Insulation types explained: batts, blanket and board
What R-value really means and where each type of insulation goes in a new home, so you can read your spec and check it adds up.
Insulation is the quiet workhorse behind a comfortable, efficient home, and it is doing most of the job of hitting your 7-star rating. The spec sheet throws around terms like batts, blanket and R-values, which can feel like a foreign language. Here is what they mean and where each type belongs, for homes across SA and Victoria.
What R-value means
R-value measures how well a material resists heat flow. The higher the number, the better it insulates. Your climate zone sets minimum R-values for the roof, walls and sometimes the floor, and your NatHERS assessment works out the mix that gets the home to 7 stars. More is not always better in every spot, the goal is the right R-value in the right place.
Where each type goes
Bulk batts do the heavy lifting in framed walls and ceilings. A roof blanket sits under the roof sheets to knock back radiant heat and, on a metal roof, to soften rain noise. Rigid board turns up in specific spots like slab edges or where space is tight and you need high performance in a thin layer.
Why installation is everything
The best insulation in the world does nothing if it is installed badly. Gaps, gaps around downlights, and batts that are squashed into place all cut the real-world performance well below the rating on the label. It is worth asking who installs it and whether the ceiling is checked after the trades have been through, because this is where a lot of homes quietly lose comfort.
Bulk batts (walls and ceilings)
- The workhorse for walls and ceilings
- Comes in a range of R-values to suit the zone
- Easy to install in framed walls
- Good value for the performance
- Only works if installed with no gaps or compression
- Does not stop air leaks on its own
Roof blanket (under the roof)
- Sits under the roof sheets to cut radiant heat
- Helps with rain noise on metal roofs
- Works alongside ceiling batts
- Not a substitute for ceiling insulation
- Needs the right facing for the job
Rigid board (slabs, special spots)
- High performance in a thin profile
- Used at slab edges and tricky details
- Rigid and moisture resistant
- Used selectively, not everywhere
- A more specialised product
Insulation is not the place to cut corners, because it is doing most of the work on comfort and your energy rating for the life of the home. Get the R-values your NatHERS assessment calls for, make sure the ceiling and walls are installed with no gaps or compression, and treat a quick post-install check as time well spent.
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Match me with 3 buildersCommon questions
What does R-value mean in insulation?
R-value measures how well a material resists heat flow. A higher number insulates better. Your climate zone sets minimum R-values and your NatHERS assessment works out the right mix for the roof, walls and floor to reach 7 stars.
What is the difference between batts and a roof blanket?
Bulk batts go in framed walls and ceilings to resist heat flow. A roof blanket sits directly under the roof sheets to cut radiant heat and, on metal roofs, soften rain noise. They do different jobs and often work together.
Is more insulation always better?
Not necessarily. The aim is the right R-value in the right place, as worked out by your NatHERS assessment. Beyond a point, extra insulation in one spot adds little while good installation and sealing air gaps matter more.
Why does insulation installation matter so much?
Gaps, compression and missing insulation around downlights can drop real performance well below the label rating. A careful install, and a check of the ceiling after the trades finish, is one of the best ways to protect your comfort and energy rating.