Property owners face a "huge shock" when the full impact of the new Housing Act on their responsibilities hits home next year, experts claim.

However, they warn the most sweeping reforms of Scotland's housing law in a generation will not have the desired effect of upgrading standards if plans to significantly reduce improvement grants go ahead.

Housing officials in Glasgow yesterday launched a consultation on the impact of the act, due to come into effect in spring, with the aim of informing homeowners, housing associations and landlords about statutory responsibilities they will face for the upkeep.

The city will be affected more than any other local authority because of the 63,124 pre-1919 tenemental properties that account for almost one-quarter of its housing stock.

Around 14,000 of the oldest properties are in extremely poor condition or have at least one serious problem, with several incidents in the city's west end illustrating the poor state of repair.

Last month, a gable end tenement collapsed, while last Christmas the rear of another tenement, on Clarence Drive, also caved. North Lanarkshire will be launching its own consultation and other local authorities, concerned that the only public knowledge about the act is the introduction of single surveys for property sellers, are expected to follow.

The thrust of the new act is to improve the condition of ageing housing stock and will see owners taking much more responsibility for repair and maintenance of properties.

Many owners could be forced to pay thousands of pounds to improve homes considered by councils to be in disrepair. If these are not carried out voluntarily then the local authority may take the action and bill the owner.

The new act also widens the powers available to local authorities to order repairs, with various types of compulsory notices replaced by a single work notice.

Although this will see authorities taking enforcement action against slum landlords and ordering them to produce five-year maintenance plans for properties, there is concern among some local authorities, mainly in the west of Scotland, that removal of grant assistance where a compulsory repair notice is served could be counter-productive.

Grants, often up to 50%, are expected to be largely replaced with loans, information, advice and training. Some working within Glasgow's housing sector have privately criticised "Edinburgh-centric" civil servants for drawing up an act using the capital as a model for all of Scotland.

They claim there is little recognition of the sheer scale of Edwardian and Victorian tenemental properties in Glasgow and the social demographics of those living in them. One Glasgow source said: "When people realise what's involved here there'll be a huge shock. That's why we've got to let people know what's just months away.

"For Glasgow, the negatives will have more significant impact than the positive - the removal of the grants being the main concern. Properties in the west end may be in a worse state of repair, but there's money there to have the properties fixed.

"This may not be the case in Govanhill or east Pollokshields. We may have just too much stick and not enough carrot."

Martyn Evans, director of the Scottish Consumer Council, said that while the organisation agreed owners must be less reliant on public money for repairs, there were people who may not be able to afford them.

He said: "There may be evidence that some people can't afford to repair or upgrade and have neither the equity or the income to borrow. In these circumstances, grants and loans are absolutely vital to maintaining housing stock. Our worry is there may not be enough grants to meet that obligation."

In 2005, the City of Edinburgh Council introduced a new scheme of assistance for homeowners providing equity loans and advice ahead of the act, replacing most of the city's housing grants.

A Communities Scotland spokeswoman said it would be talking with councils on how the act would be enforced and said councils' consultations would reflect the discussions.