Berkley Flush Glazed Fiberglass Entry Door - Half Lite Shaker (36" x 80")

Key Measurements & Sizing Information

This door is sold as a nominal 36" x 80" size, which is also commonly written as 3/0 x 6/8. The actual slab size is 35-3/4" wide x 79" tall, with a standard exterior door thickness of 1-3/4".

If purchasing with jambs to assemble a single prehung unit: this slab size typically pairs with a 36" head jamb. For inswing thresholds and saddle-style outswing thresholds, the matching leg jambs are 81-3/4", creating an assembled unit size of approximately 37-1/2" x 81-3/4" when using standard 3/4" jamb thickness. For bumper-style outswing thresholds, the leg jambs are 80-3/4", creating an assembled unit size of approximately 37-1/2" x 80-3/4".

If purchasing slab only to replace an existing door slab and keep your current frame: a 79" slab is the most common exterior slab height and is often the preferred choice even when the existing door measures 79-1/8" or 79-1/4" tall. In many replacement situations, a small height difference at the bottom can be addressed using an adjustable U-style door sweep, helping maintain proper sealing and smooth door operation within the existing frame. If your existing door measures a full 36" wide, is taller than 79-1/4", or measures exactly 36" x 80" (common with older wood doors), we also offer a line of oversize trimmable doors available in select styles.

Door Prep Options

Door prep refers to how the door slab is machined for hinges and lock hardware. We offer three options:

• Without prep (blank): no machining, ready for field preparation
• Standard prep: machined to common residential hinge and lock placements, and matched to the framing and jamb sets we offer for complete door systems
• Custom prep: hinge and lock locations machined to exactly match your existing door

If your existing door is prepped to specifications other than our standard layout, we recommend selecting custom prep so the new slab matches your existing door. See the diagram in the image gallery for a visual reference of standard hinge and lock placement.

Standard Hinge Prep

Standard hinge prep includes three hinge mortises on the hinge edge of the door, located as measured from the top of the door:

• Top hinge: 6-1/2" from top
• Middle hinge: 37-1/2" from top
• Bottom hinge: 68-1/2" from top

For Slab Only orders, standard hinge prep is reversible. The mortises are machined completely through the edge of the door so hinges can be mounted from either direction, allowing left-hand or right-hand swing installation without additional routing. This type of reversible hinge prep is compatible with 4" hinges in 5/8" radius (quarter-round), 1/4" radius (dime-round), or square corner profiles. Complete Door System orders come with standard hinge prep locations but will be mortised as hinge pockets to match selected swing and hinge shape.

Standard Lock Prep

Standard tubular lock prep is machined for a 2-3/8" backset lockset and includes two 2-1/8" bore holes spaced 5-1/2" apart. Each bore is centered 2-3/8" from the edge of the door:

• Deadbolt bore (upper): centered 40-3/8" from top of door
• Latch bore (lower): centered 45-7/8" from top of door

Premium Build Construction: Stronger Than Standard Doors

Our fiberglass entry doors are built using a Premium Build configuration featuring full-length 4" LVL (laminated veneer lumber) side stiles on both sides of the door. These engineered stiles run the full height of the slab, delivering a stronger, heavier, more rigid door than the simplified constructions used in most entry-level fiberglass doors sold at big box stores.

The fiberglass skins resist warping, rotting, denting, and rusting, while a high-density polyurethane foam core provides insulation and contributes to the door's structural integrity. Composite top and bottom rails help resist moisture intrusion and long-term deterioration. Homeowners and contractors will notice the difference in weight and rigidity the moment they handle the door, a clear indicator of the build quality engineered into every slab.

Reversible Lock Prep: No Wrong Side

Because the 4" LVL stiles run full-length on both sides of the door, hardware can be bored into either stile with equal structural support. This eliminates one of the most common installation errors, boring hardware on the wrong side, and gives buyers full flexibility on door handing. DIY homeowners get peace of mind during installation, and contractors avoid costly rework on the jobsite.

Engineered for Everyday Performance

Together, the full-length LVL stiles, insulated foam core, and moisture-resistant composite rails create a door built to perform reliably in demanding exterior environments. The result is a door that installs with confidence and delivers dependable performance year after year.

Glass Specifications

Privacy rating: Low on the Pease privacy scale (None, Low, Medium, High, Maximum).

Flush glazed directly into the door, with no frame to caulk or maintain. The glass is a 1" insulated unit with tempered safety glass on both panes. Low-E is not available with decorative glass.

Glass size, U-factor, SHGC and sound (STC) ratings are listed on the spec sheet in the Resources section below.

Surface Texture and Recommended Finish for Smooth Fiberglass Doors

This door features a Satin Smooth (white) surface with a fine linear texture and subtle vertical lines, similar to a woven linen or brushed fabric. This micro-texture provides built-in surface tooth that helps primer and paint adhere without the need for heavy sanding, reduces the visibility of brush marks and roller lines, and helps prevent runs and drips on vertical surfaces.

Before finishing, clean all door surfaces to remove dust, oils, and handling residue, then allow the surface to fully dry. For best results, we recommend using a high-quality bonding primer such as Sherwin-Williams Extreme Bond Primer, followed by a premium exterior-grade acrylic latex paint.

All six sides of the door must be finished, including the front, back, top, bottom, and both edges, to properly protect the door and maintain warranty coverage. When selecting paint colors, lighter to medium shades are typically recommended for doors exposed to direct sunlight, as very dark colors can increase surface temperatures and reduce long-term finish performance.

Fiberglass doors are shipped unfinished or factory-primed depending on selected options. Finishing should be completed promptly after delivery and before prolonged exposure to weather.

Installation Readiness for Fiberglass Door Slabs

Fiberglass door slabs are designed for installation into existing door frames or for assembly into new prehung units. Before installation, verify that the slab dimensions (width, height, and thickness) match the existing slab for replacements, or the jamb set for new assemblies.

When replacing an existing slab, the original door can often be used as a template. Align the existing door on top of the new slab to transfer hinge locations and hardware positions for accurate placement.

This door is not a trimmable model. If needed, it can be trimmed up to 1/2" off the bottom only; seal the cut edge and, ideally, cover it with a U-style door sweep. Do not trim the top or sides. Trimming a door that is not sold as trimmable voids the warranty, and modified products cannot be returned. If you need to cut a door down to fit, our Trimmable and Oversize Trimmable flush doors are built for it.

Fiberglass door slabs are heavy and should be handled by two or more people during installation. Always support the door evenly to prevent damage to corners or edges.

Complete all recommended finishing steps promptly after installation to protect the door surface and maintain long-term performance.

For complete step-by-step installation instructions, refer to the full installation guide available in the Resources section below.