The only way to build a website that:

• comes in on budget
• does what it is supposed to do

is to full specify it before you start building and to stick to the agreed specification.

We use an engineering based approach to develop a "functional specification" document that identifies every screen, every link and every downloadable on the site.

It can also includes every work of text and every image.

Usually the functional spec reveals two things:

• the site is bigger and more complex than you thought
• the possible contribution of the website to your business is greater than you thought.

With an agreed functional specification that meets your business plan and your budget, you have a good web project in hand.

Project management and the functional specifications

When the site is built, you can compare what's on screen with the functional spec. If it's in the spec but not on screen or doesn't work that way on screen, and your designer has quoted to the specs, you can send the job back and expect the extra work to be covered in the quote.

Of course, if something is in the design because you asked for it, but it's not in the functional specs, you can reasonably expect an extra cost.

Controlling project creep – the "next" box

Engineers call this adding in of extra features "project creep". It kills budgets, both money and time, and sometimes it kills projects: they get bogged down, become unmanageable and are eventually abandoned.

The answer is to stick top the functional specifications – and to commence planning the next generation before you've even finished the current version.

This is the answer engineers rely on when – for example – they are building cars. The R&D department produces continuous improvements, but the factory can't stop and rejig for every advance or production would slow and costs skyrocket.

So a cut off date is set. The specifications at that point become for example the 2011 model and it goes into production. All advances and ideas from that point forward are put in a box labelled "2012 model". Only really important changes are allowed through to the current production, for example safety issues.

A website is also a continually evolving concept. We recommend that once a functional specification is signed off (or even earlier, when you are pruning the wish-list to meet the budget) that you start a "next version" box where all new ideas and requests accumulate. You don't have to wait a year to start work on the "next" box, but you should at least finish the current version. If you don't, our experience is that it will never be ready to launch.

The functional specification, text and images

A basic functional specification identifies each page, explains what the page does, tells what the text is about or what it aims to achieve, and lists the links from that page. It will also describe essential graphics.

Typically clients then gather, edit or write the text described for each page by the functional specification.

Glide can also provide web copywriting services, so completing the functional specification so it is ready to build.

Other services include gathering up and searching for images, logos, downloadables, pdfs, videos and so on.