Flat Roof Leak Repair on a Classic Stone Home in Winnetka: A Silicone Coating Project
Flat roofs don't shed water the way pitched roofs do. They rely on membrane integrity, proper flashing, and working drainage. When any of those fails, water gets in. On this Winnetka stone home, all three needed attention. Here's how the job went.
The problem: a leaking balcony roof on a Winnetka stone home
A homeowner in Winnetka called about ceiling stains coming from a flat balcony roof over a living space below. The surface had cracked and deteriorated at the seams. Flashing had pulled away from the wall. And the downspouts had no elbows at the bottom, so water from the upper roof was dumping straight down the wall and onto the balcony instead of draining away. None of that gets better on its own — every rain makes it worse.
What we found on inspection
We walked the balcony roof and the adjoining narrow section before writing anything up. The surface had visible cracking and open seams throughout. Flashing was failing at the wall terminations. Drainage was the bigger issue — four downspouts with no elbows were pouring water directly against the structure. We also found the electrical conduit along the exterior wall had pulled away from loose straps, and the previous attachment points had left open screw holes in the flashing. We documented everything and gave the homeowner a clear scope before any work started.
The repair: Gaco Silicone Roof Coating, flashing, and drainage
We cleared all debris from both roof sections, replaced failing flashing, and re-caulked all seams and joints before the coating went down. Then we applied two full coats of Gaco Silicone Roof Coating in black. Gaco forms a seamless waterproof membrane directly over the existing surface — no tear-off required when the substrate underneath is still sound. Once the coating was done, we replaced all four downspouts with properly elbowed terminations so water drains away from the building. We also re-strapped the electrical conduit with longer straps to close the open holes in the flashing and secure everything flat against the wall.
Why silicone coating instead of a full replacement
Coating makes sense when the deck underneath is structurally sound and the problem is at the surface. If insulation or decking is waterlogged, coating over it just traps the damage. On this job, the deck was intact — the cracking, open seams, and failed flashing were the source of the leaks, not rotted structure below. Gaco addressed the actual problem without the cost and disruption of a full tear-off. For a balcony on a high-end home, that's also a lot less invasive to the building.
Completed job
The finished balcony roof and narrow section came out clean — uniform black surface, no open seams, no lifted flashing edges. Downspouts terminate correctly with elbows directing water away from the wall. Conduit is secured flat. We confirmed full cure before handing the balcony back for use. Total project cost: $6,550, covering the original coating scope plus the drainage and conduit work found during the job.
If you have a flat roof section, don't wait on ceiling stains
By the time you see a ceiling stain, the water has usually been moving through the assembly for a while. The longer it goes, the more the scope grows — and the more likely you're looking at interior work on top of the roofing. If you have a balcony roof, garage roof, or any flat section on a North Shore home and you're seeing moisture, get it looked at before the next rain. Leaders Roofing serves Winnetka, Kenilworth, Glencoe, Highland Park, Lake Forest, and the surrounding North Shore communities. Call (847) 312-2727 or reach out through the website to schedule a free inspection.