Sun Room Addition Lateral Analysis/Design

[wayniac3]

I have be asked to design a one story 20' x 12' sun room out of wood. It will have a gable roof with a mean roof height of 15'. The sun room is to be placed the back of a two story brick veneer house. It will be located in a 100 mph wind zone. The client wishes to have the sunroom built on a c.m.u./brick perimeter foundation wall in order to get the sun room floor to match the existing house floor level. I do not wish to attach the sun room to the brick veneer on the house. Therefore, I am at a bit of a loss as to how to provide adequate lateral bracing and foundation anchorage for the sun room as the client wishes have the walls for the most part consist of windows with 6x6 posts between. Could I get some input on how to approach this one?

 

[JAE]

no sarcasm. I tend to do the wrong thing: speaking before thinking (i.e. thinking out loud) too often myself....so I have emphathy for all who do also.

 

[geoffwatson]

Hello,
I assume the eaves height is about 8-9 feet above sole plate level. Would it be possible to use knee braced oak or other suitable hardwood posts, eaves beams and cross tie beams which could act as portal frames. Possibly fixing the base of the posts into the foundations directly or with steel shoes to obtain the additional stiffening effect of cantilever action.
By putting a frame adjacent to the exg house the sun room could be independent or you could chemically anchor the last tie beam and posts to the exg work.
I have designed many similar buildings in the UK but probably not for winds of 100mph.

 

[StructTaco]

I don't think cantilever diaphragms are allowed as big as this sunroom is going to be. Wood cantilever columns don't work unless you bury the post like a fencepost/flagpole footing, or bury it in a short wall and extend them up.

My two cents: use cantilever columns that are steel tubes either welded to a baseplate and bolted to the foundation or embedded in a pier at the corners.

OR

bring the brick up as posts, maybe 12x12 columns at the corners and use those as cantilever columns.

OR

Convince the client to deal with a little less open-ness and use Simpson Steel Strongwalls, 12" should do the trick

The existing house will take 1/2 of the lateral load, attach with a ledger

Good Luck wayniac3

 

[bdruehl]

i love this post discussion.. lmao!

its true, the design of such structures is really a pain the rear sometimes once you put pen to paper. i wish we could say in our calc package "build like theyve been these things forever but make sure you have a good contractor"...

i love it when i happen on to a house built 70 years ago with an old timer contractor... up in the attic for instance, and i cant figure how the heck the stick framed roof isnt falling down on my head.. and he says, "ive never seen it built any other way.. it aint goin nowhere..."...in other words.. "you silly engineer with your silly pen and paper..."....haha! good stuff