[redacted]

If you can't slope the footing drains to daylight, then you are going to have a very important sump pumping system complete with redundant pumps and backup power sources if you don't want to have a swimming pool down there. Toilets and sinks will have to have an active pumping system to get it to the sanitary sewer or septic system. Secondary access will require stairs or ramps.

[redacted]

When he says slope drains to daylight, what he means is your home built on a hill and high enough that you can just run the drains out the side of the house that is exposed to daylight, assuming you will have one side of the home exposed to daylight, and let gravity drain the water away rather than have to install pumps to lift the waste water out. Some basements, particularly up north, are built on essentially flat ground. Any waste water or ground water in or under the basement slab has to be "lifted" by electric pump to get it out. If you are building into a hillside that has at least 10' of rise, this shouldn't be an issue.

If you intend to build underground, and your footprint is 40'x80', the center of your "roof" will be at least 20' from native soil. How do you intend to put dirt back on the roof after the concrete is poured? I doubt you will build the roof structure strong enough to support heavy equipment. I guess you could use a very small tractor with front end loader, but you are still likely looking at 1000's of pounds per square foot of pressure at the tractor front tires with a load of dirt in the bucket. But I know it has been done because I have seen underground houses built into hillsides here.

Likely the biggest cost of building underground is the roof structure that is strong enough to support several feet of soil and the waterproofing necessary to keep water out long term.

Don't "waste pipes" have to go to either septic tanks or sanitary sewer systems? Where are you that you will just let untreated waste flow out?
If your water table is always far below in soil that is permeable, you may not have to have the active footing drain pumps. I built mine in clay where if you dig a 17' deep hole, you will soon have a 16-1/2 foot deep swimming pool. Once you excavate and it rains, you'll know if you have to provide for drainage.
And yes, running the drains to day light means the land slopes more than the drainpipes so they eventually surface.

WITW do you want to build underground and not have any windows to look out?? You would be living in a cave!! Not my idea of living.

[redacted]

Very glad to hear that no one will be living in this structure as underground buildings are notoriously uncomfortable and problematic if used for that purpose. And then there is the issue of meeting building codes such as providing bedroom egress, etc. Condensation and mold are the biggest problems followed by structural failures that cause leaking. The former can be mitigated by highly insulating the walls and ceiling. The latter is always an eventual reality that will require endless and expensive repairs. As such, unlike most buildings that appreciate in value over time, underground buildings depreciate in value like cars. Every underground building that we have been associated with used a dome concrete reinforced roof. You might find this story informative:

Pitfalls of Underground House

[redacted]

I am not a tornado structure expert. Frankly, I don’t know if anything can be made tornado-proof. Tornado-resistant is likely the right term and realistic objective. From what I understand, a tornado can remove the soil to the bedrock under the right conditions. So I would think any tornado-resistant structure would needed to be very heavy, securely anchored to the ground, or well below ground level. Supposedly, you can construct above-ground concrete structures that can resist tornado forces. Above-ground structures would also need to be capable of also dealing with tornado airborne debris. The Pensmore mansion is reportedly designed to be capable of withstanding an EF5 tornado and is constructed of ICF and uses Helix micro rebar to increase the strength of the concrete:

Pensmore Mansion

Short of being completely underground, ICF walls and roof are going to give you the strongest structure possible and can be designed to withstand EF5 tornado wind forces with enough concrete and steel reinforcement. Based on the size of your structure and ICF roof, it would need engineering design rather than using the Prescriptive Method.

The weak point in the ICF structure would be the windows and doors. It sounds like you can minimize or mostly eliminate those for your use. For windows, you can keep them as small as possible and install steel exterior shutters for times when maximum protection is needed. For door(s) you can install FEMA EF5 rated safe room doors. For even more protection for the doors and windows you can install exterior concrete vestibules to provide protection from wind generated missiles.

Another idea is rather than build the house in the ground, why not build the house on the ground and then bring in soil and berm up around the structure? Say you build a pond on the property close to the house and use the excavated dirt to pile up against the exterior walls extending out 8 to 10 feet or so all the way around. With a properly designed ICF roof, I would be inclined not to put dirt on top of the structure just to avoid many of the headaches of being completely underground (i.e. finding and fixing water leaks). You can also put a slight pitch on the ICF roof to facilitate water run off rather than ponding to reduce the likelihood of leaks.

