Last week I had a garden office built by a firm that specialises in these things. Surprisingly today I noticed that the roof is very uneven and bubbly looking in parts. I don't know what it's made from, but it looks like EPDM or similar. Luckily, I haven't yet paid the balance for the office, so the firm will hopefully be keen to put this right. What should I be asking them to do? Re-roof the whole thing, patch it or something else?
Picture below:
Picture below: