What the Drawings Don’t Show

This is a portfolio sample for the Written Content offering. The source material was a fifteen-minute audio briefing from a structural engineer with fifteen years of field experience, along with a short set of appended notes — the same input a retainer client would supply. I had no prior knowledge of structural engineering. The article was produced from that material alone, with no external research.

Last year we took on what looked like a straightforward office renovation. The client wanted to open up the floor plan — remove some interior walls, create better flow between the main workspace and the conference area. The building was 1987 steel frame construction. We had the original drawings. It was a simple job.

We started coring and found a mezzanine. Someone had added it in the nineties — steel angles bolted to the existing columns, no permit, no drawings, no record of it anywhere in the building file. The entire load path was different from what we had calculated. We had to stop, reassess, and redesign the structural work from scratch. By the time we were done, the project had cost the client forty thousand dollars more than the contract price and three weeks of schedule he didn’t have.

This sort of situation is common with old buildings. The drawings show the original design, not how it was built, modified, and repaired over time. Undocumented additions. Deferred repairs made with whatever was available. Work that was code-compliant in 1985 and wouldn’t be permitted today. It is all in there, and the only way to find it is to look.

I have been doing structural work for fifteen years, and the pattern I see consistently is this: renovation risk is not symmetric. Best case, you commission a thorough existing conditions assessment, open the walls, and find everything exactly as expected. You do not save any money. You avoid losing it. There is no upside discovery scenario. The walls cannot reveal that the building is better than the drawings said. Understanding this should shape every decision you make before you sign a contract.

Two years ago we walked into a gut rehab of a 1920s building. The budget was sized for a six-month schedule. We opened the exterior walls and found that the original brick had been repointed with portland cement instead of lime mortar. Moisture was getting into the wood ledger boards carrying the floor joists for years, possibly decades. The ledgers were soft enough that you couldn’t drive a nail. We had to sister every joist on the affected side of the building and rebuild the ledger connections from the ground up. The six-month project took close to a year.

The problem was not negligence. The building was not poorly maintained. Someone, at some point, made a reasonable-seeming repair with the wrong material, and the consequence was invisible for thirty years. Until it wasn’t.

A few things follow from all of this that are worth stating plainly. Add twenty percent to your contractor’s bid before you decide whether the renovation is affordable. Not as a contingency you hope not to touch — as a baseline assumption. Industry data shows that sixty to eighty percent of commercial renovations encounter at least one significant undocumented condition. Not all of them are small ones.

Do not sign a fixed-price contract before a thorough existing conditions assessment has been completed. A contractor willing to give you a firm number without knowing what is inside the walls is either planning to recover unexpected costs through change orders after the work has started, or has not done enough projects like this to know what they do not know.

Assume your schedule will slip. On any project involving structural work or load-bearing modification, add at least six weeks to whatever your contractor estimates. This is not pessimism. It is the consistent reality of renovation, and owners who plan for it make better decisions than owners who hope they will be the exception.

One more thing, and it is the one I have watched cause the most damage in recent years. Plan review times have tripled in most jurisdictions since the pandemic. Municipalities are understaffed, and permit review for any structural modification now runs twelve to sixteen weeks in most places, longer in some. A contractor who tells you to budget six weeks for permits is working from outdated experience. We have watched clients receive permit approval after their general contractor had already committed to another project. The schedule is gone. The contractor relationship has to be rebuilt from scratch, which will delay you by months.

Renovation is not unpredictable. The direction of risk is known and the preparation is straightforward. The owners who go in understanding this sign better contracts, carry better contingencies, and do not lose their contractors to permit delays they did not see coming. The surprise is rarely the building. It is the assumption that the drawings tell the whole story.