A scanned space can sit beneath a range of different ceiling conditions:
Common attic (i.e. a typical flat ceiling, where insulation is in the "floor" of the attic)
Encapsulated attic (an attic where the insulation has been moved from the attic "floor" into the attic roof system, often insulated with spray foam)
Cathedral or vaulted ceiling (no attic)
On exposed beam (roof-ceiling sandwich, common for zero pitch roof systems)
Each scenario is handled by a different Manual J construction that drives very different heat gain and loss. Getting the ceiling settings right is essential to accurate load calculations.
This article walks through every setting on the ceiling screen.
Always verify construction details and assumptions in the home. Most attics are accessible through a hatch or pull-down stairs. Bring a flashlight to check the insulation type and depth, look for R-value labels printed on the face of fiberglass batts, and make note whether the attic is vented at the gable ends (or look for soffit and ridge vents from the outside) and keep an eye out for radiant barriers on fiberglass batts or foils applied directly to the roof system.
Roof material and color are easy to verify from the curb.
Have attic ductwork? Make note of the duct insulation and air sealing while you're up there. Learn more about modeling ducts.
Note about "Is Exterior": Loads are only calculated on ceilings that are considered "exterior" — i.e., they separate conditioned living space from outdoor air. Top-story ceilings are what we most commonly focus on since lower-story ceilings typically have a conditioned room above them, so the ceiling is considered "interior" and loads should not be considered. A common exception is a ceiling for a single-story bump-out or renovation.
The "Is Exterior" toggle can be found in the upper right of the sidebar when a ceiling is selected.
Edit ceiling assumptions
Ceilings are one of the few surfaces in Amply that we don't visualize in the 3D model because they would block the view. To access the ceiling menu, open a room and tap the Ceilings in the sidebar
Once you have selected a ceiling, tap on the existing assumptions menu to make changes. In the example screenshot below, it's the menu that says "Common Attic (R30)"
Construction
Construction indicates geometry and construction scenario of the ceiling.
Common attic: A flat ceiling separated from the roof by an attic that is intentionally vented (or unvented) to outdoor air through soffit and ridge vents (or gable vents). Attic temperatures swing dramatically with outdoor conditions. This is the most common configuration in U.S. homes.
Encapsulated attic: This is a variation of an attic, and there are other special considerations that are handled automatically by Amply. See more below.
Cathedral or vaulted ceiling — the ceiling surface follows the underside of the roof rafters with no attic above. Insulation sits between the rafters or above the deck, so heat transfer moves through the ceiling system into the building without an attic buffer.
On exposed beam (or roof-ceiling sandwich): A structural assembly where the ceiling and roof are sometimes single panel (SIPs, exposed-beam construction). The exposed beams also provide a direct path to conduct from the outside to the inside
Why the ceiling configuration matters so much: An unconditioned attic above a ceiling acts as a thermal buffer — its temperature sits somewhere between outdoor and indoor conditions, depending on venting, insulation, and roof color. particularly in the cooling season, attics can reach very high temperatures, as much as 160°F, if they are poorly vented. A cathedral ceiling has no buffer, so the roof surface temperature drives heat transfer directly into the room below. The same R-value of insulation can produce very different loads in these two configurations.
Encapsulated attic special considerations
An encapsulated attic (or sealed, unvented attic) is a construction practice where insulation is applied directly to the underside of the roof deck and gable walls rather than on the attic floor. It's very common to use spray foam in this application, but other forms of insulation can also be used. Encapsulating an attic impacts three different areas of a load calculation:
Note: When encapsulating an attic, the biggest benefits are often for ductwork that is in that encapsulated attic space or via a reduction in building infiltration loads. Often the ceiling loads, into rooms below, increases (gets worse) especialy relative to a well insulated "Common Attic".
