1. Identifying and Air Sealing the Building Envelope
WEATHERIZATION INSTALLER/TECHNICAN FUNDAMENTALS
Identifying and Air Sealing the Building Envelope
WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012
July 2012

2. Learning Objectives
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
By attending this session, participants will be able to:
Differentiate between the thermal and pressure boundaries and describe the behavior and function of each.
Summarize basic principles of air leakage.
Identify the proper location of the pressure and thermal boundaries.
Identify common sites and signals of breaks in the pressure and thermal boundaries.
Identify common air sealing materials and their characteristics.
(continued on next slide)
By attending this session, participants will be able to:
Differentiate between the thermal and pressure boundaries and describe the behavior and function of each.
Summarize the basic principles of air leakage.
Identify the proper location of the pressure and thermal boundaries.
Identify common sites and signals of breaks in the pressure and thermal boundaries.
Identify common air sealing materials and their characteristics.
July 2012

3. Learning Objectives
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
By attending this session, participants will be able to:
Explain what is meant by “inside” and “outside” in terms of air barrier and how a blower door is used to determine that.
Identify typical construction details that lead to gaps in pressure and thermal boundaries and know how to treat them.
Describe treatment options for walk-up attics.
Additionally, participants will be able to:
Explain what is meant by “inside” and “outside” in terms of an air barrier and how a blower door is used to determine that.
Identify typical construction details that lead to gaps in pressure and thermal boundaries and know how to treat them.
Describe treatment options for walk-up attics.
July 2012

4. Comfort, Safety and Efficiency
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
A comfortable, safe, and energy-efficient home requires:
A fully insulated thermal envelope or thermal boundary.
A well-sealed air barrier.
Continuous thermal boundaries and air barriers that are in contact with one another.
Efficient, properly sized equipment to condition the living space and heat water.
A well-designed and balanced air distribution system.
Healthy indoor air quality.
Long-term experience with the causes and effects of building failure by weatherization practitioners has led to these basic tenets of weatherization.
A comfortable, safe, and energy-efficient home requires:
A fully insulated thermal envelope or thermal boundary.
A well-sealed air barrier.
Since air carries heat and moisture, the condition of the air barrier plays a major role in the movement of heat and moisture through the building. It also affects the size of heating and cooling systems and indoor air quality (IAQ).
A continuous thermal boundary and air barriers that are in contact with one another.
The motto is: “Seal tight; insulate right.”
Efficient, properly sized equipment to condition the living space and heat water.
Bigger is not better. For example, oversized air-conditioners make a house cold and clammy and short cycle times produce problems later. Moisture in the air condenses on building surfaces where it can cause mold and rot. (With a properly sized unit, moisture will collect on the condenser coil.) This course focuses on the first three bullets. To learn more about proper sizing of equipment, refer to Manual J.
A well-designed and balanced air distribution system.
Healthy indoor air quality.
IAQ is a key health and safety concern. We test for carbon monoxide levels, backdrafting, and mold and moisture to make sure we leave all homes safe for residents.
July 2012

5. Image courtesy of ENERGY STAR
Typical Air-Leakage
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Air leaks are commonly found in certain areas of the home.
The attic is where most conditioned air is lost. Typical air leakage sites in the attic are:
Recessed lights.
Attic hatches.
Dropped soffits.
Wall tops.
Flues.
Doors and windows, plumbing and electrical penetrations, and sill plates.
Q: What do you think is the more cost-effective approach: sealing air leaks in the attic, walls, and ceiling, or replacing windows?
A: Click to next slide to show answer.
Image courtesy of ENERGY STAR
July 2012

6. Primary Air Infiltration Sites
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
5% Fans and vents
12% Windows
Floors, walls, and ceilings 36%
13% Doors
The graph shows those typical leakage sites another way.
The attic is not separated out, but it’s the largest piece of the “floors, walls, and ceiling” category that makes up more than one-third of all air leakage.
Many people think replacing windows is crucial. According to this graph, windows come in fifth, behind floors, walls and ceilings, fireplaces, plumbing penetrations, and doors, in terms of air leakage.
Electrical outlets 2%
15% Plumbing penetrations
Fireplaces 16%
Data courtesy of the California Energy Commission
July 2012

