What Is the Best Insulation for Your Home?

Installation installer

From battling sweltering summer heat to fending off frigid winter air, the right insulation materials can make all the difference, especially to your energy bills.

Insulation provides an extra barrier between the inside and outside to keep your home comfortable year round, but with countless options on the market, what is the best insulation for your home? We‘ve rounded up the best insulation options to help you decide which is most suitable.

Best Insulation for Your Home

Here are our top choices for home insulation that are worth considering:

Fibreglass Insulation

This popular insulation material consists of super-fine, intertwined glass fibres made from sand and recycled glass. Fibreglass insulation is often referred to by another name, glass wool, because of its puffy, wool-like texture. Some manufacturers use the term “glass mineral wool” because of the inclusion of minerals like silica, dolomite, or kaolin.

Fibreglass manufacturing is like making candy floss: molten glass is spun into thin webs using a high-speed rotor and air jets. A chemical binder, which may be dyed a particular colour, glues the fibres together into mats. The mats are then cured in an oven, cooled, and trimmed.

Pros:

  • Inexpensive and widely available
  • Odourless, lightweight, and easy to install
  • Durable (it doesn’t degrade during its lifetime)
  • Non-flammable
  • Sound-proof

Cons:

  • Holds water
  • Prone to sagging over time, reducing its effectiveness
  • May cause itchiness and skin irritation

When installing glass wool, you’ll need protective gear, including long-sleeved shirts, pants, safety goggles, and work gloves. You should also wear a dust or particulate mask to avoid inhaling fibreglass particles, especially when cutting.

How Does Fibreglass Insulation Work?

What makes fibreglass insulation effective are the tiny air pockets between the fibres. These pockets can trap hot and cold air as well as sound.

That said, make sure you don’t squish the fibreglass batts during or after installation. Glass wool must retain its full thickness for optimal heat resistance. Also, there should be no gaps between the batts to prevent air from seeping.

Types of Fibreglass Insulation

Fibreglass insulation comes in two forms:

Fibreglass Batts: Slabs vs. Rolls

Fibreglass insulation is available in woven, densely packed blankets called batts. You can buy them in slabs or rolls in various sizes and thicknesses.

Fibreglass slabs come as pre-cut panels that can easily fit between studs, rafters, trusses, or joists. You can cut them to size using a utility knife and straightedge to fill tight or tricky spaces.

Meanwhile, rolls are the same product but longer, which is why they’re packaged that way. Lengths typically range from five to 12 metres.

Many insulation rolls feature partial perforations to aid in cutting. Some fibreglass batts have kraft paper bonded to one face—or backing—to serve as a water vapour barrier.

Remember to choose batts that are the closest match to the depth of the studs and the width of the bays to minimise trimming.

Loose-Fill Fibreglass

Nothing goes to waste in fibreglass production. A cyclone collects the trimmed edges from the fibreglass mats and the dust from cutting and packaging them. Then, a hammer mill chops them down to produce loose glass fibres for blown-in applications.

Loose-fill fibreglass provides good coverage for odd and hard-to-reach spots. It can be applied in enclosed cavities or open areas. Unlike pre-cut fibreglass batts and rolls, it can easily conform to the contours of the space without disturbing finishes or structures.

Blown-in fibreglass requires an insulation blower to break down the clumps and disperse the loose fibres where needed.

Mineral Wool

Mineral wool, also known as rock wool, is an insulation material made from volcanic rocks such as basalt or diabase, along with recycled slag (byproduct of smelting ores).

Mineral wool is an excellent thermal insulator, preventing heat transfer between a building’s interior and exterior. 

The production of mineral wool is similar to that of fibreglass insulation. The raw materials are heated in a furnace to extreme temperatures until they become molten.

Afterwards, a spinner wheel breaks down the molten rock into fine threads, which are then sprayed with a thermal-setting binder to hold them together.  

Mineral wool is a natural fire-retardant, thanks to its high melting point. This quality makes it suitable for insulation around chimneys and fireplaces.

Pros:

  • Affordable and long-lasting
  • Incredibly energy-efficient
  • Resistant to rot, mould, mildew, and vermin
  • Not susceptible to settling or sagging
  • Outstanding fireproofing and sound-absorbing capabilities

Cons:

  • Can clump with chronic dampness, in the case of water leaks
  • May cause temporary itchiness during installation

Applications of Mineral Wool

There’s a rock wool product for almost every part of your house. Mineral wool works great for the following applications:

Like glass wool, rock wool comes in batts and rolls. However, it’s more rigid, so it’s easier to cut than glass wool. Due to this characteristic, you can find mineral wool products in all shapes, including:

  • Strips
  • Tubes (for pipework)
  • Tapered slabs (to create falls in flat or low-slope roofs)
  • Grooved slabs (for larger, cylindrical ductwork)
  • Angled filler slabs (for roof abutments)

Cellulose Fibre Insulation

Cellulose fibre is an insulation material derived from recycled paper or other plant-based sources. Because paper is inherently flammable, the fibres are treated with fire-retardant additives that can also resist mould and pests.

