There are a number of alternatives for replacing the sewer line. It really depends on the depth and the landscaping. If your yard is landscaped like the Imperial Gardens of Japan, then you probably want someone to come in and line your pipe. This is a fiberglass liner that is installed on the inside of the pipe, which takes the shape of the inside of the pipe and seals it completely. The pipe has to be cleaned first and dirt can't be entering the pipe. So if they can't stop the dirt entering, you may have to use another technology called pipe bursting. This is where they run a machine down the inside of the pipe which opens it up by breaking it and drags a new pipe along behind it, which takes the place of the old pipe. Both of these two options are much more expensive than digging and repairing/replacing, but you have to consider the age of the pipe and the life expectancy. If your pipe is more than 35 years old and its clay, you are going to end up replacing it if you want to keep the house for a lifetime. Clay sewers have a 60 to 70 year lifespan, after that they begin breaking down, with tree roots, expansion and contraction and other natural hazards.
Roots can grow in any type piping except glued PVC and the new fiberglass. Since your house is probably either clay or cast iron or PVC with gaskets, you may be able to dig up small sections. But when considering the repair, make sure you know all the costs. Digging a complete yard will require you to do a lot of landscaping, sidewalks and even possibly street repair. This is part of the cost people don't tell you when they quote you a price.
If you've had your pipe inspected with a camera on the inside, look at the tape and decide, is it time to put a new engine in this 35 year old car, or replace the car?
Make sure you check with contractors who specialize in pipe lining and bursting technology before you decide to dig the whole thing. And make sure one of them will camera the line so you know for sure what your need to do.
Raymond VinZant Plumbing Prof.