The Do’s and Don’ts of Metal Roofing Installation
(What Homeowners Should Know Before the Project Starts)
Metal roofing is an engineered system — not a product you just “nail down.” Proper installation requires planning, symmetry, precision, and attention to details that most people never see but that make all the difference in the roof’s performance and appearance.
At Bonner Master Roofing, we take pride in installing metal systems the right way. Here are the most important Do’s and Don’ts every homeowner should understand before their roof installation begins.
✅ The Do’s
#1 Do Ensure the Roof Deck Is Straight and Solid
Metal panels are designed to sit perfectly flat against the roof deck.
If the deck is uneven or sagging, we can’t simply “shim” panels to make them look right — they will telegraph every imperfection through the finished surface.
If your roof deck isn’t straight, the proper fix is to remove the sheathing, sister the rafters, and re-sheath.
This ensures long-term performance and appearance. The panels must rest on a stable surface — they can’t “float.”
#2. Do Approve the Plan if Re-Framing Is Out of Budget
If re-framing isn’t feasible, there are still options.
When the roof deck is uneven side-to-side (left to right), we can often install the panels safely without performance issues.
Before doing so, we’ll run string lines once the old material is removed and show you exactly how the panels will lay. We’ll only proceed with your approval.
#3. Do Understand Tolerances for “Belly” or Sag
If the roof deck isn’t straight from eave to ridge, we evaluate how much “belly” (sag) exists.
-
A ¼-inch deviation over 20 feet is acceptable.
-
In some cases, we can install up to a ½-inch belly over 20 feet if performance won’t be affected.
We’ll always inspect and explain these conditions before proceeding, and again, we’ll need your approval.
#4. Do Approve the Layout for Symmetry
Metal roofing should look as good as it performs.
That means the panel layout must be symmetrical across the roof:
-
The end panels on each side should be roughly equal in width.
-
Whenever possible, standing seams should align on both sides of the ridge, and continue cleanly into valleys or hips.
This symmetrical layout makes the roof look balanced and professionally crafted.
#5. Do Leave an Expansion Gap at the Eave
Every metal roof expands and contracts with temperature changes.
When folding panels over the eave trim, we must leave an engineered expansion gap — the exact size depends on the panel length and manufacturer’s specifications.
This prevents buckling and stress on the panels and ensures long-term stability.
#6. Do Sign the “Oil Canning” and “Color Selection” Provisions
All customers are asked to sign two important documents:
-
Oil Canning Provision: Acknowledges that mild waviness is a normal characteristic of flat metal panels and not a defect.
-
Color Selection Contract: Confirms that you’ve reviewed and approved your chosen color under natural lighting conditions.
These provisions protect both the homeowner and the installer by setting clear expectations before the work begins.
🚫 The Don’ts
#1. Don't Leave Plastic Film on Panels
Metal coils are shipped with a protective plastic film to prevent scratches during transport.
Once installed, that plastic must be removed in a timely manner.
If it’s left on for an extended period of time in heat or sunlight, it can bond to the paint surface and become impossible to remove without damaging the finish.
#2. Don't Expect Panels to Hide Framing Issues
Metal panels are precision products — they will reveal, not conceal, framing flaws.
If the rafters are wavy, out of plane, or sagging, the metal will follow that contour.
For the roof to look clean and perform properly, the framing must be corrected before installation.
#3. Don't Skip the Layout Planning Step
We never “just start at one side and see where we end up.”
Every job is laid out in advance to ensure:
-
Even panel spacing
-
Balanced seam placement
-
Clean visual lines across ridges and valleys
Skipping layout leads to crooked seams or mismatched ends — and we refuse to compromise on that.
#4. Don't Assume All Roofs Can Be Installed Without Adjustments
Each roof is unique. Some require re-decking or re-framing to meet metal’s tight tolerances.
We’ll always review any issues before work begins and provide options that fit your budget and expectations.
In Summary
A metal roof is a precision system — not just a surface.
By understanding these do’s and don’ts, you’ll know exactly what to expect from your installation process and why certain steps (like layout approval or structural correction) are necessary.
When done right, your roof will perform flawlessly and look perfect for decades.