Easy Masonry Calc

How much mortar for stone veneer?

Short answer

For 100 square feet of stone veneer, a ½ inch scratch coat takes about 6.5 bags of 80 lb veneer mortar with 10% extra (Quikrete: about 17 square feet per bag). With a ½ inch setting bed on the stones as well, buy 13 bags in all, plus 11 boxes of flats at 10 square feet per box.

How to work it out

  1. 12.5 ft × 8 ft = 100 sq ft + 10% ÷ 10 sq ft per box = 11 boxes
  2. Mortar: scratch 0.5 in + setting bed 0.5 in over the wall ÷ 0.71 cu ft per 80 lb bag = 13 bags

Veneer jobs need mortar twice: once for the scratch coat on the wall and again behind each stone. People often buy for the first and run short on the second.

Adjust for your project

ft
ft
sq ft
ft
Add the height of every outside corner
sq ft
From the stone maker. ProVia’s flats: about 10 sq ft per box with ½ in joints
in
Quikrete’s coverage figure is for ½ in
in
Use the thickness in your stone maker’s instructions
More options: Corner box · Extra
ft
Linear feet per box (ProVia: 6)
%
Boxes of flats11 boxes
Bags of veneer mortar
13 bags · 80 lb
of which for the scratch coat
6.5
Wall area (net of openings)
100 sq ft
  • Corner pieces cover part of the wall face. Some makers let you reduce the flats by the area the corners cover — check your stone’s installation guide.
  • Lay stones out on the ground first, mixing boxes, so colours and sizes are spread evenly across the wall.
Check your codeAdhered veneer needs a weather-resistive barrier, lath, flashing and a weep screed installed to the maker’s instructions and local code.

For this job · affiliate link
Self-furred metal lathOver sheathing, adhered stone needs a scratch coat on lath. Self-furred lath holds the mortar off the barrier so it keys in.
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Stone veneer by wall area (½ in scratch + ½ in setting, 10% extra)

Stone veneer by wall area (½ in scratch + ½ in setting, 10% extra)
Wall lengthBoxes of flatsBags of veneer mortarWall area (net of openings)
6.25 ft6 boxes7 bags50 sq ft
12.5 ft11 boxes13 bags100 sq ft
25 ft22 boxes26 bags200 sq ft
50 ft44 boxes52 bags400 sq ft

Scratch coat

Quikrete’s Veneer Stone Mortar data sheet gives an 80 lb bag about 0.71 cu ft, enough for about 17 sq ft of scratch coat at ½ in. Over 100 sq ft that is 5.9 bags, or 6.5 with 10% extra. Comb it with a scratcher while it is still soft so the setting mortar can key in.

Setting bed and joints

Each stone is buttered on the back and pressed into the scratch coat, squeezing mortar out around the edges to fill the joints. The data sheet asks for consistent ½ in joints but gives no separate coverage, so this page uses a ½ in setting layer as an adjustable assumption — another 6.5 bags for 100 sq ft. Change it to match your stone maker’s instructions; thin, flat stones may use less, and irregular fieldstone more.

The stone itself: 100 sq ft with 10% extra is 11 boxes at 10 sq ft per box. Add corner boxes for each outside corner — the variants show a wall with two 8 ft corners. Stucco is a cheaper finish for the same wall: see how many square feet does a bag of stucco cover. Brick veneer is on how many queen size bricks per square foot.

Different size? Use the full Stone Veneer Calculator.

What you’ll need

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Frequently asked questions

How many boxes of stone veneer for a fireplace wall 6 by 8 feet?

6 boxes of flats at 10 square feet per box, with 10% extra, and 7 bags of mortar.

How many corner boxes for two 8 ft outside corners?

3 boxes at 6 linear feet per box, with 10% extra.

How much veneer mortar for just the scratch coat on 200 sq ft?

13 bags of 80 lb for a ½ inch scratch coat with 10% extra.

Sources