Robin Proctor, owner of Novus Auto Glass in Whangarei, said her staff had been "blown off their feet" trying to cope with demand for windscreen repairs.
"We're seeing 20-plus vehicles a day for a new windscreen and another 20 for repairs to chips. It's the same situation everywhere," Ms Proctor said.
Those needing a replacement windscreen could end up waiting a week.
A Waynes' Autoglass spokesman said he had dealt with 18 logging trucks in six days and had lost count of the number of cars that needed windscreen repairs.
"I worked the whole day Saturday and Sunday and even rang my competitor to take some jobs for me ... There's definitely been a big surge in demand and it will only get worse if the roadworks are not sorted out," he said.
Kaikohe Glass and Windscreens co-owner Helen Crombie said the phone had not stopped ringing since last week.
"We didn't shut over the break. Traditionally, it's busy at this time of the year but this year there's been a lot of chip-sealing in Moerewa town and also on State Highway 12, between Kaikohe and Hokianga," she said.
Aucklander Carl Buckthought was travelling to Kerikeri on Friday when his Nissan van had loose metal sprayed over its windscreen by a logging truck heading south in a 100km/h zone between Blue Goose and Oakleigh, just south of Whangarei.
The vehicle's head light, indicator light and windscreen were damaged.
"I slowed down to 40 and pulled as far to the left as I could before being hit but it didn't matter. It was quite scary and I thought the windscreen would just explode," he said.
Jim Smith, of Ruakaka, also bore the brunt of loose gravel on Friday, when heading into Whangarei: "I got the blast from a logging truck ... It was like going through machine-gun fire."
His vehicle ended up with four large chips in its windscreen.