Thermalites to medium dense

[Geo57]

Hi all

My architect specified 3.6n thermalites (internal wall), together with 90mm near full fill in a 100mm cavity to be able to get a total 300mm cavity and meet the 0.18 requirement for cavity walls

However my SE has mentioned that I will need medium dense blocks as needs to support a steel ridge

U value calculators bring this in at 0.19 (using medium dense, 90mm near full fill & outer facing brick work)

Am I going to need to amend my building regs application to go for a larger cavity, or could I increase the insulation in other areas to mitigate this (ceiling for example?)

Thanks
Geo

 

[stevie888]

Get your SE to do his job and spec a padstone to suit the blocks the steel has to sit on

 

[oliver.hughesxsuper]

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From a long-term usability point of view, it may also be worth thinking beyond the immediate structural requirement and considering how the property will function in the future.
A lot of homeowners focus on compliance and current layout needs, but accessibility and ease of movement can become important later, especially in multi-level homes. Design choices made during building or renovation can make future upgrades much easier.
I have seen discussions around home elevator solutions for homeowners planning smarter long-term accessibility, particularly where maintaining independence and easier movement between floors becomes a consideration.

For now, your architect, structural engineer, and building control team would be the right people to confirm whether adjusting insulation specs elsewhere would satisfy compliance, since SAP calculations usually look at the wider overall performance rather than just one isolated element.