Quick Definition

The roof protects your home from outside elements and impacts your home’s energy efficiency and durability.

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In Depth

Roofs tie structural walls together and regulate temperature and humidity in a building. Roofs are the first line of defense against outside heat and cold air and should be insulated. Your choice of roof materials can also help minimize heat transfer by reflecting radiant heat from the sun. In environments prone to rainy seasons, the roof keeps rain out of the building.

Here are some details on different types of roof covering materials:

  • Asphalt Shingles – Low-cost and easy to install, asphalt shingles are the most popular roof covering. Asphalt shingles are typically made up of two main components: FiberglassA synthetic material made up of plastic reinforced by glass. Fiberglass is the base material in Batt Insulation. or organic paper waste and an Asphalt binder, a Petroleum-Based product. Asphalt shingles have a shorter lifespan than other roofing options.
  • Terracotta Tiles – TerracottaA fire-hardened clay product. tiles are made from clay and come in an assortment of shapes and colors. The tiles have a long lifespan, but the UnderlaymentsA thin membrane applied to the exterior sheathing before the roofing finish material is installed. Acts as a moisture barrier, keeping exterior moisture out of the home and allowing moisture inside the home to escape. need to be replaced every 15-20 years. Corrugated terracotta tile can aid airflow at the surface of the roof. Because they are made from clay, terracotta tiles are a sustainable choice for roofing, but more expensive than other options.
  • Metal Roofs – Depending on how the material is manufactured, metal can be a solid sustainable and affordable choice for your roof. While metal heats quickly, it is also highly reflective and extremely durable. Make It Right uses rolls of GalvalumeA galvanized aluminum metal compound that mixes the light weight properties of aluminum with the weather resistance of galvanizing. to form our Standing SeamA type of metal roofing with a vertical seam at the both edges. When two panels are laid out side by side, one seam nests inside the other seam and is crimped, creating a waterproof seal. roofs.
  • TPO – Thermoplastic Polyolefin is a man-made synthetic roofing material that comes in rolls. This Single PlyTerm referring to a single layer of material. In some older construction methods, multiple plys of materials were needed for waterproofing.Today we use stronger materials that only need one ply. roofing material is Heat WeldedA method used to seal the edges of the TPO sheets together to keep water out. at the seams. This type of roofing is typically used in Flat Roof or Nearly Flat,/tooltip] roof surfaces where Water Intrusion would occur with almost all other material types. Make It Right uses this roof covering in[tooltip pxwidth="250" content="A slightly pitched roof structure or a roof built up with foam so that water sheds during storms.]Nearly Flat roof designs.
  • Green Roof – A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. (Wikipedia) Click here to learn more how Make It Right uses green roofs.

Here are some details on different type of roof structures:

