Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

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

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-11-2010, 11:45 AM   #1
Newbie
 
Join Date: Apr 2010
Posts: 10
Share |
Default

Span of roof without using a center beam


I'm building a 16x10 foot roof over my deck I want to know if I need a center beam to hold up the ridge beam is needed. The beam is 4x8x16 feet. the span is 16 ft wide 10 ft long with a cable roof. I'm using 4x4 pressure treated post.

twmackey is offline   Reply With Quote
Old 04-11-2010, 12:19 PM   #2
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Default

Span of roof without using a center beam


Supply drawings and/or parts list and your location so we can calculate loads due to snow, etc.
If I made no arith. errors, for an L/D of 180 and E = 1 million PSI for the wood I get that this beam can hold a distributed load of 9 pounds per linear inch.


Last edited by Yoyizit; 04-11-2010 at 05:15 PM.
Yoyizit is offline   Reply With Quote
Old 04-11-2010, 02:42 PM   #3
Remodeling Contractor
 
Join Date: Dec 2008
Location: Sandy Hook, CT
Posts: 3,590
Default

Span of roof without using a center beam


what is the roof pitch, the rafter sizes? And it you are using the ridge beam to hold up the roof you cannot use a pressure treated 4X4. It does not have the required strength and it twists too much in the wall space. I would use paralams for posts.
Bob Mariani is offline   Reply With Quote
Old 04-11-2010, 05:10 PM   #4
Member
 
Join Date: Jul 2008
Location: Canada (s/w ON.)
Posts: 2,294
Default

Span of roof without using a center beam


You should state where you are located, as some locations require that snow load would be considered!
Wildie is offline   Reply With Quote
Old 04-26-2010, 12:06 AM   #5
Newbie
 
Join Date: Apr 2010
Posts: 10
Default

Span of roof without using a center beam


Why can't I use presure treated posts? The width is only 14 ft after measuring and the snow load is not a problem. I'm using a metal roof. I'm using 2 x8 with 4x4's on both sides the 2x8's on both sides with bolts holding the 2x8 and 4x4's together.
twmackey is offline   Reply With Quote
Old 04-26-2010, 09:12 AM   #6
Member
 
Join Date: Jul 2008
Location: Canada (s/w ON.)
Posts: 2,294
Default

Span of roof without using a center beam


Quote:
Originally Posted by twmackey View Post
Why can't I use presure treated posts? The width is only 14 ft after measuring and the snow load is not a problem. I'm using a metal roof. I'm using 2 x8 with 4x4's on both sides the 2x8's on both sides with bolts holding the 2x8 and 4x4's together.
With no snow load, its not much of a problem! In my area, you could use 4X4's to support a snow load of 30# psf.
My roof uses a laminated beam constructed from 3-2X10's spanning 13 feet! The rafters are 8 feet from the ledger to the beam and are 2X8's. I could have used 2X6's but I may close the porch in and heat it! The 2X8's will allow R20 insulation to be installed!
Snow load in my area is a major consideration!

In your post you said its to be a CABLE roof! Did you really mean a GABLE roof?

Last edited by Wildie; 04-26-2010 at 09:15 AM.
Wildie is offline   Reply With Quote
Old 04-26-2010, 10:11 AM   #7
Newbie
 
Join Date: Apr 2010
Posts: 10
Default

Span of roof without using a center beam


Yes I meant Gable roof. with a meatal roof the snow will slide off easy and should not create problem.
twmackey is offline   Reply With Quote
Old 04-26-2010, 09:48 PM   #8
Member
 
Join Date: Jul 2008
Location: Canada (s/w ON.)
Posts: 2,294
Default

Span of roof without using a center beam


Quote:
Originally Posted by twmackey View Post
Yes I meant Gable roof. with a meatal roof the snow will slide off easy and should not create problem.
My roof was built to replace a metal roof! The snow didn't slide off and bent the metal stringers!

Certain weather conditions can freeze the snow to the metal and then it will pile up!

Don't make the mistake of ignoring your local building requirements!
Wildie is offline   Reply With Quote
Old 04-26-2010, 10:41 PM   #9
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 4,167
Default

Span of roof without using a center beam


I recommend that you discuss your project with the local building inspector. If you do not need a permit, you may still wish to comply with the IBC or your local code anyway. Without specific details of your roof design, and details about how the roof load will be supported, it is reckless for anyone on this site to offer opinions as to the adequacy of your "design".

