Roof job - advice

[KJT73]

Hi,
We have had a roof replacement. Following removal of the tiles and placement of membrane, it rained heavily. A lot of rain came through the membrane into our loft - which is now very wet in places. Water also came in and left quite large damp patches on the wall in two parts of upstairs. This was about a week ago - one patch is disappearing but the other patch is not disappearing and actually seems to be spreading in some places. We have been told this is nothing to worry about and almost to be expected this time of year. Any thoughts on this?
Thanks

 

[blup]

Give it a year to dry out, the walls are just soaked.

Blup

 

[datarebal]

Membrane quality makes a differnce

 

[^woody^]

"Expected" lol. Only if you employ crap roofers.

And no, once the source of the damp is removed, the damp should not spread. Also be aware that once-wet plaster may have salts that leave a blown surface or a permanent stain that requires sealing before painting over.

 

[TeaAndBiscuits]

Membrane quality makes a differnce

Could you expand on this a bit please for someone who is looking at getting his roof redone?

What is considered high quality membrane and what is low quality?