Council staff have spent the past two months trying to finalise a series of outstanding tenders for the mall refurbishment in order to nominate a total overall cost before works begin.

Ratepayers have been given multiple estimates of the project's expected costs since it was first flagged in 2008.

The most recent and long-standing figure was $14.9 million.

But a report to Monday's council meeting says a series of changes to the original proposal are to blame for pushing the final figure up to nearly $20 million.

They include project management costs; more expensive pavers; installing Wi-Fi in the mall; renting a dedicated site office; and shift allowances for night-time workers.

Lahey Constructions Pty Ltd is expected to be awarded the largest of the tenders - $11.5 million for construction works - at Monday's council meeting.

Councillors will also be asked to allocate an additional $4.4 million from the council's own coffers to the project in the next two council budgets.

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Wollongong Lord Mayor Gordon Bradbery yesterday defended the rise in costs, saying the figure represented all the direct and associated costs of the project, while other estimations had not.

"We've included every possible difficulty and challenge in that cost," he said, adding contingencies had been built into the final figure.

"We've tried to anticipate any expansion of costs and factored that in.

"[But] projects of this magnitude are always fraught [with danger]; they are always a challenge.

"We admit it's not going to be easy to operate a mall and a shopping precinct while we're in the process of reconstructing but, as best we can, we've put together what we think is the most feasible costing to do just that."

Cr Bradbery said it was expected final, pre-demolition works would be completed early next week, should councillors agree to the recommended tenderers.

Dismantling objects, beginning with the Church Street planter boxes, will start by next Friday.

Cr Bradbery said cladding and facades would be erected down the middle of the mall to keep the shopfronts clear from works during the day.

"Most work involving entry into retail space will go ahead in the evening," he said, but added there was a work ban between midnight and 5am unless prior written approval was granted by the council.

Cr Bradbery said he was confident the refurbishment would be done in its two-year timeframe.