Ceiling and Home Insulation

LJhin on 16/02/2023 - 14:06
Last edited 17/02/2023 - 13:51 by 1 other user

We moved into our new house and realised during the start of the summer months that our Family Room A/C struggled.

After some curious investigations, I happen to touch the ceiling which felt unusually hot/warm. The specifications indicated installation of R2-4 Batt insulation in the walls and ceiling. I was wondering how much heat should be transmitted through the ceiling if such insulation has been installed - should I measure the ceiling temperature? Where and from whom should I get help to assess if this job is done properly by the builder or not? What reference should I provide to make claims to the builder or QBCC? As much as possible, I am avoiding filing a dispute to QBCC with my builder.

Your insights would be greatly appreciated. Many thanks.

Home & Garden Insulation

Comments

Jhin on 16/02/2023 - 14:08

By the way, the other day when it was 34deg outside, our Family Room was 30deg despite the A/C dial at 18deg with an electric fan circulating the air.
- SF3 on 16/02/2023 - 14:09
  
  A/C dial at 18deg
  
  It also depends on the size of room and AC's kw power.
  
  Insulation can help so there is less work to cool down the room.
  - Jhin on 17/02/2023 - 11:17
    
    The centralised A/C is an upgrade we agreed to provide airconditioning to the whole house (4BRs, living room and family room) instead of just two split A/Cs. The builder placed a 12.5kW for the whole house which I thought might not be sufficient.
    - Euphemistic on 17/02/2023 - 11:29
      
      They may need to adjust the airflow to different areas. It’s possible the return flow is giving the AC the impression that it’s all cool when some rooms haven’t had enough cooling.
      - Jhin on 17/02/2023 - 11:48
        
        @Euphemistic: Possibly as the warmest room is farthest from the return duct. Is that still possible for the builder to do now that everything is in place?
Drakesy on 16/02/2023 - 14:24

+1

Do you have a dark roof/exterior walls.
That's where i'd start.

If the builder specc'd your house to be a literal heat island (dark colours throughout) with zero trees then no amount of installation will be able to stop the heat that's been absorbed by the property.

Also has the air conditioner been sized to the property?
- Jhin on 17/02/2023 - 11:23
  
  The exterior walls are light colored. The builder said that our western wall has glass windows and sliding door which receives heat and suggested for us to place shades and plant trees outside. My issue is that this is a turnkey project and the A/C is an upgrade wherein we relied on them to give us the correct design and cool room and so, I thought that they should have considered all the different factors to come up with the correct A/C size. We have struggled getting the ground floor cool - the electrician came twice already and the last time he came, he made changes to the A/C dial such that we can run only one zone. That means that while we are cooling the family room, the other rooms would have to wait - really defeats the purpose for a centralised system.
  - Drakesy on 17/02/2023 - 11:36
    
    I'd maybe consider tinting (ceramic tint) your windows if that's the source of the heat, although i can't see how this would heat the entire house up.
    
    Out of interest what colour is the roof?
    As for the aircon you may need a bigger unit.
    Chuck as much insulation at the problem as possible and just hope that it goes away :).
    - Jhin on 17/02/2023 - 11:59
      
      The roof color is Jasper. Will consider tinting the windows. Thanks.
      - Drakesy on 17/02/2023 - 12:04
        
        @Jhin: Ah ok,
        In that case i can see the roof getting very hot given the low albedo and transmitting into the house.
        I wonder if they do re-colouring.
        
        Jhin on 17/02/2023 - 12:16
        
        @Drakesy: Right. Havent thought about the impact of roof color during selections. Will work on the insulation and if its still an issue, then will look into roof color. thanks.
        
        Jhin on 17/02/2023 - 12:20
        
        @Drakesy: Btw, what I found interesting is that there is more heat on the family room ceiling than the bedrooms upstairs. All are directly under the sun although the roof cavity on the second floor is bigger and there's a whirly wind while smaller and no whirly wind at the family room.
Lexus101 on 16/02/2023 - 14:30
It's hard to judge because there are 3 factors involved.

A/C Cooling Capacity - Getting a slightly more powerful aircon for the space helps on warmer days.

Roof Cavity Insulation - Most ceiling insulation are pretty standard and does not help much on hot days or even cold days.

Room Size & Facing - Getting the correct sized AC installed depends on room size and facing (West facing rooms are usually a lot hotter than east facing rooms).

'
I've lived in older and newer homes and yes the ceilings are warm (even hot) on very warm days. Not much we can do about it. Unless we go crazy with over engineering the roof insulation with thicker batts, sisalation sarking and double thick boards for ceiling. Unfortunately, most of these have to be spec in during the build phase.

Gut feel tells me you need a bigger AC unit. It's the fastest and cheapest way for you at this stage.

Hope that helps.
- Jhin on 17/02/2023 - 11:35
  
  Thanks Lexus101. I tried recalculating the AC which yielded a slightly larger AC but builder just told me that its my calculation - their calculation is that they provided me with the right AC; however, we have struggled getting the room cool.
  
