INDUSTRY SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2016 USD ($)	Oct. 03, 2015 USD ($)	Oct. 01, 2016 USD ($) item	Oct. 03, 2015 USD ($)	Jan. 02, 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	$ 37,647	$ 36,165	$ 114,596	$ 101,715
Depreciation, depletion and amortization	607	640	1,897	1,937
Operating income (loss)	1,361	965	5,043	1,377
Segment assets	76,522	75,755	76,522	75,755	$ 75,755
Capital expenditures	841	859	3,617	1,379
Concrete Aggregates and Construction Supplies
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	18,156	16,759	51,267	41,414
Depreciation, depletion and amortization	316	330	1,020	1,007
Operating income (loss)	1,010	686	2,881	(170)
Segment assets	35,205	31,791	35,205	31,791
Capital expenditures	565	647	2,798	825
Doors
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	4,467	4,271	13,212	13,140
Depreciation, depletion and amortization	32	31	95	94
Operating income (loss)	543	274	1,390	1,068
Segment assets	6,695	6,471	6,695	6,471
Capital expenditures	54		106	32
Heating and Cooling
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	9,605	9,473	27,390	24,493
Depreciation, depletion and amortization	138	142	415	427
Operating income (loss)	408	692	1,205	994
Segment assets	20,563	22,628	20,563	22,628
Capital expenditures	208	146	584	355
Evaporative Cooling
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	5,416	5,658	22,715	22,656
Depreciation, depletion and amortization	118	123	356	369
Operating income (loss)	259	154	2,077	1,850
Segment assets	11,115	12,730	11,115	12,730
Capital expenditures	14	66	129	167
Unallocated Corporate
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	3	4	12	12
Depreciation, depletion and amortization	3	14	11	40
Operating income (loss)	(859)	(841)	(2,510)	(2,365)
Segment assets	2,944	2,135	2,944	2,135
Construction Products Industry
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	22,623	21,030	64,479	54,554
Depreciation, depletion and amortization	348	361	1,115	1,101
Operating income (loss)	1,553	960	4,271	898
Segment assets	41,900	38,262	41,900	38,262
Capital expenditures	619	647	2,904	857
HVAC Industry
INDUSTRY SEGMENT INFORMATION
Revenues from external customers	15,021	15,131	50,105	47,149
Depreciation, depletion and amortization	256	265	771	796
Operating income (loss)	667	846	3,282	2,844
Segment assets	31,678	35,358	31,678	35,358
Capital expenditures	$ 222	$ 212	$ 713	$ 522