Roof Repairin San Dimas, CA
Roof repair in San Dimas follows two City rules many cities skip: Planning must approve any change in roofing material or color, and every re-roof needs a Class B or better covering. The City's own papers disagree on the permit line, 200 square feet or 5 percent of the roof, so confirm it with Building and Safety.
San Dimas began as a railroad town. The Santa Fe Railroad opened it in 1887, orange and lemon groves and packing houses filled the land around the depot, and the last packing house closed in 1963, three years after the city incorporated on August 4, 1960. Subdivisions then replaced the groves. The Census Bureau's 2024 five-year estimates count 12,370 housing units, and the 1970s were the biggest building decade at 32.2 percent of them. About 63.3 percent date from before 1980, so the original roof on most San Dimas houses would now be more than four decades old.
On a roofing job, MDG Builders (CSLB #1040337) plans the scope, puts the open permit and color questions to Building and Safety and Planning, and holds the schedule, while a licensed C-39 roofing subcontractor does the tear-off and installation. Our roofing page carries the sourced prices, the San Dimas overview lists the other trades we manage here, and nearby cities run on different rulebooks, as the guides for Glendora and Pomona show.
What San Dimas's re-roof handouts and fire maps say about roofs
Where roofing permits come from in San Dimas: City of San Dimas Community Development Department, Building and Safety Division.
- San Dimas lists roof installation, replacement or recovering as work that needs a building permit. The city's page exempts only minor roof repair limited to 5 percent of the roofing material across the whole roof or a single area of 32 square feet or less, cumulative over three years. The older Re-Roof Guidelines handout (effective 01/21) used a 200 square foot threshold instead, so confirm the current figure with the counter.
- In addition to the building permit, the Re-Roof Guidelines say all changes in roofing materials, including the color of the material, must be reviewed and approved by the City Planning Department, and that residential re-roof permits are usually issued over the counter. The handout also says Planning approval is required in certain areas of the city to meet design guidelines and high fire zone requirements.
- San Dimas's Re-Roof Guidelines require a Class B or better (Class A) roof covering for every re-roof and a minimum 2:12 slope for asphalt shingles. Two layers of underlayment are required on slopes from 2:12 up to 4:12 and one layer above 4:12, and the handout says San Dimas is in Climate Zone 9 and recommends a radiant barrier and R30 attic insulation.
- The Re-Roof Guidelines allow at most one overlay of asphalt shingles on an existing asphalt shingle roof (two layers total), and no overlay where the existing roof is water soaked or too deteriorated to serve as a base. The Re-Roof Requirements sheet adds that the Building Division must verify before a second layer is permitted and that a roof already carrying two layers must be torn off before new material goes on.
- Where plywood is added over existing spaced sheathing, San Dimas's Re-Roof Requirements say the typical nail is an 8d, plywood end joints must land over a rafter and be nailed every 6 inches, field nailing is every 12 inches, and nails go every 6 inches along the eave block line and ridge line.
- San Dimas's Re-Roof Requirements call for a roof inspection after all old roofing and underlayment is removed and all damaged starter board, skip sheathing or plywood is replaced and nailed, and again after any fascia work and after the clearances around Type B vents and flues are set. The final inspection requires plumbing vents, flashings and replaced wood to be painted to match the house (primer alone is not accepted), debris removed and address numbers on the house.
- The city's single-family cool roof handout (dated 2/1/2024, written for the 2022 Energy Code) says a re-roof where more than 50 percent of the roof is replaced must use a Cool Roof Rating Council-labeled product in Climate Zone 9: for steep-slope roofs (2:12 or steeper) an aged solar reflectance of at least 0.20 and thermal emittance of at least 0.75, or an SRI of at least 16, with listed exceptions such as R-38 ceiling insulation, a radiant barrier, no attic ducts, R-2 continuous insulation, building-integrated PV, or roof weight of at least 25 lb per square foot. The 2025 Energy Code took effect after that handout, so confirm the edition.
- The Planning FAQ lists a re-roof as work that needs a building permit, and the Homeowner's Guide says re-roofing with no structural alteration qualifies for the Single Trade Permit.
Does roof repair or roof replacement need a permit in San Dimas?
Replacement does, and for repairs the City disagrees with itself. The City's permit page lists roof installation, replacement or recovering as permit work and exempts only minor repair, limited to 5 percent of the roofing material across the whole roof or one area of 32 square feet or less, counted cumulatively over three years. The older Re-Roof Guidelines handout, effective January 2021, draws the line at 200 square feet. We could not tell which figure the counter applies today, so ask Building and Safety and have the answer written on the proposal.
That gap shapes the repair-or-replace choice. Repair fits local damage over a sound deck, such as a run of slipped shingles or a failed vent flashing. Replacement fits a covering failing across the roof or a deck gone soft. Because the City's 5 percent test is cumulative, keep a dated list of every patch.
Re-roofing with no structural change qualifies for the Single Trade Permit. A licensed C-39 roofer can pull it, as can an owner-builder after ownership is verified, and a general contractor only when the roof is part of a multi-trade project unless that contractor also holds C-39.
