Replies

1. 
   Lawrence | Feb 23, 2006 05:40pm | #1

   Anything can be done--it's just the cost you may not like.

   If it is a rubble foundation you will want professional advice--that can be dicey. If it is poured it is easier. Block--needs some care.

   Underpinning involves digging out enough to maintain the initial bearing. You then connect the new wall to the old within the outline of the wall. It takes space within the room, but built in cabinetry above can make it efficient.

   You may want to pay someone who specializes in it to help you plan--then run it by an engineer to make sure what you plan is safe.

   L

    

   GardenStructure.com~Build for the Art of it!

2. 
   SamT | Feb 23, 2006 06:14pm | #2

   Jack,

   I alway think outside the box. . . it's a curse sometimes.

   Since you will want your new underground living space to be dry and comfortable, excavate outside the walls, a short distance at a time and emplace the new foundation from there.

   You will need an engineer to tell you how long a stretch of existing footing you can undermine.

   Cut off the footing, pin the bottom of the wall, and pour a new, deeper footing and wall.

   After the entire wall has been extended, put in insulation, drainage and waterproofing. Backfill.

   If you can get a 36" opening, you can use a mini-skidsteer to excavate the interior.

   SamT

3. 
   jeffwoodwork | Feb 23, 2006 06:23pm | #3

   I'm no eggspurt but I think you would want to shore up the house jack it up off the foundation.  You will have to cut some plumbing maybe even electrical, I'm thinking demo out the old foundation and footings.  Then dig down an addtional 5+ feet might as well go with 9' or 10' ceilings.  Then dig a basement (5' dirt removal) and repour footings and walls.

   If you have the room you can dig out a ramp on one side and drive a skidsteer in and slowly remove the material.  It certainly can be done I just wonder how the cost is compared to going up or going out with a remodel.

   Jeff

1. 
   jackc1702 | Feb 24, 2006 03:08am | #4

   thanks for the feedback.since the goals here are two -- control costs and find a place for my soon-to-be-teenage kids to go in the house -- i'm trying to do as much of this with sweat capital as possible.i looked up underpinning on a few engineering forums, and a few basement experts talking about working in old stone foundation homes suggested digging inside the walls by 2-3 feet to avoid underpinning or disturbing the foundation at all. my foundation is blocks on a poured footer, but i'd be happy to give up a few feet to avoid major foundation work.am i nuts, or just a little too eager to avoid going up or out?jack

1. 
   DavidxDoud | Feb 24, 2006 03:34am | #5

   i've seen what you describe many times - also seen a two story victorian brick crack and break - you takes yur chances - if your ground is stable and there are no drainage issues,  it's unlikely you'll have any problems -

   gotta get the dirt out someway,  so usually there is an entry/exit big enough for a bobcat - perhaps you can put the teens on shovel and bucket brigade? - I didn't think so....

   some areas may have permitting/engineering requirements - does your area require permits and such to do work?

    

    "there's enough for everyone"