How to repair Summerhouse roof?

[ljrc]

Hello,

Some roof shingles have come off my summerhouse and I need to repair them. I can't find single sheets of the hexaginal roof shingles (I can only find them sold in packs) and so I was thinking of simply placing a piece of felt over the damaged area, fixed in place with clout nails?

The shingles were placed directly onto the wooden boards of the roof. I have read that felt should have been placed first? If I can find single sheets of the roof shingles then I plan to lay felt before the shingles.

If anyone has any thoughts/suggestions they will be greatly appreciated!?

Thank you