A door can be built and assembled in several different ways, and each drives a different load:
Glass or solid opaque door
Solid door type (i.e., metal or wood), insulated or not
Any door with an additional wood or metal storm door
Each combination has a different impact on conductive heat transfer, so getting the door settings right is essential to accurate load calculations.
This article walks through every setting on the Doors screen.
Always verify construction details and assumptions in the home. Measure the rough opening, confirm whether the door is wood or metal, and note any storm door. When you can't tell what's inside a door, use your professional judgment based on its weight, age, and feel — a door is a small part of the load, so a reasonable estimate is acceptable.
Note about "Is exterior": Loads are only calculated on doors that are considered exterior, i.e. they separate conditioned space from outdoor (or unconditioned) conditions. An interior door between two conditioned rooms carries no load and should not be marked exterior.
The "Is it exterior" toggle can be found in the upper right of the sidebar when a door is selected.
Is exterior and Is glass
Is exterior controls whether the door counts toward the load calculation at all. Only mark a door exterior when it separates conditioned space from outdoor or unconditioned conditions.
Once a door is marked exterior, an Is glass toggle appears. Turn it on for a glass door — a sliding patio door or a mostly-glass French door or any door that is greater than or equal to 50% glass. When Is glass is on, the door fields are replaced by the full set of window options, because Manual J models glass doors as windows rather than opaque doors. These are the same options covered in Windows - verify and edit.
Edit door assumptions
To make changes to a door, simply tap on the door in the 3D model, and the sidebar will appear where you can edit the assumptions - whether it's exterior, the primary material, the core, and the storm.
Then tap on an existing assumptions menu to make changes.
Primary material
Primary material tells Amply how the door itself is built. It sets which Core material options are available and, together with the core, determines the door's U-value (Manual J Construction 11, Table 4A).
Wood: a wood or wood-based door. The
Core materialoptions becomeHollow Core,Solid Core, andPanel.Metal: a metal-skinned door built around an insulating core. The
Core materialoptions becomeFiberglass Core,Paper Honeycomb Core,Polystyrene Core, andPolyurethane Core.
Core material
Core material describes what's inside the door, which is the biggest driver of its U-value. The options available depend on Primary material.
For a Wood door:
Solid Core: a solid wood or composite fill (most common and best-insulating option, U 0.39)
Hollow Core: a hollow interior (U 0.47)
Panel: raised- or recessed-panel construction; the thin panels make this the highest-loss wood door (U 0.54)
For a Metal door:
Fiberglass Core: U 0.60
Paper Honeycomb Core: U 0.56
Polystyrene Core: U 0.35
Polyurethane Core: the best-insulating option (U 0.29)
Why core material matters: Manual J Table 4A assigns each door a U-value based on its construction, and the door's heating load is U-value × the rough-opening area. A polyurethane-core metal door (U 0.29) loses less than half the heat of a fiberglass-core one (U 0.60) of the same size.
Storm type
Storm type records whether the door has a storm door in front of it. A storm adds an insulating air gap that lowers the assembly U-value.
None: no storm door.
Wood Storm: a wood-framed storm door.
Metal Storm: a metal-framed storm door.
Adding a storm meaningfully reduces heat transfer, for example, a solid-core wood door drops from U 0.39 to U 0.26 with a wood storm, or U 0.28 with a metal storm (Manual J Table 4A).
Garage Doors
Should I be scanning garages? No unless it is living space. Garages can be a point of confusion in Manual J. They should only be scanned if it is living space. This is most typically in situations where a garage has been renovated to be living space.
If you need to scan a garage:
Treat as an Exterior Door: Garage doors should be modeled as exterior doors in your Manual J calculations. This ensures that their thermal properties are appropriately included in the load estimation.
Manual Adjustments: You may need to manually add the garage door as an exterior door after scanning.
Note: Manual J does not account for the effects of frequent opening and closing of garage doors on air infiltration loads. The calculations assume that the garage door remains closed. This is a standard limitation of the Manual J methodology.
Add, edit, or remove doors
To add a new door, change its dimensions, or remove one, see Add, edit or remove windows and doors.