7. Photos courtesy of the US Department of Energy
Finding Air Leaks
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Check typical hot spots
Flues and plumbing vents
Wire pathways
Recessed fixtures (lights and fans)
Chimney penetrations
Signals
Blower door, smoke
Dirty or discolored insulation
Photos courtesy of the US Department of Energy
No one wants to spend more time than necessary in an attic. To make the job go smoothly and quickly, bring all the tools you need and use your knowledge of the home and of building science to quickly locate and seal air leaks.
Check typical hot spots, such as:
Flues and plumbing vents.
Wire pathways.
Recessed fixtures (lights and fans).
Chimney penetrations.
Signals.
Blower door, smoke. (With the blower door running, smoke can be used to check that the seal is complete.)
Dirty or discolored insulation.
Q: When you see dirty insulation, what could that indicate?
A: That the air is being filtered through the insulation as it pours through a leak in the air barrier.
A: That the area near any dirty insulation should be inspected.
July 2012

8. Thermal Boundaries & Air Barriers
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
For maximum efficiency and comfort, the thermal boundaries and air barriers must be continuous and in contact with each other.
For maximum efficiency and comfort, the thermal boundaries and air barriers must be continuous and in contact with each other.
The air barrier (also known as the pressure boundary) is most typically the interior drywall.
The thermal boundary is often fiberglass batting.
If these aren’t continuous and in contact with each other, conditioned air escapes the home.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

9. The Thermal Boundary The Thermal Boundary
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The Thermal Boundary
Limits heat flow between inside and outside.
Is easily identifiable by presence of insulation.
The location of insulation in relation to other building components is critical to its effectiveness.
Even small areas of missing insulation are very important.
Voids of 7% can reduce effective R-value by almost 50%.
The thermal boundary is the insulation.
The thermal boundary limits heat flow between inside and outside.
It is easy to identify by the presence of insulation.
The location of insulation in relation to other building components is critical to its effectiveness. When air passes through insulation, it takes heat and moisture with it.
Even small areas of missing insulation are critical to address.
Voids of 7% can reduce the effective R-value by almost 50%. The effective R-value in the attic of a 1,000-square-foot, single-story rambler insulated to R-38 falls to only R-19 when 70 square feet of insulation is pushed aside, leaving an uninsulated or under-insulated area. This could easily happen if the installer held back to avoid blowing right up to the vented soffits and high temperature items. To avoid this, the installer should install soffit baffles and chimney dams and blow to the proper depth throughout the attic.
Common insulation materials include fiberglass batts, blown-in cellulose, and vermiculite in some older homes. If the thermal and air boundaries are continuous and in contact with each other, air will not pass through the insulation.
It is common for cold air to bypass the insulation, not just in small, older homes, but in large, new homes as well.
Q: What materials serve as both a thermal boundary and an air barrier?
A: Foam board, spray foam and dense-pack cellulose insulation, when properly installed, greatly reduces air flow.
Graphic courtesy of Dr. Energy Savers
July 2012

10. Thermal Boundaries are Obvious
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The thermal boundary is usually easy to identify.
Q: Where is the air barrier?
A: The air barrier cannot always be determined through visual inspection. Pressure diagnostics are the best way to determine the location and condition of air barriers.
Photo courtesy of the US Department of Energy
July 2012

11. Air Barrier Air Barrier Limits air flow between inside and outside.
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Air Barrier
Limits air flow between inside and outside.
Is more difficult to identify.
Is not always where you think it is.
A blower door is used to locate the air barrier.
The air barrier:
Limits air flow between inside and outside, as well as the heat and moisture carried by that air.
Is more difficult to identify than a thermal boundary because it can be hard to see.
Is not always where you think it is.
Pressure readings taken while operating the blower door are used to locate air leakage and the air barrier.
Q: What is the air barrier in most homes?
A: Usually it’s the interior drywall.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

12. Thermal Boundaries & Air Barriers
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
An uninsulated attic hatch is a gap in the attic’s thermal boundary.
Air Barrier
Thermal Boundary
An uninsulated attic hatch is a gap in the attic’s thermal boundary.
Q: Even though the air barrier is continuous, where do you think heat will travel?
A: Click to reveal heat escaping through attic hatch and explanatory text.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

13. PRESSURE & THERMAL BOUNDARIES
This photo shows an uninsulated attic hatch.
Heat travels from the room below up into the attic, increasing heating bills and reducing comfort. In the summer, heat travels from the hot attic into the rooms below, increasing cooling loads.
Photo courtesy of NRCERT
July 2012

14. Air Barrier
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
A mechanical chase containing ducts can break the attic’s air barrier.
Air Barrier
Thermal Boundary
The air barrier is continuous, but it is not in contact with the thermal boundary.
A mechanical chase containing ducts can break the attic’s air barrier.
When the air barrier and thermal boundary are not in contact with each other, air flows through insulation, bringing heat and moisture with it.
Q: Where might you see this in a home?
A: Interior walls without top plates, and in ducts, plumbing, and electrical chases.
Q: Where does the heat travel?
A: Click to reveal heat path.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

