shed roof design questions

[river place]

We'll be building a single story home that'll measure 24' x 60'  and be on a pier and beam foundation.  It looks like we'll go with the 24' universal as the starting point for wall framing and foundation.  One of the major changes will be the use of a shed roof as we'd like to have a more modern design.  With the location in south central Arkansas we're wanting to keep the roof pitch down to a minimum as the snow load is minimum plus.  We'll use a steel roof.

Half of the house length will have rooms so I'll have walls to help support roof beams.  The one end with kitchen, dining and living area will be open so I'll probably have to go with glulam or other solution. 

Does this type of design seem feasible?
Could I get away with the tall wall being 16' tall and the shorter wall 10' and still have enough roof slope over the 24' width? 
The side of the house with the 10' wall and the open area will have number of 6' sliding doors let in light and provide good views.  Will I have to align the sliding door header supports with pier placement?

Thanks

[PEG688]

  That's only a 3 / 12 pitch, generally the minimum pitch with standing seam is 4/12. There are ways around that with different type of roof "felt", the peel and stick type. You'd have to check with the manufacturer of the specific type of  metal roofing you select to get their spec for their product.

   Could you add a beam across the kitchen area  to cut the free span down?  You could wrap it with what ever you use on the lid , drywall , tongue and groove boards , or just finish it bright or clear.

  I'd say no on the door line up with the beams below question as long as your spans between beams are not max span for the floor system. I'd also think your beams would be parallel to that wall  and the 16' high wall, so your beam would be right under the wall or set back say 12" from the exterior wall. Unless I'm reading your post sideways??

  Good luck, PEG


 
     

[rick91351]

This is a shed that my neighbor up in the hills recently put in.  It is a 24 X 50 with what the truss plans show as a 5 12 pitch.  It is engineered for a 125 pound snow load.



Our shop we are doing, will be about like this building.  They should pour footings this next week or so.  Should have some pictures next week or so if you want to get an idea on size. 
 
   
http://countryplans.com/smf/index.php?topic=9342.msg120056#msg120056

[Don_P]

Rick, is it rafters or trusses under that roof... what does a slice of the building cross section look like?

I would align point loads from above over posts below as much as possible. The engineering of it looks at a load in one of two ways. A unifomly distributed load along a beam, like many joists spaced along a girder distributing their load along its length stresses a beam in one way. A point load of the same weight, all piled in the middle of the span, would stress the beam about twice as much. Figuring out the stresses on a floor girder that has a roof point load from a large header coming down on the floor girder in span somewhere does need consideration... or go brutally basic and stick a footing under it.

TJI's would probably work for rafters as well.

[rick91351]

Don it is diffidently trusses.  Roberts' Trusses in Mountain Home is one of the few local truss companies left open.  They are still cranking them out even in this recession / depression. 

There is a front beam that is like 12 by 6 or 8 sawed locally from Douglas Fir over the doors and the length of the front if I remember right.  I do remember that the truss company engineered and notched the ends of the trusses to accept the front beam.  They set on perfectly.  Lot to be said about good communication and planing in any project.

I am also pretty sure there is a center beam in it as well with two posts for support dividing it in thirds.  This because owner wanted to use it area above for storage.  I think the inspector voted that down.    Reason was the trusses were never engineered for that. 

The building is a pole building with concrete floor.  It sits on sonotubes dug to China.  They used a saddle bracket  that is engineered locally and made in Boise set into the concrete to secure the posts up out of the concrete.  The builder has a real issue with pole buildings and their longevity.           

 

[river place]

I might be able to put a beam across the open area.  I'll have to allow for putting piers in line with the beam supporting posts.   

Yeah the pitch is low but if I go with a normal pitch the one wall ends up quite tall and takes away from the goal of having a more modern design for the roof.  I suppose I could use the same material under the metal roofing uses on flat roofs. 

We also ooked at keeping the width down to 20' but we're having a hall way go along the 10 ft high wall which would have storage on the interior side of the wall and sliding doors on the exterior wall to let in light and give full views of the hill across the river. 

[Don_P]

Actually looking back through this, call your roofing supplier, 3/12 is doable, I've had 2/12 specced in standing seam by a designer that had specs from a supplier.

[Bob S.]

Have you considered making the inside hall wall a bearing wall? And using parallel sicissors trusses for the open area?

[Bob S.]

Just a add on to my post. I know your local truss company will engineer the 24' trusses for your local snow loads.

[river place]

Yes the one end of the interior will have walls that can be used to support the roof.  For the open area a parallel truss could work.

We''l be at the site this week end so I'll look into the layout a bit further.