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Community and Q&A

Switching to window bucks and liquid-applied or tape flashings

Michael Sterner | Posted in Green Building Techniques on

Building a pretty good house house in zone 7 Northern Wisconsin. 

I’ve got Zola ThermoClad windows coming from Poland but with a 16 week lead time, they’re still out roughly 11 weeks. We’ve finished the floor system and are starting to frame our main floor, rough openings, etc. 

I have a few questions about our approach…

My plans show windows being installed in rough openings at the sheathing level since we had originally intended to use a flanged window. 

Due to timing of window arrival and our desire to continue building and working on our 4″ of exterior Rockwool insulation, rain screen strapping, etc. I believe that I need to use window bucks. This is the only way I can think of that I can continue with exterior insulation and rainscreen strapping and come back to install our windows later, around September 1 when they arrive. 

Window Buck Options (in the R.O. or “applied to face”)
I am looking at 2 window buck options. One is the “Hammer and Hand” method as shown here: I would need to manually adjust all rough openings to accommodate the buck and then there is a lot of messing around to get a sloped sill. 

I am wondering if anyone has done or has feedback on just applied a buck to the face of the sheathing, perhaps using treated wood. It could be attached with brackets and perhaps angle screwing the head and still. Then, using liquid applied flashing just the same and I would then integrate it with my WRB. I would not have to adjust my rough openings and it seems like fewer steps to get the same desired angled sill. 

This seems easier but with the same or similar result? Does that make sense or what am I missing? 

We’re using CDX plywood and a Mento 1000 WRB as opposed to Zip sheathing. 

Liquid Applied Flashing or Tape Flashing a Buck
My next question is thoughts on whether it will be easier to flash using Prosoco liquid flashing or a series of tapes like 475 Pro Clima Extoseal and Contega

Prosoco Liquid Applied to Mento 1000 WRB
Lastly, I wrote to 475 to ask about using Prosoco liquid applied flashing with their Mento 1000 and they said to ask Prosoco. Does anyone know if I can use Prosoco liquid applied flashing with Mento 1000? 

I greatly appreciate your experience and feedback!

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  1. Expert Member
    Akos | | #1

    I have done the exterior applied bucks with 2" insulation without issues. This was regular 2x lumber ripped to thickness and attached with long structural screws. I added slope with a piece of clap board cut to width, simpler than beveling the bucks.

    In my case the WRB was above the rigid, so flashing was easy. In your case, you'll have to do a bit of flashing tape origami at the plane transition. Make sure to lap the joints properly, since you have a sheet WRB I would stick to tape instead of liquid applied.

  2. Jason S. | | #2

    You could run the Prosoco up behind the WRB at the head directly to plywood, just leave the WRB temporarily unstapled just above the rough opening/buck. I'm a fan of the fluid-applied for weird geometries. Worth the cost.

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