• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Brain Tease: Deck plan submittal

jar546

jar546

Forum Coordinator
Joined
Oct 16, 2009
Messages
11,095
Location
Somewhere Too Hot & Humid
You are given a set of drawings made by the contractor for a proposed deck attached to a SFR made with nominal lumber, platform construction.

The deck is planned to be 16' in length along the house and project out 12'6". There will be a properly sized beam approximately 10' from the home and the balance of the 2'6" will be cantilevered using 2x8 treated SYP @ 16" o.c.

Piers, post connections, etc. are all good. Ledger board attachment is with 1/2" lags as required. Railings are compliant. This is only a question on 1 item so again, please don't read into the question.

The contractor has specified that the joist ends will be attached to the ledger board by notching the ends (within limits) and resting directly on a nominal 2x4 which will be attached to the bottom of the 2x12 ledger in compliance with R502.6.

Is this type of connection allowed for this deck?

If not, why and what code section?
 
I think that you could meet the lateral anchorage requirements by power blocking and cross nailing the portion of the joist ends above the notches. :D

Proally have to lag the power blocks as well.

Bill
 
Load the cantilever and check the uplift at the house connection.
 
You guys are good. That is exactly what I was looking for.

In this case I would required joist hangars that are rated for the uplift or ask them to have a licensed DP sign off on their intended method.
 
Is this football or building construction? What is power blocking and cross nailing? Those two terms could mean many different things to me. How should the 2x4 ledger be attached to the larger ledger and to the house?

What loads should be considered in checking that 2.5' canti. and the potential joist uplift (unloading) at the ledger beam? What does that loading diagram look like on those joists? What loading condition produces the max. bending stress in the joists? Should there be blocking btwn. the deck joists over the beam out at 10'?
 
moment due to the overhang is something like 50*2.5/2 ftlbs. About 62ftlbs.

Uplift at the house is 62/12.5 pounds. About 5 pounds/ft. 5*16/12 pounds per joist. Less than 8 pounds/sqft of uplift. If I include the weight of the railings, joists, and deck ...

No problem.

Get some common sense.
 
dhengr said:
Is this football or building construction? What is power blocking and cross nailing? Those two terms could mean many different things to me. How should the 2x4 ledger be attached to the larger ledger and to the house?What loads should be considered in checking that 2.5' canti. and the potential joist uplift (unloading) at the ledger beam? What does that loading diagram look like on those joists? What loading condition produces the max. bending stress in the joists? Should there be blocking btwn. the deck joists over the beam out at 10'?
Click to expand...
Hi dhengr,

Check out my post near the end of this thread.

http://www.inspectpa.com/forum/showthread.php?3037-pressue-blocking/page5

Basically it's a technique to avoid using another hanger and, IMO, match or exceed the pull out (lateral) and shear of a hanger. If you've never nailed drywall to a ceiling with hangers that don't plane out, you won't appreciate the elegance and simplicity.

Bill
 
Last edited by a moderator:
Here's how I'm seeing it, feel free to correct my thinking.

If we load the overhang only there would be 50psf x 1.33'x2.5'=166.25 lbs/joist.

If I gang that load up on the outer rail the max moment is 166.25 lbs x 2.5 feet or 416 ft-lbs.

Dividing that by the backspan 416/10=41.6 lbs of uplift at the house.

Ignoring the self weight of the deck I think one nail at the house is going to take care of the uplift.

I believe it is required to block over the main beam on any cantilever.

Uniformly loading it was a bit closer with a max moment at midspan of ~1100 ft lbs. 1100 ft-lbs x 12"=13200 in-lbs/13.14"│ =1004psi stress

#2 syp has a base Fb of 1200. it'll get bumped up 15% for repetitive member and docked 15% for wet service so Fb=1200 as I see it. If it were me I'd see if they would go for 2x10's but I don't believe they have to.
 
Last edited by a moderator:
A few things to the DP:

Prescriptively, 2x8 syp makes this span acceptable.

Prescriptively, we have no way of knowing what the actual uplift is but there is a code requirement for the uplift. We have 2 choices. The use of joist hangars that address uplift or require a DP to sign off on it. Inspectors are not designers.

At one time, there was a school of thought that required the cantilevered portion to be calculated the same as a balcony at 60psf live load. This would not apply here. Food for thought.

If we went to 24" oc framing, I am not sure that the uplift would change significantly due to the lesser framing members. Food for thought.

