DIY Network

Blog Cabin: Cabin Roof Construction Despite delays, the Blog Cabin team does successfully raise the roof. And while they're waiting, there's time to create a unique crowning accessory. From "Blog Cabin" episode DBLG-102

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Installing the metal roof panels is the last phase of this roofing process.

Tin Roof: It's More Than Just Tin

Metal roofs help conserve energy by reflecting heat in the summer, saving owners up to 40 percent on energy costs and making for a more eco-friendly building practice. In fact, "tin" roofs are not made entirely out of tin, but actually a metal alloy. Moreover, there are seven steps in this metal roof installation. Starting "from the bottom up":

• tongue and groove roof decking
  
• 15-pound felt paper
  
• insulation (expanded polystyrene)
  
• lathing strips
  
• OSB plywood layer
  
• 30 lb felt paper
  
• metal panels

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Figure C

What's In a Roof?

• In a log cabin with exposed beams, the tongue-and-groove roof decking boards (figure C) will be visible from underneath, inside the house. The boards fit together much like the elements of hardwood floor. These were secured by hand — with hammer and nails, rather than using a pneumatic framing nailer — since the hand-nailing helps drive the tongue-and-groove elements together more tightly.
  

• Once the first wood layer is down, it is covered in 15-pound felt paper (figure D).

• The 15-pound felt paper is tacked into place using button-cap nails (figure E). The wide tops prevent the nails from ripping the paper.

  Figure D

  Figure E

  
  

• Expanded poly-styrene insulation offers high R-value for enhanced insulation. Wood lathing strips laid across the foam insulation (figure F) add rigidity to the roof structure and provide an air channel for ventilation of the roof underneath the meal surface.

• The lathing and foam are secured to the roof substrate using extra-long screws (figure G), like the ones that were used earlier to secure the pre-cut logs in place.

  Figure F

  Figure G

  
  

  Figure H

• A layer of OSB plywood is secured on top of the lathing, followed by a layer of thicker (30-pound) felt paper. The second layer of felt paper adds more resistance to water penetration.

• Finally, the metal panels are installed. In the case of DIY's cabin, following a considerable delay, the metal roof material was finally delivered. The color of the roof was forest green to blend in with the wooded surroundings, and in keeping with the community guidelines of the development where the cabin was being built (figure H).
  

• To install the metal panels (figure I) metal closures are installed on the top and sides of the roof structure to hold the metal panels in place. These are held secure by clip fasteners (figure J), not by screws penetrating the metal panels themselves. The panels that make up the roof fit together like pieces of a puzzle — snug and tight.

  Figure I

  Figure J

  
  

  The green metal roof, installed

DIY Green Tip #2: Pick Your Insulation Wisely: The insulation used in the walls of DIY's Blog Cabin, in the dormers and between the studs, was also an environmentally friendly selection, consisting of about 75 percent recycled cotton. The remaining 25 percent is borate, a Class A fire retardant — the highest and safest rating available. This type of insulation is also completely non-toxic, but is formulated to resist mold and pests.

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