Any roof structure should be designed to handle a reasonable combination of live and dead load, including the weight of the roof, snow load, wind load, seismic forces, and impact loading. That is one of the reasons the building code exists, to set minimum loading standards, connection details, and material standards for building construction. All structural elements must be analyzed for bending, shear, torsion, and buckling. This includes the posts. All connections must be checked for adequacy. If you build from pre-engineered plans that are approved by your local building official, you can have reasonable confidence that these factors have been considered. If you are designing this on your own, you need to check all these factors.
Daniel Holzman is online now   Reply With Quote
Old 04-27-2010, 10:24 PM   #10
Newbie
 
Join Date: Apr 2010
Posts: 10
Default

Span of roof without using a center beam


Span of roof without using a center beam-patio-cover-021.jpg

Span of roof without using a center beam-patio-cover-020.jpg

Span of roof without using a center beam-patio-cover-022.jpg

Span of roof without using a center beam-patio-cover-024.jpg
twmackey is offline   Reply With Quote
Old 10-30-2010, 11:02 AM   #11
Newbie
 
Join Date: Apr 2010
Posts: 10
Default

Span of roof without using a center beam


I kinda expected a reply either faverable or not, but just leave a guy hanging with out additional comment took me by suprise.
twmackey is offline   Reply With Quote
Old 10-30-2010, 03:23 PM   #12
Member
 
Join Date: Jul 2008
Location: Canada (s/w ON.)
Posts: 2,294
Default

Span of roof without using a center beam


Quote:
Originally Posted by twmackey View Post
I kinda expected a reply either faverable or not, but just leave a guy hanging with out additional comment took me by suprise.
Hmmm! A reply from me? From the looks of what I see in your photos, you have done an excellent job.

However, any criticism from me, would be worthless, as I have no structural engineering qualifications.

Besides, this, my wife has just spent the past summer recovering from a life threatening illness, so my internet time has been limited!
Wildie is offline   Reply With Quote
Old 10-30-2010, 03:42 PM   #13
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Default

Span of roof without using a center beam


Did you check with any officials to see if the structure meets with your location's minimum Code? The posts seem undersized, the double built-up beams near the rafter tails are not really built-up with the space between them. The rafters (1/2) the span plus the overhang load is resting on ONE header beam, I'm sure it is over-loaded. Around here, the entire structure would be required to be built with pressure treated wood for outdoor exposure. The use of OSB (rather than plywood) for the sheathing will absorb moisture from the underside and not fair as well. Need diagonal corner braces going at right angles on all posts. Need solid rafter blocking at the lower rafter bearing to prevent rotation. Don't know your location to comment on the 4x8 ridge beam, but the single beam near the tails will only carry a 25# live load per sq.ft. and 10# dead load, with no snow load.

What did the Inspector say about the posts?

ps. Glad to hear she is recovering, Wildie!

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 11-01-2010, 10:03 AM   #14
Member
 
Join Date: Jul 2008
Location: Canada (s/w ON.)
Posts: 2,294
Default

Span of roof without using a center beam


Quote:
Originally Posted by GBR in WA View Post
Did you check with any officials to see if the structure meets with your location's minimum Code? The posts seem undersized, the double built-up beams near the rafter tails are not really built-up with the space between them. The rafters (1/2) the span plus the overhang load is resting on ONE header beam, I'm sure it is over-loaded. Around here, the entire structure would be required to be built with pressure treated wood for outdoor exposure. The use of OSB (rather than plywood) for the sheathing will absorb moisture from the underside and not fair as well. Need diagonal corner braces going at right angles on all posts. Need solid rafter blocking at the lower rafter bearing to prevent rotation. Don't know your location to comment on the 4x8 ridge beam, but the single beam near the tails will only carry a 25# live load per sq.ft. and 10# dead load, with no snow load.

What did the Inspector say about the posts?

ps. Glad to hear she is recovering, Wildie!

Gary
Thanks Gary, it was serious enough that her doctor didn't think that she would make it!
Wildie is offline   Reply With Quote
Old 11-01-2010, 04:42 PM   #15
Framing Contractor
 
Join Date: Apr 2006
Location: Caldwell, NJ
Posts: 1,758
Default

Span of roof without using a center beam


Quote:
Originally Posted by twmackey View Post
I kinda expected a reply either faverable or not, but just leave a guy hanging with out additional comment took me by suprise.
Why don't you ask your building inspector what he/she thinks?

__________________
Joe Carola
Joe Carola 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
Tying new roof into old. Clutchcargo Roofing/Siding 15 11-07-2009 05:48 PM
Loft (Beam Span) kobis Carpentry 2 10-29-2009 09:43 PM
Jacking up house, full length joists raised beam off of center colums. Suggestions? slowjo Building & Construction 8 04-05-2009 09:20 PM
Q:Temp support to replace beam and posts on deck dougq Building & Construction 10 09-02-2008 04:24 PM
Beam Replacement? Steve Dailey Carpentry 5 05-19-2008 08:46 PM




Top of Page | View New Posts

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