totaled the roof and wrote me a check for $29,000. I can get the roof replaced for much lower than that. Will they ask for the difference back? The adjuster said nothing about having to turn in a receipt upon completion.
You can keep the difference for yourself. However, I would caution you on getting the best roofing company possible. I have had many clients had very poor experience with roofing companies. It is an industry that is currently fraught with contractors who are going out of business (which would be bad for you after they did a job because their warranty would be worthless!), some are con artists, others are just in such dire economic straits that they will quote you a low price to get the job and then can't finish it because they run out of money and/or the job could never be completed for that amount.
You need to make sure that the Roofing Contractor is Licensed, Bonded & Insured. Depending on the jurisdiction many contractors will list themselves as licensed, bonded and insured. Essentially the license means that he has complied with the requirements of the jurisdiction and has therefore been issued a license. Some jurisdictions require that they be tested in the particular expertise that is declared by the contractor, i.e. a carpenter in carpentry, a drywall installer in drywall, etc. In some jurisdictions the test also includes legal requirements for what makes a valid contract, etc. You should ask for a copy of the license, but I would also take it one step further and verify that he is still actively licensed with the state or jurisdiction where the work will be done.
I have seen cases where the contractor will fake everything from the license to the proof of insurance (i.e. an insurance certificate). Faking documents is easily accomplished nowadays via computers, scanners, color copiers, etc. Therefore call the state verify the license and call the insurance agent or company to verify the proof of insurance.
Some jurisdictions will require that contractors obtain a surety/license bond in order to obtain the contractors license. The bond is essentially a financial guarantee given to the state to cover if the contractor takes someone's deposit and then fails to complete the work, the state can then ask the bonding company to pay on the bond thereby reimbursing the homeowner for the deposit. Not all jurisdictions require a bond. However, if the job is large enough and/or if bank financing is involved you or the bank can require a performance bond which would essentially do the same thing, i.e. provide a financial guarantee to make sure that the work is completed.
I suggest that you obtain a Certificate of Insurance naming you as Additional Insured. Make sure that the Contractor is covered for Commercial General Liability (including Products and Completed Operations) and for Workers Compensation Insurance (if they will be bringing in workers–this is very important with roofers because of the high risk of falls!) and Commercial Automobile Insurance if they will be driving their trucks or vans onto the job site or picking up materials on your behalf. The Commercial General Liability Policy will provide coverage if during the course of work they cause damage to your home, i.e. while applying stain to your new kitchen cabinets they start a fire that spreads to your entire house resulting in a total loss.
You should also check the contractor's references to make sure that his work is top notch–a license does not guarantee quality work! And go one more step and check with the Better Business Bureau to make sure he has had no complaints filed against him. Also make sure he has been in business a few years–that way you can make sure it is not a fly by night operation that is here today and gone tomorrow (very important to back up the guarantee!) If the project is over $15,000, I would also do no more than a 25 or 30% down payment & the balance in 2 payments (one midway and the other upon satisfactory completion). Also the contract that you sign with them has to be very specific in all details (i.e. a detailed scope of work) listing that they will tear off and haul away the old roof, check the subroof, replace roof with …. roofing materials, install flashing, replace gutters, etc.
Make sure that the entire project is done to your satisfaction before you hand over the final payment and/or before you sign any release. If they subcontract any portion make sure that you get a release of all liens from them–this protects you in case they fail to pay a subcontractor and the subcontractor subsequently tries to file a mechanic's lien against the property.
I hope this helps. Good Luck!