A replacement ends with a roof you do not think about. Getting there takes four decisions made in order: which covering, what the deck needs, which rules apply at the address, and when the work should happen. We walk you through each one before the old roof comes off.
Four decisions, in this order
First, the covering. Tile, shingle, metal and flat membranes behave differently in heat, and each one weighs a different amount on the framing. We start from the roof's shape and the sun each face takes, then narrow the list.
Second, the deck. Boards or plywood that have gone soft are replaced, because new roofing is only as flat and sound as the surface under it. Third, the code at the address. Fourth, timing. The scope states what happens and in what order, so you know what to expect before work starts.
Replacement, overlay and reroof: what the words mean
A replacement removes the old covering and puts a complete new system in its place. An overlay lays a new covering over the old one. County rules allow that only when there is a single existing layer, adequate framing and a sound deck that is not water-soaked (Los Angeles County Public Works, 2025). A tear-off is the safer route whenever the deck cannot be seen.
Under the state cool roof rule, a reroof means replacing more than 50 percent of the roof, and an overlay counts as replacement (California Energy Commission, 2022). Below that line, only the part you replace is affected.
What a replacement includes
- Old covering removed and disposed of
- Deck inspected, with soft boards or plywood replaced
- Underlayment laid over the whole roof
- Flashing renewed at walls, vents and chimneys
- The new covering, installed to the maker's instructions
- Permit, inspection and the closing certificate
Signs it is time to plan a replacement
- Leaks or stains in more than one room
- Grit in the gutters or bare spots on shingles
- Cracked, curling or slipped covering across several slopes
- A roof that has had repeated fixes in the same area
The code at your address
Start by asking who issues the permit. For a City of Los Angeles address it is LADBS, and re-roofs with a Class A or B covering on solid sheathing at under 6 lb per square foot go through as express permits without plan check. For County jurisdiction it is Public Works, and a reroof needs a building permit there (LADBS, 2026; Los Angeles County Public Works, 2025). Other cities run a building department of their own or contract with the County. The scope names the office for your address.
Three rules travel with a reroof permit: cool roof values after replacement passes 50 percent of the roof, a minimum fire class for the covering, and limits on wood shake. The City of Los Angeles bars shake as a covering, and a modification request can allow limited work on up to 5 percent (LADBS, 2026). In County jurisdiction, shakes already on the roof come off, and clay or concrete tile comes off in full before any reroof.
Timing a replacement around the rain
Downtown Los Angeles normally gets about 14.25 inches of rain a year. From November to March it gets about 12.42 of them, roughly 87 percent, while June to September is close to zero (National Weather Service, 1991-2020 normals). A replacement scheduled for the dry months leaves less to protect from weather in mid-job.
Demand follows the weather. After the El Nino forecasts of 2015 and the storms of 2023, news reports described Los Angeles roofers booked up and homeowners waiting on callbacks (ABC7, 7 November 2015; FOX 11, 2 March 2023). If you plan a replacement, ask early.
Questions before a replacement
Can I replace my roof myself in California?
Yes, by acting as an owner-builder: you pull the permit yourself and answer for every inspection. The roof still has to meet the cool roof, fire class and permit rules for the address. The work is heavy and carries a fall risk, so weigh that before you decide.
How does a maker's warranty differ from an installer's workmanship cover?
The maker stands behind the product. The installer stands behind how it was put on. They are separate documents with separate terms. Ask for each in writing, and read what it excludes, before you sign.
What time of year suits a roof replacement?
Dry months leave the most room to work. Of the 14.25 inches that normally fall on downtown Los Angeles in a year, about 12.42 arrive between November and March (National Weather Service, 1991-2020 normals). Booking ahead of that stretch means the new roof is on when the rain comes.
What does it mean to replace a roof?
The old covering comes off, or one layer is overlaid where the rules allow it. The deck is repaired, and a complete new system goes on: underlayment, flashing, the covering and the ridge pieces. A replacement over 50 percent of the roof also counts as a reroof under the cool roof rules (California Energy Commission, 2022).
Does a new covering need a tear-off, or can it go over the old roof?
It depends on the office and on what is up there now. County rules allow a covering over an existing one only with a single layer, adequate framing and a sound, dry deck (Los Angeles County Public Works, 2025). Clay or concrete tile has to come off in full. A tear-off also shows us the deck.