Hello TOH discussion members. Thanks in advance for any advice you can give.

I'm in the process of adding a 14 X 26 foot addition to the back of our house. The new foundation is placed and I just discovered that the existing house is out of level by 1.5 inches over the 26-foot width of the addition. The new foundation is poured level to the low point of the existing foundation.

I do not want to level the existing house (it is on caissons and seems to be stable).

The addition will be totally open to the existing house house so I need to match the existing ceiling and floor.

Does anyone have any advice on how to handle this situation? Should I keep the depth of the addition(the two - 14-foot walls)level and slope the outside 26-foot wall? If I did this I would shim the sill plate and then grout under the sill plates.

How do you handle framing the walls when the deck is out of level? I had been planning to frame the walls on the deck and then lift them up. If I do this the studs will not be plumb; I'm thinking that I could live with this(except for the corners which would need to be plumb to match the intersecting walls).

Thanks again.