Air tightness membrane wrap to hollowcore slab?

[Lemlin]

Is this needed? One company have quoted me 500 + VAT to do it and say it is required but two companies have said it is not.

 

[RKQ]

Yes IMO there is a need to supply and fit of air tightness membrane wrap to hollowcore slab.
Otherwise the air from the cavity can enter the voids in the hollowcore slab & vice versa.

Heat loss at the wall & 1st floor junction can be significant.
Have a look at air tightness manufacturers details, Dept of Envirnoment details & Homebond manual / recommendations.

Steer clear of any Company that says you don't need it. Consult the Technical Dept of either of the 3 Suppliers, Siga, Moy or ProClima. Check their web sites for construction details.

 

[tred]

RKQ, I picked up hollowcore from a company, where the outsides are all cased in with concrete, I assume this is sufficient.