Johns Manville roofs in Ventura come in many forms. Some are multi-ply built-up or modified-bitumen roofs from decades ago; others are newer JM TPO, PVC or EPDM single-ply systems. A building that has been reroofed more than once may have a little of each. Before anyone orders repair materials, we need to know which one is in front of us.
We walk the roof, check the seams and laps, look at flashings at walls, curbs, drains and scuppers, and note every older patch. A commercial roof inspection puts that on a marked plan with photos so you can see what we saw.
Near the coast, granules wear off cap sheets, asphalt flashings crack in the sun and salt air rusts metal edges. Inland, heat does more of the damage. Either way, the trouble usually starts at the details.
The product behind the manufacturer name
JM’s commercial roofing covers TPO, PVC and EPDM single-ply membranes as well as APP and SBS modified-bitumen sheets. Those are very different materials. A torch-applied APP sheet, a cold-applied SBS sheet and a welded TPO seam each need their own repair method, and several of them do not bond to each other at all.
We identify the membrane by looking at the surface, the laps and the flashings. Where the roof has been coated or patched over, we take a small core, check the layers inside and repair the spot right away.
On an asphalt-based roof, our modified bitumen roofing page explains how those sheets and flashings are installed. Old repairs need care: roof cement over a single-ply seam, or a single-ply patch on a mod-bit roof, often has to be cut out before a lasting repair can go in. We follow JM’s published installation requirements for the product that is actually on the roof.
Seams and flashing with the field quantity
Square footage is the easy part of a roof estimate. The details are where the leaks are and where bids differ most. On JM roofs we see open laps, blistered or split cap sheets, base flashing sliding down parapet walls, cracked pitch pans, rusted scuppers and worn flashing around rooftop unit curbs.
Our estimate breaks those out one by one, with location, what is removed, what stays and what is new. That way the field price and the detail work are both visible, and you can tell if a cheap number is cheap because it skips the flashings.
If you are getting a GAF bid as well, ask that contractor to price the same seams, walls and curbs. Matching detail lists is the fastest way to compare two roofs fairly. We also check curb and wall heights during the inspection. Adding insulation raises the roof, and a curb that ends up too short to flash correctly needs to be raised before the new roof goes on, not discovered on the day of the install.
Layers needing removal beneath the repair
Older multi-layer roofs hold water like a sponge. A small split in a JM cap sheet can wet the felts and insulation for a long way around it, and the stain inside the building may be nowhere near the opening. We find out how far the moisture has gone with core cuts and, on larger roofs, an infrared or moisture survey.
Wet felts and insulation are removed. Rusted or soft deck is repaired before anything new goes on. Dry layers can usually stay, which keeps the cost reasonable.
The same work belongs in any other bid. A Holcim Elevate roof priced for the same building still has to deal with the same wet layers and deck. If tear-off turns up more damage than expected, we stop, photograph it, mark it on the plan and price the extra area before continuing. Open spots are sealed at the end of each day. You see the problem before you pay to fix it.
Related Roofing Work
Equipment work before roofing resumes
Torch work, hot asphalt and adhesives all have to be planned around what else is on the roof. Gas lines, conduit, HVAC units and exhaust fans often sit right on the flashing we need to replace, and torching next to them is not always safe or allowed. In those spots we may switch to cold-applied or self-adhered materials, or ask your mechanical contractor to disconnect and lift the unit first.
The estimate spells out which items need another trade, what we do after they are cleared and how long it takes. Your team can then schedule the HVAC tech and the roofers in the right order.
Occupied buildings also shape the schedule. Asphalt odor near air intakes, noise over offices and deliveries at a busy dock all affect when we can work. If the job needs several visits, each stopping point is sealed so the roof stays dry overnight. After every visit we send a short note: finished items, items waiting on another trade, and what is left. A curb that is still waiting does not get counted as done.
The installed product and repair record
Logistics change from building to building. A roof in Downtown Ventura may have only an alley for the hoist and street parking for the truck, so we plan staging, deliveries and debris chutes before work starts. Buildings in East Ventura or near Ventura Harbor bring their own access questions.
When the work is done, you receive the list of JM products installed, a roof plan showing each repair, and dated photos taken before the work was covered up. Areas we did not open, and items still waiting on HVAC or other trades, are listed on their own.
That becomes a roof condition report for your files. It is useful when you sell, refinance, file an insurance claim or bring in another contractor. If there is a Johns Manville warranty on the roof, confirm whether it is still active and what JM requires for repairs before the work begins. We can help with that call.
Common Questions
What do you need to identify before ordering Johns Manville repair materials?
We need to know whether the roof is JM built-up, APP or SBS modified bitumen, TPO, PVC or EPDM, and whether more than one type is present. We check that on the roof, look at the condition of seams and flashings, and find out what earlier patches are made of before choosing materials.
How do I compare a Johns Manville bid with another manufacturer?
Ask each contractor to list the same repairs at the same spots: seams, wall and curb flashings, scuppers, drains, edges and any wet insulation or deck. Then compare. A low bid that leaves flashings or wet layers vague usually covers less work, which tends to show up later as leaks.
What needs to happen before a flashing repair next to rooftop equipment?
If a unit, gas line or conduit sits on the flashing, your mechanical contractor may need to disconnect or lift it, or we may switch to a cold-applied method instead of a torch. We list that step in the estimate and keep the curb open on our list until the flashing is installed and checked.
What records do I get after Johns Manville work is finished?
You get the JM products installed, a roof plan marking every repair, and dated photos taken before the work was covered. Unopened areas and items waiting on other trades are listed separately, so the next contractor knows exactly what was done and what still needs attention.
Get your Johns Manville roof inspected
Send us the address, the areas that leak or look worn, and any drawings or warranty papers you have. We will identify the JM system, inspect the seams, flashings and layers, and give you a clear repair estimate.