The point of this was to bring attention to potential uplift which is required to be addressed in the code although there is no prescriptive method to determine what it is.
 
I believe it is required to block over the main beam on any cantilever.
Click to expand...
I don't read that into the code, I know it has been discussed before but can we go over it again?
 
When somebody decides whether or not we are engineers.. please let me know.

Honestly I had no idea if the uplift was considerable or not. Follow the prescriptive or have it signed off. Moment due to overhang wha?
 
Jar a thought provoking question

to take it the extra step could there be a Simpsonless compliant deck?

I've tried (only as a DRP) to come up with one - It ain't as easy as it sounds but it is possible

my attempt was to avoid the question of corrsivness to the hangers and the fasteners.

here in RI at the coast line the small gage nails and screws are attacked by not only the Pressure treatment but the Salt air as well

the i-1/2" ledgers do not provide enough nailing capacity to resist both uplift and lateral shear or displacement so I've attained some satisfactory results

by using 2x12 ledgers with 4x4 botom ledger extensions - thus introducing the problem of water collection in concealed spaces

the galvanized gage nails tend to disintegrate rather quickly not a good senario
 
Architect1281 said:
Jar a thought provoking question to take it the extra step could there be a Simpsonless compliant deck?

I've tried (only as a DRP) to come up with one - It ain't as easy as it sounds but it is possible

my attempt was to avoid the question of corrsivness to the hangers and the fasteners.

here in RI at the coast line the small gage nails and screws are attacked by not only the Pressure treatment but the Salt air as well

the i-1/2" ledgers do not provide enough nailing capacity to resist both uplift and lateral shear or displacement so I've attained some satisfactory results

by using 2x12 ledgers with 4x4 botom ledger extensions - thus introducing the problem of water collection in concealed spaces

the galvanized gage nails tend to disintegrate rather quickly not a good senario
Click to expand...
Simpson will definitely tell you to use stainless hangars and fasteners on the coast. I did 2 different seminars with them over the years and was consistently told that. Hot galvanized double dipped won't help you there according to them and I agree with what I see on lakefronts that get wind and spray. Could only imagine salt spray and sand.

Whatever fasteners that you use in treated lumber other than stainless will still have problems regardless of hangar use.
 
Table R502.3.3(2) could be applied here as well. I think again we are in the realm of nails. Never done it this way, still just teasing my brain. Yankee check footnote e.

Now I don't know if y'all think I'm a DP or just DRP the carpenter :D
 
Last edited by a moderator:
Yeah, unfortunately Simpson only "recommends" 316 stainless in ocean environments. They have a chart in the beginning of their catalog.

In the end, it boils down to service life. You could use HDG or Zmax and it will work.. for a few years... just like a 3-tab shingle.
 
DRP said:
Table R502.3.3(2) should apply here as well. I think again we are in the realm of nails. Never done it this way, still just teasing my brain. Yankee check footnote e.Hell, now I don't know if y'all think I'm a DP or just DRP the carpenter :D
Click to expand...
I want to throw a wrench into that statement. That table is for cantilevered balconies that are part of floor framing assemblies and take into consideration ground snow load. A cantilevered portion of a deck is not a balcony. Or is it? Would that even apply?
 
Yeah salt spary is vicious and the 12 and 16 p commons go to 50% dia in MONTHS in some conditions

(usually inexpensive dipped galv product)

even the sill plates at the foundation so I've been over thinking ways to not use'em at all
 
Don't know jar, I was actually looking for the blocking requirement and decided to throw it into the mix.
 
jar546 said:
George, you are on thin ice with that comment. There is agreeing and disagreeing, debating and there are malicious statements. That is uncalled for.
Click to expand...
There is nothing uncalled for here.

I recall a reply a couple days ago that echoed a reoccurring opinion: that AHJs get to use their judgment.

Well, get some common sense and professional judgment.

You wrote the initial post asking for what is wrong. What is wrong is that you use your "certifications" to bludgeon professionals. You are bringing back memories of why we have national and state building codes: inspectors were failing work unless they got a bribe. And builders had little or no option but to pay.
 
jar546 said:
Elaborate on how certified code inspectors are "bludgeoning" professionals?
Click to expand...
He must mean your statement when you said

"In this case I would required joist hangars that are rated for the uplift or ask them to have a licensed DP sign off on their intended method."
Click to expand...
Ya. bloody. horrible.
 
You must log in or register to reply here.
Top