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How to add outer wall thermal barrier?

Hi,

We'd like to have more of a thermal barrier on this north side wall, on the sides of the window, for now there are these batts that looks pretty terrible. There is a veranda/structure that blocks the sun but the heat still comes through a bit. Could some type of wood that could look better too act as a thermal barrier? and if that sounds feasible how thick the wood should be? I thought it could also be painted with heat reflective paint? (we have a brick veneer house with a blow in insulation).

It is for a health reasons/condition why we need to keep indoors so cool .

Your suggestions would be greatly appreciated.

After researching for claddings, we came across this

Weathertex 3660 x 200mm Classic Smooth Weatherboard, would this (or something similar) also be heat resistant for our brick veneer walls?

would be looking at only doing the front of the house. will it make it warmer in winter? we don't need it to be warmer 🙂

Kindly,

Tina

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Comments

MitchellMc

Hi @Vitriolum,

From what I can see, you’ve already got some insulation in place, but it’s visually unappealing and you’re trying to both improve the look and increase the thermal barrier on that north-facing wall. You’re correct that adding a covering can help, both aesthetically and to provide some additional resistance to heat transfer, but there are a few important things to keep in mind.

Using timber cladding over the existing batts can improve the appearance and provide a small degree of extra thermal mass, which can slightly slow heat transfer. The thickness of the timber will influence this effect: even 12–18 mm of solid timber can give some benefit, but it won’t block heat nearly as effectively as purpose-made insulation. Thicker timber adds more mass, but the improvement is modest unless paired with an air gap or reflective layer. Painting the timber with a heat-reflective paint can also help, particularly if it’s a light colour with infrared-reflective properties, but again, the effect will be limited compared to proper insulation.

Since it’s for health reasons and you really need to keep the indoor area cool, the most effective approach would likely be a combination of solutions: ensuring the existing insulation is well installed, adding an aesthetically pleasing covering (like timber battens or cladding) with a small air gap behind it, and using a reflective coating on the exposed surface. If possible, taking clearer photos or a simple sketch of the wall, window, and surrounding structure will help provide a more specific recommendation.

Can I ask what kind of cooling you have within your home? I would have thought a standard cooling system with sufficient capacity would address any heat issues, given the extent you've gone to in insulating the home.

Please let me know if you have any questions.

Mitchell

Vitriolum

https://www.workshop.bunnings.com.au/discussion/comment/60463#Comment_60463

Hi Mitchell,

thank you for your reply to both of my posts, the other one was on our garage. Yes the temperature differences can be very minimal to someone with a normal health, but for now we've needed to take more measures to keep it cooler than most houses would have their indoor temperature. The garage is 4-5C warmer to the rest of the rooms, while I understand your point that it may always be warmer even after insulation, We have split system AC's. but are willing to take those batts off altogether and replace it with perhaps cladding even if it cannot insulate as much as additional batt insulation.

I only noticed your reply after editing my post to say that we also came cross this Weathertex 3660 x 200mm Classic Smooth Weatherboard, would this (or something similar) also be heat resistant with the needed air gap? its already light in colour.

would be looking at only doing the front of the house. will it make it warmer in winter? we don't need it to be warmer

I added more photos of the front of the unit .

Thank you again,

Tina

EricL

https://www.workshop.bunnings.com.au/discussion/comment/92710#Comment_92710

Hello @Vitriolum

The Weathertex 3660 x 200mm Classic Smooth Weatherboard provides minimal thermal resistance. Its main job is to protect the wall from rain, wind, and UV, allowing for a breathable, durable facade. Generally speaking, the insulation comes from the air gap. I propose keeping the batts you currently have to retain the insulation properties you currently have. Adding the weatherboard will add a bit of insulation but not a great deal.

I also suggest having a look at this discussion - How to insulate a brick shed? by @Nuggets.

Let me call on our experienced members @Dave-1, @Nailbag and @AlanM52 for their recommendations.

If you need further assistance, please let us know.

Eric

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/112503#Comment_112503

Good Morning @Vitriolum

I have the same type of security shutters, when I was looking at my house I realised they are for heat not actuall security 🙂

They do a fair job of stopping heat, tho a thick inside curtain added to the layering would help in a large way to minimize that heat transfer.

With the sun on the walls, Instead of the paneling you have suggested I would go for a slatted drop of maybe 600mm from the eave.

