Vertical Duct Is Accumulating Elevation Error Floor by Floor

The riser is now off at the fourth floor even though each joint looked close. I rechecked from the floor benchmark and found the error has accumulated. Where do you want the correction made?

Measuring, Field Verification & Layout Marks 2nd Year YELLOW

Stop if

Stop before changing structural support, rated construction, equipment handling, specialty materials, weatherproofing, engineered movement details, or manufacturer-specific requirements without the responsible direction.

Watch out

Do not hide cumulative error by squeezing every joint or changing several fittings without a measured correction plan.

Check

current drawings and approved details
grid/floor/location and measured conditions
photos showing the installation condition
relevant manufacturer, structural, architectural, or finish information
what has already been checked

Say this to your foreman

vertical duct is accumulating elevation error floor by floor vertical riser cumulative elevation error floor by floor duct stop chaining each new section from the last joint. re-establish the riser from the project benchmark, floor elevations, and intended connection points, then determine where the accumulated error began. the riser is now off at the fourth floor even though each joint looked close. i rechecked from the floor benchmark and found the error has accumulated. where do you want the correction made?

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