DIY Doctor UK DIY Forums

Hi. We are currently having a 3m x 3.5m extension to the rear of our property and then knocking through the existing rear wall into the kitchen to create a family room.
The foundations are complete and the build underway and I was surprised when I arrived home today to find the builder using a block cavity block construction. We have asked for the extension to be rendered at the end of the build but was under the impression from the start,that the exterior wall would be made of brick in spite of this.
I am going to confront them tomorrow about this but being a novice in this was hoping for some advice.

Is block cavity block a common method of construction if rendering afterwards.

Its quite normal to use block externally if its going to be plastered.
mainly because it quicker and cheaper.
its down to thermal value what block he uses, thermalite or similar is usually used internally but it also depends on the cavity insulation aswell.
Concrete blocks usually laid externally.
He didnt have to inform you what materials he uses,But the building control officer will be able to give you more information upon request.

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