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Thresholds for exterior doors without leaks. How an Alumaster audit helped improve production.

A manufacturer of entrance doors was struggling with complaints and leaks in the threshold area. An Alumaster audit and training streamlined the installation process, restoring tightness and bringing peace back to production.

Thresholds for exterior doors — the importance of installation standards

After the audit and training, we streamlined the production process

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eliminated irregularities

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sealed zones

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authorized inspection — airtight thresholds

Combi thresholds guarantee barrier-free performance and tightness

Initial situation

One of the PVC door manufacturers (single-sash, inward-opening, VEKA SL70 profile) received a serious complaint from an end user: leaks occurring in the threshold area. The issue escalated quickly — the sales department received a pre-litigation letter, and the production team faced stress and pressure to clarify the problem as soon as possible.

As it turned out, the production team had used the full set of our components (low threshold, connectors, drip cap). The very first review revealed a clear mismatch: the components were well selected, but the installation standard across production teams was inconsistent. Seemingly minor details — no silicone in the connector channels or at the drip cap–sash interface, no drainage holes, and regular screws instead of INOX — accumulated into real issues: water was finding its way through, and during heavy rainfall streaks and moisture appeared at the floor level.

Instead of asking “which solution should we choose,” we moved together to a more important question: how to correctly install and seal the threshold so that it works in harmony with the frame, does not hinder the sash during closing, and maintains tightness under changing outdoor conditions. An additional challenge turned out to be the lack of a consistent quality checklist for the production process.

Solution implemented by Alumaster

1) Production audit and diagnosis
Together with the technologist, we went through the entire manufacturing cycle of the entrance door at the workstation:

we identified 3 critical zones: connector–threshold (SH channels), drip cap–sash, drip cap–end caps,
we verified the sequence of operations at the threshold and its compatibility with the frame,
we checked the drainage system.

2) Technical corrections – materials, tools, control points
We implemented a set of precise actions directly on the production line: silicone in the connector channels, sealing of the drip cap, drainage holes, INOX stainless-steel screws for drip caps and end caps — eliminating the risk of corrosion and threshold contamination. We defined the correct order of installing the threshold and sash, as well as hardware adjustment.

3) We conducted a step-by-step training session on the production line

4) After implementing the improvements, we returned to the factory floor and inspected a random sample from the current production batch.

VEKA

Result of the cooperation

Leaks eliminated, reduced heat loss — the entrance door regained stable tightness, with noticeable thermal and acoustic comfort (less noise and dust inside the rooms).

Consistent installation standard — a clear checklist and defined control stages that shorten working time and reduce the risk of errors; exterior door thresholds installed “equally well” on every shift.

Fewer complaints, greater durability — proper sealing and components (inox, drainage) that increase resistance to moisture, abrasion, mechanical damage, and harsh weather conditions.

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irregularities before the audit

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Audit plus training

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compliance — certified performance

Benefits resulting from the tests

Fewer complaints, more peace of mind.

Properly installed exterior door thresholds deliver: they provide tightness, a clean threshold, and comfortable use with every closing.

Everyday durability.

A solution resistant to abrasion, dirt, and changing weather conditions; it performs reliably both in private homes and in facilities with higher operating loads.

Operating efficiency.

Proper threshold installation reduces heat loss and service costs; it delivers real value regardless of the joinery type (aluminium, wood, PVC).

What our process looked like

1

Diagnosis.

Line audit: verification of the threshold, drip caps, connectors, and hardware, and compatibility with the frame.

2

Correction and standardization.

Sealing, drainage, stainless-steel screws, quality checklist; additionally, guidance on selecting the appropriate threshold for the specific profile.

3

Acceptance and consolidation.

Post-correction tests, team instructions, and ongoing control in subsequent production batches.

Would you like to see how the COMBI system can optimize your production as well?

We are happy to share our experience and help you choose a solution tailored to your door designs.

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