Every page that answers this with a number is guessing, because party wall fees are hours at a rate and both vary by area and by job. What can be said usefully is what the hours go on, which owner carries them, and how the total moves when the job changes. Work it from the rates you have been quoted rather than from anybody's average, including ours: the worksheet on this site multiplies your figures and invents nothing.
What the hours are actually spent on
Reading the notice and the drawings. Inspecting the adjoining owner's property and recording a schedule of condition, which on a house of any size is most of a morning plus the write up. Agreeing the works and the conditions with the other surveyor, which is where a difficult job costs real time. Drafting and serving the award. Then, if anything goes wrong during the work, determining it. A job with one adjoining owner, one notice and a cooperative surveyor on the other side is a fraction of a job with three owners and a basement.
Who carries the cost
The building owner normally does, including the adjoining owner's surveyor, because the work is being done for the building owner's benefit and the Act's expenses provisions follow benefit. That is the single most surprising fact about this process for most people, and it is the reason a written consent is worth asking for plainly: consent removes both surveyors and their fees from the job entirely.
How to work your own figure
Take the number of adjoining owners you must serve, and how many of them you realistically expect to dissent. Take your surveyor's hourly rate and the hours they say an award and a schedule of condition will take. Take the same for the adjoining owner's surveyor, where you know it. Multiply, add the cost of serving the notices, and you have the number. The worksheet on this site does exactly that arithmetic, and it separates owners served from owners expected to dissent, because a consenting neighbour costs you a stamp.
Questions people ask about party wall surveyor cost
Why will you not just publish an average?
Because an average would be wrong for your job and out of date within a year, and you would anchor on it. The only honest figure is the one your surveyor quotes you, and the arithmetic here turns that into a total.
Can I ask the neighbour to pay their own surveyor?
You can ask, and where the neighbour has asked for extra work for their own benefit the expenses provisions may put some of it on them. As a general position, expect to pay.
Does an agreed surveyor cost less than two?
Almost always, because one person does the inspection, the drafting and the correspondence instead of two people doing it and then agreeing with each other.