Under Coating, under subfloor, under tile, under concrete screed FAQUpdated 15 days ago
Application
Question: Which products do I use to waterproof under tile/concrete screed/subfloor?
Answer: You can use Liquid Rubber Foundation Sealant. When applying to concrete or wood that is in contact with the ground you will also need Liquid Rubber Multi-Purpose Primer, and Geo-Textile and/or Liquid Rubber Sealant & Adhesive Caulking. For wood use Liquid Rubber Deck and Patio Cleaner to clean. For concrete use Liquid Rubber Concrete Etch to remove laitance prior to application.
Question: Do I need a primer?
Answer: Yes. Liquid Rubber Multi-Purpose Primer is critical for under subfloor, under tile, under concrete screed surfaces that are on or near (within 6 ft) of grade (the ground) as these substrates will be subject to ground moisture and therefore moisture vapor drive. The primer will increase bond and help to mitigate the moisture vapor drive.
Question: How much do I need?
Answer: Liquid Rubber Foundation Sealant is applied at 1 gallon per 20 sq ft - 1 gallon per 15 sq ft when used for these projects.
Answer: To determine how much sealant or primer you need, divide your total square footage by the coverage rate provided. Example: You have a 200 sq ft surface and the coverage rate is 1 gallon per 20 sq ft. so 200/20 = 10 gallons of the Foundation Sealant. (Apply in multiple coats until all material has been used.). Coverage rates are expressed in final coverage and will include all coats needed to achieve membrane thickness.
Question: Do I need Liquid Rubber Seam Tape or Liquid Rubber Geo-Textile?
Answer: Liquid Rubber Seam Tape is quite thick so it is recommended to use Liquid Rubber Geo-Textile for this application as it provides less of an edge to be worked (e.g. kicked at) and is the less visible of the two products. You can also use Liquid Rubber Sealant & Adhesive to seal/fill cracks, joints, gaps 1/8" - 1/4" prior to applying your geo-textile.
Question: What tools do I need to apply my Liquid Rubber products?
Answer: Most of our coatings and primers are applied using a brush or 10mm (3/8") nap roller.
Question: Do I need to scuff the existing wood/coating?
Answer: Yes. It is recommended to scuff the existing wood or coating to increase the surface profile and therefore the mechanical bond.
Question: Can Liquid Rubber products be applied to concrete?
Answer: Yes. Liquid Rubber products bond very well to concrete. The concrete must be fully cured, free of laitance and efflorescence and have a moisture content of less than 5%. Liquid Rubber Multi-Purpose Primer may be required. Refer to our application guidelines for more information.
Question: Do I need to etch/grind concrete?
Answer: If laitance is present you will need to etch, grind or wire wheel the surface to remove the laitance.
Question: Do you have application guidelines/instructions to help me with my installation?
Answer: Yes. The Under Coating application guideline can be found in our Help Center (click here).
Question: Do I need a new brush/roller every time I apply a new coat?
Answer: If you wrap your brush/roller in plastic (e.g. a grocery bag) you will slow down the curing process and you should be able to use the same brush/roller for your next coat. You can go a step further and place the plastic bag in the refrigerator (Do not allow contact with food)
Question: Can I coat over an existing coating or paint?
Answer: You can apply over most acrylic/latex, polyurethane, alkyd paint, epoxy paints/coatings with proper cleaning/preparation. Keep in mind that when you apply over an existing coating or paint, if that coating/paint peels, our coating will peel with it as it is bonded to the existing coating/paint and not directly to the substrate. An adhesion test is always recommended to ensure adequate bond prior to full application.
Answer: It is recommended to remove oil based or recently applied coatings with high solvent content prior to applying your Liquid Rubber products. (oil and water don't mix and solvents can deteriorate our water-based coatings)
Question: Will the Foundation Sealant fill cracks and hide imperfections?
Answer: No. Repairs to cracks 1/8" - 1/4" should be prefilled/sealed with Liquid Rubber Sealant & Adhesive prior to geo-textile application. For concrete: Cracks and voids over 1/4" should be repaired with a suitable patching material and allowed to fully cure prior to applying geo-textile and coating. For wood: Cracks over 1/4", knot-holes, etc. should be filled with wood filler or another appropriate patch material.
Question: What if I have a problem or question with an application?
Answer: Our technical support team is here to help you, just reach out to call. email or chat with one of our representatives.