A rainbow alliance has emerged ahead of this week’s Holyrood elections focused on a big issue: housing.

The private housebuilders’ group Homes for Scotland, the Scottish Federation of Housing Associations, Shelter Scotland, the Royal Incorporation of Architects in Scotland and the Royal Town Planning Institute signed an open letter to all the parties on “Scotland’s housing crisis”.

Nicola Barclay, chief executive of Homes for Scotland, says: “We are united in one simple request, that our politicians take whatever action is necessary to end the housing pressure affecting so many of those living in Scotland.”

The letter says overall housebuilding has dropped by 40 per cent since 2007 and demand is outstripping supply, leaving a shortage of homes.

Landlords meanwhile are concerned that new taxes on buy-to-let may reduce the supply of rented property and push up rents.

First-time buyers can apply for government support schemes, but they are less generous and more thinly spread than previously.

The SNP promises £3 billion for 50,000 new homes over five years. Almost £500m of this year’s £572m spend is devoted to homes for social rent (£406m) and other “affordable housing projects” with £80m going to a shared equity scheme that will help 2000 first-time buyers.

Labour wants to double the help available to first-timers saving for a deposit, while the LibDems call for an empty homes strategy and 50,000 new homes with 80per cent for social rent. The Conservatives say we need to build 100,000 homes over the next five years and private landlords should get grants to build homes for affordable rent.

On the ground, 20 per cent of parents say their children will need substantial help to buy a home, according to Post Office research. A Bank of Scotland survey found 10per cent of 25-34 year olds already feeling under pressure to help their children get on the property ladder.

Barclay said: “With the majority of Scots aspiring to own their own home, but affordability issues clearly impacting on the ability of future generations to realise these ambitions, it is vital that we see an increase in supply across all tenures in order to meet this demand.”

For those who can get a foothold, it is now on average almost £1500 a year on cheaper to buy than to rent in Scotland. The average monthly cost of mortgage repayments, maintenance and insurance on a three-bedroom house is £525 for a first-time buyer, compared to a typical rent of £645 for the same type of property, according to Bank of Scotland.

The new Land and Buildings Transaction Tax means anyone buying a property for under £250,000 will pay up to £400 less in stamp duty than under the old tax.

But critics say the higher duty on more expensive homes which will see a £400,000 property cost £3,350 more, and a £500,000 home cost an extra £8,350, is depressing transactions and stifling movement lower down the market.

Continuing rock-bottom mortgage rates helped first-time buyer loans rise by14per cent in the last quarter of 2015 on a year earlier, according to the Council of Mortgage Lenders.

The average purchase price has risen from £170,000 to £201,500 since 2010, but there are now more deals for first-time buyers with a five or ten per cent deposit than at any time since the crash. Charlotte Nelson at Moneyfacts.co.uk says lenders are now offering “an array of incentive packages and fees, allowing borrowers to tailor their mortgage to their needs”.

Buyers need to beware of the total package, with average mortgage fees rising from £888 to £956 since June 2014.

The Help to Buy Scotland shared equity scheme was relaunched in January with funding of £65m a year, a third less than when first launched. The cash is being stretched by cutting the government’s equity stake from 20 to 15 per cent and bringing down the maximum buying price from £230,000 to £175,000 over three years. Whilst welcoming the scheme, Barclay says the new limit will “exclude huge amounts of the country” from its benefits.

Last month saw the sharpest month-on-month fall in Scottish rents on record, according to the latest Scotland Buy-to-Let Index from letting agents networkYour Move.

The average rent is now £544 per month, the lowest for 10 months. But only two of the five Scottish regions have seen rents fall year on year.

Brian Moran, lettings director at Your MoveScotland, said:“With landlords now facing an additional three per cent stamp duty on property purchases, and the Private Tenancies Bill passed through Scottish Parliament, we’re entering unchartered territory.

"What we do know, is that if landlords hit the brakes and cause a roadblock of supply in the private rented sector, tenants will be the casualties paying higher rents in the longer term.”

The Association of Residential Letting Agents says the duty hike is “very likely to cause supply to decrease even further, as landlords withdraw from the market”.