My Roof Is Leaking Through Artificial Stone

Flashing

• Chimneys, dormers or other vertical surfaces that butt up against the roof's shingles need flashing to prevent leaks. This metal flashing creates a barrier in the seam between the artificial stone and the roof’s shingles. Climb onto the roof to inspect the flashing and look for any damage, loose edges or corrosion that would allow water to leak through the artificial stone surface. Use a putty knife to scrape away any roofing tar from the flashing, if necessary, to see what you're dealing with. If any flashing is damaged, it should be replaced.

Mortar

• The artificial stone may be held together with mortar, similar to a brick surface, which can wear down over time. As the mortar chips and breaks off, it becomes a more likely source of leaks. Look for cracks of any size in the mortar, which can also allow water to flow behind the artificial stone. Worse still, when the temperature dips below freezing, any water that is present in the mortar cracks freezes and expands, further damaging the mortar and potentially causing the artificial stone to come loose.

Missing Stone

• When pieces of the artificial stone on your house fall off, the exposed material below may allow water to leak into your home. If you do not see mortar lines between the stones, they are held in place with glue. If the glue was applied to dusty or otherwise dirty surfaces, or if either surface was wet during the glue application, it may not have adhered well. Reattaching the stones correctly may stop the leak.

Locating the Leak

• If you inspect the area where you suspect the leak has formed but cannot tell the exact location of the leak, a simple test with a garden hose may help you find it. With a helper in the attic space looking for the leak, start hosing down the suspected leak area to mimic precipitation hitting the roof. If the helper does not see a leak after five minutes, try hosing down another area until you locate the source of the leak. Keep in mind that a leak may start high on the roof, run down inside the attic and hit the drywall ceiling several feet away inside the house.