What kind of loft insulation is this?

[Sparrowhawk]

I pulled back a layer of pink glass fibre to get to a cable and found this stuff. It's pre-1989 I think, when the house was reroofed from slate to tile as there's broken slate in it.

 

[ADLIan]

May be yellow glass wool. Waste product was ground to make fibres that were injected into cavity walls and blown into lofts. Can you see individual fibres? 

[Sparrowhawk]

On 26/03/2023 at 12:24, ADLIan said:

May be yellow glass wool. Waste product was ground to make fibres that were injected into cavity walls and blown into lofts. Can you see individual fibres? 

Thanks, I had another look today and yes it's got the shiny glass fibres in it.

 

Will it have the same insulating properties as the glassfibre rolls in the loft or do I need to remove it and replace with other insulation? It's only in patches of the loft so looks like it's been taken out from the rest.