Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Carpentry

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-31-2010, 04:22 PM   #1
Newbie
 
Join Date: Jul 2010
Posts: 10
Rewards Points: 10
Default

supporting flush beams and joists


Im looking to do a low level deck with flush mounted beams and no cantilevering.

Beam in the middle is two 2x8's supported by concrete piers going end to end. Should i make one large beam or have two that meet on a pier because of the long run about 20'.

Side A is a 2x8 ledger

My question is if i put a pier at F1, F2, D1, D2, B2 will sides G, E, and C have enough support for the joists. Or would i have to put a pier at every point.

Thank you.
Attached Thumbnails
supporting flush beams and joists-decknew.jpg  

illectric is offline   Reply With Quote
Old 08-31-2010, 09:47 PM   #2
Member
 
jlhaslip's Avatar
 
Join Date: Dec 2009
Location: Canadian Rockies
Posts: 1,280
Rewards Points: 500
Default

supporting flush beams and joists


a single flush beam down the middle won't hold up the outside ends.

__________________
Quote:
Originally Posted by Bud Cline View Post
Go ahead and apply for a variance, those guys at City Hall can use a good laugh.
jlhaslip is offline   Reply With Quote
Old 09-01-2010, 12:16 AM   #3
uva uvam videndo variafit
 
WirelessG's Avatar
 
Join Date: Mar 2009
Location: W by God VA (bye MS )
Posts: 558
Rewards Points: 500
Default

supporting flush beams and joists


I don;t see how you can get away without putting piers at each corner. If not, it's like you are trying to cantilever the North half of the deck.

I always have to look up span lengths, but off the top of my head a dbl 2x8 over 20' will have a little spring to it I think.
WirelessG is offline   Reply With Quote
Old 09-02-2010, 05:57 PM   #4
Newbie
 
Join Date: Jul 2010
Posts: 10
Rewards Points: 10
Default

supporting flush beams and joists


green is ledger
yellow are double
red are piers
just wondering if this works. or where i have to put the piers.


by the outsid ends i take it you mean sides E and G. i was thinking that side might be strong enough cuz its attached to the ledger and beam essentially.

not sure about the cantilevering thing. everything is flush to one level. hope this pic helps.
Attached Images
 
illectric is offline   Reply With Quote
Old 09-02-2010, 07:57 PM   #5
uva uvam videndo variafit
 
WirelessG's Avatar
 
Join Date: Mar 2009
Location: W by God VA (bye MS )
Posts: 558
Rewards Points: 500
Default

supporting flush beams and joists


[IMG]file:///C:/DOCUME%7E1/SCOTTU%7E1.SCO/LOCALS%7E1/Temp/moz-screenshot.png[/IMG][IMG]file:///C:/DOCUME%7E1/SCOTTU%7E1.SCO/LOCALS%7E1/Temp/moz-screenshot-1.png[/IMG]Calling the top of the drawing North, you are cantilevering the North half of your joist to the extent that the cantilevered span appears to be the same as the main span. This will result in significant uplift forces on the South piers.Your pier at G1 isn't doing much by itself. You need to do one of two things that I can see:

1. Add piers at A1 and A2, or

2. Move your main beam in the center further North (say up around F2) and cantilever from there.

There is no support on either side of the joints as A1 and A2, so there's no where for the shear load to transfer.

I like the added piers in the middle. There was a post in this forum section that provided allowable spans for lumber (http://www.diychatroom.com/f14/2-x-4-strength-78507/ scroll down to GBR's post).

Something to keep in mind - the beam (whether left in the middle as shown or moved to the North as I suggested) will carry half of the load on the entire deck. If you double a 2x8, you'll double the strength and stiffness. If you double the height to 2x16, you quadruple the strength and increase the stiffness by a factor of 8. I'm not suggesting you go to 2x16's - I'm just letting you know how beam strength and stiffness add up:

Adding more beams side by side is a one to one relationship (add one beam you get twice the strength, add two beams you get three times the strength, etc, etc). Whereas increasing the depth increases the strength to the power of 2 and the stiffness to the power of three. Deep beams typically are less stable, but this can be handled with adequate bridging.

Those are my thoughts.
WirelessG is offline   Reply With Quote
Old 09-02-2010, 08:16 PM   #6
Member
 
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000
Default

supporting flush beams and joists


I don't see any cantilever ?

