Public access to the site was restricted in May 2008 and banned completely in May last year due to the health and safety risk from crumbling masonry.
The borough's culture scrutiny panel yesterday (Wednesday) approved an officer recommendation to spend £90,000 on a specialist investigation - just to find out how much the full repairs will cost and how long they will take.
Cllr Richard Stainthorp said: "We can't risk heavy stones falling from a great height."
But he added: "Look at the sums of money involved in this - £90,000 is just to find out what it may cost. Those figures are going to be truly frightening."
He said it would be a "tragedy" for Reading if the ruins were off-limits long-term and Cllr Peter Beard, who sits on the project board to plan the repairs, called the Abbey Ruins "one of the most important things in the town".
A new 'heritage-style' fence will go up soon to better protect the site.
Rhodri Thomas, museum and town hall manager, said: "One of the most difficult decisions we had to make was restricting access. The problem is that the entrances to various areas are causing issues.
"We need to look at the longer-term future of the site."
Dr Julia Boorman, who chairs the Friends of Reading Abbey, gave councillors a thorough run-through of the site's history and said: "It was a foundation of national, indeed international, significance from 1121 to 1539 and the presence of such an abbey, with its Royal visitors and its pilgrims, its weekly markets and annual fairs and its role in the locality, was of great significance too for the development of Reading itself."
* THE nearby Abbey Gateway was sealed off in February this year after decorative stonework fell off, causing this year's Reading Half Marathon to be re-routed around Abbey Square. The council is planning to apply for funding grants from heritage bodies for repair work.