ATTIC ACCESS

Provide adequate insulation coverage and air sealing for the

access between living space and the unconditioned attic

OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMS

ENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings for

the 21st Century

Buildings that are more

energy-efficient, comfortable,

and affordable...that’s the

goal of DOE’s Office of Building

Technology, State and

Community Programs (BTS).

To accelerate the development

and wide application of energy

efficiency measures, BTS:

• Conducts R&D on technologies and concepts for energy

efficiency, working closely

with the building industry

and with manufacturers of

materials, equipment, and

appliances

• Promotes energy/money

saving opportunities to both

builders and buyers of homes

and commercial buildings

• Works with State and local

regulatory groups to improve

building codes, appliance

standards, and guidelines for

efficient energy use

• Provides support and grants

to States and communities

for deployment of energyefficient technologies and

practices

Technology Fact Sheet

DON’T LEAVE A HOLE IN THE CEILING

A home’s attic access, such as an attic hatch,

pull-down stairs, or knee-wall door, often goes

uninsulated, representing one of the biggest

deficiencies in the thermal barrier between the

attic and conditioned space. This gap in the

attic insulation increases heat loss in winter

and heat gain in summer, and makes indoor

living areas uncomfortable.

Such accesses are often not sealed properly.

A 1⁄4-inch gap around the perimeter of an

attic access can potentially leak the same

amount of air supplied by a typical bedroom

heating duct (~100 CFM). Unsealed, the attic

access in a home leaks energy dollars and

causes the house to be less comfortable.

To create the hatch, the installer should cut a

plywood piece or save the ceiling drywall piece

that is cut out for the hole. To ensure a tight

fit, securely fasten the trim around the hole to

the ceiling and make sure that it is flat and

level. An uneven base can cause air leakage.

Weatherstripping can be installed either on the

hatch itself or on the inside of the trim or base

where the hatch rests. Adding a latch bolt will

help ensure a tighter seal.

After the trim or base is aligned to seal properly,

insulation should be added to the attic side of the

hatch. Rigid insulated sheathing is recommended. Cut the insulated sheathing 1⁄4 inch

smaller than the hatch size to allow for clearance

when moving the access panel. Apply 3 or 4 inches

of insulation to the hatch with construction adhesive

and screws. As an added measure, glue the kraftpaper side of batt insulation to the top of the last

layer of rigid insulation. Try to achieve the same

total R-value as recommended by the 1995 Model

Energy Code (MEC)(see page 4) or DOE Insulation

Fact Sheet. Order the Insulation Fact Sheet (DOE/

CE-0180) from the Energy Efficiency and

Renewable Energy Clearinghouse or access it

from the Internet at www.ornl.gov/roofs+walls.

Hatch lid pushes up and 

out of the way for access

Air seal

gasket Trim

Insulation dams 

prevent loose-fill 

insulation from 

falling through 

access

          

SCUTTLE HOLE COVER

ATTIC HATCH

One inexpensive and common type of attic

access is referred to as a scuttle hole or attic

hatch, which is simply a removable portion of

the ceiling that allows entry to the attic above.

A scuttle hole is commonly located in a closet

or main hallway.

ATTIC ACCESS

An attic access

is a big hole. Adding

an insulated cover and

weatherstripping to an

access can reduce infiltration

and heat-loss through this

passageway. Latch bolts (not shown) may be

installed to help ensure an even tighter seal.
ATTIC ACCESS LOCATION

Location of an attic access is important. If possible, locate the

access in an unconditioned part of the house (e.g., garage,

covered patio, or porch) that is also secure against potential

break-ins. A garage location, where the vented attic is

uninsulated, can eliminate the need for sealing and insulation.

For a pull-down attic staircase, make sure that opening the stairs

will not interfere with the placement of furniture. The position

of the staircase in relation to ceiling joists might also affect

location—placing the staircase between joists instead of across

joists can speed installation because structural cross-member

framing is not as complicated.

ATTIC DECKING

Attic decking is often used to provide additional storage space or

a platform for an HVAC unit or hot water tank installed in the attic.

