What is a Shed Ceiling?
A shed ceiling in a house is one-half of a vaulted ceiling. The name comes from lean-to sheds that are added onto taller buildings. The roof only slopes one way. Shed ceilings are often found in attic spaces converted into living spaces.
They are also known as a lean-to, catslide, outshot, skillion, or pent ceiling/roof. (Skillion is a term used in Australia and New Zealand.) Shed ceilings often follow the roof lines.
Shed Ceiling Construction
Lean-to-style roof construction comes first. Then the ceiling has to be finished. The easiest finishing method is to insulate and drywall the roof rafters. Shed ceilings are very versatile. They can be covered with drywall; then finished with multiple textured ceiling options. Or with different types and styles of wood finishes.
The first photo shows a 4/12 ceiling pitch. In a 12’ wide room, the high side will be 4’ higher than the low side. The second photo is of 2/12 roof pitches. Meaning that the high side will be 2’ higher than the low side in a 12’ wide room.
Mono Truss Shed Ceilings
Some shed ceilings do not mirror the roof pitch. The roof is constructed using a mono truss sitting on the outside wall. Inside the ceiling will be flat. It can be finished the same way any other flat conventional ceiling is.
Scissor Truss Shed Ceilings
Many shed ceiling looks are achieved by using scissor trusses. One half of the truss is a normal flat ceiling design. The other half creates a vault inside the house. Interior slopes and exterior slopes do not match. (Interior has a lower slope.)
Scissor trusses allow for normal building envelope construction. Vapor barrier, blow-in or batt insulation, and vented air space throughout the entire attic. Truss-designed vaults or shed ceilings are deep enough to accept much more insulation than rafter-built shed ceilings–making for warmer homes. Interior truss slopes greater than 4/12 are not suitable for blow-in insulation.
Shed Ceiling Ideas
From drywall to wood to glass, shed ceilings provide multiple finishing options. Other than structural considerations, any type of finish is a good one–if the owners like it.
Here are a few of the most popular.
Glass Shed Ceilings
Sunrooms and house additions often use shed roofs and ceilings. Many sunrooms have all, or partial glass roofs to make for light and airy spaces. Many additions such as extensions of kitchens or bedrooms are designed with glass in the shed roof.
In the picture below, kitchen cupboards line the outside wall preventing any window installations in that location. The all-glass shed roof turns the space into a cheerful lighted area.
Exposed Beam Shed Ceilings
Shed ceiling trusses or rafters will almost always run perpendicular to the house and room below. The long wall will run parallel to the house. This means that most exposed beam ceilings on lean-to roofs will be decorative. Faux beams are made of reclaimed wood, purpose-manufactured wood, and even extruded polystyrene of fiberglass.
Regardless of functionality, heavy exposed beams provide a classic or rustic look and feel to rooms. Having skylights in the ceiling adds an extra touch of interest.
Wood Shed Ceilings
Finishing a shed ceiling with wood will add more versatility to your choices. A few of the options include:
- Tongue and Groove. Tongue and groove boards are available in many species of wood and in different widths and thicknesses.
- G1S Plywood. Install Good One Side ½” plywood on the ceiling. Cover the joints with 1 x 2 battens. Use a semi-gloss oil finish.
- Reclaimed Barn Boards. Reclaimed boards not only help the environment but make for a very interesting ceiling finish.
Shed Ceiling Insulation
Insulating shed ceilings/roofs presents a few difficulties. Rafter depths can be small–4” – 12’’–restricting the amount of insulation and the resulting R-Value.
Ventilation can be a problem. One school of thought believes that no ventilation is necessary. Another recommends a vented shed roof. Many shingle manufacturers will not warranty unventilated roofs.
How to Insulate a Shed Ceiling
Trying to vent a shed roof that meets a vertical wall almost always leads to leaking. Building aerodynamics create snow drifting and rain backing up against the vertical wall. Any vent placed in that area will leak–from rain or snow melt or both.
Moisture getting into a shed ceiling soaks batt insulation making it useless or worse. Water can leak into the interior of the house. Framing members will rot, attract insects, and mold.
The following shed ceiling/roof assemblies are two of the most effective options.
- Compact Shed Roof Assembly – Unvented
The compact roof assembly is the standard low-slope construction method. It is very effective on steeper slopes as well. Install approximately 2” of closed-cell spray foam insulation on the underside of the roof sheathing. Ensure it adheres tightly to all rafters, roofing nails, and penetrations.
Fill the rest of the rafter cavities with fiberglass batts. Install drywall or wood finishing. These types of ceilings do not require a vapor barrier. The underside of the roof deck should not get cold because of the spray foam.
Spray foam has an R-Value of 5 to the inch, eliminates air leakage, creates a vapor barrier, and stops thermal bridging. Many builders and contractors will fill the entire cavity with foam and not bother with batts. Foam is more expensive than batts.
- Icehouse Shed Roof Assembly – Vented
Icehouse roof assemblies involve two layers of roof sheathing. Install the first layer on top of the rafters and cover it with a waterproof membrane. Flash to the wall. Install 2 x 2 on top of and in line with the rafters. Add another layer of sheathing that ends about 2” from the wall. Install roofing and flashing.
Any water that gets under the flashing will just drain out of the bottom edge of the roof. The shed ceiling needs a vapor barrier on the warm side of the rafters and should be as airtight as possible because the underside of the sheathing can get cold. Warm moist air from below meeting cold air will cause condensation and wet insulation.
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