This Beaver Creek mountain home project required installing slate stack stone on a cathedral master bedroom feature wall that rises 24 feet to its peak — one of the most demanding residential tile installations in terms of height, logistics, and material weight management. Scaffolding was erected inside the occupied bedroom to safely reach the upper vault, and the slate was installed from floor to peak with continuous coverage wrapping through the arched window surround and continuing into the master bath.
The critical technical challenge on this project was substrate adhesion. Standard tile thinset is not rated for direct application to drywall — and when you're hanging natural slate stone at 20+ feet with no mechanical fasteners, adhesion failure is not an option. The solution was Mapei Eco Prim Grip, a water-based acrylic primer specifically engineered to create a bonding bridge between smooth, low-absorption surfaces like drywall and the thinset mortar system. Applied before tile setting begins, Eco Prim Grip transforms a substrate that thinset would normally slide off into a surface that provides the grip needed for heavy natural stone installation at any height.
Drywall is a smooth, low-porosity surface that standard thinset mortar doesn't bond to reliably — especially under the weight of natural stone. Cement board or Schluter-KERDI-BOARD is the standard solution for wet areas, but on a large interior feature wall that isn't subject to water exposure, installing cement board over the entire 24-foot surface adds significant weight, cost, and complexity. The approved alternative — used by professional tile contractors when the conditions are right — is Mapei Eco Prim Grip.
Eco Prim Grip is a water-based acrylic bonding primer that chemically prepares smooth, non-porous substrates — including painted surfaces, existing tile, concrete, and drywall — to accept thinset mortar with the bond strength required for tile and stone installation. It works by creating a micro-textured bonding layer that gives the thinset something to grip, converting a surface it would slide off of into one it can mechanically and chemically adhere to.
Eco Prim Grip is listed in Mapei's system approvals for tile and stone installation over drywall substrates on non-wet interior applications. It is water-based, low-VOC, and compatible with all standard thinset mortars. Applied by brush or roller and allowed to dry to a tacky, water-resistant film, it provides the bond strength needed to safely install natural stone on vertical surfaces without secondary mechanical fasteners. For this Beaver Creek project it was the difference between a 24-foot slate wall that holds — and one that doesn't.
Existing drywall inspected for fastener schedule, joint tape adhesion, and surface condition. Any loose tape or damaged areas addressed before priming. Surface cleaned of dust and debris. Drywall does not need to be sanded — Eco Prim Grip bonds to the paper face as applied.
Mapei Eco Prim Grip applied by brush and roller in a single coat over the entire tile installation area — including all wall surfaces, corners, and areas within 12" of the ceiling line. Allowed to dry to a tacky, slightly textured finish (approximately 30–60 minutes depending on conditions). Once dry, the surface is ready for immediate thinset application.
Baker-style scaffold erected inside the occupied master bedroom to provide safe working platforms at multiple heights from 6 feet through 22 feet. Scaffold boards leveled and secured. Drop cloths and protection deployed across all furniture and flooring. Working from bottom up — slate set from floor level first, then scaffold raised progressively to reach the cathedral peak.
Slate stack stone set in Mapei Ultraflex 2 large format non-sag thinset using the back-butter method — mortar applied to both the primed drywall face and the back of each stone panel. Non-sag formulation critical at height to prevent stone from slipping before thinset sets. Each course leveled before the next is placed. Mitered returns at all outside corners maintained throughout.
Upper courses cut to follow the cathedral wall angle — each piece field-measured and cut individually at the top of the scaffold. Slate fitted tightly against the arched wood window frame with field cuts made on-site. Ceiling transition sealed with flexible sealant to allow differential movement between the stone wall and the ceiling plane.
Feature walls, fireplace surrounds, cathedral applications, and specialty substrates — we have the product knowledge, the equipment, and the experience to execute stone work at any height and complexity.