Corven & Ashby, cost and risk advisory

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Constructability and Interface Review

The commercial gaps between packages, not clash detection.

How we are set up:

  • We act on the owner’s side only
  • No fee is tied to what the review concludes
What it covers

Clash detection finds two objects in one space. We look for scope in nobody’s package

Where one trade’s package stops, the next one’s is assumed to start. The distance between them is often priced by neither side. That is not a drawing error, and no model will flag it.

Those gaps are commercial rather than geometric. They arrive as change orders in month four, when somebody finally has to build the joint and discovers that two scopes of work both point at each other.

We find them while the price is still open, when a gap is a negotiation instead of a change order.

What you send us
Every trade package scope of work The scope matrix, if one exists The drawing set The specification The schedule of values The qualifications list for each major trade

Send what you have. A document that does not exist yet is itself a finding, and we will say so rather than wait for it.

What we read

Six things we open first

The order matters. These six carry most of the exposure on most projects, so they come before anything else in the set.

Package boundaries

Where each trade package is written to stop, read against where the next one is written to begin. The two rarely meet exactly, and the distance between them is the finding.

Orphan scope

Work that appears on the drawings but sits inside nobody’s scope of work. It is on the job, it will be built, and at the moment nobody has priced it.

Double exclusions

Interfaces excluded by the trade on one side and excluded again by the trade on the other. Both exclusions are legitimate. Together they are an owner cost.

Access and sequence

What each package assumes about access, protection and the condition it inherits from the trade before it. An assumption about a clean, dry, level surface is a price.

Attachment and support

Who supplies the steel, who supplies the fixing, and who is assumed to have set it out. Three questions, and on most jobs at least one of them has no answer.

Testing and commissioning

Who proves the assembly works where two trades meet, and who pays when it does not work the first time. Fire stopping and building envelope tests are where this bites hardest.

How we read it

The method, and its limits

What a review is worth depends as much on what it refuses to do as on what it covers.

What we do

Read every package scope against the two packages on either side of it, then against the drawings that show the joint between them.

What we do not do

We do not run clash detection, we do not review the design, and we do not comment on whether a detail is buildable. Those are questions for your engineer and your architect.

What decides the order

Frequency multiplied by cost. A small gap repeated across two hundred openings outranks a large gap that happens once in the lobby.

One line from a register

What a finding looks like

A curtain wall package that excludes the internal perimeter closure. A drywall package that excludes work inside the curtain wall zone. The closure appears on the drawings on every floor of the building, and neither scope of work includes it.

What the finding is worth $40k to $70k per floor

Example only. Figures on this site illustrate the format of a deliverable. They are not taken from a client project and they are not a quotation.

What lands on your desk

Documents, not opinions

Every finding carries the money behind it and points to the page of the set it came from. One call to walk it through, before your signing date.

Interface Gap Register

Each gap, the two packages it sits between, the drawing that shows it, and what closing it is likely to cost.

01

Package Boundary Map

Where the scope lines fall across the job, drawn so that the gaps are visible at a glance rather than buried in six scope documents.

02

Owner Memo

The gaps worth closing in the contract rather than in the field, with the scope language that closes them.

03
Before you commission it

Questions owners ask

Run it once the trade packages are bought or close to bought, and before the guaranteed maximum price is fixed. Earlier than that the scopes are still moving. Later than that the gaps have already been priced against you.

Is this a BIM or clash review?

No. A clash review is geometric and your design team should already be running one. This one reads scope documents, and the two find completely different problems.

Do you mark up drawings?

We reference them. Each gap points to the drawing and to the two package scopes that leave it open, so anybody can check the finding without taking our word for it.

How long does it take?

Ten to fifteen working days on a typical building, because the work scales with the number of packages rather than the value of the job.

Can this run after award?

It can, and it is still worth doing. It is worth more before, because before award a gap is a negotiation and after award it is a change order with a markup on top.

What if you find nothing?

On a well written package set the gaps are fewer and smaller, and the memo says so. We are paid the same either way.

A gap between two packages is priced by nobody and paid for by you

How this one is bought One

Take this module on its own, or take all four as a single review with one consolidated owner memo.

See the packages
The other modules

Same set of documents, read from a different side

If you are not sure which module answers your question, send the documents and we will say which one we would run first.

All four modules