Newspaper is a surprisingly effective insulator for a material most people throw in the recycling bin. Its cellulose fibers and the air pockets trapped between crumpled or layered sheets resist heat transfer well enough that recycled newspaper is the primary ingredient in commercial cellulose insulation, one of the most widely used building insulation products in North America. But “good” depends on context, and raw newspaper has real limitations involving moisture, fire risk, and durability that separate it from purpose-built insulation.
Why Newspaper Resists Heat Transfer
The insulating ability of any material comes down to how well it slows the movement of heat. Metals conduct heat quickly because their molecular structure passes energy along efficiently. Newspaper does the opposite. Its cellulose fibers are poor conductors on their own, and when you crumple or layer sheets, you create countless small air pockets. Still air is one of the best insulators available, and newspaper’s structure traps a lot of it. The combination of low-conductivity fibers and trapped air gives newspaper a thermal conductivity in the rough range of 0.05 to 0.07 W/m·K when loosely arranged, which is not far from some commercial insulation materials.
Research on particle board made from waste newspaper found thermal conductivity values as low as 0.066 W/m·K at a thickness of about one centimeter, placing it comfortably within the range that qualifies a material for use as heat insulation.1JNSMR Walisongo. Effect of Thickness on Thermal Conductivity Based on Waste Newspaper Particle Board For comparison, standard fiberglass batt insulation typically falls around 0.035 to 0.045 W/m·K, and rigid foam boards can go even lower. So newspaper is in the same neighborhood as fiberglass, though not quite as effective per unit of thickness.
How It Stacks Up Against Purpose-Built Insulation
When you compare raw newspaper to commercial insulation products, the gap is narrower than you might expect on pure thermal performance, but it widens quickly on every other metric. Fiberglass, mineral wool, and foam boards are engineered to maintain a consistent density and structure over decades. They resist moisture, fire, and compression by design. A stack of newspapers stuffed into a wall cavity can match some of their insulating power initially, but it lacks the treatments and structural integrity that make commercial products reliable over time.
The more interesting comparison is between newspaper and its own commercial descendant: cellulose insulation. Cellulose insulation is roughly 80 to 85 percent recycled paper, most of it newspaper, ground into loose fibers and treated with fire retardants and antifungal agents like borate compounds. In performance testing, cellulose fiber insulation achieved over 82 percent heat loss reduction in horizontal applications, falling only about two percent short of the analytical optimum for its thickness.2Energy Reports. Performance evaluation of cellulose fiber’s effectiveness as a thermal insulation material for productive biogas systems That is a strong result, and it shows what newspaper fibers can do when properly processed and installed.
The takeaway is that newspaper’s raw insulating properties are genuinely good. The problem is that raw newspaper lacks the engineering that makes those properties stable, safe, and durable in a real building envelope.
Moisture Is the Biggest Problem
This is where newspaper’s reputation as an insulator runs into trouble. Paper absorbs water readily. When it does, the air pockets that give it insulating power collapse, the fibers mat together, and thermal performance drops sharply. Wet newspaper conducts heat far more efficiently than dry newspaper. Even in the absence of a leak, normal fluctuations in indoor humidity can cause paper-based insulation to absorb and release moisture over time.
Research on cellulose-based thermal insulation materials found that while these materials can regulate indoor humidity to some degree by absorbing and releasing moisture, they do not fully release all the water they take in under low-humidity conditions. A residual amount of moisture stays trapped in the material, and under the wrong conditions, that retained moisture can promote mold growth.3PubMed Central. Research on Thermal Insulation Performance and Impact on Indoor Air Quality of Cellulose-Based Thermal Insulation Materials This is a concern even for commercially manufactured cellulose insulation, and it applies much more acutely to untreated newspaper, which has no chemical protection against fungal colonization.
If you are using newspaper as a temporary insulating layer, say in a camping situation or a cold-weather emergency, moisture is less of an issue because the exposure period is short. But in any long-term application, such as stuffing newspaper into wall cavities or using it as attic insulation, moisture damage is almost inevitable without a proper vapor barrier and ventilation strategy.
Mold and Fungal Growth
Mold risk follows directly from the moisture problem, but it deserves its own attention because the consequences go beyond reduced insulating performance. Untreated paper in a warm, humid environment is an open invitation for fungal species. The cellulose in newspaper is organic material, and fungi break down organic material. In a wall cavity or attic space with any moisture intrusion, raw newspaper can become a fungal breeding ground within weeks.
Commercial cellulose insulation addresses this with borate treatments. Studies on cellulose insulation treated with sodium polyborate found that the treatment effectively prevented the growth of five common fungal species and appeared to have a sporocidal effect, meaning it killed spores rather than merely slowing their growth. The treated material resisted fungal colonization for at least 124 days even under high temperature and humidity conditions.4PubMed. Assessment of fungal growth on sodium polyborate-treated cellulose insulation Untreated newspaper has none of this protection. If you are considering using raw newspaper in any enclosed space, especially one that could get damp, mold is a serious and likely outcome.
