Ceiling Insulation

[monkeybaby]

Hi, looking for some advise.

Currently, my kids bedroom are quite hot during summer and I was thinking of adding additional insulation batts in the ceiling for their bedroom.

Just wondering if

1) it is safe to add additional batts on top of existing ones. Currently we already have R4 batts installed from the builder.

2) How much extras can we add?

3) Is there a specific brand/type I should use?

Looking to DIY assuming it's safe to do so.  I've been in the roof space in the past due to roof leaks so I'm comfortable doing so.

Thanks in advance.

[JacobZ]

Hi @monkeybaby,

Thank you for your question and welcome to the Bunnings Workshop community, it is wonderful to have you join us.

I'll break it down into answers to each of your questions.
 

1. Safe to add extra batts? 
   
   Yep, it’s generally fine to add extra batts on top of the existing ones, as long as what’s already there is still in good shape (not wet or squashed down). Just make sure to avoid compressing the insulation, which would reduce its effectiveness.
    
2. How much extra can we add? 
   
   You've got R4 batts already, and in hotter areas, you want an R-value of around R5 to R6. Adding an extra layer of R2 should help boost the insulation, making a noticeable difference in how hot the rooms get.
    
3. What brand/type to use? 
   
   I'd suggest it's best to stick with glass wool batts, as they’re non-combustible and perform well. To increase your R-value to R6, you can use either Earthwool R2.0 90 x 430 x 1160mm 16.0m² Insulation or Earthwool R2.0 90 x 580 x 1160mm 21.5m² Insulation depending on the spacing of the ceiling frame. Please note that these insulation batts state that they are wall insulation, there is no reason they can't be used in a ceiling, they are just designed with the thickness and stud spacing of walls in mind.
    

Since you’re comfortable getting up in the roof space, you should be good to go, just make sure you wear long sleeves, long pants, gloves, a dust mask, and safety glasses to avoid any irritation from the insulation.

Let me know if you have any further questions.

Jacob