also tie with 1/2" through carriage bolts) it would effectively be a structural portion of the beam (increasing its clear span rating to meet your 12' requirement), which would now be a five ply lam consisting of 2 2x6 ledgers on either side of a tri- ply 2x10 beam. The joist remainder passing over the beam would be 6 1/2", below code here, but mitigated by the full 2x10 joist portion resting on the 2x6 ledgers. As for the cantilever portion, consider doing a double rim joist to address possible deflection, but this is overkill.
If you were to skip the cantilever, and just move your beam out 12' from the house, head your joists to the beam with joist hangers, you would solve all your height problems.
Good luck, Glen in Canada
I definately don't want it to feel spongy, that would be bad.
The concrete piers aren't a bad idea but wouldn't I need to cover them so they wouldn't deteriorate from freeze thaw cycle?
I avoid making concete piers any higher than needed. Even with rebar, concrete isn't great in tension, so why ask it to do more than it should. Also, I'd rather damage my car by hitting a wooden post then hit a concrete pier. It would also be easier to replace/repair the wooden post then the concrete pier.
If you are attaching the rim joist to the house you must be sure to have a sound outbound pier footing. You do not want the deck moving up and down while the rim joist remains fixed. This will stress all of your fasteners, making them prone to failure. It is best to let any deck float away from the house by having it build independently of the house on its own footings...but this isn't so good for your situation, thus making the piers structurally sound that much more important.
Glen from Canada
Just re-read one of my posts. It should read that the 3 ply 2x10 BEAM has a max. span of 11'-7" with 10'-0" clear span joists. I said joist instead of beam by mistake. The 2x10 joist span is 12'-7" @ 16"o.c. This is for 1&2 graded SPF lumber (spruce, pine, fir) PT in the same species would rate the same. 1&2's are the common building grade, I'm sure this info will translate to US standards. Generally, Ontario building standards exceed other countries (including U.S.), and are set to comfort, they far surpase potential failure points.
Glen in Canada
Umm, Glen, one minor possible correction, the joists are a total of 10' long, 8' to the beam and a 2' canitlever.
If I misunderstood you then no problem. Thanks a ton for ALL of the input, it is very helpful to me.
Even better. The span on the 2x10 tri-ply beam is now within spec, and you can move to 2x6's. Their span is 8'-10" @ 16 o.c.. The cantilever part doesn't factor in as it passes over the beam thus loading differently. I would now either notch 2x8's down to 6 1/2 " over the beam to gain height or use the beam as a rim joist with hangers, therefore move it out to 10' and skip the cantilever altogether. In Ontario 2' is the max allowed to cantilever joists over a beam without re-engineering the design, as such it is basically ignored in terms of load impact. Doubling up a few joist will also limit deflection, also be sure to put in blocking along the centre of the clear span of the joists, this will force all the joists to work together to bear load thus reducing deflection from a point load.
Glen in Canada
What about using 2x6 12oc for the joists? I want to us 12" on center for a couple reasons. I want to use Eb-Ty fasteners 24" on center and using 12" centers I can do that and stagger the fasteners if that works better.
Also, 12" centers will be stiffer then 16" centers. I am planning on blocking the 2x6's.
For decorative reasons I was planning on putting an additional 2x around the perimeter if the deck, this sounds like it will add to the structure from what you are saying, cool!
Does that sound like it will be ok?
Also, I talked to Simpson Strong-Tie and they said for the base of the posts near the garage I should use CBSQ66-SDS2 HDG $27.75 each and for the rest of the post bases should be ABA66Z for $17.29. For the post caps I can use LPC6Z at $3.71 each. I gave the retail prices btw.
12" o.c. is fine, my rating is 9'-6" for 2x6's @ 12"o.c.
Sounds like your good to go structure wise, now your down to the piers, you know my thoughts on that already!
Enjoy that view and have a beer for me when your done!
Glen in Canada
Here is what I have come up with based on everyone's help. Let me know if I messed something up =).
Looks good. What about doubling the posts on either side of the garage for extra security if one gets bumped...certainly more work, but could save a life, not to metion the deck.
Have fun with it, Glen from CanadaCustom build, heritage restoration, heritage millwork.
'Nemo me impune lacesset'No one will provoke me with impunity