Housing debates generally focus on new buildings, and there is scarce research on upgrading of existing housing. Upgrading can have positive social, health and financial outcomes for low-income populations. Upgrading the existing stock of social housing (SH) offers an opportunity to ease the effects of inadequate housing through improvements, reduce social costs, alleviate housing deficits and promote sustainability. Targeted upgrading efforts need impact sensitive processes, which involve stakeholders. These are primarily end-users, but also housing and construction companies, design professionals, etc who have specific, at times, conflicting needs and interests. Shifting from individual to more collective engagements, through innovative mediation, should bridge boundaries between stakeholders. This research premise is that by applying and refining Living Labs (LLs) in the SH context, user-valued innovations can be identified. Boundary Objects (BOs) with advanced communication tools (games, Augmented-AR, Virtual Reality-VR, sketches, Building Information Modelling-BIM) are investigated to support decision-making, contribute to idea generation and mediation. A transatlantic articulated nexus between research institutions in Brazil (BR), Germany (DE), the Netherlands (NL) and the United Kingdom (UK) will address social challenges through SH upgrading protocols. A shared research concept and design will be applied to ensure appropriate acknowledgement of cultural differences and to avoid ‘getting lost in translation’. Specifically orchestrated LLs are key, where each institution uses case studies to apply diverse tools to enable the visualisation of design alternatives and meaningful stakeholder engagement. Local and multinational transatlantic stakeholders will participate of the LLs. The continuous mutual exchange of experiences during the research facilitates learning and provides a comprehensive understanding of SH upgrading challenges and opportunities. A bridging strategy to support upgrading processes in different contexts, i.e. a protocol, will be the main outcome of the research. Outcomes include updated knowledge documentation on user-oriented SH upgrading and communication tools to intensify stakeholder collaboration. Research results will be continuously exchanged to enable up-scaling to wider contexts and to strengthen the proposed social innovation that promotes understanding of contextual aspects of stakeholder needs and values.