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Old 01-31-2010, 09:08 AM   #1
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Attic structure


I am going to finish an attic 'bonus' room. However, before I start I need to find out what regulation/code governs my changing of the 2x4 'posts' that seem to 'hold up' the house. Any idea? See pic attached.
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Old 01-31-2010, 09:11 AM   #2
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Attic structure


Are those trusses or did someone just put those under regular rafters?

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Old 01-31-2010, 09:39 AM   #3
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Attic structure


Need a bigger pic of the area with framing
What size are the rafters & span distance ?
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Old 01-31-2010, 09:39 AM   #4
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they are not trusses. they appear like something I would use as temporary support while I as installing the trusses. However, I am not a structural engineer. the 'long' one is a 2x6 and I just wondered if the long run that it goes over, about 16ft, needed a 2x8 or a post in the middle. what do you think?
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Old 01-31-2010, 09:45 AM   #5
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what size are your rafters? whats the length of the approximately?
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Old 01-31-2010, 10:00 AM   #6
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Hey, the rafters are about 16 feet long, they are 2x4's and are 'held up' with that long beam in the center which is a 2x6 and is about 13 feet until it is attached to a vertical beam and is then another 6ft long (but there it is attached to a wall in multiple locations.
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Old 01-31-2010, 10:15 AM   #7
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Attic structure


With 2x4's & that span you are going to need that support at the 1/2 way mark that exists
You can't remove them
It would need to be replaced with similar/bettet support at that point
The diagonal supports may need to stay too
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Old 01-31-2010, 10:38 AM   #8
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Ok, the goal has to be to get rid of the diagonal braces. So, can I do that by adding a verticle post halfway along onthe 2x6 that holds up the 2x4s? or can I swapout the 2x6 for a 2x8 or 2x10?
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Old 01-31-2010, 10:49 AM   #9
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Hard to say without seeing the way all support for the roof is built
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Old 01-31-2010, 10:59 AM   #10
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if thats a 2x6 beam your rafters dont look like 2x4. ceiling/floor joists r what? you have alot going on that looks kinda hinky to give online structural advise
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Old 01-31-2010, 11:10 AM   #11
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Sounds like the best plan for this particular project will be to hire someone to come see the problem and both make a recommendation based on code and what he sees and have to pay him to do it to get his knowledge of code/requirements. Thanks for your help/thoughts.
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Old 01-31-2010, 11:12 AM   #12
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Old 01-31-2010, 05:03 PM   #13
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Attic structure


You appear to have 2x6 rafters with two rows of purlins and struts to make up for the over-span of the rafters. These are needed. The diagonal bracing and the single 2x6 (purlin) could be replaced with a solid or doubled beam (sized by a S.E.), let onto trimmer posts or stud at the existing bearings. You would be using the same bearing points with the same loads. You are simply replacing the existing braces with a stronger beam. You need metal diagonal strapping to replace the angled 2x4 brace, installed flat on the wall in an X fashion to give some shear to the ridge framing and wall height. http://www.strongtie.com/products/co...c-twb-rcwb.asp


If you have a rake (sloped) ceiling, you need to furr down the rafters to accept the required thickness of insulation and air space above for your location. Where is your location, you may also require snow loads when figuring the beams?


Be safe, Gary
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Old 01-31-2010, 05:39 PM   #14
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Gary,
Great response. You cite the need of an Structural Engineer (SE) I suspect that is smart for the purlin. Thanks for the explanation. I can cut, nail, screw, etc like the best of them; however, I do not have any SE training and will follow your advice. As for the Metal X to replace the 2x4, that seems relatively straight forward to replace as the metal X will have far more stucture than the 2x4 that is there. I am in Oklahoma City and the roof is fairly steep, so I had ruled out being too concerned with snow. As for the ceiling insulation, I had planned on using 2x4 type insulation on the 2x6's to allow for the additional air flow and for heat/ A/C I am thinking/planning on using a wall mounted unit instead of tapping into the current system or using a window mounted unit. what do you think?
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Old 01-31-2010, 11:44 PM   #15
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You need 12" of joist space for the required R-38 insulation for your zip code: http://www.ornl.gov/sci/roofs+walls/...on/ins_16.html

You could use R-38C (for cathedral), but you still need 10-1/4" inches for batts, and 1" air space. OR use some rigid foam board and batts.

I would post your new question in the HVAC section/label of our forum. The pros there are eager to help as we are. Glad we could help.

Be safe, Gary

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