Local weather advisory
The National Weather Service has issued a coastal flood advisory covering Berkeley. Heavy rain and drainage loading can expose roof leaks, blocked drains, and ponding water. This is a weather exposure advisory; it does not establish damage to a specific roof.
Do not access a roof during hazardous weather. Protect people first, avoid water near electrical equipment, and request roofing help when conditions permit.
National Weather Service · Updated Oct 28, 2026, 7:20 AM UTC
Commercial roofing in Vallejo and Mare Island from our Berkeley crew: leaks where two roof sections or roof types meet, traced and rebuilt so both sides seal.
Service Areas  | Berkeley, CA
Leaks on older commercial and industrial buildings often start where two roof sections meet: an addition against the original building, a low roof against a high wall, or two different roof types butted together. A metal cover or a strip of mastic over the seam may hide the gap for a while, but the real problem is underneath, where the two roofs were never properly tied together. We repair commercial roofs in Vallejo and on Mare Island from our base in Berkeley, CA, and we open up that junction before deciding how to rebuild it.
Mare Island is the former naval shipyard, now home to a mix of businesses, industrial users and Touro University California near Club Drive, with Nimitz Avenue running along the western edge of the Historic Core. Many buildings there have been added onto over the decades. Each one gets its own roof and access check. Our commercial roof repair work at these junctions is based on what is actually on both sides, so the finished joint works for both roofs.
A roof junction can join two different heights and two different roof systems. We check both sides before deciding how much to remove. An old metal cover may hide where the membrane actually ends. If we need to open it up to see, we explain what we are looking for first, then photograph what we find and note where it is on the roof.
Our roof inspection tells you what we checked and what we could not see. A sound roof on one side says nothing about the other side. Each membrane needs its own prep and attachment method, and the repair has to tie into both. That is why a junction repair is usually more than a narrow strip down the seam. The estimate explains what has to be rebuilt.
Two sections of a building can move differently, especially if they were built at different times. We check the junction for stretching, splitting or loose attachment. The new detail has to allow for that movement. If the movement looks structural, it needs an engineer’s review, because a roof patch cannot solve a structural problem. We flag that before new roofing covers it up.
Our edge metal and coping work includes the metal covers and flashings at the junction. Those need to be fastened to solid wood, not rotted blocking. A stiff cover screwed across a moving joint just moves the stress to the next weak spot. We explain what we found and who should review any structural concern, so the roof repair and any other work happen in the right order.
An open junction can let water into the insulation on either side. We compare what we see on the roof with where the leak shows up inside. With your approval, small cores can confirm whether the insulation is wet. One wet core may mean we need to check farther out, since the wet area can extend well past the visible gap. We show you what we found before setting the repair size.
Our roof insulation and cover board repairs remove wet material and keep dry, solid layers in place. The new junction needs enough solid roof on each side to tie into. A nearby curb or drain can limit that room, and we plan around it. If the damage is widespread, the repair and each day’s opening get bigger, and you see why before approving more work.
Adding a new roof over the old one raises the surface, and at a junction that can leave the flashing or metal cover too short to work. We measure that before recommending a recover. The junction may need to be rebuilt to fit the new roof height. Wet insulation and loose attachment also affect whether the old roof can stay. A new roof should never bury a junction that still leaks.
Our roof recover and overlay estimates include the junction work along with the new surface. A full tear-off gives more room to rebuild the joint properly. We compare both options based on what we found, and you can see what each includes at the junction. A cheaper estimate may simply leave that work out, and we make that easy to spot.
Opening a junction can expose the roof over an occupied space. We find out what is below and agree with the manager on how to protect it. The two roof sections may also have different ways to get onto them. Materials and debris need a clear route, and any metal or structural work by others may affect when we can close the junction up. We plan all of that before removing anything.
A building near Club Drive may have a very different entrance and staging area than one near Nimitz Avenue. Our reroofing over occupied buildings work covers protection for each. If you also have properties in Martinez or the Port of Richmond area, we can line up the inspections, but each building keeps its own repair and daily close-up plan.
We photograph both sides of the junction before the new detail covers them, then take wide shots showing where it sits on the roof and close-ups of the finished metal and membrane. Later inspections can compare against those photos. A leak somewhere else is checked on its own until we can show it is connected.
If one junction has failed and the roofs on both sides are sound, a focused repair is usually the right call. If the insulation is wet over a wide area, a larger repair or more testing may make sense. We explain what we found and what is still open, including any structural questions, so a bigger project only follows a bigger confirmed problem.
Mare Island’s former shipyard land now has commercial, industrial and educational users, and some areas are still being redeveloped. We confirm who controls roof access and whether nearby construction affects where we can stage. On older industrial buildings, we look at any available repair history and check junctions where additions or equipment changes may have altered the roof. Knowing a building is on the old shipyard does not tell us how its roof is built, so we inspect it. Findings are recorded section by section, and we note anywhere that needs to be opened before final pricing.
Let us inspect the junction between your roof sections. You get plain photos showing both sides and the repair needed to seal them together.
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