Hi all-
I have a bouncy deck that I want to beef up a bit. I know the best way to do this would be to place a beam at midspan. However, this is proving to be a rough way to go. Looking for alternatives.
here is the situation:
The section of deck in question is roughly 16′-0 deep. Joists are 2×10 spaceed 16″ o.c. One end (actually two sides) are ledgered to the house. The other end has typical double band joist over 4×4 posts over concrete piers. The 2×10 are free spanned to the outer posts. From my memory, seems that the span is questionably within allowable distance. However, there is still a bit of bounce to the deck.
What would you guys do? Find a way to beef up joists from below, or place beam at midspan?
Thanks for your help
Replies
You're right at L/360 deflection. Not sure why you say it's rough to install a mid-span beam, but that would be the way to go.
"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
You are not satying what the layout is for the 4x4 posts. How far apart are they? with only a doubled 2x10 for a beam, they ought not be any further than 4'
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The posts are not spaced 4' more like 6' however there is no bounce whatsoever at the ends, rather it is all at the middle. Frankly, right wrong or otherwise I have rarely seen a deck with posts spaced that close.
Look, I will admit, I know the right thing to do is install the beam, however as I tried to remove a few rows of boards to access the framing below, I am having a terrible time removing the screws without damaging the boards.
I guess I was hoping for a quick fix :) Maybe doubling up, installing 2x blocking or something along those lines.
Shame on me for thinking of a quick fix :( lol
"I have rarely seen a deck with posts spaced that close."me either, but when the posts are spaced out further, the beam needs to be upsized. I space posts from 6' to 12'While the joists are at the upper limiot, the beam is severely overspnned or underdesigned, so vibrations that begin in the joists, get amplified and returned in the beam.how close to ground are you?
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Why are you removing deckboards to get to the underside? With 24-30" clearance, can't you slip in frokm the side/end?
"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
If I get a chance, i will upload a diagram of the layout. Although, i think i already begged the answer to my question
Also, How are the joists attached to both ledger and beam. Less than perfect connections = less than perfect results..
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Piffin,
Deck is approximately 20" off the ground on the house end and 24" to 30" above grade at the end. Access is not really a problem.
One post is obviously at the corner, then one in from that about 8'. So, on the end, the deck is attached at the house, post at 8', then post at 16'. Deck is attached on two sides with ledger attached with two lag screws every other joist bay then joists are attached with hangers on both ends. I agree that perhaps the outer beam should have been double 2x12 rather than 2x10. That would help, but still would probably get the deflection/bounce, albeit maybe a bit less.
Someone had suggested to me to maybe use 2x4 fastened to the side of the joist at the top below the deck boards to perhaps beef them up a bit. Then, had someone suggest doubling up every other joist or so
Perhaps the joists were installed crown down and not up, really have no way to verify of not sure how much that would add to the bounce.
Gee, Piffin, do you get paid for all your replies. :)
I see you on here quite a bit. And, I might add, you have great advice to share. Kudos!
The beam with that span should have been triple 2x12 IMO, and the obvious best solution would be anorher beam centered to shorten the span on the joists.I like a challenge is part of the reason I am here.You have a good one.If you cannot or are unwilling to get a beam set mid-span to shorten the span of joists, then there are other possibilities, but none gauranteed and maybee others here will shoot me down, but here goes...To shorten the span on the bean, you can add kickers - diaginally placed 4x4s from post to beam. They will do more good if notched tightly in place. if the kicker is a tight 4x4 @ 18" from post, the 89' span wil effectively be reduced from 8' to 5'. Actuall results will depend on the quality of the install.Then, to shorten the span of the joists, place a 2x8 under them with structural screws 18" back from the popsts and do the same kicker deail. This will absorb some of the bounce - not all, but some.
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maybee others here will shoot me down, but here goes...
Nobody shoots at the Piffmeister!
But....
Those suggestions will certainly help, but seems to me they'll be a lot more trouble and work than just pounding together a tripled 2x12 beam and installing it at midspan.
I'd also face the doubled rim joists he's got with a 2x12, glood-n-scrood....
I don't understand Jg's reluctance to place a beam. It's not that big a deal unless there's something I missed in his situation. Three pieces of 2x12, a bunch of 20d's, a couple or three short lengths of 4x4 and he's done. That's a two-beer, two-buddy, Saturday-afternoon fix....
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
not every body enjoys crawling in the mud and spiders as much as we do
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At our age, it ain't the mud and the spiders...it's the crawling part that hurts....
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Right, I'll just lay here on my back. Hand me that 2x12 will you?
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No problem. You want fries with that?
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
I say your joists definitely overspanned. They may look O.K in a book, but they have a bad length/depth ratio.
Adding anything alongside them will likely do nothing, unless you add deeper joists. (Like 2X12s)
Adding some 2X4s perpendicular to the bottom of the joists at midspan MIGHT help a little. But I wouldn't bet on it.
As you've already pointed out - Adding a beam is your best bet. I understand that you don't want to do it. But not wanting to doesn't translate into that being the best solution.
think I'd go with blocking at 4 and 8 ft - alternate offset from the 4-8 ft lines for easy nailing - precut everything, get a couple of pieces of plywood for the ground and then go to town with the pneumatic fasterner (aka nail gun) - should add some stiffness as the load gets transferred to the other adjacent framing.
Hey guys-
Thank you all for the responses
No, the beam is not a big deal. Have to remove the deck boards to dig and install the posts.
Like I said, I KNOW the beam is the right thing to do and it looks like I have an excuse to drink beer on a Saturday :)
Still thoug, 2x12 beam? Isnt that a bit much? As long as the posts supporting the beam are adequately spaced, shouldnt we be able to get by with even a double 2x8?
Its just 8'-0 of span for christs sake?
I would think that a double or triple 2x8 would be sufficient for the sake of taking the bounce out, if you are going 8 ft o.c. w/ your posts. It isn't how I would frame it starting from scratch, but I think it would solve your bounce problem. I agree w/ Piffin that if starting new, I would have put triple 2x12 ( and probably blocking @ mid span between beam too)
Bing
How did the span get reduced to 8 ft all of a sudden? I thpought the joists were spanning from the house ledger to the beam at the outside edge of the deck. I thought the boutside beam had posts that gave it a shorter span. The beam that is being proposed would be perpendicular to the joists at their mid-point.
"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
since that mid span new beam goes in at the halfway point, the span of the 16' joists is reduced to 8'
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Yep.
I agree as well. There are many things I would have done differently if framing from the start. For one, I would have consistent deck support post spacing, would have installed a mid-span beam and beefed up the outer beam/band joist.
Well, looks as though I will get that beam in.
As far as the problem with removing the deck screws and damagin the boards by doing so, any one have any ideas?
Hope everyone is having a good holiday weekend
16 dfivided by 2 equals 8, doesn't it!
I thought that he was referring to replacing the exterior beam. Thought someone had mentioned that it was also undersized and should be replaced with a larger one.
Ok, just went back and read through the thread again. He had wondered if a double 2x8 mid-span beam would work, rather than 2x12. Well, it probably would, as long as it had support posts every 4-6 feet
"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
Edited 9/4/2005 4:02 pm ET by FastEddie
I agree, he is already in a state of unhappiness from having once tried to max his spans.
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well, its not alll bad. I do have the opportunity to drink some beer. My wife will accept that, as long as something gets done :)