Owner, Bilal Yousaf, said he is heading for bankruptcy because the unit is blocking passing trade to his newsagents, Billy's Mini Market, in Rose Street, Garnethill.
He said that since the double-decker cabins arrived in December, trade has slowed to just one customer every few hours, losing him around £800 a week in earnings.
For Bilal, who supports his disabled parents, as well as his three young children, the loss of income is a major blow.
He said people are choosing to walk on the opposite side of the street and do not know his shop is still open.
As reported in the Evening Times on Friday, shopkeepers in Dundas Street have slammed the council for allowing building firm Balfour Beatty to place six, two-storey portable cabins in front of their shops.
In November, we reported small businesses losing trade in Oswald Street, after a power substation was moved onto the pavement in front of their shops.
Bilal, 32, from Ruchill, whose family has owned the newsagents since 1985, says he will go bankrupt if the situation continues.
The cabins outside his shop are used by EBS Construction workers, carrying out Glasgow City Council grant aided refurbishment of tenements at 43-47 Rose Street, which incorporates his shop on the ground floor.
They are planned to be in place until August.
Bilal said: "I can't even drop off deliveries.
"I was always concerned [ever since they arrived], even at home I can't sleep, I didn't know what is going to happen.
"I have missed mortgage payments since they went up and I am getting worried."
A statement from EBS Construction Ltd said: "We have the required permits for our site establishment layout.
"As requested, we have provided additional 'Open for Business' signage for the shop, located at both ends of the scaffold walkway."
A council spokesman said: "Permits were issued allowing work to be carried out on the building containing Billy's Mini Market.
"It is standard practice to locate work materials outside the building where work is taking place."