Earthquake and Storm-Resistant Roof Construction

1. Steel Frame Structure

• Use tubular 6x3 steel members for the frame
• Link the frame to columns on top
• Bolt the frame to the “ring beam” of the house
• Benefits:
  • High strength-to-weight ratio
  • Excellent ductility
  • Good resistance to torsional forces

2. Decking and Waterproofing

• Use high-quality marine plywood for decking
• Apply epoxy coating
• Add 2 layers of chopped strand mat with polyester resin
• Finish with non-slip gel coat
• Resembles boat deck construction for durability

3. Integration with House Structure

• If top beam not yet poured:
  • Place PVC pipes in strategic locations along formwork
  • Use all-thread to connect through to the inside
  • Can be used for ceiling mounting or upstairs floor framing

4. Secure Attachment Methods

• Avoid simple methods like bending rebar over rafter ends with spot welds
• Use galvanized ridge board and wall plate
• Secure roof to entire house structure using both welding and mechanical fixings

5. Proper Sheeting Installation

• For box profile sheets, screw in the valley (not the crest)
• Use tex screws with rubber-faced washers
• Add sealant for extra protection
• Drive screws home to pull sheets tight to the roof
• Use ample screws to prevent wind uplift

6. Wind Resistance Principle

• Prevent strong winds from getting under the roof to avoid lift

7. Additional Details

a) Insulation

• Consider adding rigid foam insulation between steel framing members
• Improves energy efficiency and reduces condensation issues

b) Ventilation

• Incorporate ridge vents and soffit vents to allow air circulation
• Helps regulate temperature and moisture levels in the roof space

c) Lightning Protection

• Install a lightning rod system integrated with the steel frame
• Provides additional protection in storm-prone areas

d) Solar Panel Compatibility

• Design the roof to accommodate future solar panel installation
• May require additional reinforcement and connection points

8. Pros and Cons

Pros:

1. Excellent resistance to earthquakes and high winds
2. Long-lasting and durable (potentially 50+ years with proper maintenance)
3. Versatile design allows for various roof shapes and pitches
4. Good insulation and energy efficiency potential
5. Fire-resistant (especially with proper coatings)
6. Can support heavy loads (e.g., solar panels, green roof systems)

Cons:

1. Higher initial cost compared to traditional roofing methods
2. Requires skilled labor for proper installation
3. Potential for thermal bridging if not properly insulated
4. May require more frequent inspections to ensure integrity of connections and coatings
5. Heavier than some alternative roofing systems, which may require stronger supporting structures

9. Cost Comparison (Philippine Context)

Note: These are rough estimates based on 2024 prices in the Philippines. Actual costs may vary depending on location, material quality, and labor rates. Prices are in Philippine Pesos (₱) per square meter (sqm).

This System:

• Estimated cost: ₱5,000 - ₱10,000 per sqm (approximately $90 - $180 per sqm)
• Higher upfront cost, but potentially lower long-term maintenance costs

Traditional Alternatives:

1. Galvanized Iron (G.I.) Sheets:

   • Cost: ₱500 - ₱1,000 per sqm
   • Pros: Affordable, widely available, relatively easy to install
   • Cons: Less durable, prone to rusting, poor insulation

2. Clay or Concrete Tiles:

   • Cost: ₱1,500 - ₱3,000 per sqm
   • Pros: Durable, aesthetically pleasing
   • Cons: Heavy, can be damaged in earthquakes, requires strong support structure

3. Aluminum Long-Span Roofing:

   • Cost: ₱800 - ₱1,500 per sqm
   • Pros: Lightweight, corrosion-resistant, good for coastal areas
   • Cons: More expensive than G.I. sheets, can be noisy during rain

4. Asphalt Shingles:

   • Cost: ₱1,000 - ₱2,000 per sqm
   • Pros: Aesthetically pleasing, various design options
   • Cons: Less common in Philippines, may not perform well in extreme heat

5. Built-up Roofing (for flat roofs):

   • Cost: ₱1,200 - ₱2,500 per sqm
   • Pros: Good for flat roofs, can include waterproofing layers
   • Cons: Requires skilled installation, may not perform well in heavy rains

Cost Analysis for a 100 sqm Roof:

1. Proposed System: ₱500,000 - ₱1,000,000
2. G.I. Sheets: ₱50,000 - ₱100,000
3. Clay/Concrete Tiles: ₱150,000 - ₱300,000
4. Aluminum Long-Span: ₱80,000 - ₱150,000
5. Asphalt Shingles: ₱100,000 - ₱200,000
6. Built-up Roofing: ₱120,000 - ₱250,000

While the proposed system is significantly more expensive upfront, it offers superior protection against earthquakes and typhoons, which are common in the Philippines. The long-term durability and reduced maintenance could offset the initial cost over time, especially in areas prone to natural disasters.

10. Long-term Considerations

Maintenance: Annual inspections recommended, reapplication of coatings every 10-15 years Adaptability: Can be modified or expanded more easily than traditional roofing Property Value: May increase due to durability and disaster resistance Insurance: Potential for lower premiums due to reduced risk of damage Environmental Impact: Longer lifespan means less frequent replacement and waste

While the initial cost is higher, the proposed system offers superior performance and longevity, potentially offsetting the higher upfront investment over time.