ᐅ Building an Extension on a Calcium Silicate Wall with Brick Slips – Any Experiences?

Hello!

We would like to build an extension to our existing building with wall thicknesses of 240mm (9.5 inches) calcium silicate bricks / 2cm (0.8 inches) expanded polystyrene insulation, and 2.5cm (1 inch) facing brick slips on the ground floor. Now the question is how to treat the wall where the extension will be attached. Should everything be removed down to the calcium silicate bricks, or should the brick slips be left in place and another layer be built onto them? It is clear that there must be a separation between the external wall connections. Our question mainly concerns the longitudinal side of the wall — should the brick slips be removed or left as they are?

Thanks in advance for the information!

benno96 schrieb:

We would like to build an extension on our existing building with wall thicknesses of 240 mm (9.5 inches) sand-lime brick / 2 cm (0.8 inches) polystyrene insulation / 2.5 cm (1 inch) facing brick slips on the ground floor. Now the question is how to treat the wall that the extension will be attached to. Should we remove everything down to the sand-lime brick, or keep the brick slips and build on top of them? [...] Our concern is basically the long side of the wall, whether to remove the brick slips or leave them in place?

Would a response reading "42" make it clear to you that there is not enough information to provide a meaningful answer?

benno96 schrieb:

It is clear that there needs to be a separation between the outer wall connections.

I do not understand this sentence.

Depending on the size of the extension, the legal protection for the original building year may become void, and then the existing wall construction may no longer meet the valid requirements.

Otherwise: gaining 4.5 cm (1.8 inches) by removing the symbolic insulation and the brick slips does not justify the effort in my opinion.

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11ant schrieb:

Otherwise: I don’t see the effort justified for gaining 4.5 cm (2 inches) by removing the symbolic insulation and the strips.

Thank you for your reply. So, the current exterior wall will then become an interior wall of the extension. The question about removing the insulation including the strips came up partly because I was wondering whether to build and plaster another wall in front of this newly formed "interior wall," or how such a situation is typically handled in construction. Also, there will be two door openings in the wall. The thicker the wall, the deeper the door frame will need to be.

By separation at the outer walls, I meant the connection of the "new" walls to the existing building. Due to different settling behavior, I understand that these should not be interlocked but rather leave some "space" to allow movement and prevent cracks. Or have I misunderstood this?

benno96 schrieb:

By separation at the outer walls, I meant the connection of the "new" walls to the existing structure. Because of different settlement behaviors, you're not supposed to interlock them but leave "space" for movement to prevent cracking. Or did I misunderstand that?

I still haven’t understood anything, to be honest.

benno96 schrieb:

So the current exterior wall would then become an interior wall of the extension. The question about removing the insulation including the facing bricks partly arose because I wondered whether one would then build and plaster another wall in front of the resulting "interior wall," or how this would be solved technically. Also, two door openings are planned in the wall. The thicker the wall, the deeper the door frame will be.

Maybe you should be open to the realization that this academic discussion has no practical value, and just share a clear comparison of the actual current situation and the intended final state. It’s best to scan the building permits/planning permission documents—yes, all of them, not just the supposedly affected floor—and also a cross-section, then mark directly on the new floorplan of the level you want to change (i.e., the ground floor once as original and once as intended). And keep in mind, scribbling directly on the plans is more helpful than "fancy drawings."

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