1. Confirm what you are installing
| Project | What changes | What to confirm |
|---|---|---|
| New slab in an existing frame | The moving leaf is replaced. | Frame condition, hinge and lock preparation, size and seal compatibility. |
| Prehung replacement | The leaf and its surrounding frame are replaced together. | Overall unit size, rough opening, sill support and wall connection. |
| Larger or different opening | The opening itself changes. | Framing, services, permits and the design of the complete entry. |
Compare front entry doors with the opening requirements in hand. Request the installation drawing for the exact configuration, including sidelights or a transom. The door jamb guide explains the frame parts you will be measuring.
2. Measure the opening and finished floor
Record width at the top, middle and bottom, and height at both sides. Check the frame depth and wall finish. For a replacement unit, establish the rough opening rather than assuming the old slab size describes it. Measure the diagonals and look for bowed or damaged framing.
Account for the finished floor, rugs and exterior landing. Confirm the swing and the space for locks, trim and any storm door. Use the maker’s required opening allowance; there is no single amount to subtract that fits every entry system.
3. Prepare the work before removing the old entry
- Inspect the delivered unit and compare it with the order.
- Have the correct shims, specified fasteners, flashing, sealants and tools ready.
- Arrange enough people and suitable lifting equipment for the unit’s weight.
- Plan how to protect and secure the opening if the work cannot be finished that day.
Locate wiring and other services before cutting or prying near the frame. A doorbell is not a reason to treat wiring casually: isolate its supply and use qualified help if its wiring or power source is uncertain. For older painted trim, resolve the lead-paint question before disturbing it.
Reference: EPA guidance on lead-safe renovation work.
4. Remove the old unit and inspect the opening
Protect nearby finishes, support the leaf and remove components in a controlled sequence appropriate to their construction. If reusing trim or a storm door, label and store the pieces. Avoid cutting blindly into the space between the frame and wall.
With the opening exposed, check the sill area and framing for decay, leaks or movement. Correct those conditions before installing the new unit. A shim cannot replace missing structural support, and new trim cannot repair water damage.
5. Prepare the sill and flashing detail
Use the specified sill support, pan or flashing system and compatible sealants. Connect that detail to the wall’s water-management layers so water has a planned route toward the exterior. The correct sequence depends on the wall and door assembly.
Keep intended drainage paths clear. Do not apply a continuous bead everywhere simply because it looks more sealed. Review the door instructions with the flashing and sealant instructions before the unit goes in.
Reference: Example manufacturer installation guide showing product-specific details.
6. Set, support and align the new frame
Position the unit using its handling instructions and keep it supported until secured. Establish a level sill and plumb, straight jambs. Place shims at the specified support and fastening points, then check the head and the gaps around the leaf.
Use the prescribed fasteners and attachment locations. Tightening against an unsupported gap can bow a jamb. Recheck alignment during fastening instead of waiting until the trim is installed. Follow any restrictions on opening the leaf before the frame is fully secured.
7. Fit hardware and complete the seals
Install the lock, strike and other hardware using their templates and instructions. Check latch engagement without pushing or pulling the door into position. Confirm the weatherstripping contacts its intended surfaces and adjust an adjustable threshold only within its allowed range.
Complete the frame-to-wall air seal with the specified materials. Do not assume loose insulation is an air seal, or that any expanding foam suits a door frame. Finish the exterior joint and flashing details before covering the work with trim.
8. Check the entry before calling it finished
- The leaf opens through its intended swing without rubbing the floor or trim.
- The latch and lock engage without lifting or forcing the door.
- Frame gaps and seal contact match the unit instructions.
- Sill support, flashing and drainage details remain intact.
- Exposed edges and surfaces receive the required finish.
- The installation and warranty documents are saved.
Inspect the entry after rain and seasonal changes. For later draft repairs, use the door weatherstripping and sealing checklist. For a leaf that rubs or drifts, start with door installation troubleshooting before trimming it.
Planning a client project?
Replacing an entry for a client? Include the opening measurements, exposure and prehung requirements in the quote request. Rustica’s contractor discount program explains professional eligibility and how to apply.
