Commercial Roofing in Napa, CA

Nobody pictures a store roof when they picture Napa, and that is exactly why those roofs get ignored. The postcard is vineyards and tasting rooms. The payroll is different: Napa Valley Unified School District, Napa County, Costco and Walmart are among the biggest employers in a city of about 79,000 people, and each of them runs on roofs that need the same attention any commercial building needs. The buildings that keep the city working are not the ones in the photographs.

We repair, coat, recover and replace commercial roofs in Napa, CA. That means retail, school, county and business park buildings first. It also means planning for three things Napa has already seen: fire, an earthquake and a flood that tested every drain.

A big-box store and a school building ask different things of a roof. The store wants no leaks over the sales floor. The school wants the work done while students are away. Napa County's own buildings add a third need: a roof the county can budget for years ahead and document for auditors.

Napa County Airport lies about five miles south of town, and the Napa Valley Business Park sits near it in unincorporated county territory. A business park is rarely one owner and one roof. It can hold several buildings with separate owners, tenants and roof ages, which means separate budgets and sometimes a shared drainage path. We start by learning who owns what, then we go up and look at each roof on its own terms.

The magnitude 6.1 earthquake in 2014, northwest of American Canyon, tested more than structures. On a roof, a quake loosens whatever is heavy and rigid. Rooftop units shift on their stands, pipe supports move, and the flashing where the roof meets a parapet or wall cracks at the joint. The membrane itself often looks fine. The damage is at the details, so that is where we look first after any significant shaking, and where an owner should look if nobody ever has. Checking the equipment curbs and supports comes first for exactly that reason.

The 2005 flood, which destroyed 1,000 homes countywide, is a reminder about water in general. When the street backs up, so do the storm lines that interior roof drains connect to. We check where each drain goes. An overflow scupper set high on the parapet wall is cheap insurance against that, and it is worth it on almost every low-slope roof with interior drains.

For a big store with a sound membrane and a few trouble spots, repair first. Reseal the penetrations, clear the drains, patch the seams, and record every photo. For a school roof near the end of its life, a full school roofing project belongs in the summer window, with tear-off done in sections so that the roof is never open over occupied rooms. For a county building on a tight budget, a coating can buy years if the insulation is dry, and an infrared survey tells you that for certain.

Cost follows a short list: how much insulation is wet, how many penetrations there are, how the roof is reached, and when work is allowed. Public owners also need a written condition report and a multi-year plan, and a public agency needs that paper trail to approve and fund the work. Verdict: survey first, then spend on the sections that earn it.

Large retail roofs are mostly about drains and equipment. A big-box store roof carries rooftop units, vents and refrigeration lines, and every one of those is a hole with a seal around it. The drains handle the water from the entire roof, so a drain that clogs can overload a section in a single heavy storm.

When a leak appears over a sales floor, tell us where the stained tile is and which direction the nearest unit sits. Water on a low-slope roof travels a long way along the deck before it comes through, and the source is usually uphill from the stain.

What not to spend on

Do not replace a sound membrane because it is old. Age is a reason to inspect, not a reason to tear off. Do not buy a premium assembly for a building that will be torn down. And do not skip the drain survey to save a few hours, because a new roof over blocked drains fails the same way the old one did. The same rule holds in Fairfield and Sonoma: look first.

Commercial Roofing Questions

One corner of our Napa store roof holds water after every rain. Does the whole roof need replacing?

Not automatically. Standing water in a single area usually means a blocked or poorly placed drain, or insulation that has compressed under foot traffic and dropped the surface. We check the drain first, then measure the slope with a level. If the insulation is dry, a tapered insulation patch or a new drain often solves it for far less than a replacement. If the survey shows wet insulation around that corner, we cut it out and replace that section only.

After an earthquake like the 2014 one, what should we check on the roof?

Start with anything heavy that sits on the roof. Rooftop units, pipe supports and conduit can shift, and the flashing around them can tear without any visible change in the membrane. Next check the transition where the roof meets a parapet or wall, because those joints crack first. Then look for new cracks in coatings and seams near expansion joints. Photograph all of it with a date, and call us if anything moved.

How do we schedule a roof project on a school building around the school year?

Plan backward from the first day of class. Tear-off and the new membrane belong in the summer break, and the design, bidding and material ordering belong in the winter and spring before. Work in sections so no part of the roof sits open overnight above classrooms. Any work during the school year should be limited to repairs, done outside class hours.

We own one building in a business park and share a drainage path with a neighbor. Who is responsible when it backs up?

Read the property lines and the park's covenants before anything else, because the answer is usually written there. Meanwhile, document the problem with photos and a drain map. Water that crosses a property line is a legal question as much as a roofing one, and a clear condition report helps both sides agree on a fix. We can write the roofing side of that record.

Is a fire-rated roof assembly worth the extra cost after the Glass Fire?

Ask what classification the assembly carries and what the building's use is. It is worth it for a building with combustible materials nearby, a wooden deck, or a record of ember exposure. It is not worth it as an add-on to a roof with nothing flammable near it. A noncombustible cover board and good edge details often deliver most of the benefit at a fair price.