Builders work in connection is the building work required to accommodate services: holes, chases, notches, sleeves, supports, plinths, access panels, fire stopping and the making good that follows all of it.
It is required on every project, it is designed by nobody in particular, and it appears in the model almost never. That is why it is the most consistently omitted category in construction measurement.
Why nobody draws it
The services engineer designs the services and shows their routes. The architect designs the building and shows its construction. The connective work between the two is a consequence of both and the responsibility of neither at design stage.
It is usually resolved on site by the contractor, coordinating between trades. That works perfectly well as a construction method and it means the work is never described in a document that a quantity surveyor can measure from.
The result is that it either gets covered by an allowance, gets deemed included in somebody's rate, or gets missed entirely and arrives as a variation.
What it actually includes
Forming openings in walls, floors and roofs for ducts, pipes and cable routes. Chasing walls for concealed services and making good afterwards. Notching and drilling structural timber where permitted.
Sleeves and puddle flanges where services pass through waterproof construction. Supports, brackets, plinths and bases for plant. Access panels and hatches. Builder's work to riser and plant room walls.
Fire stopping around every penetration, which on a residential scheme is a substantial quantity in its own right and carries compliance consequences well beyond its cost.
Finally, making good every one of those interventions to the finished standard, which is often the largest part of the value.
The three ways it is handled
Measured, where the services design is developed enough to allow it. This is the most accurate and the least common, because the information usually arrives too late.
Deemed included in the services subcontractor's rates, which is workable if stated clearly and priced accordingly, and a source of argument where it is assumed rather than stated.
Carried as a percentage of the services value, which is the usual approach. It is defensible provided the percentage is applied to a services figure that is itself sound, and provided somebody has considered whether this scheme is typical.
The failure is the fourth option: nobody handles it, everybody assumes somebody else has, and it emerges during construction as a series of small variations that individually look trivial.
Where models make it worse
A model based take-off will not generate builder's work because the work is not in the model. The schedule produced will be complete, consistent and silent on the subject, which is more dangerous than a manual measure that visibly stops.
That is a specific instance of the general problem with model derived quantities, which is that absence looks identical to zero. The wider point is covered in BIM quantity take-off, what the model does not contain.
The practical check is to look for the item explicitly. If a bill produced from a model contains no builder's work line at all, it has not been considered rather than assessed as nil.
Fire stopping deserves separate treatment
Of everything in this category, fire stopping has moved furthest in recent years in terms of scrutiny, documentation and cost. It is no longer a minor making good item.
It requires the right product for the right construction and the right service, installed by a competent party, and recorded. The recording is a cost in itself and it is a cost with a compliance purpose rather than a commercial one.
Treating it as part of a general builder's work percentage understates it on most modern schemes, and it is worth pulling out as its own line wherever the penetration count is significant.
Mixed use compounds it
Where several uses share risers, plant and distribution, the connective work multiplies and so does the question of which use pays for it. A riser serving residential above a commercial podium generates builder's work in both.
Allocating that between uses is the same apportionment question that runs through mixed use cost planning, and it needs the same treatment: a stated basis, recorded on the face of the document.
The wider apportionment discipline is set out under mixed use and regeneration.
What this means for you
Look for the line. If your bill or cost plan does not contain builder's work in connection anywhere, it is not that the scheme does not need it.
If it is carried as a percentage, ask what the percentage was based on and whether anybody has looked at the services drawings. On a services heavy scheme the difference between a conventional percentage and a considered one is real money. Our approach sits under quantities and take-off.
Suspect your quantities are missing the connective work?
Send the bill and the services drawings. We will tell you what is covered and what has been assumed away.