How To Fit Architrave
This expert guide explains how to install door architraves (the decorative mouldings around a door frame) for a seamless, professional finish. Whether you are upgrading to modern MDF architraves or traditional softwood architraves, this step-by-step process ensures tight joints and durable results.
What is architrave installation?
Architrave installation is the process of cutting and fixing decorative frames around a door opening to conceal the joint where the wall plaster meets the door timber.
When you need it / why it matters
Fitting architrave is the final structural step in doorway renovation. It matters because:
-
Visual Continuity: It connects the door frame to the rest of the room’s woodwork, such as your skirting boards.
-
Covering Gaps: It hides the unsightly “structural gap” between the door lining and the rough wall edge.
-
Material Choice: You can choose moisture-resistant MDF architraves for kitchens or bathrooms, or softwood architraves for a natural wood finish.
Architrave Material Comparison
| Feature | MDF Architraves | Softwood Architraves |
| Durability | High; won’t warp or twist. | Good; traditional timber feel. |
| Finish | Smooth; ideal for modern painting. | Natural grain; can be stained or varnished. |
| Ease of Use | No knots; easy to cut and sand. | Requires care to avoid splintering. |
How to choose: “If X, choose Y”
-
If you want a modern, low-maintenance finish: Choose MDF architraves. They come pre-primed and are exceptionally stable.
-
If you are matching original period features: Choose softwood architraves. These allow for custom staining to match existing furniture or floors.
-
If the door frame is slightly uneven: Use a thick-bead grab adhesive to “take up” the slack between the wall and the moulding.
Step-by-step installation guide
-
Mark the Reveal: Use a combination square to mark a line 6mm back from the inner edge of the door jamb on all three sides. This ensures your architrave won’t interfere with the doorâs operation.
-
Measure and Cut the Headpiece: Measure the distance between your vertical marks. Cut 45-degree mitres at each end so the inner (shorter) edge of the architrave matches this measurement.
-
Fix the Headpiece: Apply grab adhesive to the back and align it with your top lines. Secure it with 40mm lost-head nails.
-
Cut the Side Pieces: Measure from the floor to the top point of the headpiece’s mitre. Cut a 45-degree angle at the top of your vertical side pieces. The bottom should remain a square cut to sit flush against the floor.
-
Apply PVA and Adhesive: Apply PVA glue to the mitre faces (the cut ends) and grab adhesive to the back of the side piece.
-
Secure the Sides: Press the side pieces into place, ensuring the mitre joint is tight. Drive 40mm lost-head nails through the architrave and into the door casing.
-
Flush Finishing: Use a hammer and nail punch to sink nail heads below the surface. Fill these holes with One Strike Filler. Because this filler doesn’t shrink or sag, you can fill the holes flush immediately and sand them in minutes.
Common mistakes to avoid
-
Fitting Flush: Mounting architrave flush to the door lining looks “heavy” and can cause the door to bind on the hinges.
-
Dry Mitres: Skipping PVA glue on the corner joints. Without glue, the timber will expand and contract, causing a visible crack in the corner within weeks.
-
Inaccurate Filling: Using heavy fillers that require multiple applications. One Strike Filler is recommended to keep the project moving quickly.
FAQs
What is the best filler for architrave nail holes?
One Strike Filler is the preferred choice for professionals. It allows you to fill a hole in one go without the material shrinking back as it dries, which means less sanding and a faster path to painting.
How do I handle uneven floors?
If your floor is unlevel, cut the bottom of your side pieces at a slight angle (scribing) so the top mitre joint stays perfectly aligned with the headpiece.
Can I use a nail gun?
Yes, a 16-gauge or 18-gauge brad nailer is excellent for this task. However, always use a nail punch afterwards to ensure the heads are deep enough for the One Strike Filler.
Summary + next steps
Properly installed architraves provide a structural “frame” for your doors that enhances the entire room. Once your architraves are secured and filled, you can move on to the base of the room.
Ready to start your project?
-
Browse our premium MDF architraves for a fast, flat finish.
-
Select traditional softwood architraves for natural timber projects.
-
Ensure a perfect match with our full range of skirting boards.
