The group was hit by a raft of impairment charges, onerous contract costs and financing and restructuring costs.
Underlying pre-tax performance fell to a loss of £76.3m from a £17.7m profit last time due to the pandemic “with some continued underlying weakness in performance.”
SIG furloughed 2,000 staff during the first lockdown claiming £11m in government support.
Chief Executive Officer Steve Francis is confident its “Return to Growth” will see SIG return to a mid term margin target of 3% as the fourth quarter of trading saw growth in like-for-like sales and improvements in profitability.
He said: “Our teams have shown great resilience and commitment in the face of the challenging circumstances for much of the year, the effects of which clearly impacted our first half, and hence full year, results.
“I am delighted that due to our Return to Growth strategy we delivered a solid second half and have begun to return the business to growth after a long period of decline. On behalf of the whole Board I would like to thank all our employees for their significant efforts, and successes, during the year.
“The new UK management team has rebuilt its business and, everywhere we operate, we have reconnected with our employees, customers and suppliers.
“Their response has reaffirmed that we are at our best when we are a local, sales and technical service-driven business, partnering closely with our key suppliers and operating with empowered and entrepreneurial branch teams.
“That is our strategy for growth and the basis for playing a leading role in our industry in the years to come.
“This, coupled with a strong balance sheet, gives us the right foundations for the business to grow.”