  • Wooden Stud – Probably the most commonly framed roof system, wooden stud roofs are constructed on site or in a factory (i.e. modular). This roof type is comprised of several components:
    • Roof Rafters, which are spaced 16” on center, or 24” on center when using Advanced Framing, and are nailed to the top plate of the exterior walls
    • Ridge BeamA top beam used when support is needed from two oppositely sloped roof rafters or roof panels., which in a pitched roof condition, is a single or multiple 2x member at the peak of a ridge where the rafters meet
    • Plywood or OSB is typically used on top of the rafters and acts as reinforcing and bracing of the roof rafters
    • The cavity between the rafters is typically insulated with Batt InsulationStrips of insulation, usually fiberglass, that fit between studs or other framing., Blown InAn insulation product composed of loose fibers or fiber pellets that are blown into wall cavities or attics using special pneumatic equipment. ., or Spray Foam Insulation
    • Roof WrapA thin membrane applied to the exterior sheathing before a roof's finishing material is installed. Acts as a moisture barrier, keeping exterior moisture out of the home and allowing moisture inside the home to escape., laid on top of the plywood or OSB, acts as a water barrier for the roof and comes in a wide range of materials
    • Roof finish, the final layer of the roof, is typically made up of materials that are very resistant to the elements like shingles, metal roofing and TPOThermoplastic Polyolefin
  • Wooden Truss – This roof type typically uses 2x wooden components that are prefabricated into roof trusses that can be spaced 16” on center traditionally or 24” on center when using Advanced Framing Techniques. The other components that make up the roof assembly are usually the same as wooden stud roofs.
  • Metal Stud - This roof type uses an extruded steel channel shaped rafter in place of wooden rafters. Unlike wooden rafters, steel rafters connect to the top of the wall with Metal Self Tapping ScrewsScrews with special tips that allow them to be screwed directly into metal without the need for pre-drilling.. The other components that make up the roof assembly are usually the same as wooden stud roofs.
  • Metal Truss – This roof type typically uses extruded steel channel metal components that are prefabricated into roof trusses that can be spaced 16” on center traditionally, or 24” on center when using Advanced Framing. The other components that make up the roof assembly are usually the same as wooden stud roofs.
  • Plywood or OSBOriented Strand Board is an engineered wood product formed by layering strands (flakes) of wood in specific orientations. Has a rough and variegated surface with the individual strips (2.5 x 15 cm / 1 x 6 inch) lying unevenly across each other. SIP (see our MIR Insight video on SIPs) – Structurally Insulated Panels (SIPs) are prefabricated wall panel systems, typically comprised of EPS foam sandwiched by plywood or OSB on both the exterior and interior sides. SIP roofs connect to the top of the exterior wall panels with SIP screws and sometimes have a roof ridge beam. The other components that make up the roof assembly are typically similar to wooden stud roofs, except for insulation which is embedded in the roof SIP.

Metal SIP – This SIP type has metal skin on both the exterior and interior faces of the panel with an EPS foam core. Metal roof SIPs connect to the top of exterior walls with SIP screws or are suspended between the exterior walls attached to a ledger. The other components that make up the roof assembly are typically similar to wooden stud roofs, except for insulation which is embedded in the roof SIP.

Our Application

Make It Right uses all the roof types above except metal truss. Currently we build homes using the OSB SIP roof type, which provides with a strong and tight building envelope. Our standard OSB SIP roof depth is 8.25” and is R-33.

Lessons Learned

The geometry of a home or building design greatly affects the roof construction. The roofs of several of Make It Right’s home designs proved difficult and time-consuming (and therefore, more expensive) to construct before we switched to OSB SIP roofs. We use an intensive 3D modeling process before manufacturing our OSB SIP roofs. In most cases, this eliminates problems once the roofs reach construction.

OSB SIPs allow Make It Right to build higher ceilings, install gypsum easier and reduce ceiling joists needed. OSB SIPs are quickly assembled and craned into place, reducing the Dry-InThe stage of construction during which the roof, windows and doors are installed and all leaks are fixed. At this stage, subcontractors can begin interior finishing (floors, countertops, paint, etc). time.

We currently are using two roof finishes for most of our houses. The first is GalvalumeA galvanized aluminum metal compound that mixes the light weight properties of aluminum with the weather resistance of galvanizing., an aluminum-zinc alloy coated sheet steel with high heat reflectivity and anti-corrosion properties. The Galvalume sheets are formed on-site in a Standing SeamA type of metal roofing with a vertical seam at the both edges. When two panels are laid out side by side, one seam nests inside the other seam and is crimped, creating a waterproof seal. configuration, allowing us to easily attach our Solar PV Systems. The second is a TPO (Thermoplastic Poly Olefin) membrane, typically used on our flat or low-slope roofs. We have also used metal shingles, but prefer the more cost-effective Galvalume when TPO cannot be used.

Using metal straps often combats uplift caused by high winds. Make It Right uses a hybrid combination of mechanical fastening, glue and tying our exterior wall sheathing to the floor framing. By tying all of our structural systems together, we ensure that our roofs stay attached in powerful storms and high winds.