Fire Safety
Paper burns. This is obvious, but it is worth spelling out what it means for insulation. Raw newspaper is highly flammable. Stuffing it into wall cavities, around electrical wiring, or near heat sources like furnaces and chimneys creates a genuine fire hazard. Building codes in most jurisdictions prohibit the use of untreated paper products as building insulation for exactly this reason.
Commercial cellulose insulation gets around this through the same borate treatment that fights mold. Borates are effective fire retardants, and properly treated cellulose insulation meets fire safety standards for residential and commercial buildings. But the key word is “properly treated.” There is no safe shortcut to achieving fire resistance with raw newspaper. Spraying it with water, compressing it, or mixing it with other materials does not reliably bring it up to a safe standard. If you are insulating a structure where fire codes apply, raw newspaper is not an option.
For temporary, non-structural uses like insulating a cooler for a picnic, wrapping pipes for a single winter, or adding a layer inside a sleeping bag during an emergency, fire risk is lower simply because the exposure to ignition sources is limited. But even in these cases, keeping newspaper away from open flames, heaters, and stoves is important.
Settling and Long-Term Durability
Even if you could solve the moisture and fire problems, raw newspaper has a durability issue. Loose cellulose fibers, whether from shredded newspaper or commercial insulation, settle over time under their own weight. This settling reduces the thickness of the insulating layer, and thinner insulation means less thermal resistance. The effect is more pronounced in vertical applications like wall cavities than in horizontal ones like attic floors, because gravity pulls the fibers downward and opens gaps at the top.
In commercial cellulose insulation, manufacturers account for this by specifying two different density figures: the “blown” density at installation and the “design” density that accounts for expected settling over time. The design density is determined through impact testing and cyclic humidity testing to simulate years of real-world conditions.5Building and Environment. A review on the properties of cellulose fibre insulation Installers blow in extra material to compensate for the settling that will inevitably occur. With raw newspaper, there is no engineering to account for this. Crumpled newspaper in a wall cavity will compress and shift over months and years, creating cold spots and dramatically reducing its insulating effectiveness.
This settling issue is one of the less obvious reasons why raw newspaper is a poor long-term insulation choice even when the thermal conductivity numbers look promising in a lab setting. Lab measurements capture a snapshot of performance at a specific density and moisture content. Real-world performance degrades.
Newspaper as a Recycled Insulation Feedstock
The most practical and widely adopted use of newspaper’s insulating properties is not stuffing whole sheets into walls. It is grinding them up, treating them, and blowing them in as cellulose insulation. This product has been commercially available since the 1950s, and it represents one of the more successful examples of waste-stream recycling in the construction industry.
Researchers have also explored more structured approaches. One study manufactured insulation panels from several types of recycled paper waste, including newspaper, white printing paper, corrugated board, and egg carton cardboard. The manufacturing process involved crushing the materials, mixing them with water at a roughly 40/60 ratio of recycled material to water, forming them in wooden frames with a filtration system, and drying them over about a week.6Cleaner Engineering and Technology. Design and manufacture of insulation panels based on recycled lignocellulosic waste This kind of panel approach attempts to give recycled newspaper the structural integrity it lacks in its raw form, making it more suitable for building applications.
The environmental appeal is significant. Manufacturing cellulose insulation from recycled newspaper requires far less energy than producing fiberglass or foam insulation from raw materials. The carbon footprint is lower, the raw material is abundant and cheap, and the process diverts waste from landfills. For people who care about the sustainability of their building materials, cellulose insulation made from newspaper is one of the more environmentally friendly options on the market.
Does Newspaper Block Sound Too?
Insulation is not only about heat. Many people also want to know whether newspaper can dampen sound. The answer is yes, to a degree, but acoustic insulation is more complex than thermal insulation, and performance varies wildly depending on how the material is configured.
A study of thirteen commercially available insulation products found that acoustic performance differed enormously between insulator types. For a 100-millimeter-thick layer, sound reduction ranged from 10 to 27 decibels for bare insulation, and from 33 to 52 decibels when the insulator was sandwiched between two boards. Sound absorption coefficients ranged from 0.20 to 0.78, and airflow resistivity spanned from 3.0 to 2,700 kPa·s/m².7Journal of Building Engineering. Acoustic properties of commercially available thermal insulators − An experimental study Those are massive ranges, and where a particular cellulose product falls within them depends on its density, fiber structure, and installation method.
Loose cellulose insulation made from newspaper tends to perform reasonably well on sound absorption because its fibrous structure disrupts sound waves. It is not a substitute for dedicated acoustic treatments in recording studios or concert halls, but for reducing noise transfer between rooms or dampening street noise, it is a credible option. Raw newspaper crumpled into a cavity would offer some acoustic benefit, but again, the lack of controlled density means the performance would be inconsistent and hard to predict.
