Northwest Door Therma Tech 118 Insulated Garage Door

The Therma Tech 118 delivers R-9.0 to R-10.4 insulation values through a 3-layer sandwich construction with galvanized steel skins and CFC-free EPS core. At 1.5 inches thick for the 3400 series and 2 inches for the 3500 series, these doors feature a natural thermal break that reduces heat transfer at section joints by approximately 15.5%.

For Montana contractors dealing with temperature swings from -30°F to 100°F, those R-values matter. The thermal break technology maintains 7.2% lower interior surface temperatures than major competitors — measurable performance that translates to lower heating bills and more comfortable garage spaces.

Thermal Performance and Construction Details

The door’s construction uses interior and exterior galvanized pre-painted steel skins pressure laminated to a CFC-free EPS core. That EPS (Expanded Polystyrene) core provides the R-9.0 insulation in the 1.5-inch model and R-10.4 in the 2-inch version.

Specification	Value	Source
R-Value	R-9.0 (1.5”) to R-10.4 (2”)	manufacturer
Thermal Break Performance	15.5% reduction in joint heat transfer	manufacturer
Surface Temperature Advantage	7.2% lower than competitors	tested
Core Material	CFC-free and HCFC-free EPS	manufacturer
Fire Rating	Smoke and flame spread rated	manufacturer

The 2-inch and 3-inch models include a flexible joint seal running the full width, addressing the weak point where most garage doors fail — the joints between sections. Combined with the thermal break, this creates a comprehensive defense against Montana’s temperature extremes.

The four-coat paint system starts with galvanized steel, then adds bonderized coating, primer, and topcoat. Exterior faces feature wood-grain texture while interiors get a stucco-embossed Bright White finish. This isn’t decorative — textured surfaces hide minor dings and scratches better than smooth panels.

Installation Requirements and Compatibility

Therma Tech 118 doors accommodate openings from 6 to 20 feet wide and 6 to 14 feet high, with a maximum area of 280 square feet. That covers everything from single-car garages to oversized RV bays.

The track system uses 2-inch bracket-mounted rails with 12, 15, or 20-inch radius options. Installation flexibility includes standard lift, high-lift, vertical-lift, low-clearance, and angle mounting configurations. For contractors, this means one door system handles most residential applications without special ordering different models for unusual installations.

Torsion springs come standard at 10,000 cycles, with high-cycle options available. Window options include Cascade, Waterton, and Sherwood designs with multiple glass types.

The standard hardware package includes tracks, springs, hinges, and rollers. Northwest Door backs the system with a Limited Lifetime Warranty against defects in material and workmanship, requiring professional installation and periodic maintenance for full coverage.

The real advantage shows up in occupied garages. Sound-deadening properties make these doors noticeably quieter than single-layer alternatives — valuable for homes near highways or in windy areas where garage door rattle becomes a genuine annoyance.

Frequently Asked Questions

What makes the Therma Tech 118 different from standard garage doors?

The 3-layer sandwich construction with CFC-free EPS core delivers R-9.0 to R-10.4 insulation values, while the natural thermal break reduces joint heat transfer by 15.5%. Standard single-layer doors can’t match these thermal performance numbers.

How does the thermal break actually work?

The thermal break at section joints reduces heat and cold transfer by approximately 15.5%. This design interrupts the thermal bridge that typically forms where door sections meet, preventing the metal-to-metal contact that conducts temperature through standard doors.

What size limitations should contractors know about?

Maximum dimensions are 20 feet wide by 14 feet tall, with a 280 square foot area limit. The system accommodates standard lift, high-lift, vertical-lift, low-clearance, and angle mounting configurations.

Is professional installation required for warranty coverage?

Yes. The Limited Lifetime Warranty requires professional installation and periodic maintenance for full coverage. DIY installation voids warranty protection on defects in material and workmanship.

What’s included with the door purchase?

The standard hardware package includes tracks, springs, hinges, and rollers. Steel sections come with wood-grain exterior finish. Window options like Cascade, Waterton, and Sherwood designs are available but sold separately.