VENTTOOLS SITE KNOWLEDGE

Practical ventilation and ductwork guides

These are the measurements, checks and distinctions that matter when ductwork and fire dampers move from a drawing to an actual opening, ceiling void or plantroom.

Written by VentTools18+ years in ventilation installationNorthern Ireland

Built around real site decisions

VentTools guides are not written to pad out search results. Each one supports a working calculator or a recurring installation problem: measuring a rolled offset, identifying the correct bend take-off, keeping a replacement duct size practical, or separating a fire damper's nominal duct from its casing and structural opening.

General ductwork guidance is based on site experience and transparent geometry. Manufacturer-specific life-safety information is kept separate and must be checked against the current installation manual, approved project detail and fire strategy.

Choose a guide

How to measure a ductwork offsetRise, sideways movement, true resultant, travel and the straight cut between two bends. Pressed and lockseamed bend take-offsWhy centreline radius and a finished fitting's published take-off are related but not interchangeable. Fire damper opening and setting-out chainNominal duct, casing, clearance, finished aperture, lining and structural hole kept separate. Round to rectangular duct conversionEqual area, practical 25 mm sizes, aspect ratio and what still needs designer approval. Fire damper installation QA checklistA stage-by-stage check before installation, before closing the wall and before handover. How VentTools verifies engineering dataSupported product families, audit controls, source status and deliberately disabled calculations.

Corrections are treated as engineering work

If a dimension, product description or installation method appears wrong, report the exact manufacturer, model, document revision and selected method to info@venttools.com. A disputed value is checked against its controlling source before the calculator is changed.