When your roof needs work, you may face the decision between complete replacement (removing old roof) and roof-over (installing new roof over existing). While roof-over may seem cheaper and faster, it's not always the best choice. This guide explains the differences, pros and cons of each option, code requirements, and when each approach makes sense.
What Is Roof Replacement?
Complete roof replacement involves:
- Removing all existing roofing materials
- Inspecting and repairing roof deck
- Installing new underlayment
- Installing new roofing materials
- Proper installation from deck up
This is the standard, recommended approach for most situations.
What Is Roof-Over?
Roof-over (also called re-roofing) involves:
- Installing new roofing over existing
- No removal of old materials
- May skip deck inspection
- Faster installation
- Lower upfront cost
While sometimes possible, it's often not recommended.
Pros and Cons of Roof Replacement
Pros
- Proper deck inspection and repair
- Meets code requirements
- Proper installation
- Warranty protection
- Long-term performance
- No hidden problems
Cons
- Higher upfront cost
- Longer installation time
- More disruption
Replacement is usually the better long-term choice.
Pros and Cons of Roof-Over
Pros
- Lower upfront cost
- Faster installation
- Less disruption
Cons
- Can't inspect deck
- May hide problems
- Adds weight to structure
- May void warranties
- Code may prohibit
- Shorter lifespan
- More expensive long-term
Roof-over often creates more problems than it solves.
When Roof-Over May Be Acceptable
Roof-over may be acceptable only if:
- Existing roof is in good condition
- Only one existing layer
- Deck is sound (recently inspected)
- Code allows it
- Manufacturer approves
- Warranty covers it
Even then, replacement is usually better.
When Replacement Is Required
Replacement is required or strongly recommended when:
- Multiple existing layers
- Deck problems suspected
- Code prohibits roof-over
- Manufacturer requires removal
- Warranty requires removal
- Extensive damage
- Structural concerns
Most situations require replacement.
Code Requirements
Florida Building Code restrictions:
- Many areas limit roof layers
- May prohibit multiple layers
- Wind zone requirements
- Weight restrictions
Check local code requirements before considering roof-over.
Long-Term Considerations
Consider long-term implications:
Roof-Over Issues
- Hidden problems may surface later
- Deck issues can't be addressed
- May need replacement sooner
- More expensive long-term
Replacement Benefits
- Addresses all issues
- Proper installation
- Longer lifespan
- Better long-term value
Replacement usually provides better long-term value.
Frequently Asked Questions
Is it cheaper to do a roof-over instead of replacement?
Roof-over may be cheaper upfront, but it's often more expensive long-term. Roof-over can hide problems, may need replacement sooner, and doesn't allow deck inspection or repair. Complete replacement, while more expensive initially, usually provides better long-term value and performance.
Can I install a new roof over my old one?
It depends on code requirements, existing roof condition, and number of layers. Many areas prohibit multiple layers, and most manufacturers require removal for warranty coverage. Even if allowed, replacement is usually the better choice for long-term performance.
What are the risks of roof-over?
Risks include: hiding deck problems, adding excessive weight, voiding warranties, code violations, shorter roof lifespan, and inability to address underlying issues. These risks often make roof-over a poor choice despite lower upfront cost.
Does Florida Building Code allow roof-over?
Florida Building Code restrictions vary by location. Many areas limit the number of roof layers (often to one layer), and some prohibit roof-over entirely. Wind zone requirements may also affect roof-over options. Check local code requirements before considering roof-over.
When is roof-over a good option?
Roof-over is rarely a good option. It may be acceptable only if: existing roof is in excellent condition, only one existing layer, deck was recently inspected and is sound, code allows it, and manufacturer/warranty approve it. Even then, replacement is usually better long-term.
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