It must surely be an unexpected downside of the Celtic Tiger, but it is one which housing authorities are struggling to cope with: as the booming economy pushes up house prices and rents, more and more people are finding it harder to get an affordable roof over their heads.

Increasingly, people who would never before have appeared on their waiting lists are turning to local authorities for scarce housing - but local authorities such as Dublin Corporation is itself finding it hard to pay market prices for houses.

"We are getting more and more of them," says Kayanne O'Mahony, the senior official in charge of customer care at Dublin Corporation, referring to people facing eviction because they cannot afford rent increases in the private sector.

Even apart from evictions, sky-high house prices are pushing more people on low wages or incomes on to the housing lists. "There are people who would at one stage have been able to provide their own houses, but they can't any longer," says Galway's city manager Joe Gavin.

Many such people are staying in private rented accommodation instead of moving on to their own privately bought houses as they would have done in the past, says Niall O'Connell, who is in charge of housing allocations and transfers for Dublin Corporation. This, in turn, pushes rents up and those who cannot pay the rents end up on the corporation's waiting list.

Deirdre Murphy, co-ordinator with the voluntary housing advice agency Threshold in Galway, sees the crisis as arising partly out of the ease with which landlords could buy houses over recent years: "Over the last few years when it was easy to get money, landlords were getting houses on the strength of a deposit and expecting the tenants to pay the mortgage for them," she says.

The result is high rents - though, in some places, "rents are not going up because they are so high they couldn't go up any more".

Different local authorities have different ways of allocating housing to the people on their waiting lists. In the Dublin Corporation area, applicants are given points for such factors as number of children, length of time on the list, overcrowding and medical problems. In addition people can be given priority if, for instance, they are chronically ill or homeless. The corporation also has large numbers of existing tenants who want to transfer from flats to houses or from one area to another. When houses become available, the corporation looks at all the lists and makes a judgment on who will be housed. For instance, about half the houses in a 70-house scheme in Clonard Road, in the Crumlin/Walkinstown area will go to priority cases, O'Mahony says.

In Galway, things have been simpler for the past 15 years, says Gavin. The policy was that when houses became available they went to tenants of the Rahoon flats complex. New people who got on to the list went to Rahoon to wait their turn for a house. But all the tenants will have been moved out of Rahoon in the next 18 months and from then on, people coming on to the list will be considered directly for housing. Gavin expects this in itself to increase the numbers on the housing list. People who were not prepared to consider living in Rahoon didn't apply for housing in the past - the de-tenanting of the flats will remove that disincentive. Dublin Corporation faces serious problems in providing housing for those who need it. It has about 11,000 people on its waiting lists, of whom about 5,000 are seeking transfers from existing corporation dwellings. This year it will provide about 1,000 dwellings. The corporation doesn't have large land banks on which to build housing for the people on its burgeoning waiting lists, nor is there a great deal of land available to buy within its area. The corporation has been trying to address this problem by buying houses that come up for sale in the city but, says O'Mahony, "the Government puts a limit of £100,000 on what we can spend per unit."

And that, she says, is just not enough in today's market in Dublin.

O'Connell is not convinced that Dublin Corporation can solve its housing problems on its own. With all the large tracts of land located outside the corporation area, he believes a solution may have to be found which would involve all the local authorities in Dublin city and county working together.

THE State itself will have to invest more money to provide housing for those who cannot afford to buy their own, says Sister Stanislaus Kennedy of Focus Ireland. "We all know that obtaining accommodation in the private rented sector is more difficult now than ever - even for people on good salaries," she says.

"Creative ways of addressing the problem of housing supply in the public, in the private and in the voluntary sector for all people, especially those on low incomes, will have to be found," she says.

"The private rental sector is not designed to meet the needs of all families and single people on low incomes, and so it is obvious that more social housing programmes will have to be put in place to meet these needs." Murphy, in Galway, agrees: "The amount of local authority housing is inadequate at the moment for the number of people on the waiting list," she says. In Galway city, 700 people are awaiting housing and the city will build about 70 houses this year. The pressures that exist already for people on low wages and incomes in the housing market seem set to get worse, a research paper produced by the Consultancy and Research Unit for the Built Environment at the Dublin Institute of Technology suggests.

Tax incentives fuelled a boom in apartment building - but this has pushed rents up rather than down "as investors seek to achieve yields above and beyond the costs of servicing the mortgage costs of purchasing these properties," it says.

And the increasing demand for accommodation at the lower end of the market means that "typical rent levels for ordinary flatland bedsits in Dublin, many in poor and sometimes appalling condition, have risen from £50 per week in 1997 to £65, £70 and £80 per week depending on location".

The paper, published at the end of August, suggests strongly that things are going to get worse rather than better for people on low incomes. The fact that the rents paid by a sample of people studied in Dublin doubled between last year and this year is bad enough, but even more alarming, says the paper, "is the range of rent increases being faced by tenants in the second half of 1998. Twenty per cent increases are now standard, nevertheless a growing number of tenants face an increase of up to 30, 40 and even 50 per cent in some cases."