Contracts in progress (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Contract With Customer, In Progress, Revenue Recognized And Amounts Billed, Disclosure [Line Items]
Revenues recognized to date on contracts in process	$ 6,109,396	$ 17,534,449
Amounts billed to date on contracts in process	(6,370,855)	(17,791,928)
Retainage	237,542	312,130
Net contract asset	(23,917)	54,651
Contract assets	489,961	516,521
Contract liabilities	(513,878)	$ (461,870)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-12-31
Contract With Customer, In Progress, Revenue Recognized And Amounts Billed, Disclosure [Line Items]
Revenue remaining performance obligation, Amount	$ 5,700,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-12-31
Contract With Customer, In Progress, Revenue Recognized And Amounts Billed, Disclosure [Line Items]
Revenue remaining performance obligation, Amount	$ 4,800,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-12-31
Contract With Customer, In Progress, Revenue Recognized And Amounts Billed, Disclosure [Line Items]
Revenue remaining performance obligation, Amount	$ 900,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	3 years