Indoor Air Quality Considerations
One concern that does not get as much attention is what paper-based insulation does to the air inside a building. As buildings have become more tightly sealed for energy efficiency, indoor air quality has become a bigger issue. Reduced ventilation means that any pollutants released by building materials accumulate more readily. Research has flagged that volatile organic compounds with boiling points between 60 and 280 degrees Celsius contribute to indoor air contamination and can, at certain concentrations, cause building-related illnesses.8Academic Journal of Civil Engineering. Properties of bio-based insulation materials and their potential impact on indoor air quality
Newspaper contains printing inks, and some of those inks contain volatile organic compounds. In a well-ventilated attic or exterior wall cavity, this is unlikely to cause problems because the compounds disperse. In a tightly sealed interior space, especially one with poor ventilation, the picture could be different. Commercial cellulose insulation manufacturers generally test their products for off-gassing, and the borate treatment process can alter the chemical profile of the material. Raw newspaper has undergone no such testing or treatment, so the air quality implications are less predictable.
This is not a reason to panic about using a few sheets of newspaper to wrap a pipe or line a box. It is a reason to think carefully before filling an enclosed living space with large quantities of untreated newspaper and expecting it to behave like a tested, certified insulation product.
Practical Situations Where Newspaper Works Well
Despite all the caveats, there are situations where newspaper is a perfectly sensible insulating choice. The common thread is that these are temporary, low-stakes, or easily replaceable applications.
- Emergency warmth: Stuffing crumpled newspaper between layers of clothing or inside a sleeping bag adds meaningful insulation in a pinch. The trapped air pockets work the same way they do in a wall cavity, and you only need the insulation to last hours or days, not years.
- Gardening: Layers of newspaper around plants or over soil act as mulch and insulation, protecting roots from frost. The newspaper eventually decomposes, which is actually a benefit in this context.
- Packing and shipping: Crumpled newspaper insulates fragile or temperature-sensitive items during shipping. It is cheap, widely available, and effective for the short duration of transit.
- Pipe wrapping: Wrapping exposed pipes with layers of newspaper can provide enough insulation to prevent freezing during a brief cold snap, though it is not a substitute for proper pipe insulation in consistently cold climates.
- Window drafts: Rolled newspaper pushed into gaps around poorly sealed windows can reduce drafts temporarily while you arrange a more permanent fix.
In all of these cases, the newspaper is disposable, the exposure to moisture is limited or irrelevant, fire risk is manageable, and long-term settling is not a concern. These are the conditions under which newspaper’s genuine insulating properties shine without being undermined by its weaknesses.
Why Thickness and Density Matter More Than You Might Think
One counterintuitive finding about newspaper insulation is that thicker is not always better. The particle board study mentioned earlier found that as the thickness of newspaper-based boards increased, thermal conductivity also increased, meaning thicker boards actually conducted more heat per unit thickness.1JNSMR Walisongo. Effect of Thickness on Thermal Conductivity Based on Waste Newspaper Particle Board This makes sense when you consider that adding more material also adds more solid fiber, which conducts heat better than the air it displaces. The best thermal performance came from thinner boards in the one-to-two-centimeter range, where the balance between trapped air and structural fiber was optimal.
For loose newspaper, density follows a similar logic. Very loosely crumpled newspaper has lots of air pockets but little structural support, so it settles quickly and unevenly. Very tightly packed newspaper has good structural stability but fewer air pockets, reducing its insulating power. There is a sweet spot in the middle. Commercial cellulose insulation installers aim for specific density targets that hit this balance, with different targets for horizontal and vertical applications.5Building and Environment. A review on the properties of cellulose fibre insulation If you are using raw newspaper, you do not have precise control over density, which means you are unlikely to hit the optimal insulating performance consistently.
Newspaper Versus Other Household Improvised Insulators
People who ask whether newspaper is a good insulator are often weighing it against other things they have lying around. Bubble wrap, cardboard, fabric scraps, and styrofoam packing peanuts all get pressed into service as makeshift insulation. Among these options, newspaper holds up well. Cardboard has similar cellulose-based insulating properties but is bulkier and harder to conform to irregular shapes. Bubble wrap traps air effectively but tears easily and offers no moisture absorption. Fabric scraps vary wildly depending on the material, and loose synthetic fibers can be a fire hazard of their own.
Newspaper’s advantages as an improvised insulator are its availability, its conformability to odd shapes, and its decent thermal performance per unit cost, which is essentially zero. Its disadvantages relative to other household materials are its vulnerability to moisture and its flammability. If you have access to aluminum foil, combining it with newspaper can improve performance significantly, because the foil reflects radiant heat while the newspaper resists conductive and convective heat transfer. This layered approach is more effective than either material alone.
For anyone moving beyond improvisation toward an actual building project, the leap from raw newspaper to commercial cellulose insulation is worth the investment. You get the same cellulose-fiber insulating mechanism, but with fire retardancy, fungal resistance, controlled density, and code compliance built in. The raw material is still largely newspaper; it has just been processed into something that performs reliably over decades rather than weeks.