My belief is that rubble-stone foundations are best left undisturbed, especially below grade. You have your wish list. My recommendation is that you have a certified civil and structural engineer examine both the soil and structural integrity of your home in consideration of your intentions. Much of what you wish to do, if it can be done, will likely need to be accomplished within a very short timeframe - you have to keep the existing foundation stabilized! Qualified contractor, not a DIY project. All I can encourage is get LOCAL EXPERT advise before you begin. I live in N. IL. Our son owns a home the approximate age of yours. Basements then were cellars and weeped in wet season. The advise I share is based on guideance from an architect who evaluated their home for an addition. Hope this rather negative reply is taken as a recommendation to be cautious, not a put down on your desired result. Good luck.

Concrete shrinks as it hydrates. Cracking can be greatly reduced by providing a separation at walls and columns, adding reinforcement, cutting or forming control joints, using less water and using proper finishing and curing methods. Different contractors have different ideas about what is acceptable and how much they should work to avoid cracking therefore it is best to include the required precautions in the specification.

The thing about bitumen, mopped on "damp proofing", is that it tends to work as an effective exterior drainage plane, so long as: o It is not damaged during backfilling. A back hoe that drops its bucket against the concrete wall and bitumen coating during backfill will probably scrape off (or at leaste damage) the coating; o There are no cracks in the exterior concrete foundation/basement wall surface. If cracks take place, chances are very high that the bitumen will also crack (why wouldn't it?) with the result of a direct path for water infiltration. Clay and other expansive soil types expand with moisture and contract when dry. This continual annual "heave" is one good source of foundation wall cracking. If the hydrostatic level of the soil is high, the subsurface water pressure will force water into the foundation walls and any cracks which may be present over time. A plastic membrane, properly installed, will help to mitigate or prevent much of this since it is not impacted by concrete wall cracking (unless there is major structural movement or failure). You originally expressed concerns about concrete cracking. If you are truly concerned about cracking and movement, bitumen damp-proofing will not provide the necessary protection. Only a plastic membrane applied to a foundation properly designed and constructed for your soils conditions, including proper back fill, may do so. Good luck with your project.

jal, Drylok will not work unless you make the crack wider. This happened to me in a house I used to own. I used a hammer drill and made the crack wider, at least a 1/2" wide. Then I filled the crack with drylok... it worked. Not a clean job though, try to keep the floor wet were your working, it keeps the concrete dust down. There might be an easier way to get the crack wider but this worked. Also, when your all done find out where outside the water is draining to the house and change the grade so it doesn't anymore.... course 9" is a lot of rain.... Thanks Dave