I am replacing the marble threshold in my shower. The previous one had a large rust stain which I beleive was from a screw in the Wonderboard. Upon removing the stained threshold, I discovered some of the Wonderboard broken so I mixed up some thinset mortar to patch it and level it out.
Now I’m ready to install the new marble threshold, again in a bed of thinset mortar. But, I want to seal the underside first just as a precautionary measure.
With what, how much, etc?
Ricky
Replies
First, I doubt that the stain was caused the way you believe.
Likely an iron deposit in the stone, perfectly natural, though not always desireable.
Second, if you have DW screw(s) in your curb, you have a very big problem, much bigger than the stain in your marble.
Eric
I Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
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Eric -
Thank you for your response. I wasn't aware that marble could contain iron. Anyway, the threshold (and rust stain) is history.
I;m not sure what you mean about the drywall screws and a very big problem. Please elaborate.
Thanks,
Richard
Using CBU as the substrate for a curb is not the best way to go.
Floated mortar or preformed is best.
There are ways of attaching CBU, without fasteners, but it is tricky, and arguably not the best method.
There should not be any penetrations throught the threshold and thus through the membrane that is folded over the framing providing waterproofing to the threshold.
And then, not only do you have penetrations that will eventually leak, but someone use high carbon steel Dry Wall screws that will rust out about 5 minutes after getting wet.
Who ever did your curb broke just about all the rules.
EricI Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
[email protected]