INDUSTRY SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017 USD ($)	Jul. 02, 2016 USD ($)	Jul. 01, 2017 USD ($) item	Jul. 02, 2016 USD ($)	Dec. 31, 2016 USD ($)
INDUSTRY SEGMENT INFORMATION
Number of industry groups in which the entity operates | item			2
Number of reportable segments | item			2
Revenues from external customers	$ 39,887	$ 42,721	$ 73,990	$ 76,949
Depreciation, depletion and amortization	677	651	1,315	1,290
Operating income (loss)	1,655	2,830	1,044	3,682
Segment assets (a)	85,326	78,008	85,326	78,008	$ 78,008
Capital expenditures (b)	2,173	1,694	2,803	2,776
Unallocated Corporate
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	3	5	9	9
Depreciation, depletion and amortization	8	4	16	8
Operating income (loss)	(872)	(900)	(1,699)	(1,651)
Segment assets (a)	2,354	3,653	2,354	3,653
Capital expenditures (b)	29		35
Concrete Aggregates and Construction Supplies
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	18,113	20,912	31,596	33,111
Depreciation, depletion and amortization	373	357	710	704
Operating income (loss)	1,466	2,065	882	1,871
Segment assets (a)	39,736	33,518	39,736	33,518
Capital expenditures (b)	1,837	1,314	2,219	2,233
Doors
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	4,760	4,890	8,629	8,745
Depreciation, depletion and amortization	37	32	72	63
Operating income (loss)	652	537	944	847
Segment assets (a)	7,889	6,173	7,889	6,173
Capital expenditures (b)	18	30	119	52
Heating and Cooling
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	6,778	6,635	17,214	17,785
Depreciation, depletion and amortization	151	139	302	277
Operating income (loss)	(497)	(237)	68	797
Segment assets (a)	21,728	22,381	21,728	22,381
Capital expenditures (b)	267	259	365	376
Evaporative Cooling
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	10,233	10,279	16,542	17,299
Depreciation, depletion and amortization	108	119	215	238
Operating income (loss)	906	1,365	849	1,818
Segment assets (a)	13,619	12,283	13,619	12,283
Capital expenditures (b)	22	91	65	115
Combined Construction Products
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	22,873	25,802	40,225	41,856
Depreciation, depletion and amortization	410	389	782	767
Operating income (loss)	2,118	2,602	1,826	2,718
Segment assets (a)	47,625	39,691	47,625	39,691
Capital expenditures (b)	1,855	1,344	2,338	2,285
Combined HVAC Products
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	17,011	16,914	33,756	35,084
Depreciation, depletion and amortization	259	258	517	515
Operating income (loss)	409	1,128	917	2,615
Segment assets (a)	35,347	34,664	35,347	34,664
Capital expenditures (b)	$ 289	$ 350	$ 430	$ 491