Unlike traditional batts, cellulose can reach every nook and cranny while maintaining airtightness. The fibres create a thick, dense layer that can fill all voids and form around ducts, pipes, outlets, and electrical conduits.

Cellulose is competitively priced but absorbs sound better than glass or mineral wool. Plus, it’s an inexpensive solution for fixing underinsulated homes. You don’t have to gut entire drywalls to add insulation.

Pros:

  • Affordable
  • Non-toxic
  • Sustainable and eco-friendly
  • Highly resistant to air leakage
  • Provides even and complete coverage, if done right

Cons:

  • Prone to settling with improper application
  • Not immune to water damage

Types of Cellulose Insulation

Cellulose fibre insulation involves either blowing dry material into cavities or applying it as a spray. The application depends on whether you’re insulating new construction or retrofitting existing structures.

Here are the types of cellulose insulation according to installation method:

Blown-In Cellulose

Dry-blown cellulose is perfect for insulating finished walls or open attics. For enclosed spaces, the insulation process involves drilling holes into the plaster or drywall to create access points for the blower nozzle.

The installer feeds heaps of cellulose into the blower’s bin, called the hopper. Inside the hopper, agitating rods churn and break down the fibres. The blower then propels the loose cellulose down the hose and into the walls to the point where it cannot inject any more material.

You can also overlay loose-fill fibre on existing insulation batts in attics by sweeping the blower hose back and forth as if watering a lawn.

Wet-Spray Cellulose

Loose-fill cellulose will settle due to gravity, so for open walls, wet application is the preferred method. Fibres are mixed with water and, at times, adhesive to make them stick.

Cellulose is sprayed using a high-pressure water hose fitted to the end of the blower hose. Excess cellulose is scraped from the overfilled wall up to the thickness of the frame using a scrubber and then vacuumed off.

Wet cellulose is less dusty, but that doesn’t make it any easier to install. Plus, it requires drying time to harden before closing off walls. Not to mention, the application of damp fibre can be quite a drag in freezing temperatures.

DIY-savvy homeowners can easily handle dry blown-in cellulose, but wet spraying is another matter. The latter is quite messy—imagine a blizzard of shredded newsprint—and requires finesse and expertise.

Since water is involved, it’s best to let professionals do the hard work unless you have experience with this installation method.

How Eco-Friendly Is Cellulose Fibre Insulation?

Cellulose fibre uses a substantial volume of recycled paper, diverting tons of waste from landfills and reducing the demand for virgin materials. Not only that, but it also degrades over time after disposal.

The production of cellulose fibre requires significantly less energy than other insulation materials.

Even better, cellulose achieves high energy savings upon installation, which is a top priority of the green building standard.

Spray Foam Insulation

    Spray foam insulation is a popular alternative to traditional insulating materials like rigid boards and flexible fibres. It’s applied as a liquid, which quickly expands and hardens into a durable foam.

    Spray foam bonds strongly with different materials like wood, plasterboard, cement, and steel. It features high insulation efficiency in any weather.

    Installation is a breeze; it requires zero measuring, cutting, or stapling. However, special equipment and complete PPE are necessary to apply spray foam.

    Pros:

    • Made to last
    • Effective air, sound, and moisture barrier
    • High thermal resistance
    • Seamless application

    Cons:

    • Expensive
    • Requires professional installation
    • Releases toxic fumes during installation

    Types of Spray Foam Insulation

    There are two main types of spray foam insulation:

    Open-Cell Spray Foam

    This type of foam is less dense and has a spongy texture. It has a lower R-value (a measure of thermal resistance) compared to closed-cell foam but is also less expensive.

    Open-cell spray foam is commonly used in interior applications like walls and ceilings.

    Closed-Cell Spray Foam

    Closed-cell foam is denser and has a higher R-value, making it more effective at insulating. It also provides a moisture barrier and adds structural integrity to the building.

    Due to its properties, closed-cell foam is ideal for areas that require higher insulation values or where moisture resistance is crucial, such as basements and crawl spaces.

    Rigid Insulation Boards

    Rigid insulation boards are solid panels of foam with varying dimensions and thicknesses. They can provide continuous insulation—or sheathing—on exterior walls before the installation of house wrap and siding.

    Rigid foam boards don’t shift in place once installed and can withstand moisture without cracking, splitting, or rotting. They outperform other materials for basement insulation and stand out for application in spaces that touch masonry.

    Pros:

    • DIY-friendly
    • Inexpensive
    • Lightweight
    • Superior moisture resistance

    Cons:

    • Not flexible
    • Poor adhesion to uneven walls

    Types of Rigid Insulation Boards

    Rigid insulation boards are made from various synthetic materials, including:

    Expanded Polystyrene (EPS)

    EPS insulation boards are lightweight and affordable. They come in different densities and thicknesses and are often used for both walls and roofs. 