  Is there such thing as a roof cavity exhaust or something to remove and release heat from it? I know that the roof on the 2nd level has a whirly wind but not at this family room.
iamherenow on 16/02/2023 - 14:32

Seems like underpowered AC if it can't get it below 30 degrees on a hot day.
- Jhin on 17/02/2023 - 11:36
  
  The dial does go cool and air coming out is cool but it seems not sufficient to get the whole room cool.
iampoor on 16/02/2023 - 14:38

+2

If you have a pitched roof, find your manhole and access the ceiling to have a look to see if there is insulation. If it's missing, tell your builder to get it rectified, simple job and no need for QBCC.

If you have a flat roof and downlights, remove one and have a look for insulation, easiest way is to stick a phone into the hole and take a photo with flash. If there is no insulation, it's going to be a long hard chat with your builder….
- Jhin on 17/02/2023 - 11:37
  
  Thanks Iampoor. Will take your advice on the downlights. I checked for manhole and there's none but perhaps the downlights. Cheers.
CurlCurl on 16/02/2023 - 17:39

Why are you running the electric fan? Turn it off.
- Jhin on 17/02/2023 - 11:38
  
  I know it defeats the purpose - we had to push cooler air from one side of the house.
trongy on 16/02/2023 - 19:17

R 2.4 is rather low for roof insulation. The Building Code for Australia recommends between R4.1 and R5.1 for warmer climates (the higher number is for dark roofs). BCA requirements for insulation

If this is a new build I would check what the current legal minimum is. If it's an older house I would look at upgrading the insulation.
- pangwen on 16/02/2023 - 20:39
  
  I suspect when the OP says "R2-4 Batts insulation in the walls and ceiling" they mean R2 in the wall and R4 in the ceiling. I don't think I've seen R2.4 batts before (I've seen R2 or R2.5). If they have R4 batts in the ceiling, then they may actually meet the BCA requirement.
  
  The BCA requirement of R4.1 - R5.1 refers to the overall R-value of the roof system (of which the insulation is one part). The other bits are usually pretty minor in the grand scheme of things (e.g. counting the R value of the plasterboard and the air in the attic space), but if the requirement for the OP's place was R4.1, those minor additions could very well let them/the builder limp across the line.
  - Jhin on 17/02/2023 - 11:41
    
    Copy that pangwen. its a bit of a journey on this.
- Jhin on 17/02/2023 - 11:40
  
  Will check the BCA requirements - thanks for the link trongy.
Euphemistic on 16/02/2023 - 20:31

Curling insulation is a double edged sword in summer. It’ll keep some heat from the roof cavity penetrating the living space, but it also prevents any excess heat escaping though the ceiling. If you’ve got heat coming in through windows or walls it can’t get back out through the cieling.

Maybe you need to consider how to prevent heat getting in through walls/floor etc.

I’m not convinced roof insulation in our h use in summer is all that effective (but it’s better in winter). Two story house, we rarely spend time upstairs during the day. Usually have a reasonable breeze in the afternoons so open windows. What I’d like is to be able to ‘open up’ the ceiling after sundown so the heat rising from downstairs has an escape route. The cieling space can cook down quicker than the living space at present.
- Jhin on 17/02/2023 - 11:44
  
  yes, there is heat coming in from the western wall but the ceiling was the hotest from what I have observed. Not sure if placing a vent to release heat from the roof cavity would help.
JIMB0 on 17/02/2023 - 12:25

You'll likely find the insulation hasn't been installed properly. Often the installers are lazy and leave large gaps especially near the eves as it's hard to access. Best way to check is with a thermal imaging camera or with an infrared heat gun. There will be hot spots where the insulation is missing. Just a small amount missing can reduce the effectiveness greatly. Some people have even found the insulation still in its bags sitting in the roof cavity.
- Jhin on 17/02/2023 - 13:20
  
  is a thermal imaging camera or an infrared heat gun available in Bunnings or somewhere? I would like to check my walls as well.
Jhin on 17/02/2023 - 13:20

Thanks everyone for your advice. Stuck my phone on video in three downlight positions as per iampoor's recommendations and I did not see any ceiling insulation installed. Found the culprit - already told the builder to rectify as per specs and compliance cert.

On the other hand, is there any way of checking the walls for insulation other than the powerpoints? @jimbo is a thermal imaging camera or an infrared heat gun available in Bunnings or somewhere? I would like to check my walls as well.
- JIMB0 on 17/02/2023 - 14:37
  
  The IR heat guns are inexpensive and available at various places. Thermal imaging cameras are more expensive and harder to come by. If your roof is tiled you can lift some tiles and see between the brick wall and your stud wall.
  - Jhin on 18/02/2023 - 11:25
    
    Checked the devices - IR heat guns are available in Bunnings and I could hire a Thermal Imaging camera from Kennards for $130/day. Thanks for leading me to these options. Cheers

Ceiling and Home Insulation

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