A homeowner comparing three roofers looks at two numbers before anything else: the star rating and how many reviews are behind it. That comparison takes about four seconds and it happens before anybody reads a word you have written. Reviews are also one of the three things the map pack ranks on, so this is one job paying twice.
Getting reviews is not a marketing campaign. It is a habit at the end of a job, and roofers who have the habit pull away from roofers who do not.
Ask in the driveway
The single biggest improvement most companies can make is when they ask. Not by email a fortnight later, when the feeling has faded and your message is under sixty others. Ask at handover, while the customer is standing there looking at a roof they are pleased with.
The words matter less than the moment. Something like: we live on Google reviews, would you mind leaving one while it is fresh? Then text them the link before you drive away.