Young people are urged to get a toehold on the housing ladder - but in Dublin, and other high-cost cities such as Galway, you really need a minimum income of £20,000 to £30,000 to be able to buy a house.

What do you do if you don't have that kind of money, and just can't get a big enough loan from a bank or building society? There are a few options, the most likely ones being the Shared Ownership and Affordable Housing Schemes, available through local authorities.

The Shared Ownership Scheme, introduced by the Government in 1992, is designed to help people with incomes below £20,000 to buy a house of their own choosing. Under this scheme, the local authority buys the house you have selected in its area on the open market, subject to its approval, and you take out a mortgage through the authority to pay a minimum of 40 per cent of the cost; you pay rent to the authority for the remaining share, with the option to buy out the house completely over time.

Under the Affordable Housing Scheme, introduced by the Government in March of this year, local authorities will build and sell homes at very low cost - possibly three-bed semis in Dublin for around £70,000. The extra benefit of this scheme, of course, is that it increases housing supply.

There are other schemes which might help: under the "Extensions in Lieu" scheme, a local authority may pay the cost of building an extension to a house where someone who is on the housing list (for example, a single mother) is living - and there are grant schemes to adapt homes for people with disabilities. As well, housing authorities are planning a bigger role for voluntary housing associations to provide houses for purchase, as well as rental.

But for most first-time buyers, the Shared Ownership and Affordable Housing Schemes are currently the most relevant. The Shared Ownership Scheme is not an easy route - the challenge for a buyer will be to find a house - or apartment - costing no more than the maximum allowable price.

Each local authority sets its own ceiling on the price of a house you can buy under the scheme: Dublin Corporation's limit is £100,000, while Dun Laoghaire Rathdown County Council has set it at £125,000; in both Fingal and Wicklow it is £90,000; in South Dublin it is £95,000, while in Sligo, the maximum loan you can get is £50,000.

Certainly in the Dublin region, it is hard to find houses under £90,000, and people on incomes below £17,000 would find it hard to afford a house under the scheme.

The only qualifications for eligibility for the Shared Ownership Scheme (SOS) are the income limits (see panel), ability to repay, and being "in need" of a house.

But "need" in this context isn't the same kind of need that will get you on to a local authority's housing waiting-list. (If you're 22 and living in your parents' not very crowded house, you will qualify for the SOS scheme, but probably not for the housing list.)

Tenants of local authority houses who intend to hand them back to the authority, and people on the housing list, or in accommodation provided under the Rental Subsidy Scheme, are also eligible.

Declan McCullagh, administrative officer in the loans and grants section of Dublin Corporation, says that when the scheme was introduced in 1992, half the applicants for the scheme were people on its housing list, or tenants of its houses, and half "others".

Last year, 80 per cent of applicants were "others", with young bank officials, financial services workers, computer technicians, civil servants and local authority officials among people who bought their first home under this scheme.

The scheme was much criticised initially for the length of time it took applicants to get final approval for a house purchase when they found a house they wanted to buy: applicants must get provisional, then final approval for a purchase, following inspection by local authority officials to make sure the house is free from structural defects.

In a market like Dublin's, where many house sales are now clinched within a few days, this is obviously of critical importance to buyers - and Dublin Corporation has worked hard to get to a position where it can now get approval in two weeks, says Mr McCullagh. It expects to approve a record 500 to 600 shared purchases this year.

So far, schemes such as shared ownership have not made much of an impact: in 1998, only 805 people nationally - out of 2,962 who applied - actually went on to buy a house.