Short answer. Yes. Article 1724 of the Civil Code lets a contractor on a fixed-price building contract demand a price increase for a change in plans only when two things are in writing: your written authorization of the change, and both parties' written agreement on the additional price. Meet both, and the higher charge stands.
What the law says
save when there has been a change in the plans and specifications, provided: (1) Such change has been authorized by the proprietor in writing; and (2) The additional price to be paid to the contractor has been determined in writing by both parties.
Civil Code, Article 1724 — No Price Increase Without Written Consent. Read the full provision →
A fixed price is meant to hold
When you agree on a stipulated price built around agreed plans and specifications, the law treats that price as firm. The contractor can neither withdraw from the contract nor demand an increase in the price on account of the higher cost of labor or materials. That is deliberate. A fixed-price contract exists precisely so the owner is shielded from mid-project price rises and the contractor carries the risk he priced. Rising cement or steel prices, on their own, are not a ground to charge you more. The exception the law allows is narrow, and it is about changes to the work, not changes in market cost.
The two written conditions
A higher price for changed work is permitted only where there has been a change in the plans and specifications, and even then the law imposes two conditions that must both be met. First, the change must be authorized by the proprietor in writing. Second, the additional price must be determined in writing by both parties. Both are mandatory, and both must be in writing. From what you describe, you gave written authorization for the change and agreed the added cost in writing, which is exactly what the provision requires. On those facts the contractor's demand for the higher price has a proper basis.
Why verbal change orders are dangerous
The writing requirement cuts both ways, and it is where most disputes are decided. A contractor who did extra work on a spoken instruction, with no written authorization and no written agreement on the added price, is generally not entitled to demand more under this article, however real the extra work. Owners, in turn, cannot be surprised by a swollen final bill for changes they never signed off on. This is why every change order should be documented before the work is done: what is changing, who approved it, and the exact additional amount, signed by both sides.
Check the paperwork matches the demand
Before paying, confirm that the increase the contractor now claims corresponds to what the two writings actually cover. The authorization should describe the specific change, and the agreed additional price should be the figure both of you set, not a larger sum introduced afterward. If the contractor is billing for changes beyond the written scope, or for an amount above what was agreed in writing, those extra portions do not enjoy the same footing. Kept properly, the two documents are both the contractor's right to be paid more and your protection against being charged for anything you did not approve.
Cases citing this provision
These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.
- Licomcen, Inc. vs. Engr. Salvador Abainza, etc, G.R. No. 199781, February 18, 2013 — read the decision on LawPhil →
- Spouses Victoriano chung and Debbie Chung vs. Ulanday Construction, Inc, G.R. No. 156038, October 11, 2010 — read the decision on LawPhil →
- Leighton Contractors Philippines, Inc. vs. CNP Industries, Inc, G.R. No. 160972, March 9, 2010 — read the decision on LawPhil →
- Powton Conglomerate, Inc., et al. vs. Johnny Agcolicol, G.R. No. 150978, April 3, 2003 — read the decision on LawPhil →