Grout-Free Shower Panels
Engineered-stone shower panels are waterproof, but proper installation relies on tight seams and silicone sealing.
I’m deep into a house renovation that includes two bathrooms, each slated to feature cultured-marble shower panels and tub surrounds. As I’ve been researching these panels further, it appears the watertightness of these systems is reliant on a bead of caulk in the corners, which makes me apprehensive.
Furthermore, I’m finding that the actual installation seems to fall into a no-man’s-land among the trades—many plumbers don’t want to cut and fit the panels, while many finish carpenters and tilesetters don’t want to install them. Do you have any insights on these systems?
— Anne; New Hampshire
Derek Hill, Sales Manager at Syn-Mar Products, Replies
The advantage of a grout-free, engineered-stone (a type of solid surface, formerly known as cultured marble) shower system is that the panels and components themselves are completely waterproof. Our engineered-stone bases, walls, and components are permanently sealed with a fully bonded gel coat that is nonstaining and impermeable.
This means that no water will be absorbed by or seep through the surface areas of the components. So in a typical engineered-stone shower, the only portions of the installation that require waterproof treatment are the seams and corners.
By treating these locations with a high-quality silicone sealant (we recommend Nexo Flex ACS-850), the entire assembly is made waterproof. Making sure the panels are scribed and fit nicely during installation will allow the silicone joints to be as miniscule as possible, which not only will look the best but also allow the silicone to perform optimally.
Given that the engineered-stone components are impervious and the corners are waterproof once sealed, a fully waterproof substrate behind our walls and base is not required. Because bathrooms are typically higher-moisture environments, we do recommend using a water-resistant wallboard behind the panels, such as MMR drywall or cementboard.
Some installers want to waterproof the substrate using a tile waterproofing membrane or a foam-based tile substrate system. Unfortunately, this can lead to adhesion and cure problems with the silicone adhesive between the panel and the substrate, especially if the waterproofing product is particularly impervious, which then leads to system failures, so we do not recommend this approach.
As these systems become more popular, many contractors are beginning to specialize in their installation. Just as you would for a traditional tile installation, finding a contractor who has experience with these systems is critical to ensuring a good installation. Remember that such a system should be looked at as a premium bath option, just like tile, and that it has a multiday installation process.
As a starting point when searching for a qualified contractor, I suggest reaching out to the manufacturer of your specific shower system. While many manufacturers don’t offer installation services directly, often we can direct you to a short list of qualified installers who work with our products and whom we know install them well.
RELATED STORIES
- Natural and Grout-Free Shower
- Shower Wall and Tub Surround Panels Explained
- Recirculating Shower System
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Do you have more questions about grout-free, engineered-stone shower systems or something else? Get answers you can trust from the experienced pros at FHB. Email your question to [email protected].
