The Problem with No Strapping
Some metal roofs are installed directly onto a membrane on the roof deck. While this may seem fine at first, it creates major problems:

• Condensation buildup – Warm air from your attic meets the cool metal roof, causing moisture to form. This can lead to leaks, mold, and long-term damage.

• Reliance on a single membrane – The underlayment is meant to prevent leaks, but if moisture builds up beneath the roof, it has nowhere to go

The Problem with Single Strapping

Some installers use single-layer (horizontal) wood strapping, which creates a small gap between the roof deck and metal panels. While this improves airflow slightly, it doesn’t provide enough ventilation and can lead to:

• Limited airflow, meaning condensation can still form.

• Uneven surfaces, as single strapping does not correct dips and swells in the roof deck.

• Potential water trapping, increasing the likelihood of leaks over time.

• Non-pressure-treated strapping traps moisture, causing rot over time.