R19 is the better insulation in terms of thermal performance because it has a higher R-value, which measures resistance to heat flow. However, the "better" choice for your project depends entirely on the depth of your wall or floor cavity, as R19 is much thicker than R13.
The higher the R-value, the better the insulation performs. Think of it like SPF in sunscreen: R13 provides decent protection, while R19 offers more heavy-duty protection.
It is a common measure adopted by manufacturers, retailers, and even some contractors to ascertain the performance of insulation. Although R-value is important, it will not help you save on your power bills. The fact is, the energy efficiency of your home does not just rely on a number.
Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.
R19 insulation is a thicker, more robust option—offering higher thermal resistance. Commonly used in colder climates, R19 is well-suited for 2x6 wall assemblies, floors, ceilings, and attics. Benefits: Provides superior thermal protection, contributing to lower energy bills and enhanced comfort in colder regions.
R13 Insulation is a cost-effective solution widely used in warmer climates and provides adequate insulation for interior walls, basement walls, and floors, especially where temperature fluctuations are moderate.
Overall, fibreglass insulation is the cheapest and most effective insulation option available, making it a popular choice for homeowners and builders alike.
It's recommended to leave an air gap insulation of at least 25mm or 1 inch for the walls and ceilings. This should be enough to allow for ventilation and prevent moisture buildup. The same rule may be applied when using foil insulation. On roofs, the air gap should be larger, typically around 50mm or 2 inches.
Mice are curious and always searching for safe, snug, and warm nesting sites. Attics filled with blown-in insulation provide an excellent option–from the mice's point of view. As long as there is a ready food source. Mice are omnivorous and will eat and chew on almost anything including wood and electrical wires.
What time of year is Insulation cheapest?
The 2025 Insulation Tax Credit covers 30% of eligible expenses, capped at $1,200, for home improvements that meet federal energy standards. The Inflation Reduction Act allows credits through 2032, supporting long-term savings for energy-efficient upgrades like insulation, heat pumps, and solar panels.
Because spray foam can trap moisture, hide the condition of the roof, make it difficult for surveyors to inspect, which means risks like timber decay, dry rot, and not forgetting increased fire risk. If you've got it or you're buying a property that does, this is something you need to know upfront.
Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces. Use the JM insulation calculator to determine the recommended R-value for your project, as well as how much insulation you'll need.
R-values rate how well building insulation can prevent the flow of heat into and out of the home. Higher ratings mean greater insulation performance and thus more savings on your next heating and cooling bill.
Rigid Foam Boards (Polyiso, XPS): Excellent for energy efficiency, with R-values of ~R-5.0 to R-6.5 per inch. Best for basements, exterior walls, and roofs. Stone Wool (Rockwool): Fire-resistant and soundproof, with an R-value of ~R-4.0 per inch, making it great for soundproofing and safety.
Foam insulation is a common target because it's easy for them to chew through. The material offers little resistance, allowing mice to create tunnels or nests within the insulation. But mice aren't just interested in chewing for the sake of it—they're also drawn to the warmth and shelter insulation provides.
Cost and Considerations
Attic insulation installation ranges from $1.50 sq/ft. to $2.45 sq/ft. The average cost of attic insulation installation is $1.80 sq/ft.
Foam Board or Rigid Foam
Foam boards -- rigid panels of insulation -- can be used to insulate almost any part of your home, from the roof down to the foundation. They are very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches.
Natural Smells the Amish Use to Repel Mice
Traditional methods often include using natural deterrents like peppermint, pine, or other strong plant-based smells. Whether it's growing plants near entry points or using oils indoors, these scents can interfere with how mice navigate and make the space less appealing.
Potential problems with spray foam insulation
reduce air circulation and ventilation within a roof space. lead to dampness and condensation on the underside of a roof because it forms an air barrier and stops moisture from escaping. place timber-framed roofs at risk of decay.
Closed-cell spray foam and rigid foam board are hard, unattractive to rodents, and double as air barriers. Mineral wool is dense enough to discourage nesting. Fiberglass batts, especially in crawl spaces and attics, are essentially an open invitation.
Unfaced insulation is great for new construction, remodels, walls, floors, ceilings, basements, attics and crawlspaces. It's best used for interior wall applications that do not face the outside and also in rooms that don't need moisture control, like living rooms, dining rooms and studies.
Don't Install Loft Boards Directly on Joists
This can compress the insulation and create stress on the plasterboard below. Raised Boards Are Best: Installing loft boards on raised supports or Loft Legs ensures that the insulation is left undisturbed, allowing it to work at its optimal level.
10 Insulation Installation Mistakes to Avoid