Liquid-Applied Flashing Product
Hello, My name is Jim. I am building a house in climate zone 6. My windows arrived last week and I am planing on installing them in the next few weeks. My original plan was to use a peel and stick to flash the windows and exterior doors until I read Martin’s article “Liquid-Applied Flashing”.
The product that caught my eye is “Dow Corning 778 Silicone Liquid Flashing” now renamed to Dowsil 778. The fact that it can be applied at temperatures as low as -20 degreesF got my attention. It is mid January here and I doubt we will have temperatures warm enough for the other products until late March or early April.
Martin’s Article was very informative but I have two questions.
1. Has anyone tried this product and what are your thoughts? I’ve tried to find more information on people using it but can’t seem to find any “testimonials” good or bad.
2. In the article Martin writes “Surprisingly, Wagner later sent me an e-mail noting, “I want to make sure that you add the clarification that DC778 is not designed for use in single family residential construction.”
I can’t seem to come up with any idea on why they would specify that. Any ideas?
Thanks in advance,
Jim Kelly
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Hi James -
I have not used this material but hoping others in the GBA community have.
In terms of this product's suitability for residential construction: hard to cipher that out. I did some searching of DOW tech documents and could not find anything (for example: https://consumer.dow.com/documents/en-us/app-tech-guide/62/62-14/62-1444-01-construction-fenestration-technical-manual.pdf?iframe=true.) And I don't see that comment by Wagner in the article, frankly?
Thanks Peter, this is what Martin wrote about the product. The quote is at the bottom
Dow Corning 778 Silicone Liquid Flashing. This product is sold in sausages and designed to be installed with a trowel or spatula. The installation thickness is 25 mils (wet thickness). The product will not stick to housewrap, so a transitional material (Dow Corning 758 sealant) should be installed at any transition between Dow Corning 778 and housewrap.
Of all of the products mentioned in this article, Dow Corning 778 is best for installation at cold temperatures (as low as -20°F). When cured, the product has a vapor permeance of 3.1 perms.
According to Andrea Wagner, one of the best features of Dow Corning 778 is “the ease of toolability.” She told me, “This material tools very well. Installing it can be compared to frosting a cake.” (See Image #3, below.)
Surprisingly, Wagner later sent me an e-mail noting, “I want to make sure that you add the clarification that DC778 is not designed for use in single family residential construction.”
Any new finding on this LAF? I am seeing 778 as most cost effective solution for my house since ZIP is almost double the price. Any suggestions are appreciated.
Arek