Last updated: May 2026
A specification gets written. Your product is on the drawings. Six months later, the order goes to a competitor. Or worse, an import you've never heard of. The rep is doing everything right and losing the deal at the last gate.
That's spec leakage. It's the most common pain I hear from Sales Directors in building products, and I've yet to meet one whose hiring process is built to fix it.
This post is for hiring managers, GMs and MDs who keep wondering why their team hits specification activity targets but misses revenue. The diagnosis is usually upstream of the rep. It's in the brief, the interview process, and what gets weighted as "good." Most of you will spot at least one fix you can make tomorrow.
What is specification leakage in building products sales?
Specification leakage is when a product gets specified at the design stage, then gets substituted at the procurement or site stage for something cheaper. The rep wins the spec. The company loses the order.
It happens at the gap between two worlds. The architect, engineer, designer or specifier who writes the spec is solving for performance, compliance and aesthetics. The contractor, builder, QS or procurement team who buys the product is solving for cost and program. When those interests diverge, the spec gets value engineered. Your rep finds out about it after the fact, usually from a phone call that starts with "mate, just so you know..."
In construction chemicals it shows up as a specified membrane swapped for a cheaper sheet. In lighting it's a non-compliant import dropped in at tender. In facades it's a value-engineered cladding that may not meet AS 5113. In civil it's a substitution that procurement ran past the contractor in a budget meeting your rep wasn't in. Same disease, different sector.
How much does one lost spec actually cost a manufacturer?
More than most companies have ever sat down and worked out. The headline number is the gross margin on the lost order. That's the easiest figure to calculate and the one most Sales Directors stop at.
The real cost stack runs deeper:
- Gross margin on the lost order, the obvious one
- Commission already paid against activity that produced no revenue
- The rep's hours invested over the spec cycle, which in chemicals and envelope can be 12 to 36 months
- Damage to the relationship with the specifier, who now has to explain to their client why their preferred product wasn't used
- Opportunity cost of that rep's time, which they spent on a spec that didn't convert instead of one that might have
- Downstream revenue from that specifier, who is less likely to push hard for your product on the next job
A worked example. A $400,000 spec at 35% gross margin is $140,000 of margin gone when the substitute wins. Five of those a year per rep across a six-rep team adds up to $4.2m in lost margin before commission, time and downstream revenue. The numbers are illustrative, not industry research, but the order of magnitude is real. I don't talk to a Sales Director who has run the calculation against their own pipeline and isn't slightly horrified by the result.
It almost always exceeds the cost of the hiring process that produced the team. Which is the point of this post.
If you want a rougher cost-per-bad-hire framing, I built a calculator for that. The spec leakage cost sits next to it, not inside it.
Which rep capabilities actually defend a specification?
Four of them. Most hiring processes test for one and a half. That's the gap.
1. Technical reasoning under pressure
Can the rep defend the spec on technical grounds when challenged? Not the same as explaining the product. When a QS comes back with "we've got something that does the same thing for 30% less," can your rep walk through why that substitute fails AS 4654 in this application, or why it changes the warranty position, or why the failure mode under load is different?
This is the capability most companies test for in interviews. Usually badly. They ask the candidate to talk them through their product knowledge instead of putting them in a defended-spec scenario and watching what happens.
2. Commercial grit
Will they fight for the order when value engineering hits? Or will they let it go and tell themselves the deal "wasn't ready"?
Commercial grit is uncomfortable to test for in an interview because it shows up under pressure, not under polite conversation. The fastest way to get a read is a role play where the candidate has to defend a spec against a bullish QS or builder pushing for a substitution. The rep who folds in 30 seconds will fold in the field. The one who pushes back without losing the relationship is the rare hire you actually want.
3. Contractor-channel literacy
Do they understand who actually buys the product, and how those buyers think? A rep who only speaks specifier won't see the substitution coming. They'll be surprised by it every time.
This means understanding contractor procurement processes, how QS departments work, where substitutions get approved, what role the project manager plays in the call, and how distribution and merchant channels decide what to stock and push. In civil this matters more than anywhere else. In commercial interiors it's the dual-channel demand of design-led A&D firms and price-led fitout contractors that kills reps who only know one side.
Here's the line I keep coming back to: it's much easier to teach someone with industry experience how to do sales than it is to teach someone with sales experience how the industry works. That's what contractor-channel literacy looks like. It compounds slowly. It's almost impossible to fake in an interview, and almost impossible to teach to a charismatic outsider in the first 12 months.
