A roof overhead is one of the most basic human needs. Roofs keep water out, protect from solar rays, and help with heating and cooling. The roof also is an important part of your home’s curb appeal.
In Los Angeles, we average a paltry 15 inches of a rain each year spread over 36 days. We are one of the driest states in the United States. For comparison, the wettest cities in the US (Miami FL, and New Orleans LA) get 62 inches a year over 120 days. Northern States get snow in the winter, with our warm Southern Mediterranean climate that never freezes, we get rain instead. Winter is the rainy season. Since it usually doesn’t rain that much except for the occasional El Nino, which dumps double the rainfall as normal at about 30 inches- many home owners don’t think about their roofs much.
- 1 Styles of Roofs
- 2 Roof Pitch
- 3 Roof Materials
- 4 Roof Parts
- 5 Licensing & Permitting
- 6 Roof Maintenance
- 7 Roof Useful Life
- 8 Roof Replacement
Styles of Roofs
The three most common types of roofs you will find around Los Angeles are: Gable, Hip, and Flat Roofs.
Gable roofs at the simplest and most easy pitched roofs to build. They have two sides.
Hip roofs are more difficult to build and frame than gable roofs because they are more complex, which makes them slightly more expensive. They have less of a visual impact than Gable roofs because they are less “bulky”, so they are excellent if you are trying to tone down the roof element in the overall design. Hip roofs have four sides that all slope down from the center. These roofs can have overhangs on all 4 sides which makes them great for offering protection against weather.
In addition to these basic roof styles there are the less common:
Shed- also known as Lean-to roofs. I think people have a negative connotation with Shed roofs, because, well, they kind of look like sheds. I think for that reason people think they look “cheap”. I may not want a shed roof for my main house, but these style roofs can be really cool for dormers, garages, and additions.
Gambrel- Whenever I think of Gambrel roofs I think of the roofs on Barns. A Gambrel roof is basically just a Gable roof with two pitches instead of one. Framing for a Gambrel roof like a hip roof is more expensive then Gable roofs. One advantage of a gambrel roof has over Gable and Hip roofs is that it provides extra attic space. Fun fact: Gambrel is named after the hindquarters of a horse (which was the primary form of transportation until cars came around).
The steepness of the Roof is called its pitch. Keep in mind, no roof is entirely flat- that would just be bad roof design. Calling a roof a Flat roof is a bit of a misnomer- they are actually “low slope” roofs, but everybody just calls them flat roofs.
Pitch can be expressed in either degrees or rise over run. For example a 45 Degree angle is 12:12. A 9.5 Degree angle is 2:12. Gabled and Hipped Roofs need a slope of at least a 4:12 (20 Degrees) to function properly. For Slopes Less than 20 Degrees, Flat roofs are used.
flat roof 0-20% slope
Pitched Roof 20%-45%
Pitch roofs last longer and leak less. They are also more dangerous to work on because it is easier to fall off. In the graphic above you can see the different feelings the steepness in pitch can create. English Tudor houses (Left) very commonly have Steeply pitched roofs, whereas Mid century homes (Right) tend to have low pitch roofs.
Flat roofs are cheaper to construction, easier/safer to work on, and more cost effective then Pitched roofs for huge surface areas (this is why most commercial properties have flat roofs).
The steeper the roof, the longer it lasts. Pitch roofs can last 20-50 years depending on the quality of materials and installation, whereas flat roofs last 15-20 years. Pitch Roofs and Flat roofs have different waterproofing designs. You might be surprised to find out that a pitch roof isn’t actually waterproof! Pitched roofs rely on sheeting off rainwater quickly from its steep pitch before the water has a chance to settle and pond. Flat roofs with their low slopes will have ponding, and so they are built with many layers that are sealed together to be waterproof, so that standing water doesn’t penetrate the roofs surface while it waits to be evaporated by the sun.
One big difference between flat roofs and pitched roofs is that a pitched roof has an attic, which allows you to put in attic insulation, attic vents, install HVAC ducting in its most energy efficient configuration, or have vaulted ceilings. One advantage of a flat roof, is the possibility of a rooftop deck that is not possible with a pitched roof.
By far the most common roofing material in the US is Asphalt Shingles. Approximately 80% of homes in the US have them. In addition to asphalt shingles, Flat roofs and Clay tile roofs are common in Los Angeles.
Clay Tile Roofs
Less common roofs are:
Not shown: Metal Roofs as well as Cement Tile Roofs
Rafters – carry the load of the roof and are usually made of wood 2x4s
Wood Sheathing- also sometimes called decking, sheets of 1/2 thick plywood that are nailed to the rafters to provide a solid flat surface that the waterproofing materials can be attached to.
