This detail shows a sandwich-slab membrane penetration. (Detail courtesy of TAMKO Building Products.)

Sandwich-Slab Membrane Penetrations

In sandwich slab construction, penetrations are waterproofed in similar manner at both levels. The materials and application methods are similar at both locations and should be completed in accordance with the membrane manufacturers requirements.


Flashing material:
Reinforced flashing membrane required by waterproofing system manufacturer.

Adhesive: Adhesive required by waterproofing system manufacturer.

Tape: Butyl sealant tape.



1. Apply the proper waterproofing system over the substrate.

2. Set butyl tape in a 3/8-inch by 31/2-inch configuration to conform around any support collars and bolts.

3. Apply adhesive over the butyl tape.

4. Set the collar around the support and tighten as required.

5. Fill the pan around the collar to half full with adhesive.

6. Place the support pipe into the collar and tighten as required.

7. Set drainage field (if required) around the support.

8. Apply sealant at the juncture of the support and concrete.