Working with engineers
When a Building Problem Needs a Structural Engineer
Some cracks matter and most do not. The useful question is not how bad it looks, but whether anything is moving and whether somebody is going to ask you for a document.
The two real triggers
Movement, or a document somebody wants
Almost every legitimate reason to engage an engineer is one of these.
The first is evidence that something is moving or carrying more than it was built to carry. Movement is the concern rather than appearance, and the two are only loosely related. A dramatic looking crack in a finish can be nothing, and a barely visible pattern of movement in the right place can be significant.
The second is that a third party has asked for a sealed opinion. A lender before closing, an insurer before binding or when settling a claim, a building department before permitting an alteration, or an attorney in a dispute. In that case the question is not whether you need an engineer but which document is being asked for.
If neither applies, monitoring and time are often the correct answer, and an honest engineer will tell you so.
Signals
What is usually worth looking at
Not a diagnostic list. These are the observations that make a structural question reasonable.
Cracks that are widening over time, that run diagonally from the corners of openings, or that pass through masonry units rather than around them through the mortar. Cracks that appear on both sides of a wall in the same place. Separation at the junctions where a structure meets an addition.
Floors that slope enough to be felt rather than measured, that bounce noticeably under normal walking, or that have changed. Doors and windows across a whole elevation that begin to bind at the same time, which is different from one sticking door in humid weather.
Anything visibly deflecting that is meant to be straight, particularly a beam, a header over a wide opening, or a roof ridge. Rot or insect damage at a bearing point. Exposed reinforcement or spalling in coastal concrete, where the corrosion is doing structural work long before it looks serious.
Changes
Before you change what carries load
The cheapest structural engineering happens before the work, not after it.
Removing or opening a wall, cutting a new opening, adding a storey, converting an attic or a garage to habitable space, or hanging significant new load such as heavy equipment all change the load path. Whether a wall is load bearing is frequently not obvious from inside the room, and the confident answer from somebody who has not looked at the framing is worth nothing.
Adding rooftop equipment or a solar array is the same question in a form people rarely recognize as structural, because the array is light and the wind uplift on it is not.
In each of these the analysis is cheap relative to the work, and it is very cheap relative to discovering the answer afterwards.
Restraint
When you probably do not need one
This is worth saying plainly, because the incentive runs the other way.
Fine hairline cracking in drywall or in a stucco finish, without displacement and without a pattern, is usually a finish issue. Small stable cracks in a slab that have not changed are common. Seasonal door binding that comes and goes with humidity is usually humidity.
A single crack that is not moving, in a building where nothing else has changed, generally warrants a photograph with a date and a look again in six months rather than an engagement.
The reason to say this on a page like this one is that the reader is already worried, and a page that answers every worry with yes, engage somebody, is selling rather than advising.
First steps
What to have ready before you call anyone
Dated photographs, ideally showing whether anything has changed, are the single most useful thing a property owner can bring. Something in frame for scale helps. So does knowing roughly when the building was built, whether there have been additions, and whether anyone has done structural work before.
If a third party asked for this, get their requirement in writing. Lenders, insurers, and building departments ask for specific documents, and the difference between what someone assumed was wanted and what was actually asked for is a common cause of paying for the wrong thing twice.
Questions
Common questions
- How do I know whether a crack is serious?
- Change over time is the useful signal rather than size. A crack that is widening, that runs diagonally from the corner of an opening, or that passes through masonry units rather than the mortar joints is worth a professional opinion. A stable hairline crack in a finish usually is not.
- The buyer's lender is asking for a structural engineer's letter. What is that?
- It is a sealed written opinion from a licensed Professional Engineer addressing whatever the lender has raised. Get the requirement in writing from the lender before engaging anyone, because what is actually being asked for varies and the wrong document does not satisfy it.
Next
Where this leads
The rest of what a property owner needs before engaging anyone.
The background to all of this, including how an engineer differs from an inspector and what a sealed report will and will not tell you, is on what a structural engineer does. The companion question, what actually happens when a structural engineer inspects a house, is covered in what a structural inspection involves.
Start a job
Tell us what the letter is for and we will tell you yes or no
Send the address, what the document is for, and the date it has to be in hand. Some jobs this firm cannot take, and you will hear that in the first conversation rather than after you have paid and waited.