Discussions Walls and Roofs Is the ZIP Sheathing system better than house wrap? F Fred Martens 1 year ago Updated: Dec. 18, 2021 Save Like Comment(1) Share Facebook Twitter Email Print Wanting to do exterior insulation on the northside of house.
What the Zip Sheating System offers is a hybrid sheathing / weather barrier /air barrier all-in-one combo product. It is more expensive than you would spend for sheathing and house wrap together, but you will save a lot in labor as you only need to tape the joints and it is complete, rather than circumnavigating your house a second time stapling and taping a WRB house wrap.
There are some great advantages to it, but also a downside that doesn’t get at on of mention – The ZIP System is less moisture permeable than a normal combination of sheathing and house wrap. This isn’t catastrophic, and unfortunately hybrid ad-on products regularly show up on the market as quick fixes to meet energy-efficiency updates in building code that can actually cause problems.
Walls need to be able to dry for durability, and so we like to see exterior surfaces as moisture permeable as possible. This page highlights a few such products and the ensuing challenges they present –
Which is better Plywood or OSB for walls and roofs?
What really works with the ZIP Sheathing system is its ability to create a truly effective air barrier. Weather barrier house wraps like Tyvek, Home Wrap etc, are airtight as a ‘product’, but once you slam a few thousand staples into them, missing the mark with a few hundred probably and doing nothing but creating a hole for nothing, it is hardly effective as an air barrier.
Not to mention that most commonly-used building tapes have solvents in them, which evaporate over time and become brittle. So building tape on house wraps in cold climates will likely not adhere for very long. But ultimately, yes, we like the ZIP system, at least more than a lot of other common building products and wall assemblies that you will find in mainstream building industry, but it’s not perfect.
We would recommend that regardless of what sheathing and air barrier you put on, be sure to check this page about how to install siding so walls can dry. It is important to allow easy air flow behind siding, in which case you are at least giving the ZIP System its best chance to dry out if any moisture accumulates. 7
Last page I think you should check out just to explore your options is this one on the best way to insulate the exterior of old homes