4. Value-defence framing
Can they reframe a price conversation into a total-cost or risk conversation, in language the buyer respects?
Generic salespeople do this badly. They say "you get what you pay for" or "it's an investment." Buyers stopped listening to that 20 years ago. Effective value-defence framing names a specific failure mode the cheaper product is exposed to, calculates the cost of that failure, and prices the spec accordingly. It separates a rep who's defending a position from one who's apologising for the price.
In waterproofing, this sounds like "if this fails in five years, the rectification on a 30-storey strata building runs into seven figures, and the developer's PI insurance probably won't cover it because the system wasn't installed to AS 4654." That's value defence. Anything weaker than that won't survive contact with a procurement team in 2026.
How does spec leakage show up in construction chemicals?
It's the dominant sales problem in the sector. NSW Building Commission research on serious strata defects found waterproofing issues account for 42% of cases, the single largest category, with fire safety systems at 24% and building enclosures at 19%. The 2023 survey also found 53% of strata buildings in New South Wales had serious defects.
What that means for your reps: every spec is loaded with liability. A substitution at site isn't only a margin loss. It's a risk transfer back to the developer and the certifier, and your rep's failure to defend the spec is the moment that risk shifts. Hiring managers in chemicals need reps who can have that conversation in language that lands with a builder, not just a specifier.
The chemicals-specific complication is the specifier-installer-distributor triad. Three relationship surfaces. Three failure modes. There's a fourth constraint sitting underneath all three: the qualified applicator pool itself is shrinking, which means the spec can be won, the order placed, and the install can still stall. The applicator shortage and what it does to a sale is here. A rep who only manages the specifier loses to substitution. A rep who only manages the installer never gets onto the spec. The hiring profile has to weight all three, which most job ads don't.
More on civil and chemicals hiring
How does spec leakage show up in building envelope and facades?
In envelope, spec defence is compliance protection. Post-Grenfell and post-Lacrosse, value engineering on cladding can be a criminal liability question, not a margin one. A rep who lets a non-compliant substitution through is exposing the certifier and ultimately the principal contractor. Your reputation as a manufacturer travels with that decision.
The technical bar matters more here than in any other sector. Specified Select's own internal estimate, drawn from sector hiring activity, suggests around 80% of building envelope hiring cycles run aground on the technical-sales capability gap. Hiring managers can't find candidates who combine engineering literacy with commercial drive.
There's a recurring market read in the Australian Design Review on the wider A&D talent pool: "Studios are chasing capability that simply does not exist in sufficient volume, particularly at the mid level where project delivery experience holds the greatest value." The same shortage shows up in envelope sales hiring. The mid-level rep who can read a Section J thermal calc and a fire engineering report is the one you can't find. If you're hiring for this profile, here's how to hire for envelope compliance literacy.
The compliance-specific layer of this - where wrong NCC citations accelerate leakage and, increasingly, trigger defect liability - is covered in the NCC 2022 hiring guide.
How does spec leakage show up in civil and infrastructure?
The civil version of spec leakage is different. The order doesn't usually go to a substitute at site. It gets shaped before tender by a supplier who got there first. By the time the RFQ lands, the work has already been allocated in everything but signature.
That changes what defending the spec means. The defence happens 12 to 18 months earlier, in the engineering office or the asset owner's planning meeting. Hiring civil BDMs without testing for pre-tender capability means you've hired for the wrong job. You wanted someone who shapes specs. You got someone who quotes specs. The market is full of the second and short on the first.
How does spec leakage show up in commercial interiors?
In interiors, the leak runs between the design firm and the fitout contractor. Your rep wins the design conversation. The contractor swaps the product on the way to site, often without telling anyone, sometimes for stock reasons rather than cost. The aesthetic gets close enough that the designer doesn't kick up a fuss.
The dual-channel demand is what kills reps who only know one side. They navigate design-led A&D firms and price-led fitout contractors, or they fail. Mid-level interiors reps in Brisbane and Sydney are fielding multiple offers within days of going to market. The squeeze is real and it's getting harder, not easier. The retention side of the same problem is covered in why your best A&D reps are leaving.
How does spec leakage show up in lighting?
Lighting spec leakage is a cheaper non-compliant import getting dropped in at tender. The lighting designer wins the spec at design stage. The contractor or electrician finds something through a low-cost importer that "looks the same" and runs it past the principal. If your rep isn't there, it goes through.
