JCT: Can a contractor working under JCT refuse a works instruction if costs are not agreed before hand


Assuming you are referring to JCT SBC 2011 then clause 3.10 deals compliance with instructions, a similar provision exists in the JCT IBC 2011. Under this clause the Contractor has very limited reasons for refusing an instruction.

You have comply unless an instruction requires a Variation which is due to the reasons listed under clause 5.1.2 e.g. changes to access or use of site, limitations on working space / hours, requirements to complete work in a specific order. If you believe this has happened then you are obliged to notify your reasonable objection to the A / CA.

Also if an instruction for a Variation is given which requires a Variation Quotation (the A / CA must have stated this in his instruction for a Variation), in which case the Variation is not carried out until the A / CA Confirmed Acceptance (of the Variation Quotation) under clause 5.3.2.

You need to also remember that the A / CA can recover from the Contractor any additional costs to the Employer if you do not comply with an instruction within 7 days after the A / CA has notified that you are required to comply.