Christopher Cole, from Brownhills, presented a fake certificate to the Coseley resident claiming he was a FENSA registered installer, with a false registration number on it.
The 46-year-old then fitted poor quality and undersized windows with gaps which let in wind and rain, while mastic and beading was used extensively in an attempt to hide the deficiencies.
A bay window structure was not supported, resulting in cracks to the wall on both sides.
An expert surveyor described it as "wholly inadequate with no value whatsoever", with total replacement needed at a cost of nearly £5,000.
Cole had previously pleaded guilty to two offences under the Fraud Act and four offences under the Consumer Protection from Unfair Trading Regulations and was sentenced at Wolverhampton Crown Court on August 5.
The court handed Cole a 14-month jail sentence, suspended for 18 months, and ordered him to carry out 200 hours community service.
He was also ordered to pay £4,830 compensation to the resident and £3,000 costs to Dudley Council.
The case was brought to court by Dudley Council's Trading Standards team.
Councillor Nicolas Barlow, cabinet member for health and adult social care, said: "This prosecution sends out a clear message that we will protect consumers from the activity of rogue traders who flout the law and carry out sub standard work.
"This kind of activity causes a huge amount of distress to the victims who have worked hard and saved to pay for improvements to their home and are then badly let down."
Dudley Trading Standards in partnership with Age UK promotes the Fix a Home list of local approved traders who provide services of a high standard at a fair cost.
Copies are available online at dudley.gov.uk/resident/your-council/trading-standards/fix-a-home/