Short answer: People place disproportionate value on things they assembled themselves. Behavioural researchers call it the IKEA effect, and it explains something otherwise puzzling about construction sales: a rep who spent four hours building a project list in Excel will defend it against a better list that arrived automatically. The effort created the attachment, not the quality. Understanding that is the difference between a rollout that gets adopted and one that stalls.
The effect, briefly
In a set of experiments, participants who assembled simple furniture themselves valued it substantially higher than identical pre-assembled items — and higher than experts valued it. The labour created the value in their eyes.
The finding generalises well beyond furniture. Effort invested in something changes how good we believe it is, independently of how good it actually is.
What it looks like in construction sales
The pattern is recognisable in almost every manufacturer:
The personal Excel file. Refined over years, colour-coded, with columns whose logic only its author fully knows. Genuinely useful, entirely personal, and defended with real conviction.
The saved search set. A rep has built twelve filters in a project database that produce a manageable feed. That the feed misses two-thirds of the relevant market is not visible from inside it.
The hand-built target list. Four hours of research produced forty accounts. A system producing a hundred scored accounts in seconds feels less trustworthy, not more.
The manually maintained key account overview. Someone updates it every Monday. It is out of date by Wednesday and still trusted more than a live view.
None of this is irrational stubbornness. It is a predictable feature of how people value their own work, and treating it as resistance is the mistake.
Why "here is something better" does not land
When you hand a rep a superior list and their reaction is scepticism rather than relief, three things are happening at once.
The effort is being written off. Accepting the new list implies the four hours were wasted. That is a loss, and losses feel larger than equivalent gains.
Verification is impossible from the inside. The rep can see their own list is good — they built it. They cannot see whether the new one is good without working it for months. Absent evidence, the familiar wins.
The skill was part of the identity. For a senior rep, knowing how to find the right projects is part of what makes them good. A system that does it removes a source of standing, unless it is framed as extending their reach rather than replacing their judgement.
How to work with it rather than against it
Four things, in order of effectiveness.
1. Do not ask them to abandon the list. Ask them to compare it. Import the rep's own list into the system and let it run alongside the automated feed for a month. Two outcomes, both useful: either the system finds projects the list missed, which is evidence rather than assertion, or the list holds up, and you have learned something about your scoring model.
This is why the ability to ingest projects from any source matters more than it sounds. Building Radar handles projects from inbound enquiries, key account information, distributor tips, uploads from other providers and site photographs through the same scoring as projects it discovered itself. The rep's spreadsheet does not become obsolete; it becomes an input.
2. Let the effort go somewhere valuable rather than nowhere. The judgement embedded in that list — which project types are worth pursuing, which practices are worth the drive — is real expertise. Capturing it as scoring criteria means the work was not wasted; it was promoted.
3. Start with the part they dislike. Nobody is attached to duplicate checking, contact research or CRM updates. Automating those creates no loss and demonstrates value before touching anything they built.
4. Involve senior reps before the decision, not after. The hardest person to bring onto a new system is usually the best rep, because they have already solved the problem for themselves. Asking them to change reads as criticism unless they helped choose.
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The version of this that costs money
There is a less sympathetic form of the same effect, and it is worth naming.
A manufacturer maintains a hand-built process because it was expensive to create — a custom CRM configuration, a bespoke reporting sheet, a qualification checklist someone spent a quarter designing. The sunk effort makes it feel valuable, and it becomes the reason not to change anything.
The test is the same as for the rep's spreadsheet: compare rather than argue. What share of relevant projects in your market does the current process surface? What is the average project stage at first contact? If those numbers are unknown, the process is being defended on the strength of the effort that built it.
What the comparison usually shows
When manufacturers run the parallel test, the pattern is consistent: the hand-built list is strong on the accounts the rep knows and blind to everything else. Coverage, not quality, is where it falls short — and coverage is invisible from inside a curated list.
Both come from seeing more of the market, not from working the known accounts harder.
Frequently asked questions
What is the IKEA effect? A cognitive bias in which people value things they partially assembled themselves more highly than identical items they did not build. It applies to processes and lists as much as to furniture.
Why do sales reps resist better project lists? Because accepting a new list implies their own effort was wasted, they cannot verify the new list's quality from the outside, and their skill at building it was part of their professional standing.
How do you introduce a new sales system to experienced reps? Run it alongside what they built rather than replacing it, start by automating the tasks nobody enjoys, and involve them before the buying decision rather than after.
Should you let reps keep their own lists? Yes, and ingest them. A list built from experience is a useful input, and treating it as one removes the conflict entirely.
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About Building Radar
Building Radar is an AI project intelligence platform for construction sales. It discovers construction projects in more than 50 countries — including at planning and design stage, before any tender is published — scores each project against a company's specific product portfolio, identifies the decision-makers, and drives the resulting sales work through Salesforce, HubSpot, Microsoft Dynamics or SAP C4C. Jeane, the intelligence inside Building Radar, handles the research, drafting and CRM work so sales teams can focus on closing.
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