CRACKWIDTH FOR BASEMENT WITH PVC LINING?

[iyota]

I work in a pretty good company. And we're designing an RC basement under the water table. It is lined with a loose-laid PVC membrane.

For crackwidth, everyone says we need to limit the basement wall/raft crackwidths to 0.2mm. But I keep questioning why 0.2mm when there is a flexible membrane lining?? In my opinion, 0.3mm should be OK.

The limit of 0.2mm I think is for swimming pools and other RC structures with cementitous waterproofing or none.


Can I get anyone's opinion on this? And is there any guidance in the codes for flexible membrane-lined basements?

Thanks...

 

[JedClampett]

Membrane trumps cracks. Design the basement for the structural loads and not for crack prevention. Although it's not unheard of of owners removing membranes and hoping the concrete will hold the liquid.
And one thread is plenty.