Roofing Manufacturers
Johns Manville Roofing Systems in Green Bay, WI
Johns Manville's Membrane and Modified Bitumen Lines for Green Bay Roofs
Johns Manville manufactures across single-ply and modified bitumen categories, and their asphalt-roofing background gives them a strong modified bitumen line that we consider often on Green Bay's older industrial building stock.
A Manufacturer With Deep Asphalt Roots
Johns Manville's history in insulation and asphalt roofing materials predates the modern single-ply era, and that background shows up in the depth of their modified bitumen product line, including DynaBase and DynaWeld products used across torch-applied, self-adhered, and cold-adhesive systems. On the buildings around the Fox River corridor originally roofed in asphalt, that heritage line is often the closest match to existing construction.
They also manufacture TPO and PVC single-ply membranes across standard thickness ranges, which puts them in the same evaluation set as any other single-ply manufacturer when a roof's conditions call for a membrane system instead of modified bitumen, and we compare their published thickness and attachment options against the same criteria we apply to any brand.
On projects where the deck is split between an older asphalt-roofed section and a newer steel-deck addition, JM's presence in both the asphalt and single-ply categories means we can compare compatible options from one manufacturer's line before deciding whether to bridge the two roof sections with the same system or two different ones.
Insulation Products From the Same Manufacturer
Johns Manville also produces polyiso and other insulation board products, including options historically used specifically under modified bitumen assemblies, which we look at for compatibility when we're building a full JM assembly from insulation through membrane.
On buildings carrying real snow load, we also check the insulation's compressive strength rating against the expected drift loading at parapets and equipment curbs, since not every polyiso board in a manufacturer's catalog is rated the same way, and the wrong board under a heavy drift zone can crush over time even with a sound membrane on top.
Evaluating Their Systems Against Green Bay Roof Conditions
For a mill-adjacent building being recovered with modified bitumen, we check JM's application method options against the site's fire code restrictions and any active chemical or steam exhaust exposure nearby. For a distribution warehouse being specified in TPO, their membrane gets compared against wind uplift and fastening pattern requirements the same as any other manufacturer.
As with every manufacturer, published technical bulletins and detail standards drive the actual spec, not general reputation or how long the company has been in the roofing business. We also compare current lead times on JM's product lines against other manufacturers when a project is scheduled tightly, since asphalt-based products in particular can have different regional stocking patterns than single-ply membrane.
- DynaBase and DynaWeld modified bitumen base and cap sheets
- TPO membrane in standard mil thicknesses and attachment methods
- PVC membrane for chemical and grease-resistant applications
- Polyiso and specialty insulation board products
- Torch, self-adhered, and cold-adhesive modified bitumen application options
Warranty Considerations Across JM's Two Product Families
Because Johns Manville sells both asphalt-based and single-ply systems, their warranty structure differs meaningfully between the two product families, and we review the specific document for whichever system is being specified rather than assuming coverage terms carry over from one category to the other. A modified bitumen warranty and a TPO warranty from the same manufacturer can have very different exclusions around ponding water, foot traffic, and maintenance requirements.
We walk through that document with the owner before finalizing a JM spec, since the warranty terms sometimes influence which product family makes more sense on a specific roof, not only the technical performance comparison. On a mill-adjacent building where mod bit and TPO are both technically viable, a stronger warranty on one product family over the other has occasionally been the deciding factor once the owner sees both documents side by side.
Detail Standards on Buildings With Mixed Roof Ages
A lot of the older industrial buildings we work on around Green Bay have been added onto multiple times over the decades, and JM's published detail drawings differ between their asphalt and single-ply lines at parapets, curbs, and expansion joints. When a roof transitions from an old asphalt section to a newer steel-deck addition, we detail each side to its own manufacturer standard and pay particular attention to the transition point itself, which is where we most often find leaks on buildings recovered in phases over separate projects years apart.
Questions on Johns Manville Systems
Does Johns Manville only make asphalt roofing products?
No, they manufacture TPO and PVC single-ply membranes in addition to their modified bitumen line, though the asphalt side of the business is a notable part of their commercial roofing history.
Is JM's modified bitumen a fit for a torch-restricted site?
They offer self-adhered and cold-adhesive modified bitumen options for sites where torch application is restricted by fire code or site conditions.
How does JM's PVC compare to other manufacturers?
It falls in the same category as other major PVC manufacturers for chemical and grease resistance; specific product selection depends on current technical specifications and thickness needs.
Do you need to use JM insulation with JM membrane?
Not necessarily, but pairing insulation and membrane from the same manufacturer's documented compatible assembly simplifies detail and warranty coordination.
Is Johns Manville a good option for a mill-adjacent roof recover?
Their modified bitumen line is a reasonable option to evaluate for buildings originally built with asphalt roofing, alongside comparable products from other manufacturers.