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Tertius – An online construction marketplace that easily connects property developers with certified inspectors

Tertius has resulted in massive productivity gains for the building industry in DC, enabling developers & property owners to book (at a nominal cost) certified third party agency inspections. Outcome: Far more efficient matching of demand & supply for permit inspections, substantially reducing turnaround times. Tertius has driven revenue to the taxpayers, increased regulatory oversight, increased safety in the building community, saving property owners and developers thousands of dollars.

Innovation Summary

Innovation Overview

Problem? Due to the high level of demand, the Department of Buildings (DOB) was experiencing lengthy turnaround times for construction inspections. In the built environment even minor delays can cost developers a lot of money in forced down time where construction crews are idle and buildings aren’t completed so that revenue may be raised. For DOB, employing new full-time staff was a slow process given the high level of certification as a barrier to entry, and once employed, full-time staff represented a fixed overhead not not easily reduced if demand drops.

Innovation? Apply well established multi-sided marketplace approaches to the problem, Identifying independent skilled inspectors within the local community, create a marketing platform that allows them to be easily found, booked and paid for resulting in Geolocation check-in for inspectors brings transparency confirming that they were onsite at the time of the inspection, rather than signing off remotely without carrying out proper inspections as had been the accusation frequently in the space,

So successful were the implemented third-party inspection workflows through Tertius that DOB decided to apply similar workflows for the booking of DOB’s internal inspectors. This replaced an IVR (Interactive Voice Response) booking system that was very inefficient in comparison and difficult to use – which offered no information to customers seeking to book inspections.

Who benefits? This represents a win-win-win.

  • This government agency drives revenue as the marketplace actually represents a potential profit centre as utilisation and volume throughput grows, while boosting efficiencies and transparency for both internal and third-party inspections at the same time.
  • Developers are happy in that they can book an inspector in minutes, receive quotes, and pay in one motion, and have inspections carried out in days rather than weeks – often resulting in a substantial net savings for their project.
  • Finally, inspection agencies and contractors save time and admin costs in quoting, finalising proposals and being selected for work, scheduling, and reporting findings thereby increasing their overall throughput of paid inspections.

Objective? Using modern best practice enterprise-grade marketplace platform technology to transform efficiencies in the building/construction inspection ecosystem. Tertius also provides an opportunity to create an experience overlay on top of slow, inflexible and often ageing legacy software solutions that have been deployed over many years, using API integrations to read, extract and record back key information. (In the case of DOB, they use for permit and inspection record keeping. Tertius deeply integrates with this. The same can be achieved for any software application being used by a government agency servicing building/construction inspections).

How institutionalised? The visionary behind Tertius, the Director of DOB, Ernest Chrappah, has championed the 3rd party marketplace approach in the DC area. DOB released a policy that REQUIRED all inspections for building developments to be requested/booked via Tertius. This required consultation at the highest level, including the Mayor of Washington DC, Muriel Bowser. The initiative has been fully supported by the DC government due to the demonstrative productivity gains being made, and transparency being brought to the building inspections process.

Scaling? The tech underpinning the Tertius marketplace,, is an API's-for-Everything PaaS development ecosystem that has a 10 year pedigree in innovating Product, Service, Community type multi-sided marketplaces. It is not a SaaS or even a Low Code platform. This means there are no limits to the enhancement pathways for DOB and other government agencies that wish to leverage the core inspection workflows/user journeys that are represented by Tertius.

Future roadmap? In terms of inspections for the real estate developers, two other sister agencies in the District of Columbia have contracted to build inspection workflows specific to their needs, one being the Department of Energy & Environment (DOEE) for inspections that are pre-breaking ground before building developments can start, and the other being Department of General Services (DGS).

And building and construction inspections are just one type of inspection type; the same scalable, flexible and extensible code base could be AFFORDABLY applied to ANY inspection type, be it for internal inspectors or leveraging the third-party inspector framework; e.g. elevator or conveyances, environmental, health and hygiene, social services type inspections.

Innovation Description

What Makes Your Project Innovative?

To date such marketplaces have primarily been entrepreneurial pursuits, e.g. Uber & AirBnB, but increasingly enterprises are exploring how multi-faceted user journeys can better connect customers, advisors, partners - to build stronger communities & deliver increased levels of service.

Leveraging modern multi-sided platforms, many firms can uncover excess capacity or underutilised resources or skills, etc. & allow for efficient interactions via a modern & intuitive user experience.

End result related to the construction industry is keeping all of us safer! Applying marketplace approaches to a specific problem – how do we increase the available supply of inspectors & increase our oversight – was as a result of the creative 'out of the box' thinking of Director Chrappah, supported by thought leadership of & the experienced team at platformOS.

Taking a Design Thinking & Agile development led to a purpose-built MVP being developed in just six months.

What is the current status of your innovation?

As of Q4 2022, the marketplace solution has achieved the outcomes that were envisaged: to create a third-party marketplace for certified private-sector building inspectors, extended to accommodate the booking of public-sector internal DOB inspectors, and bring significant efficiencies across the board.

The DOB continues to run stakeholder engagement sessions to identify where user journeys can be improved and enhanced, these being deployed in an Agile way. In the same vein we continue to enhance workflows for our sister agencies, DOEE and DGS, in an iterative way. The potential for Tertius to service other inspection types is also being considered.

