A report has backed controversial claims that closing small schools improves results and morale - a blow to campaigners fighting the proposals.
The Welsh Local Government Association's 30-page document, Planning School Places, says the problems of surplus places and crumbling buildings can kickstart reorganisation plans.
But the report calls for greater clarity from the Assembly government over a surplus places threshold and whether a school building is "fit for purpose" so that local authorities can plan closures more effectively. The WLGA estimates pound;1.6 billion is needed to bring all school buildings in Wales up to scratch.
The report also suggests that providing "area schools" could solve the problem - merging smaller establishments on to one site - to release much-needed capital for investment.
It gives the example of Pembrokeshire, which launched its school reorganisation plan in 1996 and ploughed capital money into remaining sites, part of a pound;100 million plan over the past 10 years.
"This approach has resulted in school changes being seen by communities as a positive action," the report says.
WLGA education spokesman John Davies said the evidence seemed to show that small schools making way for new sites led to "improved educational attainment" and "higher morale among teachers and learners".
But Welsh-language campaigner Cymdeithas yr Iaith says small rural schools could still be kept open if councils used the buildings for other activities such as sports clubs or social services.
Cymdeithas's education spokesman Ffred Ffrancis is currently leading a 75-mile protest walk across Gwynedd with supporters this week. Protesters are carrying a "postbox" where parents and campaigners can deposit letters with their views on Gwynedd council's plan to axe 29 primaries.
It will be handed in at County Hall in Caernarfon today. Mr Ffrancis said: "We have had hundreds of letters so far."
Llantrisant-based academic Professor David Reynolds, from Plymouth University, produced the report Small School Closures in Wales last November, which agreed about the benefits of providing new larger schools. He said the WLGA report hit the nail on the head by calling for clarity on surplus places and "fit for purpose" buildings.
An Assembly government spokesperson said "fit for purpose" referred to schools that "were in a good condition and able to deliver the modern curriculum".
The government "does not stipulate" acceptable surplus places levels.