Building Homes or Extensions/Pergola-knee braces

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Expert: - 9/1/2010


Question
Hello Mr. Johnson:

I have a an almost completed pergola over a deck that sits off the ground about 18". The deck itself is 16x16 and the pergola is 14'x15'. The contractor we hired to build has left the job unfinished. Anyway, the posts are 6x6 and the header is a double 2x8 with 2x8 rafters. The top has lattice work 2x2 strips 6" OC. We are experiencing some racking and wondered what you can suggest to remedy our problem. All in all it is well built and is aestheiticly pleasing, just not as stable as we would like. Thank you in advance.

Answer

knee brace example
Hi Tracy, your subject line "pergola knee braces" pretty much answers your own question.  You need to add knee braces.  I am attaching a simple diagram.  Your knee braces should be 4x4's in this instance or you can buy decorative corner bracing for exterior applications. A knee brace is simply a piece of wood cut at 45 degree angles at each end and nailed or screwed into the beam and the post.  My example is not to scale.  Your braces can be smaller.. two to three feet in length should be enough.

I hope this information helps please feel free to write again regarding this or other matters sincerely bruce e johnson

Bruce E. Johnson

Expertise

I can answer any construction related question in regards to carpentry, concrete, drywall, masonry, structural elements of any type of building, residential or commercial. Interior or exterior.

Experience

Custom Commercial and residential buildings. Churches, theaters, schools and auditoriums. Most recently I am working with the Catholic Church on several design build committees. I have a website related to scheduling and project supervision. Although my expertise is more related to multimillion dollar commercial, educational and theatrical projects my generous credentials in residential and remodelling construction make me a viable source of information regarding all forms of building questions.

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