*4.1. Descriptive Analysis of the Barriers in SMEs*

The reliability of the data is α = 0.924, which allowed the following analyses to be performed. Table 5 shows the barriers to implementation in SMEs and is ranked according

to the results of the RII. The CEI1 barrier "lack of collaborative work between academia and industry" has a more significant impact on SMEs compared to large companies; SMEs do not create links with academia; the reason is that they are focused on their processes and perceive these relationships as over costs. In addition, the projects they present are very temporary and have low investment, so they require high agility without losing resources [20].


**Table 5.** Barrier impact by project stage, type of project, and company size. Data sorted by RII.

The TFL1 barrier, "low knowledge in professionals", has a significant impact on SMEs, i.e., the academy does not meet the competencies required by the companies to implement LC in their projects, and therefore, they have a long learning process in the members of their projects [78]. The large company has developed academies in its organization with customized knowledge, reducing the impact of this barrier [79].

From the table above, we can indicate that SMEs have three high-impact barriers, such as "Lack of collaborative work between academia and the construction industry" (CEI1), "Low knowledge in Lean in professionals graduated from the university" (TLF1), and "Lack of commitment of top management with the implementation" (CEI3) and are forcing the slow progress of Lean implementation in organizations.

#### *4.2. Difference in the Evaluation of the Barriers*

The Kruskal–Wallis test analysis was performed on the barriers to lean implementation grouped into (a) project stages (design, construction, and operation), (b) project types (buildings, infrastructure, energy, and mining), and (c) by company size.

The results and analysis of the Kruskal–Wallis tests determine that the barriers to implementation in the stages and types of projects are similar; therefore, their study is not significant. On the other hand, the result of the Kruskal–Wallis test of the SME groups and large companies had 76% of different barriers, with independent impacts and difficulties. Therefore, the study focuses on the barriers to lean implementation by company size, similar to other studies [18,22,80].

For the exploratory factor analysis (EFA), the KMO was greater than 0.5, and Bartlett's sphericity or correlation matrix was not an identity matrix (approx. Chi-square = 2755.743, *p*-value = 0.000). Therefore, the researchers can say that factor analysis is useful with these data, and the sample is adequate for analysis and representation. By using a loading of 0.4 and a Varimax rotation, the results of the EFA analysis showed that the barriers could be classified into four factors, as shown in Table 6.


**Table 6.** Exploratory factor analysis-rotated factor matrix for SMEs lean implementation barriers.

#### **5. Discussion**

The group of barriers "collaboration, education, and implementation" is perceived with more impact in large companies; respondents argue that it is because of the large number of people to train, adapting the areas of logistics, administration, resources, and others. In addition, the excessive effort to control many processes and people; in addition, it requires investment for massive training and multiple professionals with knowledge in Lean. On the other hand, the SMEs can start the implementation by hiring people with expertise in Lean and perform other functions simultaneously, which does not take them many resources. They have the facility to manage small groups of people. Similar results were obtained in [81] From the point of view of Construction 4.0, the use of BIM and

Artificial Intelligence [82] and Cloud Computing [83] can help us to improve the identification of waste and mitigate the barrier CEI10. Moreover, to promote greater collaboration and communication among project stakeholders, Construction 4.0 components such as BIM [82,84] and social media [85,86] reduce the impact of the barrier CEI9. In addition, the use of IoT (Internet of Things) [87], artificial intelligence [88], and data analysis [89,90] help us to improve lean planning in construction projects and hence mitigate the impact of the barrier CEI5.