15. Moisture
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Moisture flows with warm air through breaks in the air barrier, causing damage when it condenses on cool surfaces.
Air Barrier
Moisture flows with warm air through breaks in the air barrier, causing damage when it condenses on cool surfaces.
Thermal Boundary
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

16. PRESSURE & THERMAL BOUNDARIES
Plumbing chases often create breaks in the air barrier.
Upon closer inspection, the dirty insulation reveals a break in the air barrier at the plumbing chase.
Photo courtesy of NRCERT
July 2012

17. PRESSURE & THERMAL BOUNDARIES
That dirty insulation revealed a gap in the air barrier of many square inches.
The attic is completely open to the home below.
The effective R-value of this insulation is greatly reduced.
Photo courtesy of NRCERT
July 2012

18. PRESSURE & THERMAL BOUNDARIES
This photo shows a typical air barrier leak.
Follow the wiring to locate breaks in the air barrier.
Someone used a much bigger drill than was necessary to drill wire chases.
Photo courtesy of NRCERT
July 2012

19. PRESSURE & THERMAL BOUNDARIES
Plumbing chases are typical locations for air leakage.
Photo courtesy of NRCERT
July 2012

20. Construction Details
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Other construction details can result in gaps in pressure and thermal barriers.
Changes in ceiling height
Knee-wall attics
Walk-up attics
Dropped soffits
Above kitchen cabinets
In bathrooms
Above vanities
Above built-ins
At duct chases/bulkheads
Other construction details that result in gaps in pressure and thermal barriers are:
Changes in ceiling height
Knee-wall attics
Walk-up attics
Dropped soffits
Above kitchen cabinets
In bathrooms
Above vanities
Above built-ins
At duct chases and bulkheads
July 2012

21. Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Attic
Not only is the top of the wall uninsulated...
This drawing shows how changes in ceiling height create gaps in the thermal and pressure boundaries.
The top of the wall is uninsulated. Heat will flow from the conditioned space through the break in the thermal boundary up into the attic.
Conditioned
Space
Conditioned
Space
Graphic courtesy of Anthony Cox
July 2012

22. Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The interior wall cavities act as a chimney that robs the house of heat and conditioned air.
Often there is no wall cap in this kind of construction.
The open wall top allows even more heat loss because the interior wall acts as a chimney, carrying conditioned air and moisture away from the conditioned space.
Graphics courtesy of Anthony Cox
July 2012

23. Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Open Wall Cavity
A photo of that construction detail in a real-world situation shows:
The wall top is not insulated.
There is no top plate on the shortened wall to prevent convective heat loss through the wall cavity.
Photo courtesy of the US Department of Energy
July 2012

24. Knee-Wall Attics Open Wall Cavities Main Attic Knee-wall Attic
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Main Attic
Open Wall Cavities
Knee-wall Attic
Knee-wall attics, typical in 1½-story, Cape Cod-style homes, are common sources of gaps in the pressure and thermal boundaries.
Even when the ceiling height of the living space below doesn’t change, the knee-wall itself is usually uninsulated.
The interior wall is also often left without a top plate. Convective heat loss occurs through the wall cavity.
Graphic courtesy of Anthony Cox
July 2012

25. Kitchen wall cabinets mounted under soffit or valance
Dropped Soffits
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Kitchen wall cabinets mounted under soffit or valance
Pressure and thermal boundaries often become misaligned at dropped soffits.
This drawing shows a change in ceiling height and a dropped soffit—two causes for the gaps.
Even without a change in ceiling height, dropped soffits cause misalignment in the pressure and thermal boundaries. The pressure boundary, which is the sheetrock, drops below the level of the attic floor and is not typically sealed at the top.
Graphic courtesy of Anthony Cox
July 2012

26. Attic insulation can hide dropped soffits.
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Attic insulation can hide dropped soffits.
Attic insulation can hide dropped soffits.
When there is a change in ceiling height, locating dropped soffits while in the attic is relatively simple.
Finding dropped soffits can be tricky when there is no change in ceiling height except for the dropped soffit.
Use vent ducts and other clues to locate dropped soffits in the attic.
Graphic courtesy of Anthony Cox
July 2012

27. Q: What pressure reading would you hope to get in this test?
Pressure diagnostics determine whether the soffit is connected to the conditioned space.
Q: What pressure reading would you hope to get in this test?
A: Close to 0 Pa, indicating the soffit is sealed off from the attic.
Photo courtesy of NRCERT
July 2012

