Thermostone vs Breeze Block

[Zehroni]

which is better to use for two story extension to build the inner walls, Thermostone or Breeze Block. I was under the impression that Breeze block is better and heavier and hence hold the wall ties better. however, a brick layer came to day to provide me a quote and he suggested using Thermostone block instead of breeze block

 

[acurachris]

I was under the impression that Breeze block is better and heavier and hence hold the wall ties better

I don't think that would be a viable reason to suggest "breeze" blocks on a two storey extension; never heard that before!

The thermos tone (mean thermalite?) typically offers better thermal capacity; so it will likely keep your extension warmer than using concrete blocks. These are used in house builds all the time and they're not falling down due to the wall ties not holding! It's going to be easier to lay the thermalite blocks too, based on them being much lighter, so you could argue it's quicker to lay.

What do your building regs say? My extension was specified to use "To achieve minimum U Value of 0.28W/m2K" cavity wall. My spec would be 100mm outer brick, 100mm cavity with TW50 40mm Kingspan insulation and Celcon Solar lightweight blocks. That gives me around 0.25-26W/m2

 

[Zehroni]

below is what my building regs say.
EXTERNAL CAVITY WALLS
( to achieve min U'value .28W/m2K) Generally 303mm cavity wall built off foundations of 102mm facing brickwork outer skin to match extg, 100mm cavity with full fill of Dritherm 32 (to achieve 0.25W/m²K) or Xtratherm CavityTherm ( to achieve0.18 W/m²K) insulation batts as work proceeds installed strictly in accordance to manufacturers' recomendations. Inner leaf of 100mm Celcon Standard blockwork with12.5mm plasterboard on dabs with skim coat Gypsum plaster finish. Galvanised ms extra length wall ties at 750mm centres horiz. & 450mm centres vert. staggered with extra at reveals built in as work proceeds. Close cavity off at cill & jambs with type H Cavicloser from Cavity Tray Ltd or similar approved. Bottom of cavity to be filled with lean mix concrete to within 150mm of DPC. All brickwork to be in common brick below ground level. Incorporate DPC to both leafs as indicated, inner to marry up with floor DPM. Build in windows and door frames as work proceeds with cavity closers. Bed 100x50mm eaves plate to top of wall strapped down. At abutment with existing brickwork tooth and bond as indicated or mechanical fix work with Furfix or equal starter channels and maintain cavities where appropriate.

 

[acurachris]

 

[tony1851]

I doubt you'll find any breeze blocks at the builders' merchants nowadays.

 

[Leofric]

Didn't think breeze blocks had been used for inner leaf of external walls for years ! Thermalite blocks are lightweight aerated concrete and are a common block for inner leaf of cavity walls ,especially since maximum 'U' values were lowered in recent years.
As the previous post says you need to consider the 'U' value you need to achieve which also has to be taken into account in the overall energy rating of the dwelling.
There are different sorts of Thermalite blocks with some giving better insulation than the standard block.
Internal blockwork partition walls would tend to be lightweight aggregate concrete blocks in my experience.