Discussions

Hi there!  
I’m wanting to have my crawl space converted into a full sized basement. I’ve been trying to find out as much information as I could online but haven’t come up with any solid information. Has anyone ever done this? And if so, can you please provide me with the pros/cons, costs, etc? We currently have a 4 ft crawl space with over 1600 sq ft.

The reason I said started of with wow is because of what I would consider to be the biggest con. This is something that can be done, but it will cost much more than the idea of just a basement. The house will have to be raised, the structure that currently supports the house (pony walls) will likely be removed, the area will have to be excavated, sewer and water lines disconnect. At a certain point you will be looking at constructing the basement, which will be likely done in a conventional method, it’s the preparation work that makes something like this costly, but it t is doable.

There is a house on Grand Valley Rd. just one mile west of 18th street and they just did this. It took a long time and was a major undertaking. The house was lifted. It looked like much of the interior was gutted. The yard got torn up by the big trucks and equipment they used. You could drive out and ask them who did the work.

Another option for what you are asking, that I have seen, is where the house is lifted from the crawl space and a support wall is built on top of the existing foundation. There no excavating and the electrical, HVAC, plumbing, we're all quite easily reconnected. This basically gave the house a raised bungalow appearance.  
 
I assume that you are on a rural property and have some latitude with the construction process as it takes up a fairly large footprint to lift the house on beams and block it while the new walls are built underneath it.  
 
Surprisingly, the footings and foundation required for the crawl space were sufficient to build the wall on. It basically became a hybrid basement with the bottom half being 4 feet and the upper half being approximately 6 ft. This gave them a 9 foot finished height in the new basement. This was allowed in there area but I have no idea what local building codes would allow here.  
 
Hope this helps. Good luck!

Great option, something that never crossed my mind, always enjoy new ideas.

Lifting it and building a pony wall to bring the ceiling up to full height is definitely the way to do it vs excavating down.  
That said, I would never do that either. If I lived in town, I’d move. If I lived on an acreage, I’d add on to the main floor. Both much more cost effective IMO.

What is the crawlspace walls - concrete, ICF, PWF? What is the water table? What are the soil conditions? Note that disconnecting the top of the existing crawlspace wall from the floor may affect the ability of the wall to resist soil pressure - goes from 4' supported top and bottom to just supported at bottom. The wall on top will most probably hinge at the connection point. What about adding a second floor on top instead?

You are absolutely correct, but that is to be expected given your profession!... LOL.  
 
In the particular case I was looking at, the high ground water level was exactly why they initially went with a crawl space and not a full basement. The crawl space walls were concrete and the addition / pony wall was built on top of it and anchored to prevent any, what you described as hinging. Wouldn't soil loads be minimally impacted by building a pony wall on the existing foundation and crawl space wall, as opposed to putting on an entire second-story? The main structure remains unchanged. I would be interested in your opinion on that. Thanks!  
 
I suspect that if the OP was going to proceed with this, that obtaining a building permit would entail an engineering report to cover off the points that you raised.  
 
I hope they are able to find a solution that works for them in this situation. I would love to see how they end up doing it, if it does proceed.