I have just finished the grouting on my new shower suround.My question is this: To ensure maximum adhesion between the grout and the silicone, should the grout be sealed prior to applying the silicone (base of wall and inside corners), or should the silicone be applied first, ? As for the sealer, I’m planing to use SurfaceGuard, by Custom Building Products.
Thanks,
R
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Replies
silicone?
I think if you use silicone caulk it would be a mistake.
I have found silicone to not adhere well and to cause problems later on when you will have to recaulk.
Go to color matched caulk from your tile supplier. Comes sanded or not.
I seal after.
Ummm .... silicone sealant (caulk) in the locations noted is required (TCNA and good practice). Grout first, then silicone, then grout sealant.
Want more input? http://www.johnbridge.com/vbulletin/showthread.php?t=85634&highlight=silicone
Next time - use Laticrete SpectraLok Pro grout = no sealer needed.
Jeff
I stand corrected.
From the TCA handbook.
Now let’s take a look at the types of materials used to finish a movement joint, including the specifications requirements for those products. First let’s consider the backup strip material. The backup strip, remember, is the component which is embedded into the body of the joint. The TCA handbook states that “a backup strip shall be a flexible and compressible type of closed-cell foam polyethylene, butyl rubber, or open cell and closed cell polyurethane”.[7] The size of the backup strip must fit neatly into the joint without compacting, and must allow a space for a sealant material to be applied which embeds 1/2 of the depth of the joint. Sealant cannot be bonded to the backing material.
Here are the requirements for a sealant material. Approved sealants include urethane, polysulfide, and silicone, the latter being the most readily available, not to mention the most cost effective. When specifying a silicone sealant, it is important to remember that the material must be 100 % silicone in its make-up. A common siliconized/acrylic bathtub caulk will have a tendency to shrink and subsequently pull away from the tile work. In addition, any material used as a soft joint compound to finish a movement joint in traffic areas must maintain a shore hardness of 35 or greater. Materials used for traffic areas will be noted as “Use T” materials, while “Use NT” materials are used in non-traffic areas. Most sealants which are formulated as a siliconized/acrylic hybrid only maintain a shore hardness of 10. For traffic areas, urethane based sealants are often best, due to the greater shore hardness they possess.
One major reason for the reluctance on the part of architects and designers to specify the appropriate volume of movement joints relates to the fact that the look and cosmetic value of a soft joint compound disrupts the natural flow and appeal of the finish work. Quite simply, the shade and color of the soft joint compound used often times does not match the chosen grout color. One recommendation is to contact a local representative for tile installation, or soft joint materials. Quite often a sealant manufacturer will have a very broad array of colors available in sealant materials, or can even color match a sealant to the grout color in order to meet the specific color requirements for the project.
One advantage to a silicone based sealant is that it will contain a fungicide, and therefore can be specified for wet areas. Sealants used in the finish of movement joints must comply with ASTM standard ASTM C-920.