Wrong tiles

[PCAnimal]

Hi I've got a 12.5 degree pitch roof and 8 years the roofer installed marley roof tiles which are suitable for 15.

In the last 2 years I've got a small leak coming through near the vulux. This only happens in very heavy rain I've had a roof around and they say the only solution is to rip them off and start again with 12.5 pitch. The original builder is nowhere to be seen.

I don't get why it didn't leak from the get go in heavy rain. Why would it take this long.

Any advice please

 

[datarebal]

Post a picture inside and out

 

[Alastairreid]

I don't get why it didn't leak from the get go in heavy rain. Why would it take this long.

It probably has been leaking from the get go but the membrane keeping the water out, only now the membrane is failing.
Standard velux go down to 15° with correct guage. Always a weak point.