On 14 Sep 2006 04:06:53 -0700, wrote:

can you convert the house into a houseboat by adding pontoons?

Be better off driving piles either inside or outside the foundation,
(or both) and taking the weight of the house on steel beams, assuming
bedrock is anywhere within reach. With any luck, the foundation won't
continue to sink as long as the weight of the rest of the house
is off it.