Can I Build a Basement Under a Ranch House?

Dear Real Estate Adviser,

I am looking at a raised ranch house, which unfortunately doesn't have a basement. I'd like to know if it makes sense to build a basement underneath or build an attached one. Or should I just be content to live with the ranch house like it is?

-- Krishna

Dear Krishna, So you're looking for a third level of living space, eh? Raised ranch/descended basement?

A raised ranch home typically "raises the roof" of a conventional ranch design to create additional living space. This was a relatively popular construction style from the mid-1940s through the 1980s and was a little more common in rural communities than cities. A raised ranch home's bottom level, which generally features a garage, either sits at ground level or at slightly below grade and can serve as either a finished living area or quasi-basement.

These two-story homes were typically built with gable roofs and a flight of stairs at the main entrance that leads directly to the top living area. Some raised ranch homes were built into hills to a degree that the home's full size wasn't immediately evident from the curb. In fact, these remain particularly attractive to upwardly mobile Hobbits in Middle-earth. Oops. Sorry, wrong column.

Since the foundation in your average raised ranch home is typically a slab, digging a basement underneath could be prohibitively expensive, though possible. After all, just about any structure can be underpinned to allow digging below. But there is more involved here than just jacking up the house and digging. There would be rewiring, re-venting, re-piping, damp-proofing and many other aspects that would need to be addressed, plus you may face potential issues such as broken windows from the house resettling. Flooding complications can arise from soil instability, neighborhood drainage paths or a high water table. Plus, building codes in many areas require windows and emergency egress in any new basement construction.

Talk with a few contractors, and you'll get a pretty good picture of the job's complexities. It's evident that such jobs can cost up to half as much as a house is worth. If you think that's an exaggeration, read accounts in various online forums of folks who literally got in too deep in such projects. These are definitely not for the do-it-yourselfers unless you are a skilled builder.

For less money, you could build a small above-ground addition with a modest-size basement (assuming the soil allows it) and not have to tear into the original foundation. The above-ground component would also add resale value to your home while the basement under the current structure wouldn't. Plus, a project dug behind the house wouldn't necessitate you finding temporary digs when the real dirty work ensues, unlike a subterranean one.

Only you can answer the question of whether you should "just be content" to live with the home as it is, though I suspect your bank account will have a say. Whatever you plan, interview three contractors and vet them thoroughly. Oh, and whatever your budget is, account for 10% to 20% in unexpected additional costs.

Happy ranching!

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