With regard to the condensation and mold issue, it is all about keeping the interior surface temperature above the dew point temperature. The dew point temperature is a function of the dry bulb temperature and relative humidity (or wet bulb temperature). Perhaps see our psychrometrics calculator to get a better feel for this:

Borst Psychrometrics Calculator

So you can keep the interior surface warm (via more insulation between it and the cold ground temperature) and/or dehumidify the interior air. The former can involve significant insulation expense. The latter can involve significant operational expense and the humidity level may also be well below people comfort level.

Thanks everyone for the advice

Ever thought about using Precast Concrete for the roof. We have a 30x40 garage with the upper level being the main garage and the lower having a small garage door. This could that been all underground if we wanted.

About a quarter of the way down you can see the precast concrete being installed....I am sure if it can hold cars it should be able to hold some dirt.

https://goo.gl/photos/ATo7Lc5yrR4EVwCt8

Posted By newbostonconst on 25 Mar 2019 02:44 PM
Ever thought about using Precast Concrete for the roof. We have a 30x40 garage with the upper level being the main garage and the lower having a small garage door. This could that been all underground if we wanted.

About a quarter of the way down you can see the precast concrete being installed....I am sure if it can hold cars it should be able to hold some dirt.

https://goo.gl/photos/ATo7Lc5yrR4EVwCt8

Thanks, I'll ask about that.

I have used precast and love it, but it does require good access to the site for a long truck and free space for the crane to set up. Sharp turns in the road and tight lots may rule out precast.

I don't see anything different than build a basement in case u not going to do "Furrer bunker" in couple of levels deep. Drainage in my area is required for everything below grade level. Clay and send is not an issue as well: u will need to put bigger footers - I have the same soil. I would recommend you to do soil test yourself: buy pocket penetrometer online. U probably need rent excavator to go deep enough to your level. Also you probably whant to put concrete roof on top of your construction - in my area no one knows how to build that from residentional contractors (I wanted to build concrete 1st floor floor upon the basement, and end up go with wooden joists instead) I would consider to not hire a company, but do everything yourself using helper labor and renting concrete pump. Also there will be an issue with shoring system: companies who have them will not what to rent it to you unless you going to build 100 floor building with millions sq ft space. U still can go with self made wooden shoring system, but then you will have a lot of wood wasted at the end of your project, and u will have headakes with inspections if you need to do any before pouring the concrete. Saying all of that I give up building concrete flooring and plan to go with wooden joists on the 1s floor.

I don't see anything different than build a basement in case u not going to do "Furrer bunker" in couple of levels deep. Drainage in my area is required for everything below grade level. Clay and send is not an issue as well: u will need to put bigger footers - I have the same soil. I would recommend you to do soil test yourself: buy pocket penetrometer online. U probably need rent excavator to go deep enough to your level. Also you probably whant to put concrete roof on top of your construction - in my area no one knows how to build that from residentional contractors (I wanted to build concrete 1st floor floor upon the basement, and end up go with wooden joists instead) I would consider to not hire a company, but do everything yourself using helper labor and renting concrete pump. Also there will be an issue with shoring system: companies who have them will not what to rent it to you unless you going to build 100 floor building with millions sq ft space. U still can go with self made wooden shoring system, but then you will have a lot of wood wasted at the end of your project, and u will have headakes with inspections if you need to do any before pouring the concrete. Saying all of that I give up building concrete flooring and plan to go with wooden joists on the 1s floor.

I don't see anything different than build a basement in case u not going to do "Furrer bunker" in couple of levels deep. Drainage in my area is required for everything below grade level. Clay and send is not an issue as well: u will need to put bigger footers - I have the same soil. I would recommend you to do soil test yourself: buy pocket penetrometer online. U probably need rent excavator to go deep enough to your level. Also you probably whant to put concrete roof on top of your construction - in my area no one knows how to build that from residentional contractors (I wanted to build concrete 1st floor floor upon the basement, and end up go with wooden joists instead) I would consider to not hire a company, but do everything yourself using helper labor and renting concrete pump. Also there will be an issue with shoring system: companies who have them will not what to rent it to you unless you going to build 100 floor building with millions sq ft space. U still can go with self made wooden shoring system, but then you will have a lot of wood wasted at the end of your project, and u will have headakes with inspections if you need to do any before pouring the concrete. Saying all of that I give up building concrete flooring and plan to go with wooden joists on the 1s floor.