With the latest figures showing first-time buyers are feeling the pinch of rising house prices, there is concern that the cost of getting on to the property will leave people struggling to become debt free.
In addition, all homebuyers are seeing their loan repayments rise, as the rate rises begin to take effect.
The proportion of income used to pay mortgage interest has risen from 16.3 per cent to 16.6 per cent in April, with the five rate rises since last August starting to take effect.
With the last two rate rises – in May and July – not included in the CML survey, there are even signs that affordability could worsen as mortgage repayments rise.
CML director general Michael Coogan said: “Affordability is becoming worse.
“Financial difficulties are set to rise so it is essential borrowers speak to their lender if they are having repayment,” he added.
Mortgage loans in the UK are worth over £1.1 trillion, according to the CML.