So think of a rectangular frame that has horizontal slast in it, these are screwed just behind he gutter to the underside of your eave. It will create shade/stop the sun from impacting your brickwork. You dont need all the bricks coverd, just part during the hotter period of the day.

I would also consider a screen for being in front of the metal shutters. Anything to stop the sun before it gets close will work in your favour.

Dave

AlanM52

Hi @Vitriolum,

When needing to insulate from heat think of gaps and airflow.

You could start with this.

Twinwall Polycarbonate Sheet.jpg

Long gaps.

Screenshot 2025-12-15 163328.jpg

High thermal insulation.

Add a 2nd sheet (boost insulation) spaced off with square Velcro pads - Airflow.

You will need a light timber frame or maybe use wire mesh panels.

Install the poly sheet(s) on the back of decorative panels.

I also have a recycled water version of the above.

Cheers

Vitriolum

https://www.workshop.bunnings.com.au/discussion/comment/123787#Comment_123787

Hi Dave, and thank you all for your replies. We actually have a shade structure in front of this window 🙂 another thought was if it would help to ad some insulation on the back of that structure if it make a difference on how warm the wall behind it gets?There is still 1m or so gap between them, here is a photo of it. @AlanM52 as its not getting direct sunlight would Sunlite sheet this still work as a thermal barrier on the house wall? or better on the back of the shade structure if sticks out too much on the wall of the house but I like your suggestion on adding decorative panel over it if its not too thick, and is it possible to see what panels may be thin enough? what did you mean by recycled water version of this?

Thank you again

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EricL

https://www.workshop.bunnings.com.au/discussion/comment/131242#Comment_131242

Hello @Vitriolum

Thank you for sharing those extra pictures of your window. Let me tag @Dave-1 and @AlanM52 to make them aware of your questions. Looking at the shade structure that you have, I believe this covers the side of the house effectively reducing the temperature. If you were to add insulation to this structure, I would suggest covering both the wall and ceiling so that there is no way for the ambient heat to get through. Doing only the wall would not be an effective solution.

Eric

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/135801#Comment_135801

Good Evening @Vitriolum

Mmmmm I have a question tho dont think it will change the idea I have in my head 🙂 Is that shade structure a solid piece of material? As in its not a tarpaulin/softer material.

Whichever way Adding anything for a thermal insulation purpose will actually capture more heat within that area. Having a solar run fan at one end to blow air through that space would be a better return on your dollars. The problem with a thermal barrier is yes it does slow heat, but also captures heat. Having anything spaced in between may be adding heat and slowing its escape. The screen that @AlanM52 has mentioned might lower temperture but I really dont think it will over a period of time (sun goes down and whatever material you have has to shed heat) so the drop it gives will still hold the heat longer so its an iffy iffy if it will help.

When I was watering my tomatoes the other afternoon (4pm ish) direct Hot sun on me, I sprayed water over the concrete/mesh and immediatly felt the local temperture drop to a cool feeling. I filed that away as I live on the coast (nowhere near the sea, closer to the escarpment) and evaporative cooling isnt really supposed to work here. Out West, Wagga way evaporative cooling works very well as the air is dryer.

Sooooo I am thinking of a few things you could try..

- Fan facing down the aisle between shade and wall (a strong fan)

- Misting fan run on a timer. So on and off during that day.

- Water spray on teh shade cover periodicaly (on a time, 5mins every hr maybe)

I have seen Indian clay pipe evaportaive coolers. Think terracotta pipes around 400mm long and stacked on top of each other. Water is then run over the terracotta pipes and cools the air passing through the pipes, dropping the ambiant temperature around the air con. Its not a thermal insulator but will create a cooler area. I would love to give it a go here but its more humid so less cooling output.

Dave

AlanM52

Hi @Vitriolum,

With regard to @Dave-1's last comments regarding heat retention here is a Foilboard water cooled version using misting systems or kits.

The same principal can be used to drain heat from other heat insulation materials.

Double panel version.

Single panel version.

Both using Misting Systems AKA Misting Kits.

I am addicted to Smart Home Automation not inside the house (boring) but around the house and out in the yard.

Basic Alexa (or Google) system to control the 'water panels'.

Voice command 'Alexa... Turn on water panels'.

The system can be automated by adding one of more (different sides of the house) wi-fi temperature & humidity sensors.
Via Amazon Routines Alexa can determine when to turn on/off the system.

Can also be manually controlled via the phone app.

Cheers

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