Stone adds an elegance and beauty to a home, a fireplace, feature wall or any other project that it is used on. But to ensure the desired results it is important that our stone veneer is installed properly. Proper installation ensures the final project has the visual appearance desired, but there are also important aspects physically such as the proper surface preparation (i.e. moisture barrier, etc.).
The majority of our stone veneer is installed by professional masons but we also get a lot of inquiries from those who want to take on the project themselves. Either way, it is helpful to know how to properly install your stone veneer to make sure it is being done correctly. Before you begin any installation it is important that you know and understand your local building codes and requirements.
In this article we will use our installation manual to help you understand everything from how to determine the amount of stone you need, what tools are required, how to prepare the surface and how to install the stone. We will also include a video that walks you through each of these steps. Additionally we will talk about Polymer Modified Mortar and it’s uses and benefits.
Measure total square footage of area to be covered with Kodiak Mountain stone veneer. For example, a wall may be 12 feet at the base and 12 feet high12 x 12 = 144 square feet.
Determine the area of all large openings such as windows and doors. For example, the wall in part A) may have a window measuring 3 feet by 4 feet 3 x 4 = 12 square feet.
Determine the linear footage of corner stones needed. Each linear foot of corner stones also accounts for approximately ½ square foot of area. For example, the wall in part A) may have 24 linear feet of corners24 x ½ = 12 square feet of area.
Deduct the area of openings and corner area square footage from total square footage: A – B - C = needed square footage of rock. Example from parts A), B), and C) yields the following: 144 - 12 - 12 = 120 square feet of flats are needed, along with 24 linear feet of corners.
Some extra quantity of stone is desirable for fitting and cutting. Please add 10%.
– Grinder complete with masonry cutting blade
– Circular Saw complete with both wood and masonry blade
– Safety Glasses
– Dust Mask
– Grout Bag
– Soft Bristled Brush
– 1 ¾ Roofing Nails
– Tin Snips
– Wheel Barrow
– Masonry Trowel
– Spacers or shims
– ¼ Margin Trowel
– Hammer Tacker complete with Staples
– Stiff Bristle Brush
I. Preparing the Surface
1. Moisture Barrier
If you are installing the stone over wallboard, paneling, plywood, or other rigid woodrelated
sheathing, it is necessary to cover the wall surface with a moisture barrier. In
most cases, building codes are satisfied by using 2 layers of tar paper or two-ply 60
minute grade D paper. Be sure that the sheets overlap from the bottom up. Overlap 2
inches on the horizontal seams and 6 inches on the vertical seams. Flashing, weep
screed, and appropriate drainage means are required at stoppage points of stone
veneer and at any places of potential penetration.
When stone is to be installed over clean brick, block, cement board or other masonry
surfaces, no moisture barrier is necessary.
Check your local building codes for required flashing specifics and to ensure these
instructions meet specific moisture barrier requirements.
2. Wire Lath
Directly over the moisture barrier, cover the area with a wire lath. We recommend
using at least a 2.5 lb (1.71 Kg) diamond mesh expanded wire lath meeting the
requirements of ASTM C 847. Overlap lath sides and ends no less than 1. Be sure
the lath is attached with the small cups pointing upward. Attach the lath using
galvanized nails or staples every 6 on center vertically, and 16 on center
horizontally, trying to penetrate studs with each nail. Use staples or fasten any loose
areas between the studs. Use tin snips to cut the lath. With corners, ensure that the
lath is tightly foldednever have a seam on the corner, and nail the lath on both faces
of the corner.
II. Mixing the Setting Mortars
You will need three different mixes for your stone veneer installation: scratch coat,
mortar, and grout. Each differs and requires specific amounts of different materials.
While each mason tends to have their own recipes, we have found the following
proportions to work well:
Scratch Coat – 1 part Type S Masonry Mortar, 2 parts Masonry Sand
Mortar – 1 part Type S Masonry Mortar, 2 parts Masonry Sand
Grout – 1 Part Type S Masonry Mortar, 3 Parts Sand
NOTE: If mixing your own mortar from scratch, ensure that all ingredients comply with, and
are mixed to meet ASTM standards and/or local building codes:
Cement: ASTM C 150, Type I, or masonry cement meeting ASTM C 91.
