Questions & Answers

Hey all,

I’m having a contractor remodel a bathroom and install a new shower. I’ve done a couple Kerdi showers myself, but brought in pros this time due to the size and complexity of the project.

Today, they finished installing Hydro Ban sheet membrane over the shower pan. They used a generous amount of sealant around the bonding flange where the membrane connects.

After they left, I noticed two air pockets around the drain area. One is fairly large (covers about 1/4 of the drain’s circumference), and the other is small — both are shown in the annotated photo below.

I know air bubbles can usually be cut and patched, but since this is such a critical area, I’m wondering:

• Is a simple cut/patch still appropriate here?

• Or should I have them cut out and replace the entire area around the drain (e.g. a 24"x24" section)?

• Would it be smart to require liquid Hydro Ban over the full pan once the fix is made, just for added protection?

The rest of the membrane install looks good — no major wrinkles or bad seams or other air pockets that I can find.

Edit:

After a closer look, I’m now concerned that the sheet membrane was bonded to the bonding flange mostly with sealant, not thin-set. It was installed about 14 hours ago, and the area around the flange still feels soft or spongy when pressed.

That raises some new questions:

• If the membrane was adhered primarily with sealant, does the whole area around the flange need to be removed and replaced?

• Can the bonding flange be cleaned well enough for thin-set to adhere properly afterward?

• Or would this require replacing the bonding flange entirely to ensure a watertight tie-in?

I appreciate any advice, especially from those who've dealt with similar issues around drains. Thanks!