DIY cavity insulation

[Alexmash]

I am renovating/extending a brick bungalow. We have removed the roof so have exposed the top of the cavity wall. We only have one remaining wall of the existing bungalow that is external and we will be insulating it internally but it seems a wasted opportunity to not up the insulation whilst we have that cavity exposed. It needs to be a solution that is budget and DIY friendly. I have seen polystyrene balls - is this the best option?  Thanks in advance. 

[Mr Punter]

With the polystyrene beads they get mixed with a small amount of adhesive as they are installed, so if you later make a hole in the wall they don't just continue to escape.  You would not be able to do this easily.

[SimonD]

15 minutes ago, Mr Punter said:

With the polystyrene beads they get mixed with a small amount of adhesive as they are installed, so if you later make a hole in the wall they don't just continue to escape.  You would not be able to do this easily.

 I've lost count of the number of houses where I've been showered by the things. I reckon loads of the installers skimped on the adhesive as it cost them, especially during the grant funded years.

[ADLIan]

Be aware that retrofit cavity wall insulation is notifiable work under the Building Regs. Product must have BBA, or similar, 3rd party certification that normally covers both the product and its installation.