I've asked someone I know to project manage some small improvements to a flat I'm buying. It's an informal arrangement - he has no particular credentials in this area but he needs work and he's someone I know and trust and has recently done up his own place. We agreed an hourly rate but now he wants to charge me half that rate for travel time to and from my place. Is this normal? It's not a massive commute - about 30 minutes by car.