Single Groove MDF Pre-Primed Architrave (18mm x 69mm x 4200mm) is an interior architectural trim used to frame internal doorways and window openings, cleanly covering the gap between the timber door casing or window frame and the surrounding wall plaster.

Primary Uses & Key Features

• Doorway & Window Framing: Creates a crisp border around interior door frames and window cills, hiding unsightly structural gaps and raw plasterboard edges.

• Modern Minimalist Aesthetics: Features a single precision-machined groove running along the face, creating a subtle shadow line that suits contemporary and urban interior designs.

• Substantial 18mm Thickness: The 18mm depth matches standard 18mm skirting profiles, ensuring a flush, seamless junction where the architrave meets the skirting board without requiring plinth blocks.

• Factory Pre-Primed Finish: Sealed in a white primer coat, saving preparation time on-site and offering a smooth surface ready for a satin, gloss, or eggshell topcoat.

• Moisture-Resistant MDF: Manufactured from high-density MR-MDF, providing a straight, knot-free trim that will not warp, twist, split, or shrink over time.

• 4.2m Length: A single 4200mm length provides enough material to cut both upright jambs and the top header for one side of a standard single door frame with minimal timber waste.

Available for collection from our Rugby branch or local delivery using our own fleet.

Delivery is kerbside and the final offloading position is always subject to safe access and the driver’s discretion.

Please tell us before delivery about:

• Narrow roads or restricted entrances
• Parked vehicles or limited turning space
• Overhead cables, trees or other obstructions
• Soft, sloping or unsuitable ground
• Any other access concerns

Enter your postcode on the product page to check your delivery area. We’ll confirm the delivery date after your order is placed.

What is the best way to secure 45-degree mitred corners on Single Groove architrave?

Apply PVA wood glue or specialized mitre adhesive (cyanoacrylate activator spray and glue) directly to the 45-degree cut faces before pressing the corner together. Drive two fine brad nails across the joint from opposite directions to clamp the corner tightly while the adhesive cures.

Does an 18mm architrave flush-fit with 18mm skirting boards?

Yes. Because both the architrave and skirting share an 18mm thickness, they sit on the exact same plane where they meet at the bottom of the doorway. This eliminates the need for plinth blocks and prevents awkward overhangs.

How do you align the shadow line groove at the top door corners?

When cutting your 45-degree mitres on the header and side jambs, measure accurately from the inner reveal line rather than the outer edge. Aligning the precision groove across the mitre cut ensures the shadow line flows continuously around the entire door frame.

Can Single Groove MDF architrave be used in high-moisture rooms like bathrooms?

Yes, because it is manufactured from moisture-resistant MDF (MR-MDF). However, ensure all cut edges, mitres, and the bottom face touching the floor are fully sealed with primer or sealant to prevent moisture ingress.

How do you fill and finish nail holes on pre-primed architrave before painting?

Sink nail heads slightly below the board surface using a nail set. Fill the indentations with fine-surface MDF filler, allow it to dry, sand smooth with 240-grit sandpaper, and apply a coat of primer before painting with your chosen topcoat.