Ceiling loads: The amount of heat transfer between the ceiling of the room and the attic
Encapsulation creates a "partition buffer zone" in the attic that makes temperatures in the attic much closer to indoor design temperatures (70F in the winter and 75F)
The "ceiling" material gets set to automatically to drywall with an U-value of 0.6
Relative to a "Common Attic", this will often increase the loads on the ceiling
The insulation on the roof deck is assumed to be R19 (3" of closed-cell foam or a typical fiberglass batt)
Attic Duct loads: If ducts are present in the space, it dramatically reduces the heat loss and gain experienced by the ductwork. Learn more about verifying and editing ducts.
Infiltration loads: Encapsulating an attic can significantly reduce the air leakage in the building
The benefit from this is most accurately characterized by a blower door test
You must account for these changes in your air infiltration assumptions. Learn more about verifying and editing infiltration loads in Amply
Example image of an encapsulated attic with spray foam:
How to indicate that you have an encapsulated attic in Amply
Open a room
Select the ceiling in the side bar
Make sure you mark the ceiling as exterior
Use the
Is Encapsulatedtoggle
Note on defaults: Since attic encapsulation is relatively rare in homes, we do not provide a way to make it a default with in a project. Therefore, each space beneath an encapsulated attic needs to be marked as such in the ceiling settings.
Attic Venting
Attic Venting describes how the attic exchanges air with the outdoors, and only applies when Construction is set to the "Common attic" option.
None: No intentional outdoor venting. Common in newer construction and in retrofits where the underside of the roof deck has been insulated with spray foam.
FHA Vented: Federal Housing Authority required surface area for venting/ The attic has open soffit and ridge vents or gable-end vents on opposite sides of the attic that meet minimum size requirements. These intentionally connect attic air to outdoor air. The default for most U.S. homes.
FHA + Extra vents or Attic Fan: if additional venting is present or is assisted with a powered exhaust fan
ATTIC FAN WARNING: If a powered attic exhaust fan is present (or you are thinking about adding one), be absolutely sure there are appropriately sized gable-end vents (or ridge vents) on the opposite side of the attic from the fan. The use of an attic exhaust fan without proper fresh air intake can cause the attic to be depressurized and to draw conditioned air from the second story of the building into the attic which can cause a whole range of comfort as well as health and safety issues for the occupants.
If you are not sure, look from outside the home for soffit vents under the eaves and a ridge vent along the peak of the roof. Both visible = vented. Neither visible = likely unvented, but check the attic itself to confirm.
Roof Material
Roof Material describes both the material on top of the roof and its color. Both affect how much solar radiation is absorbed into the roof deck and ultimately transferred down through the attic and ceiling.
Color matters as much as material. A dark roof can absorb 80-90% of incoming solar radiation, while a white roof reflects 60-80%. This single setting can change cooling loads by 10-20% in a hot climate.
Common options in Amply include asphalt shingle, wood shake, metal panel, tile, slate, concrete, and membrane — each paired with a color (dark, light, or white).
For cooling-dominated climates, picking the right roof material and color is an important assumption to get right. Verify both at the curb before you walk into the home.
Insulation
Insulation is the R-value of insulation in the ceiling assembly itself - typically batts or blown-in cellulose/fiberglass laid across the attic floor for an attic construction, or batts and rigid foam between/above the rafters for a cathedral or sandwich construction.
For
Common atticAmply supports values fromR0up toR60— covering everything from an uninsulated attic to a high-performance superinsulated home.For
Cathedral or vaulted ceilingandRoof-ceiling sandwich, the range is narrower because insulation is constrained by rafter depth.
If you can see the insulation in the attic, measure or estimate its depth and check the face of any batts for printed R-value labels. If you can't see the insulation directly, for example, a finished cathedral ceiling, our smart starting assumptions provide a reasonable default based on the home's year built and climate zone. We also recommend checking with your local building inspector to understand what was common for different vintages of homes in your area.
Set your changes as the default
Once the ceiling matches what's above the top story of the home, turn on Use as default. Amply then applies the same settings to every subsequent top-story room you scan. Override it for individual rooms that sit under something different (e.g., a vaulted living room inside an otherwise flat-ceilinged home, or a top-story room with a different roof material).