(North) Green is a ledger - attached to the house
...you are not required to have piers at the house attachment
Middle support is from a beam
South side is supported by piers/double joist as a beam...as are other areas

The piers should be under the connections between the joists for proper support

Whats on the East side ?
Scuba_Dave is offline   Reply With Quote
Old 09-02-2010, 08:20 PM   #7
uva uvam videndo variafit
 
WirelessG's Avatar
 
Join Date: Mar 2009
Location: W by God VA (bye MS )
Posts: 558
Rewards Points: 500
Default

supporting flush beams and joists


Oops...from some reason I thought green was a rim board. There is no cantilever.
WirelessG is offline   Reply With Quote
Old 09-02-2010, 09:31 PM   #8
Registered User
 
Join Date: Mar 2009
Posts: 9,967
Rewards Points: 2,000
Default

supporting flush beams and joists


The 2006 Prescriptive Deck Code says: "No hangers at opposite sides of the same beam", pp. #5 and 7:
http://www.lancova.com/deckinfo.pdf

Ideas?

Gary
__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Old 09-02-2010, 10:01 PM   #9
Newbie
 
Join Date: Jul 2010
Posts: 10
Rewards Points: 10
Default

supporting flush beams and joists


scuba - hmmm. I was thinking about putting posts under sides g, c and e. That would make more sense cuz each side of the joists is supported by something that is sitting on or attached to concrete. On the east and south side is a fence.

Gbr - .......*%&^ *%. So a beam cant have joists on both sides? im gonna get back and see if i can think of something else. The only other thing that comes to mind is to dig a little deeper to put the beam lower so the joists sit on top. I plan on digging and putting stone and landscaping underneath. Is the beam touching the stone ok? I planned on 4" so it might be the solution.
Attached Thumbnails
supporting flush beams and joists-3ddeck.jpg   supporting flush beams and joists-3ddeck2.jpg   supporting flush beams and joists-3ddeck6.jpg  

Last edited by illectric; 09-02-2010 at 10:03 PM.
illectric is offline   Reply With Quote
Old 09-02-2010, 10:04 PM   #10
Member
 
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000
Default

supporting flush beams and joists


Ah...I was thinking the joists were going to sit on the beam
Good catch

How far is it from the door to step down to the ground ?
Myself I went pavers at my last house instead of building a deck
But only 1 step down from back door
Scuba_Dave is offline   Reply With Quote
Old 09-02-2010, 10:17 PM   #11
Newbie
 
Join Date: Jul 2010
Posts: 10
Rewards Points: 10
Default

supporting flush beams and joists


its about 35" to the ground so with the deck approx 26". Not sure what im gonna do now.
illectric is offline   Reply With Quote
Old 09-03-2010, 09:44 AM   #12
uva uvam videndo variafit
 
WirelessG's Avatar
 
Join Date: Mar 2009
Location: W by God VA (bye MS )
Posts: 558
Rewards Points: 500
Default

supporting flush beams and joists


You can offset the joist spacing on either side of the beam. This would cause a stagger in you deck nails/screws, but I don;t think it would look bad.
WirelessG is offline   Reply With Quote
Old 09-03-2010, 11:10 AM   #13
Newbie
 
Join Date: Jul 2010
Posts: 10
Rewards Points: 10
Default

supporting flush beams and joists


ive had multiple people tell me its fine on both sides of beam. Guess maybe its in your area. I will be goin to the inspector so i will know for sure next week
illectric is offline   Reply With Quote
Old 09-03-2010, 12:06 PM   #14
Member
 
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000
Default

supporting flush beams and joists


If you will have 26" to the ground that is plenty of room to have the joists sit on the beam...I think?
7.5" for the 2x8 beam, that leaves 19.5"
Less work IMO

Scuba_Dave is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Deck with not enough space for beams and joists alexeygu Building & Construction 10 06-22-2010 10:00 PM
Protecting Joists and Beams with Bituthene rocketdoctor Building & Construction 1 10-02-2009 12:46 AM
Deck project - Shim beams or joists? jcims Carpentry 1 08-08-2009 09:02 PM
Adding supports for beams and joists pinkertonpv General DIY Discussions 2 08-13-2008 03:04 PM
crawlspace clearance under the beams and joists ? chuckgo Building & Construction 4 09-07-2007 02:49 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.