Foundation Repair Warranties
As with almost any product there can be a wide variety of warranty coverages. Founation repair warranties are no different. They can vary from state to state - so by law a warranty from Missouri may not be the same as one in Illinois. But as a consumer you have some protection from both the state and the Federal Trade Commission on how products are advertised and warranted. See more at https://www.ftc.gov/tips-advice/business-center/guidance/businesspersons-guide-federal-warranty-law.
A foundation repair warranty is only as good as the company backing that warranty. If the company goes out of business your warranty could become worthless. Some foundation repair companies belong to dealer networks that actually combine together to form a national warranty - so even if that dealer goes out of business - your warranty is still valid. This is something you should check the details on when choosing a contractor.
Length of Warranty
So you would think longer is better right? Maybe not. For example sometimes "Lifetime Warranty" means 7 years in some states. There is also Limited Warrantys. So here is some things to consider.
Lifetime warranties usually mean the lifetime of the structure. It could also mean the lifetime of the structure while you own it. Big difference.
X Number of Years Warranty
Different foundation repair products may carry a different type of warranty. For example mudjacking may only cover things for a year. This is because the ground around a driveway could change, water could infiltrate under it causing further heaving or settlement. Foundation piering should be a one time deal - so the warranty should be extensive.
No matter the length of the warranty - you want one that can be transferred at least once. What that means if you repair your foundation and decide to sell you house in a couple of years the new buyers will also have warranty protection. That could make or break a real estate transaction.
Keep in mind you most likely will need to notify the company of the sale and do a transfer application. This may or may not come with a transfer fee.
Review carefully what exactly the warranty covers. It may only be the product and product defects. It may also include labor to resolve any issue with the foundation repair. It is important to understand what will happen should you have to have the repaired area fixed again because of some reason.
Ask up front if there is a charge for a inspection associate with a warranty claim.
The warranty will also ONLY cover the area of the foundation that was repaired. It is possible that if you only piered half the house - the other half could develop problems in the future. That would not be covered.
Should you start noticing cracks to appear after the work is completed there may be a problem - but many engineers recommend a few months (a heating and cooling cycle) before repairing sheetrock and trim to allow structure to relax back once the foundation is repaired. This is normal.
Acts of God usually are not covered. Things like floods, earthquakes, etc. no one can predict and aren't covered.
Usually interior damage of the structure like sheetrock, windows, doors etc aren't covered before during or after the job. It is possible some damage could occur during a building lift process but that is rare.
Voiding Your Warranty
There are going to be some things you could do to actually void your warranty. For example you must maintain your landscaping in a way that water is drained properly from around your foundation. You should also ensure your gutters are working properly. Any number of basic maintenance things could void your warranty. Be sure and review this section on your warranty paperwork.
Adding to the structure or building next to it could change the weight of the structure or undermine the soil next to it. This could also void your warranty.
When in doubt ask up front. Get it in writing. Then you should be covered.