Dear forum,
I am inexperienced with construction and am unsure if the procedure followed by our general contractor is correct:
My wife and I are currently having a single-family house built by a general contractor. The walls are made of lightweight expanded clay aggregate blocks. Due to a communication error, one wall (the inside of an exterior wall) was drilled with several holes. Depth about 8 cm (3 inches), diameter about 6 cm (2.5 inches). These were intended for toggle switches, but it was the wrong location. Now the holes have been filled again, using polystyrene boards, which were then plastered over. I only noticed this (the repaired spots were no longer visible) when I tapped the areas with my fingers and they sounded hollow. When tapping, I actually punched a small hole in one of these spots. The site manager said that the workers were instructed to do it this way, and that the surface was soft only because the plaster had not yet dried. The workers were there about 3 or 4 days ago.
As a layperson, I can’t imagine that this method complies with recognized technical standards. A solid wall made of expanded clay blocks patched with polystyrene boards and then plastered? These spots will surely remain weak points forever. If I lean too hard against the wall with my elbow, I might put a hole right there. Shouldn’t these holes be filled with something hard, like mortar or similar material?
I am inexperienced with construction and am unsure if the procedure followed by our general contractor is correct:
My wife and I are currently having a single-family house built by a general contractor. The walls are made of lightweight expanded clay aggregate blocks. Due to a communication error, one wall (the inside of an exterior wall) was drilled with several holes. Depth about 8 cm (3 inches), diameter about 6 cm (2.5 inches). These were intended for toggle switches, but it was the wrong location. Now the holes have been filled again, using polystyrene boards, which were then plastered over. I only noticed this (the repaired spots were no longer visible) when I tapped the areas with my fingers and they sounded hollow. When tapping, I actually punched a small hole in one of these spots. The site manager said that the workers were instructed to do it this way, and that the surface was soft only because the plaster had not yet dried. The workers were there about 3 or 4 days ago.
As a layperson, I can’t imagine that this method complies with recognized technical standards. A solid wall made of expanded clay blocks patched with polystyrene boards and then plastered? These spots will surely remain weak points forever. If I lean too hard against the wall with my elbow, I might put a hole right there. Shouldn’t these holes be filled with something hard, like mortar or similar material?
A
Allthewayup28 Feb 2024 22:50MitteDE schrieb:
Thank you both for your responses. xMisterDx mentioned the issue of thermal bridging when using mortar.
Does this not apply to the options you suggested (lightweight masonry mortar LM21 or slot plaster)? Google results indicate that LM21 lightweight masonry mortar has very high thermal insulation. Yes, LM21 is a special mortar with better insulation properties than standard masonry mortar. The Tiroplan product even contains expanded polystyrene beads. Slots in exterior walls up to certain dimensions are permitted and are not significant in thermal bridge calculations.