The decking is often installed directly on top of the ceiling joists;

this limits the amount of space available for insulation and lowers

the attic’s average R-value.

To ensure proper insulation depth, the attic decking must be

raised above the ceiling joists. To accomplish this “edge-nail”

2x4’s or 2x6’s to the tops of the ceiling joists where the decking

is to be located or, as an option for trusses, lag 2x4 members to

the truss webbing at the desired height. Install the decking

securely to the top of the raised lumber after the insulation has

been installed.

ATTIC STAIRS

Pull-down stairs are another common type of attic access. The

frame for the stairs fits in a rough opening and leaves a gap,

much like that for a door or window, which must be sealed. If

the gap is small (less than 1⁄2 inch), caulk can be used as the

sealant. If a larger opening exists, then non-expanding foam or

a backing material (backer rod) is recommended in conjunction

with caulk. Expanding foam can be used, but care must be

taken because of its highly expansive nature; it could warp the

frame and interfere with the ability of the stairs to open or close

properly. To ensure a tight fit between the stairs’ flat panel and

the frame, weatherstripping or gasket material should be added

either to the frame or the panel. Latch bolts may be installed to

help ensure a tighter seal.

To insulate attic stairs access, a lightweight, moveable box can

be constructed from rigid foam or fibrous ductboard to fit over

the stairs from the attic side. Insulating kits are also available

through weatherization suppliers or from local hardware stores.

As with all home projects, follow the attic stairs manufacturer’s

instructions for proper installation. Manufacturer’s guidelines often

provide unique techniques and safety considerations for each

particular unit. For safety and the extended life of the stairs, be sure

to cut the stairs to the proper length. This action will prevent strain

on the hinges and reduce wear on the pivotal joints of the stairs.

An attic stair cover box is made from rigid insulation. It drops

down from the attic side to seal and insulate the pull-down

stairs.

PULL-DOWN ATTIC STAIRS

     

Weatherstripping

Weatherstripping Panel

     

Cover box pushes up 

and out of the way for 

access

Seal gap between 

frame and rough 

opening with 

caulk, backer rod, 

or foam

Insulation dams prevent 

loose-fill insulation from 

falling through access

INCREASE ATTIC INSULATION LEVELS UNDER DECKING

For many products, an insulation depth of 10 to 14

inches is needed to achieve an R-30 to R-38 insulation

value. Thus, a 2x4 or 2x6 extension needs to be added to

a 2x6 joist to provide sufficient depth before installing

decking.

2x6

2x4
ceiling 

joist cover box

sits on stairs frame

shim

sealant

stairs frame

weatherstripping

ATTIC ACCESS

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ATTIC STAIRS COVER BOX

Pay careful attention to inside

and outside dimensions plus

height requirements for the

specific measurements of the

attic staircase being installed.

The cover box should

rest squarely on top of

the attic stairs frame.

Shim and seal the gap

between the frame and

rough opening and

install weatherstripping.

Assemble side

pieces, end pieces,

and brace as shown.

The cover piece will

drop in and be attached with adhesive and nails.

223⁄4" 233⁄4" 243⁄4"

531⁄2"

521⁄2"

511⁄2"

CONSTRUCT AN ATTIC STAIRS

COVER BOX

Use the template shown here to cut

pieces from a single 4x8 foot sheet

of 1⁄2-inch rigid insulation for a box

531⁄2 inches long (511⁄2 inches

inside), 243⁄4 inches wide (223⁄4

inches inside), and 9 inches high

inside. This box will fit stairs with

an outside framing dimension of

531⁄2 inches by 243⁄4 inches. Adjust

dimensions to fit the specific stairs

being installed. Be sure to carefully

measure both inside and outside

dimensions to the appropriate

length, width, and depth clearances

for the cover box.

Create the box as shown: Apply

adhesive/mastic and use roofing

nails to construct the two end and

two side pieces. Assemble the side

and end pieces into a box using

adhesive and longer nails. Add the

center support brace and cover

piece with glue and nails. A faced

insulation batt may be glued to the

cover piece with adhesive applied to

the paper backing.

