Capital Economics has only forecast two rises to 4.25pc, but this will still bring a major shock to homebuyers.
The consultancy has also raised its expectations for 10-year gilt yields as borrowing costs around the world soar, another factor that flows into mortgage pricing.
Ashley Webb, a senior economist, said altogether this means that average mortgage rates for new loans at the end of the year will now be 4.8pc, 0.8pc higher than his previous forecast.
Mr Webb said this squeeze on buyer affordability would hurt house price growth in the years ahead.
He said: “The drag on overall activity from higher interest rates will be a bit bigger and last longer than we previously thought.
“This will influence the housing market the most. In due course, we will probably revise down our forecasts that house prices will rise by 3.5pc in the year to Q4 2027, and by 3.0pc in the year to Q4 2028.”