28. Dropped Soffits
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
If you see soffit-mounted cabinets, remember to investigate during attic inspection.
If you see soffit-mounted cabinets in the kitchen, bathroom, or elsewhere, remember to investigate them when you inspect the attic.
Graphic courtesy of Anthony Cox
July 2012

29. Vent pipe for kitchen exhaust fan helps locate area over kitchen cabinets.
A vent pipe for the kitchen exhaust fan helps locate the area over kitchen cabinets and the dropped soffit found there.
Photo courtesy of the US Department of Energy
July 2012

30. A closer look reveals a dropped soffit and misaligned pressure and thermal boundaries.
Open Wall Cavities
A closer look reveals a dropped soffit and misaligned pressure and thermal boundaries.
Photo Source: US Department of Energy
July 2012

31. Where Is the Air Barrier?
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Cape Cod 1½ Story House
Q: Where should the air barrier be?
A: It should encompass the living space and nothing else.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

32. Where Is the Air Barrier?
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Targeted air sealing defines air barrier
By air sealing at key junctures, we prevent air leakage and can add insulation with good effect.
Click to reveal key junctures.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

33. Where Is the Air Barrier?
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Pressure and thermal boundaries now aligned
After targeted air sealing, the pressure and thermal boundaries are aligned and will stop heat from flowing to unconditioned areas of the home.
Note location of insulation, the orange layer, in the area behind the knee wall. Many people insulate the roof there, or just the ceiling of the first floor, with nothing on the knee wall to stop heat from traveling out and up through the attic vent.
  If the space behind the knee wall of the mini-attic is too small in which to work, the whole space can be blown full of dense-pack cellulose.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

34. Plumbing pipe and dirty insulation are clues…
Plumbing pipes and other penetrations through the building envelope are good places to look for breaks in the air barrier.
Dirty insulation is often an indicator of air leakage. The insulation filters the air, collecting dirt, dust, and moisture as the air passes through.
…that an attic bypass is allowing air flow through the insulation.
Photos courtesy of the US Department of Energy
July 2012

35. An innocent looking fireplace and built-in china cabinet…
Built-in cabinets are often the source of significant air leakage.
Photo courtesy of the US Department of Energy
July 2012

36. …hides an attic bypass you can park a car in.
An extreme case of an attic bypass: Pressure readings taken inside the silverware drawer from within the house read close to 50 Pa with the blower door running.
Q: Where should this bypass be sealed? At the walls or the ceiling?
A: Click to next slide to reveal proper sealing.
The client wondered why her silverware got cold in the winter.
Photo courtesy of the US Department of Energy
July 2012

37. Other Foam board, fiberglass in plastic bags, etc.
General Guidelines
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Energy Blast Services
US Dept. of Energy
The Daily Green
Main qualities of air sealing materials:
Stop air flow
Last as long as the surrounding building materials
Safe to work and live with
General guidelines for sealing materials:
Gaps ≤ ¼” = Caulk
Gaps ¼”–3” = Spray foam
Other = Foam board, fiberglass in plastic bags, etc.
Gaps ≤ 1/4” Caulk
Gaps 1/4” – 3” Spray foam
Other Foam board, fiberglass in plastic bags, etc.
July 2012

38. Drywall Repair
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Sometimes sealing air leaks requires repairing damaged drywall.
Sometimes sealing air leaks requires repairing damaged drywall.
Photos courtesy of the US Department of Energy
July 2012

39. at the level of the attic floor and sealed with the two-part foam.
Shielding prevents blown-in cellulose insulation from touching the chimney.
The hole is capped
at the level of the attic floor and sealed with the two-part foam.
That exceptional bypass is now sealed at the floor level of the attic.
Sealing at this level allows for easy alignment of pressure and thermal boundaries without filling the entire cavity (and silverware drawer) with insulation.
Shielding prevents cellulose or other insulation materials from coming into contact with high-temperature elements, like the chimney shown here.
Photo courtesy of the US Department of Energy
July 2012

40. Photo courtesy of the US Department of Energy
The pressure and thermal boundaries are now continuous and in contact with each other.
Photo courtesy of the US Department of Energy
July 2012

41. Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
In older homes the ceiling level changes in closets, causing gaps in the pressure and thermal boundaries.
The uninsulated bedroom and bathroom walls are exposed to outdoor temperatures.
In older homes, the ceiling level changes in closets, causing gaps in the pressure and thermal boundaries.
The uninsulated bedroom and bathroom walls are exposed to outdoor temperatures.
Photo courtesy of the US Department of Energy
July 2012

42. Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The pressure boundary is re-established by capping the hole with foam board at the same level as the rest of the attic and air sealing.
New insulation will be blown over the repaired pressure boundary and the existing insulation.
The pressure boundary is re-established by capping the hole with foam board at the same level as the rest of the attic and then air sealing.
New cellulose will be blown over the repaired pressure boundary and the existing insulation.
Photo courtesy of the US Department of Energy
July 2012

43. Photo courtesy of the US Department of Energy
The pressure and thermal boundaries are now continuous and in contact with each other.
The pressure and thermal boundaries are now continuous and in contact with each other.
Photo courtesy of the US Department of Energy
July 2012

44. Where Is the Pressure Boundary?
Walk-Up Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Where Is the Pressure Boundary?
Where Should It Be?
Where is the pressure boundary? Where should it be?
Deciding where to place the pressure and thermal barriers in this situation depends largely on convenience for the homeowner.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

45. If the client does not use the attic often:
Walk-Up Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
If the client does not use the attic often:
An insulated, airtight cover can be installed on top of the stairwell.
The pressure and thermal boundaries are aligned at the level of the attic floor.
This approach brings the stairwell into the conditioned space.
It is also cheaper and faster than the alternative.
If the client does not use the attic often:
An insulated, airtight cover can be installed on top of the stairwell.
The pressure and thermal boundaries are aligned at the level of the attic floor.
This approach brings the stairwell into the conditioned space, and it is cheaper and faster than the alternative.
This treatment is most efficient in terms of materials and home energy performance.
This treatment would be inconvenient if the homeowner uses the attic fairly often.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

46. If the client uses the attic fairly often:
Walk-Up Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
If the client uses the attic fairly often:
The pressure and thermal boundaries must be established at the stairs, stairwell walls, and door to the attic stairs.
This approach leaves the stairwell open to the attic and outside the conditioned space.
If the client uses the attic fairly often:
The pressure and thermal boundaries must be established at the stairs, stairwell walls, and door to the attic stairs.
This approach leaves the stairwell open to the attic and outside the conditioned space.
This is less efficient than creating the pressure and thermal boundaries at the level of the attic floor. Stretching those boundaries to include the stairwell and walls creates more surface area for heat loss. Also, it is not typically possible to achieve as high an R-value in the walls and stair treads as can be installed on the attic floor.
A well-insulated, counter-weighted, hinged hatch is another option for much-used attics.
Graphic developed for the US DOE WAP Standardized Curricula
July 2012

47. Since these attic stairs were used often, it was better for the client to keep the stairwell “outside,” which means dense-packing the stairwell walls with insulation.
Since the attic stairs were used often, it was better for the client to keep the stairwell “outside,” which means dense-packing the stairwell walls with insulation.
This worker (who is also a trainer) is drilling the holes in preparation of installing insulation.
Photo courtesy of the US Department of Energy
July 2012

48. Here, cellulose is being blown into stairwell walls.
Photo courtesy of the US Department of Energy
July 2012

49. The door is insulated and weather-stripped.
Walls are insulated and plugs replaced.
The door to the living space is weatherstripped and insulated.
Photo courtesy of the US Department of Energy
July 2012

50. The final step in aligning the pressure and thermal boundaries is to insulate and air seal the stairs.
The final step in aligning the pressure and thermal boundaries is insulating and air sealing the stairs.
If the bottoms of the stairs were left untreated, a large gap in the thermal boundary would exist, allowing substantial heat gain (in the summer) and loss (in the winter) through the attic.
Photo courtesy of the US Department of Energy
July 2012

51. The spray foam must be covered since it is located within the living space.
The spray foam must be covered because it is located within the living space.
If this were in a basement, the spray foam could be treated with a fire-rated coat of spray finish. Since it’s inside the home, a sheet of plywood makes a proper barrier for covering the spray foam.
Photo courtesy of the US Department of Energy
July 2012

52. Summary
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
For maximum efficiency and comfort, the thermal and pressure boundaries must be continuous and in contact with one another.
Electrical and mechanical chases, missing top plates, knee walls, dropped soffits, and changes in ceiling height are common trouble spots.
Targeted air sealing defines the pressure boundary.
For maximum efficiency and comfort, the thermal and pressure boundaries must be continuous and in contact with one another.
Electrical and mechanical chases, missing top plates, knee walls, dropped soffits, and changes in ceiling height are common trouble spots.
Targeted air sealing defines the pressure boundary.
Present this slide as an interactive discussion, soliciting personal examples from the trainees. Add your own personal examples and knowledge to supplement.
July 2012