We’ve added Karnak roof coating and repair products to the lines we carry at all four Oates branches, in Houston, Fort Worth, Austin, and Greenville, South Carolina. Karnak has manufactured roof coatings, cements, and sealants since 1933, and carrying the line means our customers can put coating and repair material on the same order and the same delivery as their metal deck, panel, and fastener material. The product we’re leading with is Karna-Flex, an elastomeric sealant made for the seams, fasteners, and flashing details that give metal roofs the most trouble.
What the Karnak Roof Coating Line Includes
Karnak manufactures out of Clark, New Jersey. The company is family-owned and certified as a woman-owned business, and its catalog is built around repairing, restoring, and maintaining low-slope and flat commercial roofs.
Roughly half the line is field material. Asphalt coatings, emulsions, elastomeric roof coating products, and reflective aluminum coatings are all applied across an entire roof plane, and their coverage is rated in gallons per 100 square feet of roof. The other half is detail material, which goes wherever a field coat can’t do the work by itself: seams, laps, curbs, flashings, penetrations, and exposed fasteners. Karna-Flex is detail material.
On the buildings most of our customers work on, the detail material is where the repair actually happens. Exposed-fastener and standing seam roofs tend to begin failing at the joints and the fastener heads rather than in the middle of a panel, so a coating applied over unsealed seams will hide a leak rather than repair it. A Karnak roof coating and its matching sealant are meant to be specified together, and that’s how we’d suggest ordering them.
Karna-Flex, the Featured Product
Karnak classifies 502MS Karna-Flex as a repair product rather than a coating. It’s a rubberized thermoplastic sealant with a butter-like consistency, thin enough to work with a brush or trowel and heavy enough to hold a bead from a caulking gun. Karnak lists it for prepared metal, concrete, single-ply, spray polyurethane foam, plywood, asphalt built-up, and modified bitumen, with the qualification that PVC and TPO membranes should have weathered at least four years before it goes on them.
What suits it to metal is elongation. Karnak rates the product at 500 percent, with low temperature flexibility down to minus 40 degrees Fahrenheit, and metal panels put both numbers to work. A roof that expands and contracts through every heating and cooling cycle will eventually work a rigid sealant loose, while a flexible one moves with the panel rather than releasing from it.
Coverage varies by detail rather than by roof area. A swirl coat over exposed fasteners covers roughly 250 fasteners per gallon, and a quarter-inch bead from a 30-ounce cartridge runs about 75 lineal feet. For seams and cracks 1/16 inch or wider, Karnak specifies a three-step detail: a layer of Karna-Flex, embedded Resat-Mat fabric, then a second layer over the top, with about 24 hours to cure. Where a crew is continuing into the 502 Elasto-Kote system, those repairs cure before the field coat goes down.
The sealant bonds to wet or dry surfaces, which gives crews some room on timing between rain events. It comes in white, black, and gray, though Karnak advises against white over asphaltic substrates, since asphalt tends to bleed through it, and specifies black on those roofs.
502MS Karna-Flex Specifications
| Elongation | 500% |
|---|---|
| Tensile strength | 40 psi |
| Low temperature flexibility | -40°F |
| Application temperature | 40°F to 120°F |
| Cure time | Approximately 24 hours |
| Coverage | 4 to 8 gal per 100 sq ft of sealed area, at 1/16″ to 1/8″ thickness |
| Colors | White, black, gray |
| Sizes | 3-gallon buckets, 1-gallon cans, 30 oz caulk tubes (white) |
Karnak also makes 505MS Karna-Flex WB, a water-based version with the same 40 psi tensile strength. It’s white only, low odor, low VOC, and rated resistant to mold and mildew growth.
Coating or Sealant: Choosing Between Them
| Field Coating | Karna-Flex Sealant | |
|---|---|---|
| Purpose | Resurface and protect a whole roof plane | Seal seams, laps, fasteners, penetrations |
| Where it goes | Across the roof surface | Into the joint, crack, or fastener head |
| Coverage basis | Per 100 sq ft of roof | Per 100 sq ft of sealed area, not whole roof |
| Applied with | Brush, spray, or roller | Brush, trowel, or caulking gun |
| Sequence | After details are sealed and cured | First, then the field coat |
| Reinforcement | Not typically required | Resat-Mat fabric on seams and cracks |
Coverage figures on both sides of that table come from Karnak, and they’ll move with substrate condition and film thickness. Our branches can work through quantities with you before you commit to an order.
Working a job that needs Karnak roof coating or Karna-Flex now?
Call the branch nearest the site and we’ll go through substrate, quantities, and freight with you.
Karnak Aluminum Roof Coating on Metal Buildings
The reflective end of the line is Karnak aluminum roof coating, and 97 Fibered Aluminum Roof Coating is one of the products in that group. It blends asphalt with pure aluminum pigment flakes and reinforcing fibers, and Karnak lists it for modified bitumen membranes, metal corrugated roof decks, steep asphalt that has aged 90 days, and cured Karnak emulsion coatings.
The aluminum pigment reflects solar radiation instead of absorbing it, and Karnak states the coating helps reduce indoor building temperatures. On warehouse, shop, and light industrial roofs, that’s generally why it gets specified.
97 Fibered Aluminum Roof Coating Specifications
| Property | Initial | 3-year aged |
|---|---|---|
| Solar reflectance | 0.63 | 0.55 |
| Thermal emittance0.46 | 0.46 | 0.53 |
| Solar Reflectance Index (SRI) | 62 | 52 |
Those reflectance values are Cool Roof Rating Council listed. Coverage runs 1 to 1.5 gallons per 100 square feet, application temperature is 50 to 120 degrees Fahrenheit, and the cured film holds from 15 to 180 degrees. The product meets ASTM D2824 Type III, ASTM D3805, ASTM D962 Type II, and TT-C-498C.
The UL Class A fire rating applies over specified modified bitumen systems rather than universally, so a fire rating called out on a different assembly needs to be verified against that assembly.
Karnak also references the National Roofing Contractors Association drainage standard for cold-process coatings, which calls for no standing water 48 hours after rainfall stops. Coatings and emulsions perform on roofs that drain, and a roof that ponds needs its drainage corrected before any coating is applied.
Ordering Karnak Roofing Products Through Oates
Oates has supplied metal roof deck, floor deck, form deck, PBR and R panel, corrugated and FRP panel, skylights, and fasteners since 2004, and Karnak roofing products now order through the same channels.
Our four locations are Pasadena, Fort Worth, Buda, and Piedmont, South Carolina, and all four handle will call and delivery, with freight available to job sites outside the delivery radius. Because coating and sealant come off the same order as deck, panel, and fasteners, that’s one account, one rep, and one delivery window rather than two.
Our sales team has spent years working with metal deck and panel, so questions about whether a given product belongs on 26-gauge exposed-fastener panel or an aged modified bitumen membrane can get answered on the phone. We supply material and don’t install roofing. Warranty coverage on Karnak products is administered by Karnak directly, though the branch can point you toward the right documentation.
Karnak Roof Coating FAQ
Request a Karnak Roof Coating Quote
Karnak roof coating and sealant orders run through the branch closest to the project. Send quantities, substrate, project location, and the date material is needed, and we’ll confirm stock, freight, and lead time. Will call and delivery are available from all four locations.
