Found it, Loved it, Bought it, Now I want to live in it. Not a real cave. More of an excavation tunnel. An 80 + year old rock quarry with a 14k sq cave.

I wish to build a Large Load bearing wall to close in the front of my cave.
Than I wish to build a 20' X 40' platform 12' underneath clearance. I intend to use the front wall in my platform build. Then add two possibly more post / beam.

This structure needs to support traditionally framed 3 bedrooms. Sort of loft stile or mezanine like.

Cant decide between wood and steel. Can not determine cost on either. I would like to cantaliever 3' off the front for a porch on the second floor even if I can't spel.

So span would be two segments of 20' with 3 ' cantaliever on each end or 46' and then 16" centers or 15 rows.

Then there is the post. I figured wall, 20ft, 40ft or use of four. Not sure on diameter or load requirements for this. I might have as many as 35 people up there for a party in the cave some night. hmmm.

Intend Pier foundations going as deep as I can. I am not sure how much of bedrock I am suppose to mess with.

Well as you can see I hope this thread is as much fun for some of you as it is me. I am building my home. I appriciate your advice.

Curt Sleeper

 

Curt,

I can't help you with any engineering advice but have some general experience with structures.

There are a few issues that will have to be dealt with:

Have you consulted a building inspector in your area?
It is a requirement that there be more than one exit.
You will have to ensure that there are no traces of harmfull gasses or radon coming from the cave walls.
There has to be continuous ventilation for the occupants and because of the confined nature of a cave there may be occupancy limits.
There is a possibility that the cave will be damp and you will need a means to deal with this.
You will have to determine how you will provide water and sewer.
You also will have to find out first if you can find a company willing to give you insurance.

 

Thanks, I have considered and research almost all of your concerns. The property used to be ( 1960 - 1985 ) a public roller skating facility. The local building inspector agrees on egress and we have over 40' from two seperate doors. There is below 3 part per ?? of radon throughout the cave. Mostly 1s and 2 like any other house. Action limit is 4.

I am looking to compare cost and rigidity between manufactured lumber, lumber and possibly steel. I understand that steel is a little expensive currently.

I think I have found most of my answer at the local building supply. Thanks anyway.

Curt

 

Hmmmm...


1) radon - if this thing is wide open, how do you know what your radon levels are? If one side is getting full ventillation, it will significantly lower your radon levels. Once you close it in, they will go up.

2) if you're on bedrock already, you probably don't need a foundation or pier. Just build on top of the bedrock.

3) get a local structural engineer to look at it.

4) can you hang your structure from the ceiling? If it's solid rock, you may be able to get a cool structure cheap. steel rod in tension is a lot cheaper than anything in compression.