Building Homes or Extensions/Pavillion


QUESTION: I just built a 24x48' pavilion.  10 each 6x6's, in the ground 36 inches, in 18 inch diameter holes poured at same time as 4 inch slab.  Posts are 12'oc, ten foot high ceiling. 2x10 header inside and out of post attached with 10 inch carriage bolts at each post.  4/12 pitch trusses 24" oc, with 2x4's nailed to trusses angled from outside to center of structure, with 7/16 osb decking and hurricane brackets attached to trusses.  I plan on finishing the ceiling with 4 inch tongue and grove planking the whole ceiling.  My concern is while putting on shingles I could feel movement in building maybe a couple inches standing on peak of roof.  Today I started installing 6x6 knee braces to post, through header.  Carriage bolt in header and threadall through knee braces and posts with washers and nuts.  Should I be concerned with the movement?  Is there something I should do.

ANSWER: Keith,

Adding the knee braces should help, and in your case is a really good idea.  Those 6x6 posts will flex at that length.  You could also have used 2x6s, nailed well.

The length of the knee braces is important, they should be set at a 45 degree angle and sit at about 1/4 to 1/3 down the post length.  Be sure to install them on all four sides of the structure if your post layout allows.

Also be sure to install lateral bracing along the top side of the truss bottom chords, per manufacturer.  This stiffens the ceiling plane.  Once your finished ceiling is installed, that will perform the same function.

Please send along pictures and I may be able to add better advice.

Thank you,
Steve Major

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QUESTION: Steve thank you for your follow up.  I installed corner knee braces at all corners attaching them to the posts at 45 degree angle.  I installed 2x10 headers across both ends attaching them to nailing brackets to the end trusses every 2 foot and tied the 2x10x12's together with splice nailers.  The 6x6 corner knee braces come down 4 foot from the ceiling, about 6 foot from the ground.  I can barely get the structure to move now.  Thank you for your response.  A follow up is, should I worry about checking in the posts.  Some are very long and deep.  Reading the internet it is said not to worry you cant stop it from happening.

steel hoops
steel hoops  

6x6 #1 southern yellow pine posts at your spacing are probably over-designed for the compression (straight downward) load, and some checking is normal, so it should not be a problem.

If any particular post appears to be badly checked to the point that it may split through, I would wrap three welded steel "hoops" around the post (similar to those on a wooden barrel) per the attached drawing.

Best of luck,
Steve Major

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Stephen Major (Owner--Major Design Group)


I can answer any questions regarding the design and construction of homes and additions. This includes trade-specific questions (how-to) in all major building trades: framing, foundations, site prep, electrical, HVAC, plumbing, water treatment, interior finishing, trim & cabinetwork, exterior finishing, roofing, siding. PLEASE indicate your state or region, so I can provide the best possible answer. PLEASE provide photos whenever possible.


30 years experience in building design and construction, all hands-on, including the construction of dozens of single-family homes and hundreds of remodeling projects in the northeastern US.

Author: "Architectural Woodwork - Details for Construction" published by Van Nostrand Reinhold (now Wiley).

BS Cornell University.

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