Of all your home’s features, your roof may be the one you least interact with. It seems passive — simply sitting atop your house, keeping out the rain and sun. But in truth, your roof is a complex structure that is vital to your home’s energy efficiency, safety, and comfort.
Have you ever wondered how roofing works? Or what makes a roof nice and sturdy? Once you understand the fundamentals of roofing, you’ll see why regular roof maintenance is so critical. You’ll also be able to make informed decisions about your next roof repair or replacement.
What is a roof?
In a nutshell, a roof is any overhead barrier between a building and the elements. Any structure can have a roof. But of course, a garden shed or picnic pavilion has very different roofing needs than a house.
For homes, the function of roofing is two-fold: (a) help maintain the building’s interior temperature and (b) defend the internal structure against rain, snow, and other precipitation.
A house’s roof typically has three parts:
- The roof frame is the underlying structure that provides the shape of your roof. It’s built from either rafters or trusses, which may be visible in your attic.
- The roof deck comprises the panels that cover the frame. They are the base for your shingles or tiles, depending on which materials you choose.
- The roof itself can be built from various materials, depending on your roof’s shape.
For flat or low-slope roofs, you may use layers of tar and asphalt (which is called Built-Up Roofing, or BUR), or Modified Bitumen Roof (MBR), a type of rolled roof made with asphalt, rubber, and fiberglass.
For hip or gable roofs, you may use metal panels, concrete or synthetic tiles, or any variety of shingles.
No matter your roof style or materials, all those parts must be in good shape for a healthy roof. A roof deck that has gaps or weakened boards could lead to shingles coming loose, which hurts the roof’s overall integrity. The roof frame must be strong enough to support your choice of materials — especially heavier options like concrete tiles.
How roofing is done
Roofing with shingles
Shingles are one of the most economical roofing materials. They last about 25 to 30 years, depending on climate and other factors. Whether you choose traditional three-tab shingles or “architectural” shingles, they’re progressively nailed onto the roof deck. Once complete, the overlaying rows of shingles provide a protective barrier.
To install shingles, roofers follow these steps:
1. Remove the old roof.
Shingles can technically be laid on top of old shingles, but this could make it harder to spot damage in the roof deck.
2. Apply the underlayment.
Roofers will often put down a layer of tarpaper, also called builder’s felt, to help the shingles stay put. This underlayment also protects the roof while the job is in progress.
3. Install the shingles.
The shingles are nailed down in rows, starting from the edge, and overlaid onto the decking.
4. Add the flashing and trims.
A roof’s seams and valleys are the most likely places for water to collect. Flashing are metal pieces that cover the valleys, while trim protects the seams. Both help prevent water from pooling — and therefore damage to your roof.
Roofing without shingles
If you’re not using shingles, your options depend on the shape of your roof.
Flatter roofs generally use built-up roofing materials. As mentioned above, Built-Up Roofing, or a BUR system, typically uses asphalt or synthetic alternatives.
How Built-Up Roofing is installed:
- Roofers roll down the ply sheets over the roof deck. These are typically made of fabric infused with minerals or other materials. “Cool roof” BURs may include a mixture of fiberglass and acrylic to deflect sunlight.
- They apply one or more surfacing materials, usually asphalt, and fasten with hardware or adhesives.
- They finish with a top coat (usually tar) and a layer of gravel.
For sloped roofs, you can use single-ply roofing, another roll-down roofing method, or standing-seam metal roofing.
Also called rubber membrane roofing, single-ply roofing is made from various plastics and rubbers. Options for rubber membrane roofing include:
Thermoset membranes, which comprise layers of rubber polymers:
- EPDM
- CSPE
- Neoprene
Thermoplastic membranes, in which layers of plastic are melted into polyester or fiberglass
Standing-seam roofing may be made from galvanized steel, copper alloys, or Galvalume. This roofing material comes in panels, usually 12 to 24 inches wide.
How standing-seam metal roofing is installed:
- Roofers put down the underlayment, which helps protect the roof deck from water.
- They install the metal panels in rows, typically parallel to the roof’s slope.
As you can see, every roof is a complex system no matter the materials used. Each part interacts with the others to form a cohesive protective barrier. If there’s damage to one part, the other parts become vulnerable.
Keep Your Roof System in Tip-Top Shape
When you need to repair or replace your roof, you might consider an overlay (i.e. applying new materials on top of the old ones). One of the main drawbacks of a roofing overlay vs a tear-off is that you won’t be able to inspect the roof deck. A weak structure leads to weakness in the roof itself. If your roof is older or you’ve already had cracks or shingle loss, your deck could be subject to water damage and rot.
Don’t leave it up to chance. Reach out to Sentinel Roofing for an inspection. We’re happy to talk through your options and explain which roofing materials would work best for your home. Call us at 352.789.4598.