Masonry sand: ASTM C 144, natural or manufactured.
Pigments: ASTM C 979, mineral oxide type. Do not exceed color manufacturers limitations.
Mixed mortar should comply with ASTM C 270, Type S requirements
Mixed grout should comply with ASTM C 270, Type S proportions
*See below for information on Polymer Modified Mortar
Combine mortar and sand in a wheelbarrow and mix them together. Do this before adding any water.
Add water slowly, mixing continually while mixing. Avoid adding too much water as this can make the mix an unsuitable consistency.
Continue adding water and mixing until a consistent paste is formed, free of excess clumps.
III. Scratch Coat
Cover the entire wire lath with an even, ½ layer of mortar. Work the mortar with a cement trowel then scrape off the excess.
While the cement is still wet, gently scrape it with a fine bristled brush or hair pick. The resulting grooves rough up the scratch coat this added friction creates a better bond when the stone is applied. The brushing should be gentle enough that no mortar is removed.
Let the scratch coat dry sufficiently. Drying can take anywhere from 8 to 24 hours depending on temperature, humidity, airflow, and mix used. Once dry, the scratch coat should have a light gray color.
IV. Applying the Stone
Before applying stone, ensure that proper measures are taken to divert water runoff
away from the stone. This can be done through the use of cant strips, gutters,
and flashing. Excess run-off and splashing can, over time, stain the material. Also
ensure that the stone will not be applied below the water level, and will not be
subjected to chlorine or other chemicals that may discolor the stone.
Mix a batch of mortar according to the recipe and directions in this manual.
Before any installation, it is always wise to lay out a section of stone on the
ground, preferably 15-30 square feet. This exercise will help you better blend
colors and stone sizes when you apply the stones. The goal is to achieve a balance
of stone sizes, shapes, colors, textures, and thicknesses. Proper blending can also
be achieved by selecting and mixing different stones from different boxes during
Cornersit is helpful to install the corners first. Alternate the short and long returns as you install them.
When installing flats, start from the top and work your way down; this will help keep the stones clean from dripping mortar. However, with Ready Stack, we recommend starting from the bottom and working your way up. When using Ready Stack, work your way up, pushing each piece tightly against the stone next to it and below it. Use a level as you work. We recommend these stones be installed side by side to keep the entire row the same height. This will ensure that with each new row, you have a flat level surface to work on.
Before mortaring and installing, dry fit each stone to ensure it will fit in the desired place.
Using a trowel, apply a ½ inch layer of mortar to the back of the individual stones. Press the stone against the wall, and gently press it into place. If mortar drips onto another stone, wait until the mortar is dry, then brush it off with a dry whisk broom.
Stones can be cut or trimmed for fitting purposes. A power saw with a masonry blade works best. You can also trim small pieces off with a widemouth nipper, or cut a stone in half with the back of your hammer, a trowel, or a hatchet. Cut at an angle so as to best disguise the cut. Cutting can also be concealed through the grouting process.
In extraordinarily hot weather, dampen the back of each stone just prior to installation, as well as the surface to which the stone will be applied. Note that in cold weather below 40 degrees Fahrenheit (5 degrees Celsius), mortar will not cure properly.
Note: For tight fit/dry-stack veneer installation it is suggested to use a Polymer Modified Mortar.
Mix a batch of grout according to the recipe and directions given in this manual.
The hole in the tip of the grout bag should be no larger than a ½ inch to begin with. You can always cut the hole bigger if needed, so it is best to start small.
The grout bag should be approximately half full with the mixture. Twist the top end of the bag until some grout is pushed back into the bucket. This will eliminate air bubbles, and help the grout stream to be smooth and consistent.
Keeping the top end twisted, gently squeeze the grout into the joints. Gaps between stones should receive a ½ inch layer of grout.
