Christian

Is there anyone who can help me with information about thermal expansion cracking of the slab or walls in a passive house? I have a technical concern regarding passive raft foundation and (ICF) concrete walls for a passive basement construction (part of a passive dwelling). In technical terms: Any solution to accommodate anticipated differential movement between the raft foundation concrete with an underfloor heating system and the concrete walls that sits on the raft foundation? My concern is regarding the thermal expansion of the concrete in a raft foundation with an underfloor heating system. The temperature of the concrete in the passive raft foundation may fluctuate with 8°C / 15°F or more, compared to the temperature of the ICF concrete basement wall, depending on the season and the heat from the underfloor heating system. With the size of the raft foundation plat, this will induce a calculated expansion of the foundation slab concrete with 2-3 mm. The ICF concrete walls, supported by the foundation system, does not expand, as the temperature do not fluctuate similar. Perhaps we should made expansion joints between the raft foundation plate and the ICF wall, allowing them to slide the anticipated 2-3 mm on each other? However, to make the basement construction strong, we would want to connect the raft foundation system concrete and the ICF concrete wall with reinforced steel. Have anyone heard of this problem and any solution or guidance on how to solve it? Are there any experience about this potential problem anywhere? Expansion cracks in a concrete slab can potentially damage technical installations in the slab, including the heating pipes in the floor/foundation plate. I would very much appreciate any tips / advice. :-)