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Detailing a Water-Resistant Barrier on a Parapet Wall

deerefan | Posted in General Questions on

I plan on using Carlisle WIP 300HT over the sheathing as the primary WRB on a flat roof with parapets. The outside wall WRB is Delta Vent SA. How should the parapet WRB be detailed? Should the WIP 300 go up onto the parapets and then lap onto the wall? I am concerned it may have trouble adhering?

Insulation with PTO membrane will go over top as the main water barrier. Thank you.

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  1. Expert Member
    Peter Engle | | #1

    Unless the parapet wall is very tall, or unless you want to install cladding on the inside of the parapet wall for aesthetic reasons, it is generally not necessary to have any underlayment or WRB on the vertical parapet walls other than what the membrane requires. The TPO membrane manufacturers all have details for running their membranes up the inside of parapet walls, over the top, and terminating them on the outside at the top of the parapet. Just follow the details for your membrane and you'll be fine.

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