Clogged roof drain: causes, consequences and solutions

The flat roof drain plays a crucial role in evacuating rainwater. When clogged, it can lead to water infiltration, roof covering deterioration, and structural damage to the building.

Knowing how to unclog a roof drain and taking preventive measures can help avoid costly repairs. In this article, discover the causes of a clogged roof drain, warning signs, and effective cleaning solutions.

Signs of a Clogged Flat Roof Drain

Stagnant Water on the Roof

When water no longer drains properly, it forms pools that stagnate on the roof. This indicates a drainage issue that, if left unresolved, can lead to leaks and accelerate the deterioration of roofing materials. A waterlogged roof is more prone to cracks and premature wear.

Water Infiltration Indoors

A clogged drain prevents proper water evacuation, causing it to seep under the roofing membrane. This results in moisture stains on ceilings and walls—an issue that can quickly worsen.

Prolonged infiltration can damage insulation and promote mold growth, which poses health risks.

Mold and Unpleasant Odors

Excess moisture encourages mold growth, which appears in damp corners of walls and ceilings. These fungi emit unpleasant odors and can cause respiratory issues, especially for allergy sufferers.

If you detect a persistent musty smell, have your flat roof drainage system inspected.

Roof Covering Sagging

When a large amount of water accumulates, it exerts extra pressure on the roof structure. The excessive weight of stagnant water can cause the roof covering to sag, compromising its waterproofing and increasing the risk of collapse.

Any sunken areas on the roof should be inspected immediately to prevent major damage.

How to Unclog a Roof Drain?

1. Preliminary Inspection

Before any intervention by a flat roof contractor, check the drain’s condition to identify the blockage source. A visual inspection can reveal visible debris, but a camera inspection may be necessary to examine the inside of the pipe and locate deeper clogs.

2. Manual Debris Removal

Wearing gloves and using a rake, remove leaves, branches, and any visible debris that may be blocking the drain entrance. This step restores water flow and prevents new obstructions from accumulating.

3. Using a Garden Hose

Direct a high-pressure water jet into the drain to dislodge small blockages and check if water flows correctly. If the water backs up or drains slowly, this suggests a deeper clog requiring further action.

4. Using a Plunger or Plumbing Snake

A plunger can help suction surface clogs by creating air pressure that dislodges obstructions.

For deeper blockages, a plumbing snake is recommended. This flexible cable with a brush scrapes and breaks down debris obstructing water flow.

5. Specific Cleaning Products

Use biodegradable detergents to dissolve grease and organic residues that may cling to the drain walls. Choose eco-friendly products to avoid damaging roofing materials and contaminating collected rainwater.

6. Camera Inspection

If the drain remains clogged after several attempts, a camera inspection can precisely locate the obstruction. This method is particularly useful for identifying deep blockages caused by roots or mineral deposits that require specialized intervention.

7. Professional Intervention

If none of the previous solutions work, calling a professional roofer ensures thorough cleaning and necessary repairs. An expert can diagnose potential structural issues and offer tailored solutions for effective and long-lasting drainage.

Preventing Roof Drain Clogs

Regular Maintenance

• Clean drains at least twice a year (spring and fall).
• Inspect after major storms.

Installing Protective Grates

Grates prevent leaves and debris from accumulating while allowing water to flow freely.

Antifungal Treatment

Applying a preventive treatment against moss and algae slows their development.

Insulation and Winter Heating System

Installing a heating system prevents ice buildup in drains.

Unclog Your Roof Drain with Our Roofing Experts

A clogged roof drain poses a major risk to your building. Regular inspections and proper maintenance prevent blockages and extend the lifespan of your roof.

If you suspect a problem or need professional flat roof drain cleaning, Les Couvreurs Duro-Toit is at your service to ensure a healthy and efficient roof all year round.