Why Your House Is Losing Heat And How to Fix It

Thermal bridging is one of the most common and least visible causes of heat loss in residential buildings. Most insulated homes have it. Most homeowners have never heard of it.

Here is what it looks like in practice: you insulated the house, the numbers look good on paper, but in the middle of winter certain walls still feel cold to the touch, the heating system runs harder than expected, and the indoor temperature never quite settles the way you hoped. The insulation is not failing. The problem is what the insulation is missing.

Getting a house right in a cold climate takes several layers working together. Passive solar design decides how much free heat the building collects, and thermal mass decides how long it holds onto it. Thermal bridging is the layer that determines how much of that heat leaks straight back out through the framing.

This post explains what thermal bridging is, where it hides in a typical house, and how we eliminated it at Cedar Residence, a custom high-performance farmhouse we designed in Monroe, Maine. (Read the full project story: Cedar Shingle Modern Farmhouse in Monroe, Maine)

What Is a Thermal Bridge and Why Does It Matter?

A thermal bridge is any point in a building's envelope where heat moves through faster than it does through the surrounding materials. Heat always flows from warm to cool, and it will always find the path of least resistance. In a well-insulated wall, that path is the framing.

Different materials conduct heat at very different rates. Insulation is deliberately chosen because it conducts heat slowly, trapping warmth inside. But the wood studs, metal fasteners, and structural elements that make up the frame of a wall conduct heat much faster than the insulation beside them. Every one of those elements is a gap in the thermal protection of the building.

Thermal bridges are places in the building envelope through which heat escapes more easily. They are not failures of workmanship. They are a structural reality in almost every conventionally built home.

The impact is larger than most people expect. A 2x6 wall insulated with R-19 fiberglass batts sounds well protected. But research from Oak Ridge National Laboratory shows the actual whole-wall performance of that assembly is closer to R-12.8 when the batts are installed perfectly, and only R-11 when they are installed with typical imperfections. The difference between the label and reality is almost entirely explained by thermal bridging through the studs.

Where Do Thermal Bridges Occur?

Thermal bridges come in three forms: structural (framing members like studs penetrating the insulation), geometric (corners and junctions where more exterior surface area faces the cold than interior), and material (highly conductive elements like metal ties and brackets crossing the thermal layer). In practice, all three show up together in a typical home.

These are the most common locations where thermal bridges occur and where heat loss is highest:

• Wall studs: the most widespread bridge in wood-frame construction, repeating every 16 inches across every exterior wall. Steel studs are significantly worse than wood, conducting heat roughly 400 times faster. This is the bridge a double stud wall is specifically designed to break
• Window and door frames: wood or metal framing around openings creates bridges at every perimeter, often compounded by poor installation details
• Rim joists: the horizontal framing at the top of the foundation wall is one of the most common and most overlooked heat loss points in residential buildings
• Roof rafters and ceiling joists: framing in cathedral ceilings and flat roofs creates the same bridging effect as wall studs, but with higher stakes since heat rises
• Slab edges: an uninsulated concrete slab extends to the exterior perimeter, creating a direct conductive path between the cold ground and the interior floor
• Corners and junctions: where walls meet floors, ceilings, or other walls, the geometry creates more exterior surface area than interior, drawing heat out faster
• Metal connectors and fasteners: structural ties, hurricane clips, and screws that penetrate the insulation layer each create a small but real bridge

In a standard home, all of these weak points add up. The rated insulation value tells you how the insulation performs in isolation. It does not tell you how the whole assembly performs once every bridge is accounted for. That real-world number is always meaningfully lower.

The Impact of Thermal Bridging on Home Performance

Most homeowners think about insulation in terms of energy bills. Thermal bridging absolutely affects those, but the consequences reach further than monthly costs.

• Higher energy bills: your heating system has to work harder to compensate for the heat leaking through every bridge. In a poorly detailed house, thermal bridges can account for up to 30% of total heat loss
• Cold spots and discomfort: walls and floors near thermal bridges feel noticeably colder than surrounding surfaces. For anyone spending long hours at home, this is felt as persistent, hard-to-fix discomfort regardless of how high the thermostat is set
• Condensation and mould risk: the cold surface of a thermal bridge causes warm indoor air to condense when it makes contact. Over time this repeated cycle of wetting leads to mould growth, peeling paint, and in serious cases, structural deterioration inside the wall
• Reduced real-world insulation performance: a wall rated R-19 may perform closer to R-11 once all the framing bridges are accounted for. The gap between the label and the actual performance is almost entirely explained by thermal bridging

Addressing thermal bridges is therefore not just about efficiency. It is about comfort, air quality, and the long-term health of the building.

How to Eliminate Thermal Bridging in Your Home

Thermal bridging is a design problem, and the earlier it is addressed, the less it costs to solve. The goal is simple: keep the insulation layer continuous so heat has no easy path through the envelope.

