How to raise ceiling on one-story

I'm adding onto an existing structure (old woodworking shop). This will require full new roof, but there are already some slight hiccups in the existing building even beyond having to work around an existing space.

The building as-is has an unfinished main section (wall studs are visible, but ceiling joists are not due to insulation and a poly sheet rolled across to cover entire ceiling). This area is roughly 25' x 26' and has concrete slab set on block foundation that is filled with some type of agregate to support the huge slab.

Then at the front is another finished section which has a floor 16" above the slab floor of the main area and has a kitchen and a bath with crawlspace underneath. This has normal flooring rather than the slab. The property slopes from front down to the rear. Originally the main area had a garage door on back which was at truck bed height for easy transfer of lumber into the shop. This kitchen/bath area is finished with an 8' ceiling.

I intend to raise the floor of the main area to facilitate ease of access due to balance issues related to brain surgery. As it is now, this would give me 8' ceilings throughout.

The new finished structure would have an unfinished, but finishable attic space with stairway access leaving an effective upper story load on exterior walls.

I would prefer a 9' or 10' ceiling throughout. The roof is coming off anyway. What would it take to raise the current walls in order to have a higher ceiling without just tearing out and rebuilding the exterior walls? The new roof would have a 30 degree slope with gabled ends. Also, in the kitchen, the plumbing wall for sink and fridge is against exterior wall that would have roof slope down to it. New walls for the addition would, of course, be built to the taller spec.

Here is a pic of the Workshop plan as it is now. I've drawn these plans myself (.png files should be viewable in all browsers).
http://homepage.mac.com/vrdaver/Sites/Old_Workshop.png

Interior pic of main area of shop.
http://homepage.mac.com/vrdaver/Sites/IMG_3262.JPG

Pic of Front of current workshop.
http://homepage.mac.com/vrdaver/Sites/IMG_3277.JPG

Pic of back of current workshop.
http://homepage.mac.com/vrdaver/Sites/IMG_3271.JPG

And a pic of the proposed expansion plan. Some how the dimensions on this plan got off. From front to back, it should be 36' with the main room being 24' 5".
http://homepage.mac.com/vrdaver/Site...shop-House.png

Sorry this is so long, but I wanted to be thorough.

 

I'm not an architect, but if I were doing this, I would remove the top plate and sister the longer 2 x 4's for all load bearing walls. Any interior non load bearing walls you can just box in.

I don't know about your local code which might require 2 x 6 instead of 2 x 4 for all new wall construction, in which case, you might have to replace the bottom plate at which point it might not be worth it. As I'm looking at your drawings I think you should go to a structural engineer or an architect for a consultation. You have a very long span to support and you might need 2 x 6's on all walls anyway.

 

All the wood required for sistering sounds a bit pricey. I may have to just live with an 8' ceiling and be thankful i'm not some of the people on here I've read of that have under 8'. However, would it be possible to sister the 2 end studs and then add a wood i-beam header at the top? Would that simplify things and still be structurally sound (hopefully even stronger). I've been considering using wood i-beams for the joists in raising that floor anyway. By the way, I neglected to mention before that this is not a DIY project. I have a contractor, but he's been out of the business for a while.

i-Beam wall would look something like this
http://homepage.mac.com/vrdaver/Sites/i-beam.png

 

Hey, That is a neat idea. As long as the old top plate and the I beam are tied together really well , it shouldn't be a problem. Any structural engineers care to comment?. The only downside would be a little extra cutting for the plumbing and electrical.

 

I'm not so hot on the i-beam idea. It won't be wide enough to put the second floor on. You would need to double it up and that may not be worth the cost. You would probably have to use dimensional lumber in that case anyhow.

My idea is to build a short 2x4 wall on top of the old one and bolt them together.

 

Thanks for your reply. I guess I had been concerned with rolling of the top portion, but really if the end pieces are sistered as in my illustration, it would be no worse than the i-beam solution.

Sorry, I'm merely a layman and not a builder at all. I barely even know the terminology (and probably misused THAT.)… much less what's needed for true structural integrity.

So would this be a strong solution? There will be a new attic with floor and stored furniture items above this and room to be finished at a later date. As you can tell in the photos, the original building has such a low pitch that the only thing above the current ceiling level is insulation and the roof. So, I'm equally concerned about the current wall's ability to hold up that additional weight. The raising of the ceiling will have to be a secondary "wish". But if I need to shore up that wall's strength anyway, maybe the raising of the ceiling height could be tackled as well with nominal added expense?

http://homepage.mac.com/vrdaver/Site...ll_section.png