MATERIALS NEEDED :

• 1⁄2-inch rigid insulation

• Insulation batt (optional)

• Duct sealing mastic or

construction adhesive

• 1-inch roofing nails (8d or

16d)

• Tape measure, sharp utility

knife and straight-edge, or

table/circular saw

• Weatherstripping/gasket 

material with adhesive

All pieces can be cut out of one 4'x8' sheet of rigid insulation. Use a table saw for

smooth, accurate cuts.

COVER

BRACE

SIDE

side

END

end

END

end

SIDE

side

21⁄2"

511⁄2"

21⁄2"

21⁄2"

233⁄4" 91⁄2"

91⁄2" 91⁄2" 9" 9"

91⁄2"

511⁄2" 21⁄2"

243⁄4"

521⁄2"

521⁄2"

521⁄2"

243⁄4"

233⁄4"

233⁄4"
For more information, contact:

Energy Efficiency and

Renewable Energy

Clearinghouse (EREC)

1-800-DOE-3732

www.eren.doe.gov

Or visit the BTS Web site at

www.eren.doe.gov/buildings

Or refer to the Builder’s Guide

Energy Efficient Building

Association, Inc.

651-268-7585

www.eeba.org

Written and prepared for

the U.S. Department of

Energy by:

Southface Energy Institute

404-872-3549

www.southface.org

Oak Ridge

National Laboratory

Buildings Technology Center

423-574-5178

www.ornl.gov/ornl/btc

The Model Energy Code

can be obtained from the

International Code Council by

calling 703-931-4533

MECcheck, a companion

compliance software

package, can be ordered from

DOE by calling

1-800-270-CODE

or downloaded directly

from the Web at

www.energycodes.org/

resid/resid.htm.

ATTIC ACCESS

NOTICE: Neither the United

States government nor any

agency thereof, nor any of their

employees, makes any warranty,

express or implied, or assumes

any legal liability or responsibility

for the accuracy, completeness,

or usefulness of any information,

apparatus, product, or process

disclosed. The views and opinions of authors expressed herein

do not necessarily state or reflect

those of the United States government or any agency thereof.

KNEE WALLS

Another type of attic access is a knee-wall door.

A knee wall is typically a partial height wall that

is usually found in the upstairs level of

finished-attic homes. Knee walls are notoriously

leaky and often poorly insulated. Make sure

that the knee-wall door is weatherstripped and

has a latch that pulls it tightly against the frame

and weatherstripping to achieve a solid seal.

Use construction adhesive and screws to attach rigid insulation to the attic side of the

door. Some attic doors are full-height interior

doors which should be insulated,

weatherstripped, and equipped with a tight

threshold.

Inspect the rest of the knee wall and adjust

insulation levels to meet those recommended

in the 1995 MEC or DOE Insulation Fact Sheet.

If not enough insulation is installed, first air

seal the knee wall before insulating. Consider

covering the back of the vertical knee wall with

rigid insulation. Insulated sheathing, with the

seams caulked or sealed with housewrap tape,

reduces heat flow and minimizes the comfort

problems commonly associated with drafty

attic knee walls.

In new construction, an improved approach is

to insulate and air seal the rafter space along

Add R-value to a knee-wall door by adhering

rigid insulation boards (sandwiched together

with construction adhesive and screws) to the

back of the door. Pay special attention to the

clearance between the insulation and the door

frame and air sealing details.

Printed with a renewable-source ink on paper containing at

least 50% wastepaper, including 20% postconsumer waste.

February 2000 DOE/GO10099-768

the sloped ceiling of the knee wall. The rafters

should be covered with a sealed air barrier,

such as drywall, rigid insulation, or foil-faced

hardboard. One advantage of this approach is

that the storage area as well as any ductwork is

now inside a more tempered space.

ATTIC KNEE WALL

KNEE-WALL DOOR

The attic knee wall is often underinsulated and leaky. Install adequate insulation and air seal around

the living space for continuity in the building envelope when addressing the knee-wall door.

Seal Attic

living

space

Seal

Hardboard

Seal all edges of rigid 

foam insulation 

Attic space

Desired 

ventilation

Unwanted air leakage Attic ventilation

Knee wall

Seal

outlet

box to

drywall