14 x 14 freestanding deck plans needed

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Old 12-26-13, 04:52 PM
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14 x 14 freestanding deck plans needed

I'm planning to build a free standing deck, 14 X 14. Due to height restrictions I need to construct a flush beam frame. Problem is not much info on the net on how to specifically frame it up.

Does anyone know of a resource that gets pretty specific on the plans?

Putting together a dropped beam seems to be the most popular but it just won't work for me. My situation limits the framing to 14" max so a flush beam setup would work. It may a tad bit close to the ground but it will work.

What I need to know is this:

1) How to frame floor? Double rim? Double perimeter? One double beam? 2 double beams? etc.

2) Size of beams and joists

3) Where to locate support posts and footings? Using 2000 psf I needed nine 12" footings. easy enough to figure out where to put them with dropped beam. How about flush beam?

4) Is it possible to cantilever a flush beam framing set up.

Like I said, a dropped beam seems pretty clear cut. Flush beam appears a little more mysterious. So, if someone with ability to post a pic could post a rough draft that would be a great start.
 
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Old 12-27-13, 08:13 AM
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You really need an architect who knows the local codes. That way you won't get stuck, if you decide to sell the house some day.
 
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Old 12-27-13, 03:33 PM
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Should I take that as the skill needed to construct a flush beam deck can't be found from someone here?
 
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Old 12-27-13, 04:25 PM
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Yes & no. From what I've seen here & it's only an observation, people tend shy away from giving structural advice. I can only guess at the reasons behind it. Personally, I have never designed a deck. I have only built them.
 
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Old 12-27-13, 06:51 PM
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Sounds like you'll need 3 rows of double 2x8 beams, connected by 2 spans of 2x8 joists suspended from the beams with joist hangers (no cantilevers), with all supported on 6x6 columns. Just about everything one needs to know about deck design and construction can be found in the IRC-based Residential Wood Deck Construction Guide (DCA6). I'm having trouble trying to attach the link to same.

Some of the regulars will be along shortly to provide the link if mine doesn't show up. Or browse through some of the older threads/posts by others to find the link.
 
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Old 12-27-13, 07:45 PM
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Thats pretty much what I figured out. 3 sets of 2x8's, 4 posts under each beam will keep me below 2000 psf. Couldn't really find anything that says I need to double up the perimeter or just the front and rear beam. There is an issue of "not hanging joists off both sides of the beam, unless I'm reading that wrong. I was planning on gluing and screwing the front and rear 2x's to make one solid beam...and splitting the 2 2x8's in the center beam, one on each side, and hanging the joists off of each 2x8. I'm not sure whether I should glue and screw the center beam and hang joists off both sides or split them to each side of the post.
 
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Old 12-27-13, 08:23 PM
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"Splitting a beam" is allowed by DCA6, provided that the columns are notched to support each member. I personally don't care for the idea, as in effect you are now asking a single 2 x 8 to act as a complete beam. More "wiggle" in the deck, as the single 2 x 8s want to rotate as the joists are loaded, along with greater live load deflection than a double (contiguous) 2 x 8 beam would have. You may want to check with your building permit office, but I think off-setting joists on opposite sides of single beams by a few inches would get around the "no hanging joists on both sides of a beam" prohibition.

Also, you only need 3 columns, not 4, under each beam line to stay well under the 2000 PSF limitation. You had earlier (correctly) stated that you'd be using 9 columns, total.
 
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Old 12-27-13, 08:56 PM
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After recalculating it comes out to 4 posts per beam.

3 posts per beam:

A1 - Area: 3' 6" x 3' 6", Load: 780PSF
A2 - Area: 7' 0" x 3' 6", Load: 1560PSF
A3 - Area: 3' 6" x 3' 6", Load: 780PSF

B1 - Area: 3' 6" x 7' 0", Load: 1560PSF
B2 - Area: 7' 0" x 7' 0", Load: 3119PSF
B3 - Area: 3' 6" x 7' 0", Load: 1560PSF

C1 - Area: 3' 6" x 3' 6", Load: 780PSF
C2 - Area: 7' 0" x 3' 6", Load: 1560PSF
C3 - Area: 3' 6" x 3' 6", Load: 780PSF

