When the excavator hits rock the soils report did not show, or the siding comes off to reveal rot the drawings never mentioned, the change order is won or lost in the next few hours. Stop work in that area. Photograph it undisturbed. Send written notice to the owner before anyone continues. Carrying on and pricing it afterwards destroys the one thing the claim depends on — proof of what was there before you touched it.
Most differing site conditions construction disputes are not about whether the rock was there. They are about how much of it there was, whether the documents should have warned the builder and whether the owner was given a fair chance to look. Every one of those questions is answered by evidence that disappears once the area is dug out, hauled away or framed over.
What counts as a differing site condition
Contracts that address this usually split it into two types. The wording varies, but the logic is consistent.
- Type I — the condition differs materially from what the contract documents showed or indicated. Rock at 3 feet when the boring log showed clay to 8 feet. A footing drawn on native soil that turns out to be fill.
- Type II — the condition is unknown, unusual and differs materially from what is ordinarily found in that kind of work, even if the documents said nothing about it. A buried fuel tank. A slab of old foundation under a lawn. Undocumented utilities crossing the footprint.
On remodels the common cases are hidden: rot in a sill plate behind sound-looking siding, knob-and-tube wiring in a wall the scope assumed was current, joists notched to half their depth by a previous plumber. Whether these qualify depends on what the documents said and what a reasonable builder would have expected in a house of that age. That argument is far easier to make with photographs of the condition as found.
What does not count: conditions a site visit would have revealed, conditions the documents disclosed and the bid ignored, and ordinary variation the contract put on the builder. If the specification said to expect some rock and include rock removal in the price, there is no claim for rock.
Why the first hours decide the claim
The purpose of a notice requirement is to let the owner see the condition and decide what to do about it while there are still choices. Move the footing. Redesign the drainage. Accept the added cost. Bring in an engineer. Once the rock is broken and trucked off, none of those options exist and the owner's only remaining move is to dispute the bill.
That is why the language matters. The AIA A201 general conditions, widely used on commercial work, require the contractor to give notice before conditions are disturbed and in no event later than 14 days after first observance. Federal contracts carry a similar requirement. The key phrase in both is before conditions are disturbed. A builder who notices rock on Monday, keeps digging through Wednesday and writes it up Friday may be inside 14 days and still outside the clause.
There is also a quantity problem. A change order for unexpected rock is priced on volume, hours and equipment. Without photographs and measurements taken before excavation, the volume becomes an estimate the owner has every reason to doubt. Five truckloads becomes a number on an invoice rather than a documented fact.
Keeping the crew moving to protect the schedule, then sending a price once the work is done. It feels responsible. It hands the owner a clean defence — no notice, no chance to inspect and no way to verify the quantity — and it turns a compensable condition into an absorbed cost.
The first-hours sequence
This is the order that holds up. It fits on one laminated card in the truck.
- Stop work in the affected area only. Not the whole job. Move the crew to other work where possible and note the time the stop began.
- Leave it undisturbed. Do not break, remove, patch or cover anything. If safety requires shoring or a barrier, install it and photograph that too.
- Photograph it properly. Wide shot showing location on the site, medium shot showing extent, close shots showing the material. Put a tape measure, grade stake or scale in frame. Note gridlines, stakes or room names.
- Find the document it contradicts. Write down the sheet number, detail, boring log or specification section that showed something different. This is what makes a Type I claim.
- Send written notice the same day. Email counts if the contract allows it. A phone call does not, though you should make one as well.
- Invite inspection. Ask the owner, architect or engineer to see it, and record when they came or that they declined.
- Open a separate cost code. Labour, equipment, standby time and material for this condition are tracked separately from the first hour, not reconstructed later.
- Resume only on a documented direction — a written instruction, a change order or a directive — or after the inspection window you named has passed.
Step 3 is where most claims quietly fail. Phone photos with no scale, no location and no date context prove that rock exists somewhere. There is more on photographing site conditions so the images hold up later, including how to keep them attached to the right job and date.
What the written notice should say
Notice is not a claim and it is not a price. It is a dated statement of fact that preserves the right to ask for one. It can be four or five sentences.
- What was found — rock, buried concrete, rot in the sill, undocumented gas line.
- Where — address, area, gridline or room, with photographs attached.
- When it was first observed — date and time.
- What the documents showed — sheet, detail or report reference.
- What has been done — work stopped in that area, condition left undisturbed, crew reassigned.