For New Construction

Continuous exterior insulation is the most effective starting point. A rigid foam layer installed over the wall sheathing covers every stud and junction without interruption, doing what cavity insulation alone cannot. Combined with foam-wrapped foundations and raised heel trusses at the roof, the entire building is sealed in one unbroken thermal blanket.

Advanced framing reduces the number of framing members in the wall, leaving more cavity space for insulation and fewer bridges in the structure. And careful junction detailing at every transition — where walls meet floors, roofs, and window frames — keeps the insulation layer connected at the points where it most commonly breaks down.

A double stud wall is the other proven route to the same result. Instead of adding rigid foam outside the sheathing, it splits the wall into two separate stud rows with a deep insulated cavity between them, so no framing member ever runs continuously from the warm side to the cold side. It is a common choice in Climate Zones 5 to 7 and can reach whole-wall values around R-44. Our Passive Home Guide: Double Stud Wall covers the assembly in detail, including insulation options, acoustic benefits, moisture considerations, and how the cost compares to a standard wall.

For Existing Homes

A retrofit layer of exterior insulation is the most comprehensive fix, covering many bridges in a single move. Where full exterior insulation is not practical, targeted interior insulation at specific problem areas, rim joists, window reveals, and exposed structural elements, can make a meaningful difference. Moisture management becomes more critical with interior approaches, so proper detailing matters.

For existing homes, a thermal camera in winter is the most direct way to find bridges. Studs show as warm stripes on the exterior, rim joists glow as bright heat loss zones, and window perimeters reveal poor installation. Knowing where the bridges are is the first step to fixing them.

Cedar Residence: Eliminating Thermal Bridging in a High-Performance Maine Home

Cedar Residence is a custom home we designed in Monroe, Maine for Mike and Susan, a retired couple building their forever home in Climate Zone 6. For retirees spending most of their time at home, cold walls near windows are not a background inconvenience. They are a daily lived experience. Eliminating thermal bridges was as much a comfort decision as an energy efficiency one.

Walls: EPS Nailing Panel

The exterior walls are wrapped in three inches of EPS rigid foam using a Nailing Panel: EPS foam with an OSB face bonded to the exterior. The EPS covers every stud continuously. The OSB gives the cedar shingle cladding a solid nailing surface. Combined with cavity insulation inside the wall, the assembly performs at more than twice the level of a standard Maine home.

Foundation: Foam-Wrapped Perimeter

The foundation is wrapped in four inches of foam on the exterior, continuing the insulation from the wall down to the footing. This eliminates the rim joist and slab edge bridges that are among the most common and most overlooked heat loss points in any home.

Roof: Raised Heel Trusses

Raised heel trusses allow insulation to run full depth all the way to the exterior wall plate. In standard construction, insulation gets compressed thin at the eave, creating a cold spot at the ceiling perimeter. The raised heel eliminates that, keeping the thermal blanket unbroken from foundation to roof ridge.

What This Means for Your Project

The details at Cedar Residence were designed for a high-performance new build in a cold climate. But the underlying decisions translate to any project. Here is how to think about each scenario:

• Building new with a concrete slab: specify continuous exterior insulation from the start. The cost is far lower during construction than as a retrofit, and the performance difference is significant for the life of the building.
• Building new in timber frame: combine exterior insulation with advanced framing to reduce the number of bridges in the structure and maximize cavity insulation depth. If you would rather keep all the insulation inside the sheathing, compare it against a double stud wall.
• New construction at the roof: raise the heel trusses. It costs very little at the build stage and eliminates a cold spot that appears in almost every standard home.
• Renovating an existing home: exterior insulation is the most comprehensive retrofit. For targeted spots like rim joists and window reveals, interior insulation works well when moisture is properly managed.
• Not sure where to start: hire a thermal imaging inspection in winter. It will show exactly where your heat is going and which bridges are most worth addressing.

For any project, the conversation starts with the wall assembly. If the insulation only sits between the studs, thermal bridging is present regardless of the R-value on the label.

References

• Passive House School. The Science Behind Thermal Bridges. passivehouseschool.com
• Green Building Advisor. Thermal Bridging: How It Works. greenbuildingadvisor.com
• Luths Services. What Is Thermal Bridging & How to Fix It. luths-services.com

Explore the Full Building Science Series

Thermal bridging is one of several building science principles we addressed at Cedar Residence. Keep reading:

• What is Passive Solar Design — why your home's orientation may matter more than its square footage
• Thermal Mass and Radiant Floors — how to turn your floor into a heat battery
• Passive Home Guide: Double Stud Wall — how a two-row wall assembly stops thermal bridging without exterior foam
• Cedar Residence Project Story — the full build in Monroe, Maine

We also offer a double height wall design house plan — Supergreen House.