Summary: Build a walkout basement foundation or a raised concrete slab foundation when building a new home on a hill or a steep slope to avoid water problems.
We have a piece of land with about a 9 foot difference in height between the proposed left and right corners of our future house. What are your suggestions on the best way to minimize cost on building a concrete slab foundation? RB
You can’t build a concrete slab foundation on that steep of a slope.
If you have enough land area you can have your excavator scrape a level spot for your house, but that will create a low point in the land and a horrendous potential for water problems.
Water is a builder’s worst enemy.
In your case, a raised slab will be 9 feet higher on one side and building that will be rather expensive as it will require a foundation wall to hold the "compacted" fill dirt/sand.
You could make it a little lower by "leveling" the land a bit, but each foot you level, increases water problems.
A walkout basement may be an alternative. By building a walkout basement you will be digging into the "hill", pouring a slab, and building a foundation wall on the sides that remain below grade while wood framing the rest of the walls.
A picture of a typical walkout basement can be found on byoh.com at: http://byoh.com/basementwalkout.htm.
Water is easily controlled with this type of foundation. It will cost you more than you were planning, but you are potentially increasing the living area of your house.
You don’t have to finish that area off, but it’s there for future expansion of your living area.
Get together with a good foundation contractor and a professional land surveyor on your job site and discuss your options.