Packing Bottom Plate of stud wall due to uneven floor

Hi Guys,

I am building a stud wall in my kitchen which has an uneven floor. The floor seems to slope up to where the chimney is, so my bottom plate is not going to be sitting firmly against the floor without some special attention. The slope is not consistant either, so it is not a simple matter of letting the bottom plate sit on the floor and then use different length studs.

What should I use for shims/packing underneath the bottom plate so I can make it level? I have some new eaves linings which I was thinking of using as there is a chance that whatever I use will be exposed to moisture, being in the kitchen. I also have some masonite. I was going to make fine adjustements with sheets of wet-and-dry sandpaper.

Would any of these materials do? I am mindful that whatever I use needs to be able to withstand considerable compressions, and I don't want the framing to move after it has been gyprocked. Is there a commercial product that is designed for this kind of purpose that can withstand high pressure and moisture ?

Any advice appreciated.

Non shrink grout available from Bunnings about $20 for 29kg bag

We've shimmed bottom plates like this with treated pine ripped to size and offcuts of laminate and/or alcor folded over to suit. Both of the latter two are non absorbent.

Stewie