How to Add a Drip Cap Above an Exterior Door

Short answer: A door-head drip cap is a sloped piece of flashing above the door that helps shed water out and away. Its upper edge must be integrated with the WRB and its ends coordinated with the door’s side flashing and cladding. A cap placed over siding—or a line of caulk by itself—does not repair a broken drainage path.

This guide is for planning a retrofit or replacement cap. Door frames, nailing fins, trim, siding, and WRB details differ. Use the current instructions for your specific door and flashing products, and confirm the proposed detail with a qualified installer if the wall layers cannot be identified without dismantling the opening.

Swipe the diagram to see the full wall section and labels.

Before you start: identify the door and wall layers

Find the door’s make, model, and installation instructions before removing siding or trim. Check whether the door has an integral flange, a separate casing, a factory-supplied cap, or an existing metal flashing. An existing head piece may already be part of the tested door installation; do not cover or alter it without checking the product instructions.

Gather these details

• The door installation and flashing instructions, plus instructions for the WRB, cladding, flashing tape, and proposed metal cap.
• Photos of the full door head, both upper corners, jambs, siding joints, existing flashing, and any staining or soft material.
• A tape measure, pencil, labeled sketch, and a safe ground-level or stable platform for access.
• Eye protection and cut-resistant gloves when handling sheet metal; use tools only as directed by their manufacturers.
• A plan to keep the opening protected from weather and maintain a usable exit while trim or cladding is removed.

Working above a door involves overhead handling and fall risk. OSHA’s extension-ladder guidance is written for workers, not a substitute for a homeowner safety plan. Do not stand on the door, an unstable ladder, or unsupported cladding. If you cannot reach the head without leaning or working at an unsafe height, stop and hire help.

How to plan and add a door-head drip cap

1. Trace the water path and inspect the opening. Look for staining at the top corners, swelling or soft trim, failed joints, and water marks on the interior. Check whether water can drain out behind the cladding. Fix the source of moisture and any damaged framing or sheathing before installing new trim.
2. Read the exact door instructions. Confirm whether a separate cap is required or recommended, how it relates to the frame and jamb flashing, and whether the manufacturer specifies a particular sealant, fastener, or sequence. Some door instructions give their own cap length: for example, the cited JELD-WEN pre-hung door guide calls for the frame or head-trim length plus 1/4 inch total. That is a product-specific example, not a universal overhang dimension.
3. Expose only what you can safely restore. Where the approved detail requires it, carefully remove enough cladding or trim to reach the WRB and existing head/jamb flashing. Keep removed materials organized, protect the opening from rain, and do not tear or puncture the drainage plane. If the WRB, flashing layers, or door flange are damaged or inaccessible, pause for a repair detail rather than hiding the area.
4. Map the layers before drawing the cap. Sketch the door frame, head casing, WRB, sheathing, cladding, drainage space, and side flashing in cross-section. The wall’s upper WRB layer generally needs to lap over the flashing’s back leg so water can drain outward. The sides and any flashing tape must tie into the same approved drainage path. The exact order depends on the door and wall system.
5. Measure the opening and profile separately. Measure the across-the-head length as the door instructions direct. Then record the head trim’s top depth, distance from wall plane to the intended drip edge, cladding and drainage-space build-out, rear-leg requirement, slope, and any specified return, hem, end condition, or corner. Label each measurement and photograph the tape at the location.
6. Have the profile checked before fabrication. Send the drawing, photos, door model, wall/cladding description, and dimensions to a sheet-metal fabricator. Ask them to confirm the bend sequence, material compatibility, developed width, ends, laps, and attachment detail. Do not assume a generic drip edge shape will fit an exterior door head.
7. Install and restore the assembly to its instructions. Follow the door and flashing manufacturers’ order for lap, tape, sealant, fastening, and side connections. Keep the cap sloped outward and the intended drainage route unobstructed. Do not use caulk as a replacement for the WRB lap or cover drainage openings. Reinstall the cladding with the clearances and joints its manufacturer requires.
8. Check the finished water route. Confirm the cap sheds toward the exterior and beyond the vulnerable head trim as detailed; verify that water from the WRB can exit and that the upper cladding does not rest on or reverse the cap’s slope. If anything differs from the approved detail, get it reviewed before closing the wall.

What to measure for a custom drip cap

Do not confuse the visible door-frame width with the finished cap length. Use the door and flashing manufacturers’ specified reference points, then give the fabricator a dimensioned sketch that shows both the across-the-opening length and the side-view cross-section.

• Overall length: across the head trim or frame from the manufacturer’s reference points. Record the desired extension beyond each end only when the approved detail specifies it.
• Top projection: from the wall or casing reference plane to the drip nose, accounting for cladding thickness and any drainage space.
• Rear leg: the upstand or attachment leg needed to connect behind the WRB as specified. Do not guess its height or lap.
• Slope and drip edge: show the outward fall and the nose or hem shape the fabricator and wall detail require.
• Ends and obstacles: note end returns, side-jamb flashing, trim blocks, siding profiles, fasteners, and other parts that affect fit.
• Material and finish: ask about options compatible with the door, fasteners, adjacent metals, and exposure; do not choose solely by appearance.

Where Trimgy can help with the profile

When a fabricator confirms that a custom sheet-metal cap is appropriate, Trimgy can help you draw its cross-section and view a trim-price estimate. The drawing interface displays dimensions in inches and uses quarter-inch increments. The current pricing options list 22-, 24-, and 26-gauge steel, plus .032-, .040-, .050-, and .063-inch aluminum thicknesses; the current selectors and fabricator determine what is appropriate and available for a particular order.

The estimate uses the drawn profile, selected thickness and color, and linear footage, and returns trim pricing per linear foot. The pricing service rejects a profile with a developed stretch-out over 48 inches. Trimgy does not inspect your doorway, establish a code-compliant wall detail, select compatible materials for your assembly, or certify that a drawing will fit or prevent leaks. Have the fabricator review the sketch and installation detail before ordering.

Sign-in or account creation is required to use the drawing workspace. To place an order, the current order panel also requires a saved profile, selected thickness and color, start/end edge selections, a non-intersecting drawing, and linear footage in multiples of 10. Shipping quotes use the project’s delivery address, including a valid ZIP code; applicable tax is calculated separately in the order flow. The instant trim estimate excludes both shipping and tax, so review the charges and total shown before payment.

If your wall and door detail has been reviewed, open Trimgy’s drawing workspace to sketch the profile and see an estimate. Treat the drawing as a fabrication-planning aid—not an installation plan.

Common mistakes to avoid

• Putting a cap over the cladding without reaching the WRB. Water may still get behind the flashing instead of draining over it.
• Using caulk as the water-management plan. Sealant is only used where a product’s detail calls for it; it does not replace correctly lapped flashing and WRB.
• Assuming one overlap dimension fits every door. A measurement in one manufacturer’s instructions applies to that product and detail only.
• Forgetting the jamb connection. A good-looking cap can still leave a path behind the side flashing at either upper corner.
• Measuring only the door frame. Casing, siding, drainage space, wall plane, and end conditions all affect length and profile.
• Closing the wall before checking drainage. The WRB and cladding must leave the intended route for incidental water to exit.
• Treating the instant estimate as the delivered total. Shipping and tax are excluded from the estimate; review the separate order flow before paying.