Detailed Answer
Installing roofing in rain is a bad practice that leads to serious problems. Here is why and what should happen if rain arrives mid-project.
Why rain is problematic
Moisture entrapment
Shingles or metal installed over a wet deck seal moisture between layers. This leads to mold growth, wood rot, and premature decking failure — sometimes within just 2-3 years.
Adhesion failure
Self-seal adhesive strips on shingles require dry surfaces to bond. Wet shingles are far more likely to blow off in the next windstorm.
Underlayment issues
Synthetic underlayment is water-resistant, but water pools on its surface can be trapped under shingles. Felt underlayment absorbs water and wrinkles, creating an uneven surface.
Safety hazard
Wet roof surfaces are extremely slippery. Worker falls cause serious injuries and expose you to liability.
What a reputable contractor does when rain threatens
- Checks weather forecasts before starting each day
- Only tears off sections they can waterproof before potential rain
- Carries emergency tarps on every job
- Tarps all exposed decking and underlayment at the first sign of rain
- Waits for the deck to fully dry before resuming (minimum 24 hours after rain)
If your roof is mid-replacement and rain hits
- The crew should immediately stop installation
- All exposed areas must be tarped securely
- Do not allow installation to continue on wet surfaces, even if the crew offers to
- Check the attic for any water intrusion after rain stops
- Ensure the deck is dry before work resumes
Red flag: A contractor who installs shingles in the rain is cutting corners. This is one of the clearest signs of low-quality workmanship and should cause you to question every aspect of their work.