    Extruded Polystyrene (XPS)

    XPS insulation boards are denser and more moisture-resistant than EPS. They’re fantastic for flat roof and underfloor applications.

    Polyurethane (PUR) and Polyisocyanurate (PIR)

    These insulation boards offer excellent thermal performance with a high R-value per inch of thickness. PIR is an upgraded version of PUR, offering even better insulation properties.

    Phenolic Foam

    Despite their slimmer profile, phenolic foam insulation boards offer efficient thermal performance. The only downside is that it’s the priciest product among the bunch.

    Frequently Asked Questions

    What Is the Most Budget-Friendly Insulation for Your Home?

    Fibreglass insulation is easiest on the pocket and offers the best value for money. On average, the price of a 300-mm thick fibreglass blanket is £8 per square meter. Mineral wool is a close second, costing around £10 per square meter.

    What Is the Most Eco-Friendly Insulation for Your Home?

    Cellulose fibre insulation scores plenty of green points as home insulation. It uses up to 85% of post-consumer waste paper, the most recycled content in the insulation field.

    Instead of ending up in landfills and emitting carbon in the atmosphere, discarded newsprint, cardboard, and office paper find a new purpose as insulation.

    Moreover, the energy demand for producing cellulose is a mere fraction when compared to foam, fibreglass, or mineral wool insulation. 

    What Is the Best Insulation for Soundproofing Your Home?

    Thermal insulation isn’t a direct replacement for soundproofing. That said, there are a few insulation materials that offer acoustic insulation.

    Mineral wool is a standout choice, thanks to its greater density. It has an STC (Sound Transmission Class) rating between 45 and 52.

    STC measures how well a building partition can block out noise. So, if mineral wool has an STC rating of 52, it means that it can reduce the volume of sound by 50 decibels as it travels through the wall.

    What Is the Best Insulation Against Pests?

    Cellulose insulation can keep away pesky critters like ants, termites, and cockroaches.

    Boric acid that’s added to the cellulose fibre to make it fire-resistant is also an effective insecticide. It can slowly poison insects by contact and ingestion.

    Insects exposed to boric acid may carry the substance back to their nests, causing trouble to their colony.

    What Is the Best Insulation Against Fires?

    Mineral wool has an extremely high melting point, above 1,300 °C, which makes it the best insulation for fire-proofing.

    It’s non-combustible, which means it doesn’t ignite or burn when exposed to flames or high temperatures. It doesn’t provide a fuel source for fires, making it an effective barrier against the spread of flames.

    What Is the Best Insulation for Warm Climates?

    In warm climates, the primary goal of insulation is to reduce heat gain rather than heat loss.

    Reflective or aluminium-faced insulation can reflect radiant heat away from your home and keep indoor spaces cooler. It can also prevent condensation buildup during humid days.

    What Is the Best Insulation for Cold Climates?

    Houses in cold regions can benefit from thick, fluffy insulation materials like glass or rock wool batts and cellulose insulation.

    To make things even better, you can add barriers that stop cold air and moisture from getting in. Lastly, seal up any gaps where the heat might escape.

    Doing all this helps your insulation perform better and keeps your home cosy and energy-efficient.

    What Is the Best Insulation for Solid Walls?

    The best way to insulate a solid wall is to fit rigid insulation boards to the interior wall surface. Typically, this method proves more cost-effective than external wall insulation.

    You can move from room to room to minimise disruption. On the downside, it can slightly chip away several inches of your usable space.

    Is Denim Insulation Any Good?

    Yes, denim insulation, often made from recycled jeans, can be effective as an insulation material for homes. It has good thermal and acoustic insulating properties, meaning it can help regulate indoor temperatures and reduce noise transmission.

    Additionally, it’s considered more environmentally friendly compared to traditional insulation materials like fibreglass, as it repurposes old denim that might otherwise go to waste.

    However, it has some drawbacks. Denim insulation is more expensive than traditional fibreglass insulation, making it less attractive to homeowners on a tight budget. It requires a vapour barrier to prevent moisture from penetrating and affecting its performance.

    Best Insulation Conclusions

    So, what is the best insulation for your home? Choosing the best insulation for your home requires thoughtful consideration, as each material presents its own distinct hits and misses.

    Fibreglass insulation, while cost-effective, might not be as eco-friendly as cellulose fibre. While cellulose insulation excels in fire resistance and soundproofing, its installation can be more intricate. Meanwhile, spray foam insulation boasts exceptional sealing properties but at a higher cost.

    Ultimately, the ideal choice relies on a balance between factors such as budget, environmental concerns, availability, and ease of installation. Before making a decision, consult an insulation professional to determine what will work best for your needs. 

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