Brick or concrete as an RF shield?

Not likely.

As a ham myself for almost 20 years, I understand what you're saying, but all the VHF/UHF in the world isn't going to help in a regional disaster where the scope of the 'dead zone' is beyond VHF/UHF range... like Katrina, or a tsunami, or anything else that affects a large geographic region (like maybe when the Yellowstone caldera finally blows).

At some point, you have to get help from outside the affected area - and probably the only way to contact them (outside of satellite) is going to be HF. If the people who have power CAN'T HEAR YOU DUE TO LOCAL INTERFERENCE ON THEIR END, then what have you actually accomplished? Yes, you've done some local triage. You've probably gathered a list of needed supplies and ordered your 'need' list.

When you've done as much as you can inside the affected area, who are you going to ask for help now?

For a wire to not be an efficient RF radiator, typically it has to be 1/4 wavelength or longer. For the freqencies we're talking about (up to 30MHz), 1/4 wavelength can be as short as 2.5 meters (since 28MHz is around 10 meters).

14 MHz is only 20 meters, so a piece of wire 5 meters long (or even a combination of wires that are segmented together through a panel) can become a radiator (aka transmitting antenna).

You can see where this is going. It's hard to get the frequency low enough where the typical wire layout in even a small home won't tend to transmit RF energy. The lower the frequency, the smaller the frequency spread. You can't transmit as much data in 2-10MHz (8 MHz of total RF spread) as you can in 2-30MHz (28 MHz of spread), and so the throughput rate of the device would be so small that it would no longer be a viable product.

They're caught between physics and the market.

When you're in a disaster, you're not really interested in getting help from other people who are also in the affected area, who are also without power.

You want help from people *outside* the affected area. And if this goes forward, they won't be able to hear you. Which means there's no reason to keep the radios in the first place.

This is the problem with rail in most places. Most urban/suburban areas are so poorly laid out that rail is only able to service a very few number of people from "near door" to "near work". This is made several times worse if they are only able to put the rail 'where people will let them', which usually means the rail doesn't service many people along the route - because it's in the boonies.

They might have a way to block Skype, or it could just be a large amount of jitter from you to the Skype gateway you were trying to reach.

I'm assuming the system is electric, but it could only meet the "no CO2" if the electric power is nuclear, hydro, solar, etc... If it's traditional electric power, it's just moving the source of the CO2 and perhaps the efficiency.

First and foremost... ask if you can bring a radio onboard before even thinking about any of this. Their radio operator will probably notice your operations.

Second, the Sailmail service doesn't even require an amateur radio license. It works over commercial frequencies.

http://www.sailmail.com/smprimer.htm#Getting%20Connected%20via%20Radio

Third, the modem required for Sailmail is several hundred dollars, not counting the radio and the antenna (another thousand plus)...