Thousands of armed forces personnel are living in sub-standard accommodation because of Government short-term cost-cutting, the Whitehall spending watchdog has warned.

The National Audit Office (NAO) said a “fix on fail” approach to maintenance by the Ministry of Defence (MoD) has led to the build-up of a £1.5 billion backlog of repairs in military accommodation.

It said the MoD is failing in its commitment to provide all personnel with high-quality subsidised accommodation, potentially undermining efforts to improve retention rates across the services.

As of last year, almost 80,000 servicemen and women – more than half the total – were occupying single living accommodation (SLA) blocks on either a full or part-time basis.

Of those, the NAO said more than a third – 36% – were living in “poorer grade” premises while almost 2,400 were in accommodation considered to be so bad they were not charged any rent.

The Armed Forces Continuous Attitude Survey found that fewer than half – 49% – were satisfied with the overall standard of their accommodation, compared with 58% in 2015.

The NAO said that among the common complaints raised by personnel were issues with basics such as heating and hot water, limited storage space, poor or expensive wifi, and a lack of cooking facilities.

While the MoD plans to spend £1.5 billion over the next 10 years on replacement and renovation work, the NAO said it could be “some time” before there is any significant improvement given the decades of under-investment.

Gareth Davies, head of the NAO, said: “Decades of under-investment has left many of the barracks where members of our armed forces live in a poor state.

“Problems with heating and hot water are not conditions that they should have to tolerate. MoD needs to get this right if it is to retain service personnel in the long term.”

Meg Hillier, chairwoman of the Commons Public Accounts Committee, said it is another example of short-term thinking by the MoD.

“Delaying repairs until the last-minute means MoD now faces a bigger bill to get things up to scratch. In the meantime, thousands of members of our armed forces are left living in sub-standard accommodation,” she said.

“These are the people we ask to go out and fight for our country. The least they should be able to expect is a hot shower and a decent roof over their heads.”

A spokeswoman for the MoD said: “Our armed forces personnel are at the heart of everything we do and it is only right they are provided good quality and affordable living accommodation.

“We have invested £1.2 billion over the last decade on construction and upgrades of our accommodation and continue to invest in a range of new-build and renovation projects.

“We thank the NAO for their report and will carefully consider their recommendations.”