A number everyone quotes, but almost no one has actually measured

Ask anyone in construction how much material gets wasted on a typical project, and you'll get a confident answer — often a round number like "10%" or "15%." What you rarely get is a number backed by measurement. In our earlier study on Egypt's construction sector, we mapped out why waste happens — the human, managerial, and site-level causes. But that left an obvious follow-up question unanswered: how much material is actually being lost, material by material, and can we trust what practitioners tell us against what actually happens on real sites?

Building in a reality check

This time, we didn't just ask 113 professionals to estimate waste rates across 14 commonly used materials — from ready-mix concrete and steel reinforcement to sand, mortar, tiles, and paints. We also went and got the receipts. Working with a first-grade contractor, we pulled actual procurement and quantity-surveyor records from three live projects — two bridges and one commercial building in Cairo — and compared what the survey respondents believed was being wasted against what the paperwork actually showed.

That's a step a lot of construction-waste research skips, understandably, because it's slow and depends on contractors being willing to open their books. We also ran the questionnaire itself through a validation process most survey-based studies don't bother with — pilot testing with ten professionals, expert review, and Cronbach's alpha reliability checks — before sending it out to 250 professionals.

What the numbers actually showed

The headline result: estimated waste across materials clustered between 5% and 9% — moderate, not dramatic, but financially real given how much of a project's budget goes into materials. Sand came out worst at 8.56% average waste, followed closely by mortar (8.13%) and masonry (7.94%). On the other end, reinforcement steel was the best-controlled material at just 5.15% — likely because it's expensive enough, and easy enough to track by weight, that sites already treat it carefully.

The part we found most reassuring — and slightly humbling — was the validation step. When we compared survey estimates against the real project data, the two datasets showed a moderate positive correlation (r = 0.62). They didn't match perfectly (there's real variation between, say, a bridge project's deep-foundation concrete waste and a commercial building's), but they moved together well enough to suggest that when practitioners estimate waste, they're not just guessing — they have a reasonably accurate feel for what's actually happening on their sites.

The trust gap: contractors, subcontractors, and owners

One finding that stood out beyond the raw numbers: main contractors were named as both the biggest source of waste (53.1%) and the group most willing to do something about it (55.8%) — a fairly healthy alignment between responsibility and motivation. Subcontractors didn't fare as well: seen as significant contributors to waste, but less willing to act on it, which points to a familiar problem — oversight and accountability don't always reach down to the subcontractor level. Interestingly, project owners, despite having the least hands-on operational role, were seen as more willing to support waste reduction than their day-to-day involvement would suggest — probably driven by reputational or strategic incentives rather than site-level pressure.

Why this matters beyond the numbers

Beyond quantifying waste, respondents estimated that better site controls and management practices could realistically cut overall waste by around 27% — a meaningful number when you consider that materials often account for 50–60% of total project costs. But we were also careful not to oversell that figure: it's an aspirational, stakeholder-estimated ceiling, not a guaranteed outcome, and the sector's own "readiness" to embrace circular-economy practices scored only moderately, with a lot of uncertainty rather than resistance.

Where this leaves us

Taken together with our earlier paper on the causes of waste, this study starts to build something Egypt's construction sector has lacked: an empirically grounded, materially specific benchmark for where waste actually happens and how much it costs. The next step, we think, is turning these numbers into something actionable — material-specific benchmarks that policymakers and contractors can actually measure themselves against, rather than working off the round numbers everyone's been quoting for years.

Read the full paper, "Assessing construction material waste in Egypt through stakeholder estimation," open access in Discover Sustainability (2026) 7:328. https://doi.org/10.1007/s43621-026-02602-5

Authors: Mohamed M. Ghoneim, Abbas Atef Hassan, Osama Morsy Moussa & Ayman Halabya, Department of Civil Engineering, Military Technical College, Cairo, Egypt / Department of Architecture and Urban Planning, Port Said University, Egypt