I'm kind of sceptical of the 'N' part of this 'functional NBC shelter'. Thing is, to protect yourself from nuclear blast you need to dig in deep. And to be protected from gamma radiation you need a very thick barrier of concrete and lead. We're speaking several meters thick. I doubt you can 'dig out' something like that all by yourself.
And if he actually tried, no wonder his house was declared 'unfit for human habitation'. Propably while digging he damaded the foundations and the whole thing was in risk of collapsing on his head.
You sound like a Fedora hat who has read a couple articles in Newsweek over the years and has come to believe he understands what he is talking about.
Several meters? Did the laws of physics change again on me?
After a lifetime of masturbating in between XBox playthroughs you've probably never packed a sandbag in your life.
Depending on it's configuration, you should already have four sides of earth ten meters wide on every side of you. It is the roof and entrance you worry about in expedient shelters.
What I know about this subject would cause your head to explode if I tried to simply download a few terabytes of my collected information into your skull.
One man can dig out a suitable nuclear shelter in soft ground in about 8 hours. With some old tires, some sandbags (which can literally be made from almost anything) and any natural features you can make use of (stone walls/rock hedge/natural elevation) you could build a shelter that would easily withstand well over 100,000 rads of skyshine outdoors for several months.
I started inside the front porch steps and in three days had a spectacular expedient shelter with my geiger counter, ventilation pump and thermal cooker all built from junk I had laying around the house. I bought a couple plastic drums and had a 200 gallon reserve of water sitting beside it which also acted as a neutron barrier in front of my primary entrance. The air intake was four old expired carbon gas mask filters that would have pulled air through the crawlspace after most of the fallout had already grounded. I don't know how I might have fared in there against heavier-than-air chemical weapons but nuclear I would have sailed through.
I'm only good at a few things in life, Potato - and this is one of them. Really, really, really good. It's like being sheriff of a ghost town that finally vanished off the map.
The real sticking point of any expedient shelter is the expedient toilet filling up. There's your deal breaker that might force you to surface to empty it.
The walls were lined with plastic sheeting and plywood, it was very clean inside when I was done with it. All up I think it took me a month but in a rush I could have completed it in a few days.
P.S. Do you know where your snarky attitude about civil defense comes from? Foreigners wanted that money and they first had to teach you to ridicule any notion of protecting yourself from anything ever for any reason. They got that tax revenue that was once slated for you. Sheeple are very easy to train to sneer on command, it just takes some cliches. They went to work on dismantling civil defense right after they shot Kennedy in the head.