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Community and Q&A

Techniques for Tar paper

John Nooncaster | Posted in Energy Efficiency and Durability on

Michael Chandler, GBA Advisor wrote here:
https://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/18747/crinkled-housewrap-or-tar-paper-under-exterio

“Many of the tapes that are made to stick to housewrap won’t stick to tarpaper…. That tape is critical, especially at the windows and doors. .”

Given Conditions —
Zone 4 — Mixed Humid — New construction — Sip panel walls with brick veneer

I assume tape referred to in tha above comment is the package sealing type tape available with tyvek, correct?

What about compatibility (adhesion) of vycor type products and tar paper?

My builder is planning on using tar paper only. What impact will this have for window sealing techniques. I’m familiar with the proper techniques using Tyvek (etc) but how is it best to seal a window to be waterproof and air tight when using tar paper?

Is a rigid sill pan with caulk better with tar paper than a vycor/flex wrap formed pan because of sealing to the tar paper?

What about wrapping the jambs with tar paper and then sealing with foam. Interactions between foam and tar paper? How about sealing the tar paper to the sheathing? If caulk is desired, what type is compatible?

On Monday, I’m checking on the “WRB in a can” products? Is it worth the expensive since air sealing of the sheathing is not a major concern with sips?

Thanks in advance for your responses

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    John,
    Traditionally, when using asphalt felt ("tar paper") as a WRB, you need to depend on laps, not tape, for watertightness. If you think like a roofer, and if you lap upper courses over lower courses, you should be fine. Many builders prefer to minimize the use of caulk, since caulk can restrict drainage.

    Either a rigid sill pan or FlexWrap will work fine, as long as the pan drains over the WRB below.

  2. John Nooncaster | | #2

    What about airtightness?

  3. GBA Editor
    Martin Holladay | | #3

    John,
    Like most WRBs, asphalt felt is not an air barrier. You have many options for establishing an air barrier, but don't expect asphalt felt to help.

    For more information on air barriers, see Questions and Answers About Air Barriers.

  4. Matthew Amann | | #4

    Butyl tapes stick better to it than asphalt based tapes/wraps.

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