In the coming month we will be launching a mobile phone wrapper app for Tertius that will offer downloadable iOS and Android apps of the Tertius application to be used primarily by developers and inspectors. Being founded on a web application itself this wrapper provides an affordable way to maintain the mobile app interfaces.

Innovation Development

Collaborations & Partnerships

Through Harmen van Sprang of Sharing Cities Alliance, a platform for cities to share ideas, Director Chrappah was introduced to Neal Gorenflo of (a Civil Society organisation promoting “people-powered solutions for the common good”). Neal then introduced DOB Director to platformOS.

A Design Thinking process with the key stakeholders ensures alignment; viz. DOB admins, inspectors, third-party inspection agencies, and developers.

Users, Stakeholders & Beneficiaries

  • Developers & their clients: Realised substantially reduced turnaround times for building inspections for the full cycle construction process.
  • DOB: reduced cost of inspector overheads, fuller transparency of inspections being carried out professionally.
  • Third-party inspection agencies: reduced admin overhead to receive RFPs, quote, & to be booked, in a MUCH shorter time than is typical.
  • The District of Columbia: substantial productivity gains across the building / construction ecosystems.

Innovation Reflections

Results, Outcomes & Impacts

The Tertius platform provides a convenient options for customers to shorten the timeline to complete inspections. Tertius brings a supply of customers directly to each inspector & provides a platform to conduct and report inspection activity – streamlining the process.

  • Revenue: Since its launch (Oct 2021) over $4.2MM has been paid to third-party inspection agencies.
  • Shorter Wait: Time from inspection request to completion shrank from as much as four weeks to as little as two days, saving developers & property owners thousands of dollars.
  • Growth: With a quarter over quarter growth, inspections conducted through Tertius are projected to grow 67% (from 90,000 to 150,000) in the first year of operation.
  • Accountability: Audit logs allow DCRA to review every step in the process, ensuring the required inspections occur, are flagged when they don’t occur promptly, & increases the speed at which inspection results are reviewed by DOB – enabling DOB to surpass its Service Level Agreements.

Challenges and Failures

With such digital innovation, especially within a political environment, the change in process can be daunting for certain parties. With Tertius there was initially push back by third-party inspection agencies used to the pre-existing more manual processes.  We suspect that there was also angst being experienced by inspection agencies in that DOB now had fuller transparency, including, for example, the requirement for the inspector to geolocate at the time of the scheduled inspection - but this we believe has had the effect of weeding out the ‘bad actors’ in the ecosystem.

As a result Director Chrappah did feel the need to reaffirm to District of Columbia Mayor Muriel Bowser, that significant gains were being enjoyed as a result of the mandated use of Tertius, thereby gaining political support from the top down. Since gaining the demonstrated support of the Mayor, all parties in the process are now fully engaging. Otherwise, there have been no significant challenges or failures.

Conditions for Success

Leadership, & the willingness to take a risk with a new transformative approach - applying multi-sided marketplace concepts to the problem at hand - was key. In addition, apart from his innovation mindset, Director Chrappah had to draw on his personal conviction to follow through with a less established software vendor that had proven results in the space - after all, the “Nobody got fired for choosing IBM” mindset is pervasive in government circles.

The presumption is that there is an existing software that records permitting requirements against addresses for developers. Initially any Tertius-like solution would overlay & integrate with this, but there might well be opportunities to modernise the core permit record system using platformOS itself, gaining efficiencies and saving costs. As was the DOB experience, we’d suggest seeking higher level political buy-in and support to ensure a common front, to better counter self-serving complaints arising from lobbyists, or similar.


After deploying Tertius, the advantages to DOB were quickly recognised by DOEE for ‘pre-breaking ground’ inspections. Similarly, the core workflows of Tertius were leveraged by DGS in the District of Columbia. There is great potential to service all manner of inspections, particularly where inspections can be outsourced to trusted private-sector agencies - to be able to boost the supply side seamlessly as demand increases and decreases in less robust cycles. This might apply to inspections such as elevators and other conveyances, health and hygiene, environmental initiatives, social services, roads and transport, etc.

NOTE: Tertius & the underpinning tech stack of platformOS is NOT delivered as a static SaaS, or even as a limiting Low Code solution. The code logic is replicable in elements or as a whole, and can be quickly customised to specific use cases.
In addition, platformOS is a PaaS developer ecosystem, and working with system integrators in each region is encouraged.

Lessons Learned

Learnings gained as shared by DOB Director, Ernest Chrappah:

  • Be emboldened by progress.
  • Think differently and invite measured risk in changing how you do business.
  • Anticipate downstream needs so that resource allocation does not become a limitation.
  • When you seize an opportunity, get a product into the marketplace quickly, then perfect it.
  • Identify the problem that you actually want to solve. Then solve it.
  • Evaluate opportunities to integrate for efficiencies.
  • Never stop engaging with the community and stakeholders impacted to learn about features and adjustments that will add value.

Learnings by platformOS:

  • The importance of applying Design Thinking to discovery & planning to optimise achieving the desired outcomes first time, rather than having to re-work development
  • PlatformOS & DOB agreed that using the Agile methodology was key to delivering the Tertius MVP much faster (holding costs down), to then iterating off the back of user feedback.

Project Pitch

Supporting Videos


  • Diffusing Lessons - using what was learnt to inform other projects and understanding how the innovation can be applied in other ways

Innovation provided by:

Date Published:

24 January 2023

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