Felt Paper/Underlayment– the bottom layer of waterproofing. Felt paper impregnated with tar.
Roof Material– this is the covering, can be Shingles, Cap Sheet, or Clay Tiles.
Vents- Pitched roofs have vents that help control temperature inside the house and reduce energy cost
Flashing– metal strips or plastic covers that are used to make transitions and protrusions in the roof (bathroom vent pipes, skylights, chimneys) water tight.
Gutters/Scuppers and Downspouts– system used to channel rainwater collected from the roof, off it, and away from the house.
Licensing & Permitting
The California Contractor State License Board regulates contractors. Roofers are required to obtain a C-39 Roofing License from the state to work on roofs. I recommend to always hire a licensed roofer- roof repair and maintenance is highly specialized and not a job for a handyman.
Safety: The largest risk for a roofer is falling. Roofing is one of the top ten most dangerous jobs in the US- there are about 80 roofer deaths each year from an estimated work force of 250,000.
How dangerous is your roof?
Injury risk depends on the steepness of the roof, if the surface below the roof is hardscape or soft, proximity to power-lines, and the Height of building. As I mentioned early, flat roofs are relatively safe to work on because they don’t have as high a risk for falling. Same with single story roofs with a normal pitch.
If your roof is over 20 Feet above the ground, workers are suppose to wear a safety harness or install a guardrail. It is always a good idea to verify the roofing company you hire carries Workman’s comp insurance. All reputable companies have it- don’t be afraid to ask.
Permitting: The cost of permitting a roof is fairly inexpensive- the building department only charges $150-$200 for a permit. A building inspector will come out two times, first after tear off and the second time when the roof is finished to final it. This does not cost a lot of money or cause much delay. Some homeowner’s don’t want to bother with a permit- the fact is that if you are caught by the city, they just give you a light slap on the wrist. The Roofer is fined $200, and they are required to pull a permit. Many roofers recommend getting a permit, not only because its the correct way to do things, but also because the roof is easily visible from the street, so it is easy for a city official to make a citation if they are in the neighborhood. West Hollywood is very strict, the city of Los Angeles is pretty lax.
Most homeowners are reactive about doing roof maintenance. They wait for the roof to leak and then scramble to call a roofing company when it is raining. The disadvantage of doing things this way is that the roofing industry in Los Angeles is seasonal. Roofers are very busy in the winter (Nov-Feb) which is the rainy season and slow in the summer (May-Sept). In the winter month they could have a 6-8 week backlog, where as in summer months it may only be two weeks. Chances are if you are having a leak it could take a roofer a week or two to get to you in the busy season. You will also pay slightly higher prices, maybe a 10%-15% premium, in the winter rather than in the summer, because there is higher demand.
If you have a roof leak and are waiting for a roofer, a temporary fix is to put up a rain tarp with sandbags. Roofing companies usually charge between $500-$700 to put up a rain tarp. A handyman can put a rain tarp up.
Roof Useful Life
Shingle : 20-30 years
Flat Roof : 10-15 years
Clay Tile Roof: 20-30 years (underlayment) Tiles 50 years
Wood Shake: Special, see article
Concrete tile: 50 years
Slate Roof: Lifetime 100-200 years
Rock Roof: 30-40 Years
Metal Roof: 40 Years
Around the halfway point in a roof’s useful life, it will start needing routine maintenance. Some of the components in the roofing system have shorter lifespans, and need maintenance sooner such as gutters (20 years), flashing (10 years), and sealing around protrusions (5 years).
Every roof has a bunch of stuff sticking out of it that make protrusions. Some example of protrusions are vent pipes for bathrooms, Ventilation for gas burning appliances like heating furnaces, AC Condensers (if located on the roof), satellite dishes and Antennas, skylights, and ducting. Each protrusion is an area of a potential leak. They are sealed with Mastic, which is a goopy tar like substance. They need to be retarred every few years to keep them waterproof.
Transitions (chimney, walls, pitched to flat roof connections, valleys, protrusions) and Edges are the areas of the roof most prone to leak.
For houses with fireplaces, the transition where the roof meets the chimney is a common leak source.
Another transition is from a wall to the roof.
Or a pitched area of the roof to a flat area.
Water runs over the Edges of the roof. Sometimes there is space in between the gutters and the edge roof that water can get in between and damage the fascia boards.
Patching is an economical and effective solution for a roof that is overall in good condition with just a few bad spots. Patching is much less costly than a complete roof replacement and only takes a day. As time goes on, the same problem areas may require additional patches, and as the roof gets older, other problem areas may appear. At some point as the roof deteriorates, it will just be cheaper to replace the roof than keep patching it each year.
