When a contractor sets up screed boards with rebar, which penetrates the vapor barrier, what happens when the rebar is pulled - leaving a hole in the vapor barrier? What are alternative methods for setting up screed boards to eliminate this issue?
laser screeds or don’t worry about it. Those are just about your only choices - that I know of
I forgot. A few contractors are placing little metal feet on the pegs that disengage once the concrete is poured thereby NOT puncturing the Vapor retarder and still allowing the use of regular screeds. little feet are often metal tube on small plate with a few tack welds
See the article posted on Stego’s website: “Don’t Puncture the Vapor Retarder”
This is what I generally say in my specs:
“Do not use screed stakes in areas where vapor retarder is installed.
Use screed pads to hold screed posts.
Do not pierce vapor retarder.”
does anyone have a link to a specific product for the screed pads that screed stakes would be attached to? seems like a non-metallic product would be better as a left-behind than the metal feet type.
we have quite an issue with vapor up thru the slab here in the northwest and are always having to push the contractors to see the issue
Try “G-3” device from Dayton Superior; also dee Concrete Accessories and C&H Concrete Specialties for variations of what is shown in article Ron noted in the link.
My bias is to simply say that they cannot penetrate the vapor retarder. When you get into specific techniques you are unnecessarily getting into means and methods.
Knowledge of these devices are useful if the contractor says he cannot comply with your requirements.
WR Grace has two Tech Letters that might be of interest:
Rebar chairs
http://www.na.graceconstruction.com/custom/waterproofing/downloads/tech_letters/WP-015.pdf
Prep and Repairs
http://www.na.graceconstruction.com/custom/waterproofing/downloads/tech_letters/WP-033.pdf
It is interesting to note that for horizontal applications they recommend concrete or brick blocks, pavers, or dobies as rebar supports.