Technical FAQ
How do I install natural
thin stone veneer?
With a polymer-modified adhesive mortar system. We recommend the LATICRETE® Masonry Veneer Installation System (MVIS™) for setting our thin veneer.
The 2022 edition of the masonry code (TMS 402/602) calls for polymer-modified adhesive mortars on thin adhered veneer in place of site-mixed Type S. MVIS meets that requirement, and Laticrete backs the full system with a manufacturer warranty when its instructions are followed. The steps below follow Laticrete’s data sheet, and each one links to Laticrete’s own video of the work.
What goes on the wall
Wood or steel framed wall
15-year Laticrete system warranty available
Concrete or CMU wall
25-year Laticrete system warranty available
On concrete, CMU or cement board, the 2022 code allows direct bond in qualifying cases, with no lath and scratch coat.
Structure and substrate LATICRETE MVIS product The Stone Mill veneer
Before you start
- Wall surfaces between 40°F and 90°F during install.
- Substrate sound and clean, with no sealers, oil or curing compounds.
- Wall deflection no more than L/600.
- Stone backs free of dust and loose crumbs.
- Carry substrate expansion joints through the veneer.
- Flashing, weep screed and grade clearance per local code and Laticrete’s MVIS details.
Step by step
1. Prep the wall
Make sure the wall is sound, clean and between 40°F and 90°F. True up rough concrete with MVIS Premium Mortar Bed. On sheathed framing with wire lath, render the wall with MVIS Premium Mortar Bed first.
2. Waterproof
Where waterproofing is required, apply MVIS Air & Water Barrier to the substrate per Laticrete’s instructions before any setting mortar goes on. Flash openings and terminations per your details.
3. Mix the mortar
Use about 5.9 quarts of clean water per 40 lb bag of MVIS Veneer Mortar. Add the powder to the water and mix about a minute with a slow-speed drill. Let it slake 5 minutes, then remix and go.
4. Set each stone
Skim-coat the whole back of the stone, then load more mortar on top. Press it to the wall and slide it 1″ to 1½″ diagonally and back. Aim for 100% coverage with squeeze-out on all sides, and trowel off the excess.
Watch: MVIS Best Practices Part 4, masonry method for natural stone →
5. Or comb the wall
For the tile-setter method, comb mortar onto the wall with a notched trowel and back-butter stones 8″ × 8″ and larger. Spread only what you can cover in 15 to 20 minutes, and pull a stone now and then to check coverage. Ledger boards or shims help hold courses level.
Watch: MVIS Best Practices Part 5, large-panel natural stone →
6. Point the joints
Wait at least 12 to 24 hours at 70°F, longer when it’s cooler, then point with MVIS Pointing Mortar. Keep mortar out of expansion joints. In cold weather, protect the finished work until it’s fully cured.
The numbers
| What | Figure |
|---|---|
| Water per 40 lb bag of MVIS Veneer Mortar | About 5.9 qt |
| Slake time before remixing | 5 minutes |
| Slide to set each stone | 1″–1½″ |
| Mortar coverage target | 100% |
| Back-butter when combing, stones this size and up | 8″ × 8″ |
| Most mortar to spread on the wall at once | 15–20 minutes’ worth |
| Cure before pointing, at 70°F | 12–24 hours |
| Coverage per 40 lb bag, veneer method | 28–33 sq ft |
Why not Type S mortar?
Type S is a general-purpose masonry mortar. The 2022 code change replaced it with polymer-modified adhesive mortars for thin adhered veneer. Laticrete’s short videos show the difference.
- Type S mortar vs MVIS adhesive mortar (video, about 1½ minutes)
- MVIS vs traditional lath comparison (video, under 2 minutes)
- TMS 402/602-22 code change flyer (PDF)
Laticrete resources
- MVIS system page — products, warranties and downloads
- MVIS overview video — the full system in about 10 minutes
- Full MVIS video playlist — every install and product video
- Specifications and details — flashing, weep and wall details over concrete, CMU or framing
- MVIS Veneer Mortar data sheet (PDF)
- MVIS Simple System flyer — wall assembly diagrams (PDF)
- MVIS product selection catalog (40-page PDF)
- MVIS frequently asked questions (PDF)
- Technical design manual — direct adhered stone, masonry veneer and thin brick facades (PDF)
- Free MVIS training — LATICRETE University courses, including AIA credits
LATICRETE® and MVIS™ are trademarks of LATICRETE International, Inc. Videos, data sheets and details belong to Laticrete. Laticrete’s current data sheets and your local building code govern every installation.
The next step
Technical support
from the mill.
Substrates, detailing, stone selection — one call gets a real answer.