You can specify the right insulation product, at the right R-value, and still not get the performance in your home you were expecting.

Because how insulation gets installed matters just as much as what you chose.

In this episode, I share what to specify, what to ask your team, and what to check during construction, so your insulation delivers what you’re paying for.

Listen to the episode now.

Hello! This is Episode 424, and Way #24 of the 44 Ways to Create Your Sustainable Home series. We’re continuing with Section Five: The Building Envelope.

In the last episode, we went through the types of insulation, what R-values mean, and how to think about products for your ceiling, walls, and floor. 

This episode is the follow-up: what happens when the product is specified, the quote is signed, and the installer shows up. Because that’s where a lot of the thermal performance of a home is either delivered or lost.

Way #24 is: Install Insulation Correctly.

Did you know that a 5% gap in your insulation coverage can reduce its effectiveness by up to 50%? 

So, you can invest money in specifying the right product, achieving the right R-value, choosing the right type for your climate, and testing it through modelling. And all of that work can be significantly undermined by how the product is installed. 

And unfortunately, once the building is lined, any rectification becomes more challenging.

Insulation is a building product where the rated performance on the data sheet and the actual in-wall performance can differ significantly, purely because of what happens during installation. For example, an insulation batt that’s the right R-value for your climate, however gets installed with a gap, compressed into a space, or disturbed by another trade after the fact, will not be delivering what you paid for.

The point of insulation is that it creates a continuous thermal envelope that buffers heat loss in winter, and heat gain in summer, helping you maintain stable indoor air temperatures. But the moment there’s a hole or gap in that continuous insulative layer, the performance of it as a whole is undermined.

The challenge is that, during construction, you can have lots of different trades working in a home after the insulation is installed, and needing to move it around or put services through it, and potentially disrupting its continuity as a result. 

You can also have contractors who haven’t upskilled in the installation requirements, or even read the manufacturer’s specifications, and they’ll haphazardly install it, or jam it into spaces rather than cutting it neatly and snugly to size.

Insulating your ceiling…

Gaps typically form around penetrations: recessed downlights, exhaust fans, pipes, ceiling roses, and any other service that breaks the plane of the ceiling. These are predictable locations, and they can be addressed at design and specification stage.

Recessed downlights can be a common cause of ceiling insulation gaps. If using recessed downlights and wanting to run insulation over the top of them, you’ll need to specify insulation-contact-rated fittings (also called IC-rated or IC-F rated in Australian standards), which are thermally safe for insulation to be placed over them directly, and won’t create a fire hazard. 

One of the really common occurrences is that the electrician gets up in the ceiling space to finalise the connection of light fixtures after the insulation is installed. In working in that space, the electrician lifts insulation batts out of the way, and forgets to return them to their original placement after they’ve completed their work, leaving a great big gap in the insulative layer. 

A proactive builder and electrician will manage this as part of their quality control during construction, but it’s always worth checking and discussing during your site meetings with your builder, and we’ll talk more later in this ‘44 Ways’ series about the construction check you can include to catch an issue like this before the builder finishes your project.

Insulating your walls…

When it comes to the wall framing and installing insulation, there are specific measures in the way the frame is set up that can assist with the installation of a continuous insulation layer, specifically if you’re using timber framing.

The first option many builders in the high performance space are adopting is using 140mm studs on their external walls instead of the standard 90mm. 

The second is the California corner. A California corner uses a different arrangement of studs, allowing insulation to be tucked into the corner cavity, to ensure continuity of that thermal envelope.

The third is a staggered stud frame. The insulation can be installed in a more continuous way through this wall, and this stud arrangement can also assist with improving acoustic isolation between spaces either side of the wall as there’s reduced structure-borne sound transmission in this stud arrangement.

Lastly, many high performance builders are now also including a battened cavity on the interior face of the stud frame, so the zone for plumbing and cabling occurs within that cavity, and not through the insulative layer. 

The insulation product itself will usually dictate how it needs to be installed…

The various insulation products available have varying installation requirements. Some products will require installers to wear protective gear when installing it. Many types can produce fine dust and particles when being worked with and cut, and some products have high volatile organic compounds or VOCs, or are irritating to skin and eyes. 

If you’re DIYing any insulation installation, ensure you read all instructions and warnings provided by the manufacturer. Equally, be aware your builder should be managing the safe installation on site according to the manufacturer’s instructions.

Certification and compliance requirements…

In various locations, including Australia, there are increasing requirements for installers of insulation to be certified. So, check the regulations where you live to see what’s required. It is being rolled out in more locations, and also the requirement for the installer to provide a certificate after installation.

In this Episode, I cover:

• Why installation is where insulation performance is delivered, and may undermine what you’ve invested in
• Where gaps in insulation coverage most commonly form, and how to design them out at specification stage
• Why recessed downlights are one of the most common sources of ceiling insulation gaps, and what IC-rated fittings do
• How to think about insulation and wiring together, and why sequencing the insulation installer and electrician matters
• What thermal bridging actually is, and why steel framing is a bigger concern than timber
• Three framing strategies that reduce thermal bridging: 140mm studs, California corners, and staggered stud frames
• Why Anticon can underperform under compression, and how batten spacing and roof ventilation affect what you actually get
• The trades sequencing problem after insulation is installed, and how site supervisor photos before ceiling lining protect you
• The questions to ask your architect, designer and builder before the contract is signed

Plus a whole lot more.

LISTEN TO THE EPISODE NOW.

RESOURCES:

Episode 415 >>> 44 Ways #15: Use Energy Modelling During the Design Phase

Episode 417 >>> 44 Ways #17: Get a WUFI Analysis Done on Your Floors, Walls and Roof

Episode 422 >>> 44 Ways #22: Review Building Wraps to Manage Moisture for Climate

Episode 423 >>> 44 Ways #23: Choose Appropriate Insulation

Australian Government’s guide to installation, R-values, and insulation products >>> YourHome: Insulation

Industry body for insulation manufacturers and installers >>> Insulation Australasia

A free guide to simplifying sustainability across research, planning, design, materials, and building, from Amelia Lee’s 30+ years in residential design and construction >>> 44 Ways to Create a Sustainable Home

Access the support and guidance you need to be confident and empowered when renovating and building your family home inside my signature online program >>> HOME Method