Ask the counter which threshold it uses, 200 square feet or 5 percent, before a roofer prices a repair.
Does Planning have to approve my roof color in San Dimas?
Yes, for any change. The Re-Roof Guidelines say every change in roofing material, color included, must be reviewed and approved by the City's Planning Department, and that some areas need Planning approval to meet design guidelines and high fire zone requirements. Matching the old material and color is the simple case. A switch from shingle to tile, or brown to gray, is a Planning question. Planning answers at (909) 394-6250, and its Planning Division page explains the counter.
Houses near the old downtown may face more. City Council adopted Town Core Design Guidelines in 1993, after a 1991 survey found more than 320 significant structures and two potential historic districts, and the LA Conservancy notes that San Dimas has no historic preservation ordinance. The guideline PDFs on the City's site are scanned images we could not read, so we cannot say what they require for roofs. Ask Planning whether they reach your parcel before choosing a material.
Bring the product name and a manufacturer's sample to Planning, so the approval names the exact color.
Do San Dimas re-roofs have to be cool roofs, and how hot do roofs get here?
Often, yes. The City's single-family cool roof handout, dated February 1, 2024 and written for the 2022 Energy Code, says that when more than 50 percent of a roof is replaced in Climate Zone 9 the product must carry a Cool Roof Rating Council label. For steep roofs of 2:12 or more that means an aged solar reflectance of at least 0.20 and thermal emittance of at least 0.75, or an SRI of at least 16. Listed exceptions include R-38 ceiling insulation, a radiant barrier, no ducts in the attic, R-2 continuous insulation, building-integrated solar and a roof weighing at least 25 pounds per square foot. The 2025 Energy Code came later, so ask which edition governs your permit.
The climate explains the rule. NOAA's 1991 to 2020 normals for the Pomona/Fairplex station, 3.0 miles east-southeast of central San Dimas, show about 70.5 days a year at or above 90 F and 10.7 at or above 100 F, with August highs averaging 92.4 F. That station's monthly records rest on only 11 to 15 years of data. The Re-Roof Guidelines also recommend a radiant barrier and R30 attic insulation for this climate zone.
A pale color is not automatically a cool roof: the label and the rated numbers on the product sheet are what count.
How many layers, what slope and what fire class does a San Dimas re-roof need?
The City's handouts set the basics. Every re-roof needs a Class B or better covering, asphalt shingles need at least a 2:12 slope, and underlayment is doubled on slopes from 2:12 up to 4:12 and single above 4:12. At most one overlay of asphalt shingles may go over an existing shingle roof, none where the old roof is water soaked or too worn to carry one, and a roof already carrying two layers must be torn off before new material goes on.
Where plywood is added over spaced sheathing, the Re-Roof Requirements sheet calls for 8d nails, end joints over a rafter and nailed every 6 inches, field nailing every 12 inches, and nails every 6 inches along the eave block line and the ridge line. A roofer who has read those details will mention them. Rain shapes the calendar too: the Pomona/Fairplex normals give 14.47 inches a year, and 11.47 of them fall from December through March.
Is my San Dimas house in a fire hazard zone, and does that change the roof?
Possibly. CAL FIRE's updated Local Responsibility Area map for San Dimas, dated March 24, 2025, shows Very High, High and Moderate zones. The City's fire severity zone page says the council must adopt the zones by ordinance within 120 days of receiving the maps and may raise but not lower a designation. We could not confirm that the council has adopted them, and the City's parcel map is a graphic we could not read for zones, so we cannot say which streets sit in which zone.
What a zone changes for a roof is also open. The City's ADU handout requires the California Wildland-Urban Interface Code for any ADU in a Fire Hazard Severity Zone, and the Re-Roof Guidelines send certain areas to Planning for high fire zone requirements, but the City pages we opened do not list roof-covering rules zone by zone. Check your parcel on the City's March 2025 map or CAL FIRE's viewer, then ask Building and Safety for the roof assembly your address needs and have it written on the proposal.
What inspections does a San Dimas re-roof go through, and when can roofers work?
Three checkpoints are named. The Re-Roof Requirements ask for an inspection once the old roofing and underlayment are off and every damaged starter board, skip sheathing or plywood piece is replaced and nailed. Another follows any fascia work and the setting of clearances around Type B vents and flues. The final inspection needs plumbing vents, flashings and new wood painted to match the house, since primer alone is not accepted, plus debris cleared and address numbers on the house.
The permit also runs a clock. Under the Homeowner's Guide, work must begin and pass an inspection within 180 days of issuance, with an approved inspection on the books at least every 180 days afterward. Permitted work hours are Monday through Friday from 7 a.m. to dusk and Saturday from 8 a.m. to dusk, with none on Sundays and holidays, and the job card hangs near the work. Ask the roofer to schedule inspections into the calendar from the first day.
How much does roof replacement cost in San Dimas, and who should I hire?
