Intangible assets - Costs and accumulated amortization (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Cost
Finite-Lived Intangible Assets, Gross	$ 5,790,000	$ 5,790,000
Accumulated amortization
Finite-Lived Intangible Assets, Accumulated Amortization	(2,388,334)	(1,641,667)
Intangible assets, net	3,401,666	4,148,333
Non-compete agreement
Cost
Finite-Lived Intangible Assets, Gross	530,000	530,000
Accumulated amortization
Finite-Lived Intangible Assets, Accumulated Amortization	(493,889)	(443,889)
Trade names
Cost
Finite-Lived Intangible Assets, Gross	2,700,000	2,700,000
Accumulated amortization
Finite-Lived Intangible Assets, Accumulated Amortization	(740,000)	(560,000)
Customer backlogs
Cost
Finite-Lived Intangible Assets, Gross	360,000	360,000
Accumulated amortization
Finite-Lived Intangible Assets, Accumulated Amortization	(360,000)	(210,000)
Facility management contracts
Cost
Finite-Lived Intangible Assets, Gross	2,200,000	2,200,000
Accumulated amortization
Finite-Lived Intangible Assets, Accumulated Amortization	$ (794,445)	$ (427,778)