I have a project where I am the GC/builder/developer. Expensive area of California, so this is a big budget job. We are adding a single-level 1500 sq ft addition to an existing 1950’s single level ranch home. We would like the addition to have 10′ ceilings throughout. The existing house is an architectural mess – 7’2″, 7’6″, 8’1″, 8’6″, 8’9″ top plate heights and a terrible roof design. The top plates and roof design make it impossible to tie ceiling and roof lines together. 

We already know that we will be tearing the entire roof structure off and replacing with a new roof truss system with higher ridge, increased pitch and attic storage. The problem is bringing the existing mismatched top plates in line with the top plates of the addition.

My framing sub would prefer to scape the house to the deck and reframe with new walls. I agree that this would probably be the most efficient method from a framers perspective. But the demo cost, disposal cost and recycling requirements that would be placed on the project make it a wash. Also, the city (who just spent 4 months to approve design review) would not look too kindly on this approach (submitted demo plans showed a more selective demo). There is a chance that they would be none the wiser, as the city only approves planning/zoning/design, while the building permitting and inspecting is handled by the county. Typically, city officials don’t return to the property until cert of occupancy.

So, I am weighing the following options:

1. build knee-wall with Simpson Strong-Rod system on top of existing plates 
2. add 11 7/8 to 18″ LVL or PSL (depending on need/location) on top of existing plates, with whatever hardware spec’d by engineer to eliminate hinge effect
3. leave one wall in tact, demo the rest to the subfloor
4. take my chances with the city & scrape the entire building to the subfloor and reframe. 

Thoughts on above options? Alternative options that we haven’t seen? Thanks.