Let the grout begin to dry until it is firm, but not solid. This usually takes 30 to 60 minutes. Be sure to not let grout fully dry or striking will be impossible.
Use a wooden or metal striking tool to rake out the excess mortar. This helps you achieve the proper depth, and also forces the mortar into the joints to achieve a thorough seal along the stone edges. When striking, the grout should crumble away. If it smears or gathers too much, then it is too wet and needs to dry for a few more minutes.
Use a soft bristled brush to sweep excess dust off the stone and further smooth the joints. Never use wire brushes, and make sure brushes used are dry, as wet brushes, combined with the grout, may stain the rock.
Polymer Modified Mortar
At Kodiak Mountain Stone, we supply SPEC MIX Polymer Modified Stone Veneer Mortar. For information on other brands please inquire with the manufacturer.
In March of 2016 we released the following bulletin to our dealers, masons and users of our products:
DATE: MARCH 2016
REGARDING: The use of Polymner Modified Mortar for tight-fit/dry stacked veneer installation
TO: All Kodiak Mountain Stone Dealers, Installers, and Users:
We believe quality stone demands quality installation. Mortar has changed. We ask that you all stress the importance of using Polymer Modified Mortar for tight-figt/dry stacked veneer installation. These new Polymer Modified Mortars are more workable, and they bond better.
Type N or Type S mortar should not be used for installing tight-fit/drystacked installations. Polymer Modified Mortar should be used for these tight-fit/drystacked installations. Conventional Type N and Type S mortars are designed for laying up block and brick, and are not required to have high bond strength. Polymer Modified Mortars on the other hand are made specifically for bonding and provide very high bond strength. Type N and Type S mortar are adequate for installing stone applications having grouted joints because the grouted joints provide additional bond to the sides of the stones; and also because the grouted joints act as a secondary attachment. In addition, the grouted joints also seal the stone walls from water accumulation behind the stones which can cause debonding when frozen. But tight-fit/drystacked stone installations don’t have these grout joint “safety valves”.
SPEC MIX® Polymer Modified Stone Veneer Mortar (PMSVM) is a technologically advanced adhered veneer mortar for use in bonding adhered manufactured stone veneer, natural thin cut stone and thin brick to a cementitious substrate. PMSVM is designed to provide excellent workability, cohesion, high bond strength, sag resistance, water resistance, efflorescence minimization, and durability. SPEC MIX PMSVM is the ideal solution for architects and contractors with projects where an immediate and ongoing need for mortar delivering high bond strength and sag resistance during installation is required. In applications where mortar joints are not utilized,such as dry stack applications, SPEC MIX PMSVM should be used to gain additional bond strength and “pop-off” protection. Installing natural thin cut stone veneer is aided by the unique anti-sag and high bond properties of SPEC MIX PMSVM.
In addition to custom mix designs that are available for specific applications or properties, the SPEC MIX Polymer Modified Stone Veneer Mortar is designed to be compatible with the characteristics of most all specified adhered masonry veneer units. It is acceptable for all types of construction: concrete, masonry, wood frame or steel studs, with submittals available upon request.
HIGH BOND STRENGTH
NON-SAG PERFORMANCE & REDUCED CRACKING
REDUCES POP-OFFS, CALL BACKS & REPAIRS
RESISTANCE TO WATER PENETRATION & EFFLORESCENCE
PRE BLENDED WITH SAND TO MINIMIZE LABOR & WASTE
CONSISTENT QUALITY CONTROL WITH EVERY BAG
GREAT WORKABILITY AND BOARD LIFE
Approximate Coverage Rates 80 LB. (36.3 KG) Bag:
Scratch Coat: 20-23 Square Feet
Bonding Coat: 24-26 Square Feet
Joint Grout (1/2″ Joints): 38-40 Square Feet
Full Installation (scratch, bond & joint): 13-15 Square Feet
*NOTE: coverage is approximate and will vary depending on workmanship, method of installation, substrate, style of stone, waste and regional variation.