Types of Loft Insulation

[bobsy12]

Looking for some top layer insulation to go at right angles to the base layer. Went into Wickes today and noticed that their top layer mentions "perforated to 400mm and 600mm for easy fit". Seems to mention this on all of their insulation.

The last time I bought top layer, the width was around 1.2m with no perforations.

I can understand if the base layer is sized up for 600mm and 400mm but don't understand why the top layer is also 600/400. I asked the sales rep about this and he didn't seem to understand the difference.

I assume perforations means that the insulation tears easily, so maybe no good for a top layer?

Can anyone give me some advice please?

 

[PrenticeBoyofDerry]

The perforation help you to split the insulation at those measurements if desired. The effects of heat loss by using this as a continuous insulation layer, will be very minimal, if at all. I would not be over concerned if using this.