Why does water get behind stone veneer when the face looks solid? The answer sits behind the stone, where the wall has to manage water. This guide explains how stone veneer water damage starts and what a weep screed and flashing do.
Water gets behind stone veneer through mortar joints, cracks and capillary action. A weep screed at the base lets moisture that reaches the weather-resistive barrier (WRB) weep out. Flashing must lap over the screed, and kick-out flashing belongs where a roof meets the wall. Check the details against your veneer maker’s instructions and your local code.
How Stone Veneer Water Damage Starts
Water gets behind stone veneer through mortar joints, cracks, and capillary action. Projul, a contractor blog that covers stone veneer installation, names these three routes. Once water is behind the stone, the wall has to move it back out.
MCAA, a trade association, makes the same general point about any cladding system. Its article on manufactured stone veneer says water management is key. The sections below cover how installers handle it at the base.
Before you order stone, estimate quantities with the Stone Veneer Calculator. The tool handles quantities. This article covers the water details.
What a Weep Screed Does at the Base
A weep screed gives moisture a way out at the bottom of the wall. Projul says it allows moisture that reaches the WRB to weep out at the base. MCAA says framed walls need a weep screed or other flashing at the foundation termination, so liquid water can exit the system.
Echelon Masonry, an installer, gives the placement rule. The screed must attach to the bottom part of the exterior sheathing. Echelon and Projul both put the screed at least 4 inches above grade. Projul adds that it should sit at least 2 inches above hardscape.
Stone should stop above the screed. Projul says stone that extends below the screed will trap moisture.
Why Flashing Has to Lap Over the Screed
Flashing must overlap the weep screed. Echelon Masonry says the flashing goes over the sheathing and fully overlaps the vertical part of the weep screed. Its guide uses 6 inch flashing for this step.
The WRB goes on in layers too. Echelon says the layers start at the bottom of the wall and overlap the weep screed. Manufacturers can differ on the layer count, so check your product’s instructions.
Where Kick-Out Flashing Fits at Roof Intersections
Kick-out flashing goes at the bottom of a roof-to-wall intersection. Projul says that without kick-out flashing, water runs behind the veneer and into the wall cavity.
This roof detail is a separate check from the base screed. Look at both before the stone goes on.
What to Check Before the Stone Goes On
Check the base, the flashing, and the stone line before setting veneer. Use this list as a planning check, not a code check.
- Screed: attached to the bottom of the sheathing and at least 4 inches above grade (Echelon Masonry; Projul).
- Stone line: no stone below the screed (Projul).
- Flashing: lapped over the screed, with kick-out flashing at roof-to-wall intersections (Echelon Masonry; Projul).
- WRB: layers that start at the bottom and overlap the screed, following your product’s instructions (Echelon Masonry).
This article gives no weep spacing. The figures in the sources do not agree, and a code text was not checked here. Get the spacing from the veneer maker and your local code.
MCAA’s article on manufactured stone veneer puts it briefly: “Don’t skip flashing steps.”
Quantity Check With the Calculator
The calculator’s example works out to 682 sq ft of flats and 88 linear feet of corners. The example uses an 800 sq ft wall, 120 sq ft of openings, 80 linear feet of outside corners, and 10 percent waste.
- Corner coverage. 80 x 0.75 = 60 sq ft.
- Net area before waste. 800 – 120 – 60 = 620 sq ft.
- Flats with waste. 620 x 1.10 = 682 sq ft.
- Corners with waste. 80 x 1.10 = 88 linear feet.
The tool’s quick answer rounds to about 680 square feet, but it does not say that waste is included. The 620 sq ft figure is before waste. The corner length also appears twice: once as linear feet to order, and once as the wall coverage the corners take away.
The tool’s 200 sq ft preset with no openings and 40 linear feet of corners checks out the same way. Corner coverage is 40 x 0.75 = 30, so flats are (200 – 30) x 1.10 = 187 sq ft. Corners are 40 x 1.10 = 44 linear feet.
Run your own wall, openings, and corners in the Stone Veneer Calculator. It covers quantities only. It does not check flashing, weep details, or code.
FAQs About Stone Veneer Moisture
Why does water get behind stone veneer?
Projul, a contractor blog, says water reaches the back of stone veneer through mortar joints, cracks, and capillary action. The wall behind the stone needs a planned way for that water to leave.
What does a weep screed do?
A weep screed sits at the base of the wall and lets moisture that reaches the weather-resistive barrier (WRB) weep out. MCAA, a trade association, says framed walls need a weep screed or other flashing at the foundation termination.
How high should a weep screed sit above grade?
At least 4 inches above grade. Echelon Masonry, an installer, and Projul, a contractor blog, both give that height. Projul adds that it should sit at least 2 inches above hardscape.
Can stone extend below the weep screed?
No. Projul, a contractor blog, says stone should not extend below the weep screed because it will trap moisture. Keep the stone line above the screed along the whole wall.
What is kick-out flashing for?
Kick-out flashing goes at the bottom of a roof-to-wall intersection. Projul, a contractor blog, says without it, water runs behind the veneer and into the wall cavity.
How does flashing relate to the weep screed?
Echelon Masonry, an installer, says the flashing goes over the sheathing and fully overlaps the vertical part of the weep screed. Its guide uses 6 inch flashing.
Do WRB layer counts differ between manufacturers?
Manufacturers can differ on the WRB layer count, so check your product’s instructions. Check your local code too before you lay the barrier.
Sources and Further Reading
References Used in This Article
- Echelon Masonry, “Lightweight Veneers Install Guide” (installer), accessed 2026-11-11.
- Projul, “Stone Veneer Installation Guide for Contractors” (contractor blog), accessed 2026-11-11.
- MCAA, Christopher Abell, “Installing manufactured stone veneer” (trade association), accessed 2026-11-11.
The moisture guidance here comes from installer, contractor and trade-association pages, not a code text. Check the weep and flashing rules that your code or the veneer maker requires. Reviewed for accuracy by Prof. Dr. Khalil Mudassar, PhD. Last updated 2026-11-11.
Shakeel Muzaffar is the Founder and Editor-in-Chief, with over 15 years of experience in digital publishing and online tool development. He oversees editorial quality and formula verification to ensure accurate, practical, and easy-to-use calculators.