No San Dimas price survey turned up, so this page prints no San Dimas price. The nearest sourced figures are for Los Angeles. Angi's Los Angeles page, updated July 31, 2026, shows $4 to $12 per square foot for asphalt shingle, $7 to $15 for tile and $7 to $16 for metal, with $1,000 to $3,000 more for tear-off. Remodeling magazine's Cost vs. Value 2025 report prices its reference Los Angeles roof at $36,417 in asphalt and $62,069 in metal without publishing the roof's size. Roof area, not house size, drives the bill.
Roofing is CSLB class C-39, which CSLB describes as installing products and repairing surfaces that seal, waterproof and weatherproof structures, including shakes, shingles, roof tile, slate and metal systems. Check the license with our contractor license guide and ask for the roofing subcontractor's license number and certificate of insurance. Since January 1, 2025 the state's unlicensed work limit is $1,000, but CSLB bulletin 24-07 says it never applies when a permit is needed, so a permitted San Dimas re-roof needs a licensed contractor at any price.
Roofing photos from San Dimas and nearby communities
Seven roofing scenes tied to San Dimas streets and to nearby places such as La Verne, Glendora and Pomona, from shingle tear-offs and tile flashing to finished roofs under the foothill sun.
Where these San Dimas roof figures come from
The sourced table for every roofing price is on our roofing price page, and the roofing cost guide explains why Angi and Cost vs. Value sit so far apart. A new roof often comes with other work, and the San Dimas rules for it are on the fencing page, the painting page and the kitchen remodeling page. For a foothill city with firmer fire rules, read the roofing guides for Glendale and Pasadena, and see how general contractors use subcontractors for who answers for what.
| What it covers | Typical range |
|---|---|
| Asphalt shingle, typical single-family roof | $10,000 to $25,000 |
| Concrete or clay tile | $7 to $15 per sq ft |
| Metal | $7 to $16 per sq ft |
| Remodeling Cost vs. Value 2025, Los Angeles | Asphalt $36,417. metal $62,069. |
| Extras | Tear-off $1,000 to $3,000. solar detach and reset $500 to $1,000. |
San Dimas roofing questions, answered
What is the 25% rule for roofing?
We found no San Dimas or state code section by that name. The thresholds that matter here are the City's own: its permit page exempts repairs limited to 5 percent of the roof or one 32 square foot area, while its older Re-Roof Guidelines say 200 square feet. Ask Building and Safety which one it applies, since the two papers disagree.
How much should a 2000 sq ft roof cost?
Price it by roof area, because a 2,000 square foot house can carry a much larger or smaller roof. Angi's Los Angeles page lists asphalt at $4 to $12 per square foot, tile at $7 to $15 and metal at $7 to $16. We found no San Dimas survey, so a measured written proposal is the real price.
Do I need a permit for roof repair or roof replacement in San Dimas?
A replacement needs a permit, and the City's page exempts only minor repair. Its limit is 5 percent of the roof or one 32 square foot area, counted over three years, while an older handout says 200 square feet. Confirm the current figure with Building and Safety before any repair starts.
Does a 20 year old roof need to be replaced?
Not automatically. Judge it by condition: a sound deck with local damage can be repaired, while widespread failure or a soft deck points to replacement. We found no sourced roof lifespan for San Dimas, so ask for photographs of the flashing, underlayment and deck instead of relying on a number.
Does a San Dimas re-roof have to be Class A?
The City's Re-Roof Guidelines require a Class B or better covering for every re-roof. Whether your parcel needs Class A depends on its fire zone, and the City pages we opened do not list roof rules zone by zone. Check the March 2025 fire map and ask Building and Safety for the rating.
Do I need Planning approval to change my roof color in San Dimas?
Yes. The Re-Roof Guidelines say every change in roofing material, including color, must be reviewed and approved by the Planning Department in addition to the building permit. Call Planning at (909) 394-6250 with the product name and color, and get the approval before the roofer orders material.
What is the best month to replace a roof?
We found no sourced price pattern by month, so we will not name one. The weather record does guide timing: 11.47 of the year's 14.47 inches of rain fall from December through March, while August highs average 92.4 F. Ask the roofer how an open deck is covered if a storm arrives.
Can you stay in your house while the roof is being replaced?
Usually yes, since the work happens on the roof, though it is noisy. Under the City's Homeowner's Guide, permitted work runs Monday through Friday from 7 a.m. to dusk and Saturday from 8 a.m. to dusk, with no work on Sundays and holidays. Plan around those hours for pets and work calls.
How many layers of roofing are allowed?
In San Dimas, at most one asphalt shingle overlay on an existing asphalt shingle roof, so two layers in total. The City allows no overlay where the old roof is water soaked or too worn, and a roof already carrying two layers must be torn off. We did not check the state code on this.
What can I do if I can't afford a new roof?
Start with a written inspection, because a sound deck with local damage may need repair only. We did not find a San Dimas program that pays for roofs, and we did not research state or federal ones. Collect two or three itemized proposals and compare them line by line.
Ask for a roof inspection in San Dimas
Tell us the street, roughly when the house was built and whether the roof has leaked. We put the open permit and color questions to Building and Safety and Planning before we call back.