- What is needed — inspection by a named date and direction on how to proceed.
- A reservation — a sentence stating that cost and schedule impacts will follow once the extent is known.
Leave out opinions about who is at fault and leave out numbers you have not worked out. A rough figure written in a hurry becomes the figure the owner holds you to.
Pricing comes after, and that is fine
Builders often delay notice because they do not have a price yet. That gets the order backwards. Notice protects entitlement. Pricing establishes amount. The second can follow by days or weeks without damaging the first, provided the costs were tracked from the start under their own code.
When it is time to price it, build the number from the actual hours, equipment and disposal tickets, plus standby and schedule effects, and apply the markup the contract allows. The method for that is covered in how to price a change order line by line. Disposal tickets and equipment logs from the separate cost code are what make the number defensible.
If the owner agrees the work must proceed but will not agree the price, the usual tool is a directive rather than a stalemate. A construction change directive lets the work continue on a documented instruction while cost is tracked and settled afterwards — which only works if the cost code was opened on day one.
What does not protect you
- A text to the homeowner — it may count as notice in some disputes, but it rarely says where, what or which document was contradicted.
- A mention in the daily log only — a log is evidence, not notice. The owner has to be told.
- Telling the site super for the owner — unless the contract names that person as the one who receives notice, it may not count.
- Photos taken after excavation — they show a hole. They do not show what was in it.
- A contract without a clause — many residential agreements say nothing about differing site conditions. On a fixed price job with no clause, the risk usually sits with the builder. Better to know that before the dig than after.
None of this is legal advice. Notice periods, recipients and permitted methods are set by your contract and the law where the job is. Read the clause before the job starts, not when the bucket hits rock.
How this runs in BuilderSolve
The daily log is where the condition is recorded on the day it is found — time, location, crew and photos together on the job. From that entry the AI assistant can draft the change order and the schedule shift for the area that stopped. Nothing is sent or applied until a person approves or rejects the draft. The change order carries an audit trail, so the date notice went out and the date the owner responded are fixed rather than remembered.
The branded client portal gives the owner one place to see the photos and the change order rather than a scattered thread of texts. Budget vs. actual shows the separate cost code climbing in real time. QuickBooks stays the book of record — the platform reads from it in one direction and does not write back.
For builders who want the paperwork handled, the BuilderSolve operations and admin team drafts the written notice from the field photos and log, and the finance team builds the change order pricing from the tracked costs. What the platform and team do not do is decide whether the condition is compensable under your contract. That is a contract question, and on a large one it is worth a lawyer's hour.
What to do before the next dig
- Pull the contract for every active job with excavation or demolition left. Find the differing site conditions or concealed conditions clause, or confirm there is none.
- Write down the notice period, the named recipient and the permitted method for each.
- Put a one-page notice template on every super's phone with the seven items above.
- Set up a standing cost code for unforeseen conditions so it exists before it is needed.
- Tell the crews the rule in one line — if it is not on the drawings, stop that area and call before you dig further.
Common questions
what is a differing site condition in construction
A differing site condition is a physical condition on site that differs materially from what the contract documents showed, or an unusual unknown condition not ordinarily expected in that kind of work. Common examples are rock where borings showed clay, buried foundations or debris, undocumented utilities and concealed rot in a remodel. Whether it is compensable depends on the contract language and on prompt written notice.
how long do you have to give notice of differing site conditions
It depends on the contract, but the safest answer is before the condition is disturbed. The AIA A201 general conditions require notice before conditions are disturbed and no later than 14 days after first observance. Many residential contracts set shorter periods or have no clause at all, so read your own agreement before work starts.
do I need a price before sending differing site conditions notice
No. Notice preserves the right to claim and should be sent the same day the condition is found. Pricing follows once the extent is known and costs have been tracked under a separate cost code. Sending a rushed figure with the notice often backfires because the owner treats that early number as the ceiling.
can I keep working after finding a differing site condition
Work can continue elsewhere on the job, but the affected area should stay undisturbed until the owner has had the chance to inspect or has given written direction. Disturbing it first removes the evidence of what was there and can defeat the claim, even if notice is sent within the contract deadline.
what if my contract has no differing site conditions clause
On a fixed price contract with no such clause, the risk of unforeseen conditions usually falls on the builder. Notice and photographs still help in any negotiation or dispute, but the stronger fix is adding a clause or a defined allowance for unforeseen conditions before signing the next contract.