The IESANZ designer community is small enough that reputation effects are immediate. A rep who keeps losing specs gets a reputation for "not defending", and that reputation reaches the next designer they meet before they do. In a community this tight, hiring a rep who can't defend specs is hiring a problem you can't quietly fix later.
In lighting, this typically plays out at value engineering when a contractor proposes a cheaper non-compliant import - the full lighting-specific pattern is here.
What interview questions actually test for spec defence capability?
The questions you're using probably don't. Most building products interview processes test for product knowledge, sales activity history, and "fit." Those test for one and a half of the four capabilities at most.
The questions that work pressure-test the candidate against a defended-spec scenario. Walk-through scenarios with hostile reframing. Try this one in your next interview round: "You've spec'd Product A on a $20m hospital project. The QS has come back with a substitution from Manufacturer B at 30% less. The builder's program is tight. What's your call in the next 48 hours, and what's the email you send the architect?" The good answer is specific, technical, and shows the rep already has the relationships they need to make the call.
I keep a running list of the questions I've seen separate strong spec-defending reps from average ones. The full set is here. Worth running before your next interview round, even if you don't change anything else about your process.
Why is spec leakage a hiring problem, not a rep problem?
Most Sales Directors I talk to start the conversation by blaming reps. "We're losing too many specs at site." Two questions in, the conversation usually shifts to onboarding, sales training, then commission, then leadership. Three or four conversations in with the same MD and we eventually land on the hiring process.
You hired the rep you have. You wrote the brief, picked the criteria, designed the interview, made the call on the offer. If your reps consistently lose specs at the substitution stage, the hiring profile is selecting for the wrong things. Possibly product knowledge over commercial grit. Possibly likeability over technical reasoning. Possibly tenure in your specific category over contractor-channel literacy.
Generic recruiters can't tell you this because they don't know what spec defence looks like in your sector. They'll send you reps who interview well and lose specs. The fix is upstream, in the brief and the interview, not in the rep you've already hired.
If you've placed someone in the last 12 months and you're not seeing spec defence behaviour, the rep probably isn't the problem. Look at the brief that got them through your process.
Most spec losses aren't a rep problem. They're a hiring problem. Specialist hiring is the structural fix for leakage. The full case for why I built around that is in why I built a specialist building products recruitment agency.
Frequently asked questions
What is specification leakage in building products?
Specification leakage is when a product gets specified at design stage by an architect, engineer or designer, then gets substituted at procurement or site stage for a cheaper alternative. The manufacturer wins the spec but loses the order. It's the most common revenue leak in technical building products sales.
Why do reps lose specs at site even when they win at design?
Because design and procurement are different conversations with different incentives. The designer is solving for performance, compliance and aesthetics. The contractor or QS is solving for cost and program. Without a rep with commercial grit and contractor-channel literacy at the procurement stage, the spec gets value engineered.
How can I tell if my reps can actually defend a specification?
Run a defended-spec role play in the interview. Give the candidate a scenario where a QS or builder is pushing for a substitution and watch how they respond. The strong ones reframe the conversation around failure modes, compliance risk and total cost. The weak ones either fold quickly or default to "let me check with my manager."
What's the most expensive sector for spec leakage?
Construction chemicals and building envelope. Both carry liability exposure on top of the margin loss, because substitutions can compromise compliance and warranty. In waterproofing, the cost of a future defect on a multi-storey building can run into seven figures. Civil is also expensive but for a different reason: the work gets shaped pre-tender, and reps who only respond to RFQs don't see the loss happening.
Are spec losses a hiring problem or a sales management problem?
Both, with hiring upstream. If your hiring brief weights the wrong things, no amount of sales management will close the gap. The four capabilities that defend specs (technical reasoning, commercial grit, contractor-channel literacy, value-defence framing) are mostly hired for, not trained in. Get the brief right and the rest of the management job becomes possible.
How long does it take to ramp a rep into spec defence capability?
12 to 18 months in most building products sectors, longer in chemicals and facades. That's the runway for a strong technical hire coming from an adjacent product. For a non-industry hire you're looking at 24 to 36 months and a meaningful drop-out risk.
Related reading: the difference between the two roles that bleed specifications.
Spec leakage is one of seven components in the all-in cost of replacing a sales rep - the full 8-lever retention framework that prevents it is here: How to Retain Sales Reps in Australian Building Products.
For the sector-specific hiring lens, see the civil sales recruitment guide.