loft room built 4 yrs ago major leak with rain

[ohmeohmy]

and builder not replying to my messages. What to do next?

We had this recently. Check your roof tiles as they may be cracked or displaced. One way to tell is whether the felt is wet.

Is the work guaranteed? Think ours is for 5 years, but check the contract as they will try and say the roof is excluded.

Thanks for reply. it is a flat roof bit. From the way it is coming in I think there might be cracks in the walls. Felting itself should hold for 10+ yrs.