Significant main drain build up...

Had a camera run down my main to locate it for a new basement bathroom. Starting around 20 feet (still under the slab, but only about 8" from foundation), the drain has significant buildup. It's a 4" cast iron drain and the inside diameter is down to 1.5-2" from the buildup. The house was built in 1959. I'm just looking on some thoughts on this and opions on what to do next.

• Is this normal for a house of this age?
• Would snaking it only be a temporary fix and possibly break the pipe?
• I've got the basement floor torn up now and don't want to come back in 5 or 10 years and rip it up again to fix this...for this reason my thinking is that I should have it all ripped up and replaced...any thoughts on this? I do plan on being in this house for a while (10-20 yrs).
• There is about 20 feet of drain under slab then another 40-50 feet to the street...any ideas on costs? I'm in the Washington DC area.

Thanks in advance for any suggestions/thoughts/opinions-
Jeff

Any idea of what is causing the buildup?
It might be better just to replace the pipe now when the basement is already torn up...
At least replace the pipe section you can reach from the basement...
That way if you have to replace more later you only have to dig outside the house...
I would bite the bullet and do it while it is only a little headache...
While you have the floor torn up to replace the pipe you might want the drain to be snaked and cleaned to see what was causing the problem...
If it is roots or a problem farther out from your house you will probably have to replace that pipe later anyway...

I guess normal use is causing the buildup?

all of the buildup is on the bottom of the pipe so I guess it's just normal buildup of "crap" flowing through it. The top side of the pipe doesn't have any buildup at all. Again, I don't really know...Is this normal?

I kind of agree w/ what you're saying, that now might be the time while I'm already into the floor. I'd hate to have to destroy my ceramic tile floor in another five years.

Jeff

From what you have said I surely wouldn't do anything other than get some one with a man size Snake and clean and flush with a lot of water.

If the pipe is filled from the bottom with sediment, have it snaked and cleaned as suggested by Plumber1,,,
After this is done, have another camera run down and see if there is a reason for the pile-up in the piping...
It could be that there is an obstruction ahead of the build-up or that there is a belly in the main closer to the city sewer...
If so, that will have to eventually be fixed as well...