Why roof leaks matter in San Anselmo
San Anselmo is a town of about 12,800 people, incorporated in 1907, set among the hills of the Ross Valley with Mount Tamalpais to the south. San Anselmo Creek, a branch of Corte Madera Creek, runs right through the center of town, along the banks where most of its antique shops and restaurants sit, and much of southern and western San Anselmo is built on its natural floodplain.
The town averages about 47 inches of rain a year, with January the rainiest month, and its history shows what heavy storms can bring. The creek has flooded downtown roughly every 15 to 23 years, in 1925, 1940, 1963, January 1982 and at the end of December 2005. The worst, on January 2, 1982, followed more than 8 inches of rain in 12 hours.
Floods come from the ground, not the roof, but the storms are the same. When rain falls that hard for that long, every weak point on a roof gets tested at once. Add the town's older housing, some with raised foundations dating back to around 1920, and the mature trees that shade many streets, and San Anselmo roofs face a tough winter.
The roof problems San Anselmo homeowners call about
Older roofs with layered repairs
Homes from the early twentieth century have often been reroofed several times, and old flashing under newer roofing is a common leak source. A roofer may need to open the surface to find it.
Tree debris and moss
Mature oaks and bays drop leaves into valleys and gutters, and shaded slopes grow moss. See the moss and debris guide for safe removal.
Low-slope roofs in Sleepy Hollow
Up Butterfield Road in Sleepy Hollow, a small group of Eichler homes designed by Claude Oakland in 1974 carry low-slope roofs and skylights. The flat roof page covers their typical leaks.
Storm and limb damage
Big storms and soaked ground bring down branches, especially on tree-lined streets near the creek and up the hillsides.
Telling a roof leak from storm-day water
During a major storm in San Anselmo, water can show up in a house from several directions: through the roof, through walls and windows in wind-driven rain, and in lower floors from rising ground water. A stain on a ceiling or upstairs wall that grows during rain points to the roof. Water at floor level or along a lower wall points somewhere else.
After the storm, check the attic if it is safe, photograph every stain and note which rooms were affected. That record helps both the roofer and any insurance claim, and keeps the roof repair separate from other storm damage.
If the house has a low-slope porch or a later addition, look there first. Those sections often have the gentlest pitch on the property, and their joint with the main house takes runoff from the roof above.
Getting a San Anselmo roof ready for winter
Because San Anselmo's storms can be long and intense, preparation pays off more here than in drier parts of Marin. In September or October, have the gutters and valleys cleared and the downspouts checked, so water leaves the roof and is carried away from the foundation. Look at the roof with binoculars for lifted shingles, cracked ridge caps and moss on the shaded side, and have any overhanging limbs checked.
For older homes near the center of town, it is worth having a roofer look at chimney flashing, roof-to-wall joints and any low-slope porch roofs before the rains. Those are the spots most likely to have been patched over the decades. If a repair is needed, the dry season is the time to do it, because once the winter storms arrive the dry windows are short. Keep a simple storm kit ready too: buckets, towels, a flashlight and a note of where the main breaker is.
A San Anselmo roof checklist
- Clear gutters, valleys and downspouts before the first storm.
- Trim branches that overhang or touch the roof.
- Check upstairs ceilings and walls after every heavy rain.
- On older homes, find any records of past reroofs and their dates.
- Keep buckets, a flashlight and the breaker location handy for storm nights.
Nearby areas
San Rafael lies just east, down the valley, with its Eichlers and older neighborhoods covered on the San Rafael page. Larkspur and Mill Valley are a short drive south toward the bay. For the leak checker and the storm season ring, see the Rainline Marin overview.
Fairfax sits just west, farther up the valley, and Ross lies to the south along Corte Madera Creek.
San Anselmo roof questions
Can creek flooding cause roof leaks?
No, flooding comes from the ground. But the same long, heavy storms that raise San Anselmo Creek also test roofs hardest, so leaks and high water often arrive together. Keep the two problems separate when you call for help.
My house sits on a raised foundation near the creek. Does that affect the roof?
Raised houses stand taller and catch more wind at the eaves. They also tend to be older, so the roof may have several layers of past repairs worth checking.
Are the Sleepy Hollow Eichlers like the ones in Terra Linda?
They are a small, later group of Eichler homes, and like other Eichlers they have low-slope roofs and skylights, so membrane seams, drains and skylight curbs are the main leak points.
How much rain does San Anselmo get?
About 47 inches a year on average, with January the rainiest month. That is close to twice Novato's average.
Should I wait for spring to fix a winter leak?
No. With so much rain from December to March, a leak left alone soaks the same decking again and again. Get it covered and inspected, then schedule the permanent repair for the next dry window.