4 posts per beam

A1 - Area: 2' 8" x 3' 0", Load: 374PSF
A2 - Area: 5' 4" x 3' 0", Load: 748PSF
A3 - Area: 5' 4" x 3' 0", Load: 748PSF
A4 - Area: 2' 8" x 3' 0", Load: 374PSF

B1 - Area: 2' 8" x 6' 0", Load: 748PSF
B2 - Area: 5' 4" x 6' 0", Load: 1497PSF
B3 - Area: 5' 4" x 6' 0", Load: 1497PSF
B4 - Area: 2' 8" x 6' 0", Load: 748PSF

C1 - Area: 2' 8" x 3' 0", Load: 374PSF
C2 - Area: 5' 4" x 3' 0", Load: 748PSF
C3 - Area: 5' 4" x 3' 0", Load: 748PSF
C4 - Area: 2' 8" x 3' 0", Load: 374PSF

I suppose I could make the footing for load area B2 (center footing) 20 inches and still get away with 9 holes. This was calculated using 12" for each footing.

Or go with 4 posts at 12 inches. Probably less work to just go with 3 per beam and make the center footing 20 inches or so.

This is figured with 0 cantilever.

Getting the footings correct is easy enough. I was more concerned with the framing.

After I get something on paperwork I will try to post it and get some feedback.
 
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Old 12-27-13, 09:00 PM
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Offsetting the joists will give me a hideous looking screw pattern on the decking. I wish they would have worded that part with a little more thought and explanation and less allowance for self interpretation.
 
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Old 12-29-13, 11:39 AM
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This is what I have so far. Open to feedback.
 
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Old 12-29-13, 02:03 PM
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I still can't find anything that shows an alternative to hanging joists off the opposite sides of the center beam.

DCA6 says:

"Joists shall not frame in from opposite sides of the same
beam". "Allowing joists to span from opposite sides of the beam without appropriate consideration could potentially lead to a condition where beam capacity is exceeded".

It doesn't give any alternatives. I'm wondering if a triple 2 X 8 for the center beam would be the answer. Instead of notching it, use a post cap for a triple beam (if I can find one).
 
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Old 12-29-13, 06:54 PM
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I agree with your frustration regarding the DCA6 advisory not to hang joists off of opposite sides of a center beam. I initially thought their thinking was that too many joist hanger fasteners/holes (coming from opposite directions at the same locations) could compromise the integrity of a beam's cross-section. Hence my suggestion to offset the joist hangers. The current DCA6 commentary doesn't elaborate on this matter. I'm not understanding the thinking that a beam could be overstressed by joist hangers applying lateral forces, from opposite directions, on a center beam. If anything, loads applied in opposite directions would tend to neutralize each other, resulting in relatively small shear and compressive forces acting perpendicular to nominally larger tensile/compressive forces developed as a beam resists bending moments longitudinally.

Your best path forward might be to work up a sketch showing joists hanging from both sides of your built up 2 x 8 beam, and take it down to the AHJ people who will be issuing your building permit. If they like it, you should be good; if they don't, perhaps they could explain why such is unacceptable.

Guess there's a reason I chose to go into bridge construction, inspection, and rehabilitation instead of staying in design, as I lack the ability to envision what the DCA6 engineers are trying to convey.
 
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Old 12-29-13, 07:05 PM
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I forgot to mention that I agree with your idea to not notch the tops of columns. But if you change your mind and decide to notch the 6 x 6 columns (nominal thickness = 5-1/2"), the through-bolt size shown on your sketch will be too short. There won't be enough stick-through (1/2" for a 6" bolt) for adequate hex nut grip and two flat washers.
 
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Old 12-30-13, 11:13 AM
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I was planning to notch the front and rear beams. If I use 3x beam in the middle I would just use a post cap.

No permit required for this size deck. But I might have them look at the plans just to see what they say.

Either way, I'm hanging off both sides of the beam. With a triple in the center and the span lengths being well under the max I don't see a problem.
 
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Old 01-06-14, 12:55 PM
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Dek Block offers free plans on their website for ground level decks, including flush beams. Granted, it will be for use with their pier blocks, not traditional footers.
 
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Old 01-06-14, 01:26 PM
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jim61,

Why would you want to (or need to) notch the beams? Never a good idea, as it can seriously affect any beam's load-carrying ability. If significant enough, and under certain loading conditions, to the point of complete failure.
 
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