The group of barriers to "organizational vision and system" is closely related to the lack of knowledge on the part of the clients, the permanence of the people during the implementation, and the company's offer. SMEs compete for the new market, reach directly to the customer and try to offer Lean-based services. However, customers are unaware of the lean philosophy and subcontractors and suppliers. SMEs significantly impact their barrier due to the high level of informality in their projects [91] and the hiring of professionals with low knowledge of Lean. As a result, they perceive the industry as non-productive [92,93]. In addition, large companies work with large investment projects; these projects are awarded in most cases by the government. However, the government has institutions that do not require the use of Lean. Likewise, when large companies use Lean, they cannot integrate state agencies due to their low knowledge, little knowledge of the project's value, and a low response to the acceptance of decisions [65]. Regarding this group of barriers, Construction 4.0 proposed the use of BIM [84] and augmented reality [94] to improve scope definition, customer value, and information sharing, thereby reducing the presence of VOS 1 and VOS 3 barriers. In addition, elements such as ECD (Common Data Environment) [84,95–97], cloud [83,84,98], data sharing [84,99], and social media [84,86,100] will help us to improve information sharing between teams, suppliers, and subcontractors, decrease fragmentation in the construction industry, helping the organization to combat the barrier VOS 3.

The group of barriers "Lean theory and philosophy" refers to the learning process of Lean, which should be formed from the university stage [101] and requires that leaders support the implementation by motivating the team, sustaining the practices, and supporting their learning [102]. It seems contradictory that SMEs have a more significant impact on these barriers concerning large companies, despite having few workers, and it should be easy to train, monitor performance, progress the team, and implement. However, the cause is that SMEs execute short-duration small projects with very temporary workers. Construction 4.0 can help us reduce this group's barriers by transferring knowledge using cloud computing [97].

The group of barriers "Lean tools, coordination, and information flow", SMEs tend to hide information to evade taxes and not abide by labor laws; this is a factor that overflows and affects professionals, obtaining a work culture of distrust between themselves and the other actors of the project. In addition, if the work team does not record data of problems and the best solution, they do not take advantage of solutions to similar problems and therefore do not have data support to select the right tool [103]. Likewise, the SME'S projects that are in progress do not have time to plan, coordinate and train the work teams; therefore, it requires quick actions of key tools of simple understanding for people. However, the teams are more focused on putting out fires, and the implementer has a false perception of low experience and knowledge.

#### **6. Conclusions**

The barriers of "lack of collaborative work between academia and the construction industry", "high cost of implementation", and "contracts do not require the use of Lean" are of direct impact on the implementation of Lean. Moreover, actions are required with solutions to improve the productivity of construction in general according to the size of the companies. Most studies explored barriers to LC implementation in large organizations. However, small and medium-sized companies are part of the world's economic engine, and their distinctive characteristics cause different impacts on LC implementation barriers.

Before the study, there was only evidence of barriers focused on Lean tools and no analysis of the type of companies. However, the study showed that the impact of Lean barriers in Peru is focused on the size of organizations. Moreover, this may help educators, implementers, and researchers to focus on adapting Lean thinking to the size of their organization, leaving aside the type of project (buildings, infrastructure, etc.) and the stages of the project (design, construction, operation, etc.). In addition, it is recommended that educators link curricula to the demands of companies and that companies invest in funded research to address the problems in their projects. Moreover, many professionals select incorrect tools when faced with a problem or otherwise work with Lean tools but are unaware of the theoretical underpinnings and are unable to obtain the full potential of Lean.

Finally, the study is biased toward the snowball sampling model, where the sample was selected conveniently to obtain results related to the study's objectives. Reducing the impact of barriers on LC implementers can help facilitators take precautions and rethink their implementation strategies. Moreover, for future research, consider strategies to reduce the impact of lean barriers, and create a roadmap. The roadmap must incorporate the lean principles, implementation barriers, construction 4.0, and lean maturity models; verify the implementation barriers through a lean maturity assessment in the organizations to corroborate the responses of the interviewees; and finally, perform a validation of the grouping of barriers through lean principles.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/buildings12101637/s1, Evaluation Survey.

**Author Contributions:** Conceptualization, C.H.-O. and A.A.E.-R.; Formal analysis, C.H.-O.; Methodology, A.A.E.-R. and R.F.H.; Supervision, R.F.H.; Writing—original draft, C.H.-O. and A.A.E.-R.; Writing—review & editing, R.F.H.. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

