Optilyte/Optilite lightweight aggregate blocks

[Jane W]

Hi Everyone, 

 

I wondered if anybody had used or come across Interfuse Optilyte/Optilite blocks?

They appear to decrease the U-value of the wall enough when used instead of Plasmor Fibolite or other lightweight aggregate blocks to meet building regs without making the wall deeper or having to use insulating plaster. Its hard to find a price online so wondering if it's a niche product, although E H Smiths have given me a price of almost  £3000 for 1620 blocks.

I'm really looking for a way to make a brick and block, full fill dritherm 32 150mm cavity wall meet building regs cost effectively without thermolites. 

[LSB]

WE used H&H lightweight for the U values, but they can be brittle, we have one break when drilling into to put in window frame (luckily temp one) and had to replace it.

Anywhere that we are likely to hang things or need extra strength such as above windows and under the roof we use heavy blocks.

 

So, before you proceed do check about this.

 

WE are doing block / block 150mm cavity with insulation batts and this meets building regs.

 

 

[Oz07]

On 01/10/2026 at 20:42, Jane W said:

Hi Everyone, 

 

I wondered if anybody had used or come across Interfuse Optilyte/Optilite blocks?

They appear to decrease the U-value of the wall enough when used instead of Plasmor Fibolite or other lightweight aggregate blocks to meet building regs without making the wall deeper or having to use insulating plaster. Its hard to find a price online so wondering if it's a niche product, although E H Smiths have given me a price of almost  £3000 for 1620 blocks.

I'm really looking for a way to make a brick and block, full fill dritherm 32 150mm cavity wall meet building regs cost effectively without thermolites. 

Are you in or close to Leicestershire? Interfere are based there and you can deal with them direct on direct loads. At 1620 that's getting on for full load isn't it? I think I've used them optilyte before but can't recall exactly was a while ago. Im pretty sure you can still get a 150mm cavity to meet regs on a non airated block.

 

Give interfuse a call let us know how you get on. They have hiab wagons

[Jane W]

On 03/10/2026 at 10:17, Oz07 said:

Are you in or close to Leicestershire? Interfere are based there and you can deal with them direct on direct loads. At 1620 that's getting on for full load isn't it? I think I've used them optilyte before but can't recall exactly was a while ago. Im pretty sure you can still get a 150mm cavity to meet regs on a non airated block.

 

Give interfuse a call let us know how you get on. They have hiab wagons

Yes we are in Leicestershire,  in fact only a very short distance from them. I'll get in touch with them directly,  thank you 👍