I recommend working with a roofer for roof repairs. It is actually harder to fix a leaking roof than replacing it.
If you hire a handyman, they will probably buy a can of Henry’s Roof Patch and smear it around with a brush. This method does not fix a roof leak. So stick with the pros when it comes to your roof.
Replacing a roof is one of the most expensive home improvement projects. When it’s time to replace the roof it can definitely sting in the pocketbook department. It takes 3-5 days to install a new roof. One thing to keep in mind is that the weather forecast needs to be clear of any rain before the roofing company can get started. If the roof is off and it rains, it can cause catastrophic damage.
I recommend getting three bids before you hire a roofer.
One Roofer term you should know is a “square”. Roofers estimate the cost of a roof replacement by calculating how many squares it has. The more squares, the more expensive. A Roofing crew can do about 20-30 squares a day. A Square is equal to 100 Sqft. It is a 10 Foot by 10 Foot Square.
You can get a rough idea of how big your roof is in squares, by looking at the square footage of your home. Let’s say you have a single level house that is 1,500 sqft and your roof is a low pitch, then your roof size will probably be 16 or 17 squares. When a roofer comes out to estimate the job, they will measure your roof and tell you how many squares it is. Let’s say you have a two-story house that is 4,000 sqft. Well, the footprint on each floor is about 2,000 sqft. Let’s suppose also that this roof has a steep pitch, then add some extra squares to account for the steeper pitch, maybe this roof would be 25 or 26 squares.
|Roof Type||Cost Per Square|
|Shingle (very steep roofs can be more expensive)||$250|
|Clay Tile (price varies by choice of underlayment)||$250-$325|
Tear off is the first part of the job. If your roof only has one or two layers, sometimes you can just add a new layer ontop the existing layers. Doing this saves time and money. If your roof already has two or three layers, then you will probably need to tear all the old layers off and start a fresh. Tear off usually takes one day. If there is more than 1 layer to tear off, that might be an additional expense.
The removed roofing material is quite heavy. If the roofer can pull a dumpster or the back of their truck close to the roof this will save money because they can throw the old roof debris directly into the dumpster. If there is no dumpster or car access, tearoff will be more expensive because workers will have to carry the debris from the side of the house to the dumpster location which is more work and takes more time.
Sheathing is 1/2 inch or 5/8 inch thick plywood that is placed across the rafters and what the underlayment and roof material sits on. Sometimes when the roofing material is torn off, it reveals that the Wood Sheathing underneath it is damaged. This is especially common for a roof that has been leaking for a long time. The roofer will replace any damaged wood sheathing before they install the new roof. They typically charge $50 to $100 per piece for new sheathing.
Once the tear off and any sheathing work is completed the roofer will schedule a delivery of the materials. If your home has easy access then a truck with a crane or conveyor belt can hoist the materials to the roof. This saves time and money. If there is not good truck access- the materials will need to be carried by hand up ladders to the roof. This adds extra cost to the job.
Underlayment & Flashing
The underlayment is a waterproofing material that is installed between the sheathing and the roof material.
Whichever roof material you are having put on, it is installed on top of the underlayment.
Most manufacturers have a warranty on their products. Warranties can range from 10-20 years. In addition, the roofing company usually will have a warranty on their labor, usually 5 years or so. If you have problems, you can call them back to fix a problem. Keep in mind that most manufacturer’s warranties void when you transfer the property, so if you sell your home, the warranty usually doesn’t transfer to the new buyer.
Title 24 “Cool Roofs”
The State of California passed energy efficiency standards for construction in 1975. In 2008, the Energy Commission expanded those requirements to include cool roofs for new roofs installed in all residential buildings.
What are Reflectance and Emittance?
Reflectance is a measure of how much energy from the sun is absorbed. Emittance is how quickly the energy absorbed from the sun is released.
Simply put, Dark Materials absorb more sunlight and release less heat. So to comply with Title 24, lighter color roof coverings are required. Here is a comparison:
In this experiment, the daytime surface temperature difference between the non treated and cool roofs is 40 degrees! Cool roofs save energy because homes doesn’t need as much Air conditioning.
Exemptions: If you are making a roof repair, or only replacing less than 50% of your roof, you do not need to comply with the cool roof requirements. However, if you are installing a new roof in Los Angeles then the new roofing material you install must comply with the City requirements.
The city of Los Angeles requires these values for new roofs:
Here is a link to City_of_Los_Angeles_Cool_Roof_Fact_Sheet__FAQ.