All of the structures had additions, and these were typically for; 1) adding enclosed living space, 2) adding kitchen and bathroom facilities on older structures, 3) enclosing an existing open porch area. Four (4) out of six (6) could be made habitable, and three (3) of six (6) had been recently occupied prior to the building’s removal. One (1) house had been occupied by homeless persons without heating, kitchen, or bathroom facilities. Three (3) of the six (6) structures were found to have asbestos containing materials (ACM) requiring abatement. Two  (2) of the structures contained only non-friable asbestos which could have been “wet demolished” by mechanical means but would have required the entire demolition wastes load to be disposed off in a hazardous materials landfill. Only one building had LBP only on the inside, typically LBP was found on exterior window and door trim, where it was used in gloss and semi-gloss paint for durability.

 

Two (2) of the six (6) buildings were on property slated for immediate commercial or multi-family redevelopment, two (2) were on property slated for long-term redevelopment, and two (2) buildings were on land not slated for redevelopment. The latter two (2) structures may have been left vacant for an indeterminate length of time if they had not been used for this project. During the course of the project, one building verbally committed to the deconstruction project, on a site slated for commercial redevelopment, was demolished. In addition, two candidate buildings, on sites slated for redevelopment, were moved. One structure that was considered for the project was considered too dilapidated for a reasonable deconstruction and another was passed over due to scheduling conflicts and was subsequently partially renovated by the owner. The average size of the six structures was 1,476 SF.

 

Based upon literature review and anecdotal information, this sample of structures would appear to be representative of residential demolitions in the United States. Also, approximately 94% of all residential buildings built each year in the US are light wood-framed construction (NAHB, 1994).

 

Data Collection

On-site labor was documented by recording each worker’s activities on a 15-minute time increment.  There have been several well-documented deconstruction pilot projects in the US with this detail of data collection, most notably the Fort Ord Pilot Deconstruction project conducted by the Fort Ord Reuse Authority  (Cook, 1997) and the Riverdale Pilot Deconstruction Project conducted by the National Association of Home Builders Research Center  (NAHBRC, 1997). These projects provided models for creating the data collection process. Data is divided into two categories; the deconstruction of the structure and the processing of the salvaged materials. The cost of a traditional demolition was calculated for each structure, including disposal costs. Salvage revenues were estimated using a percentage (25-50%) of retail prices from local building materials suppliers and the experience of a former used building materials store owner/operator in Gainesville, Florida. Disposal costs were estimated by weight and costs data provided by the wastes haulers for the project.

Worker labor activities were sub-divided into categories by the location in, or component of, the building in order to calculate the costs of deconstructing a particular component of the building, and the costs to salvage a unit of a particular material. The latter information was used to assign a unit cost of extraction and processing that could be compared to the pricing units for materials, i.e. number, linear feet, or board foot of material. Labor productivity data was collected in the following task categories:

(S) upervision 

Directing and planning the flow of work on the job site.

(Decon) struction

Labor involved in the initial removal of materials from the structure. Any manual or mechanical procedure required to remove materials for salvage, either the direct handling of a material or removing other materials to gain aPCCEss to the salvage material.

(Demo) lition

The hand or mechanical removal of building materials for direct disposal.

(P) rocessing

Preparing materials for redistribution in reusable form.  Denailing is the most typical processing activity.

(N) on-production

No work is being performed. Includes breaks and the unloading and clean-up of daily tools, but excludes lunch.

(C) lean-up / (Dis) posal

Sweeping and/or removing debris or demolition materials from a work area and/or disposal into a roll-off container. 

L) oading/unloading

Loading or unloading materials from the site onto a truck for transport and at the final storage area.

The largest percentage of time on any deconstruction was the deconstruction activity, an average of 26% of total time. The next greatest percentage of time was spent in processing materials at an average of 21%.  Disposal and cleaning required an average of 17% of total time. Demolition required an average of ~12% of total time. The house with the largest percentage of time spent for deconstruction was the house at 901 SR 301 (47.8%). This house was being removed for redevelopment and had a very short time frame for the deconstruction. It was also located on a major highway in the corner of a shopping center site, and materials were redistributed by placing them neatly in separate piles at the site and posting “Free Materials” signs to encourage passersby to remove the materials themselves. All of the materials were removed within one day after the completion of the deconstruction.

 

Table Two - Sample Data Sheet

Location:				Completed by:			Date:
Worker	#1	#2	#3	#4	#5	#6	#7
7:30
Activity
Room
Location
Material
Activity	Supervise	Decon	Process	Demo
	S	Dec	P	Dem
	Clean/Disposal		Non-Prod	Load
	C/Dis		N	L
Location	Site	Wall trim	Cabinet	Fixtures	Int W Fin	Ceil Fin	NL Int W
	Wall Cav	Attic	Floor Str	Roof Sh	Roof Str	Ext W tr	Ext W Fin
	Ext W sh	Ext W Str	Floor Fin	Subfloor	Roof trim	Roof Fin	Chimney
	Found
Material	Debris	1x3	1x4	1x5	Wood	Metal	Hardware
	E Panel	Outlet	Wire/Pipe	Tin	Tar paper	1x6	4x4
	1x3 Wd flr	2x4	1x8	1x10	2x10	2x12	1x4 Wd flr
	Bldg paper	4x6	4x8	4x10	4x12	6x	Drywall
	Pl/Lathe	Beadbd	1x12	2x6	2x8	Brick	Concrete
	Arch Salv

 

The house with the lowest percentage of time in deconstruction was the house at 711 NW 7^th Avenue (12%). This structure was in the poorest condition of any of the structures and therefore had the lowest amount of salvage. Commensurately, this building had the highest percentage of time spent in disposal and cleaning (39.6%). Excluding the house at 711 NW 7^th Avenue which had a very low salvage rate and very little processing (4.3%), processing was a relatively consistent percentage of time between 18 – 30% of total time. The house at 711 NW 7^th Avenue had the highest percentage of time spent in demolition, consistent with low deconstruction and high disposal and cleaning efforts.

 

Table Three - Labor Time by Work Categories

Category Hours
		S	Dec	P	Dem	Dis/C	N	L	Total
2930	hr	60.50	179.50	204.80	0.00	100.00	52.75	80.00	677.55
2014 SF	%	8.93	26.49	30.23	0.00	14.76	7.79	11.81
per SF	hr	0.030	0.089	0.102	0.000	0.050	0.026	0.040	0.336
711	hr	20.50	24.33	8.67	42.95	80.50	14.33	12.25	203.53
1436 SF	%	10.07	11.95	4.26	21.10	39.55	7.04	6.02
per SF	hr	0.014	0.017	0.006	0.030	0.056	0.010	0.009	0.142
14	hr	62.13	113.56	124.56	26.67	81.00	27.00	42.87	477.79
2059 SF	%	13.00	23.77	26.07	5.58	16.95	5.65	8.97
per SF	hr	0.030	0.055	0.060	0.013	0.039	0.013	0.021	0.232
2812	hr	29	133.13	217.63	39.13	63.25	53.75	21.5	557.39
1238 SF	%	5.20	23.88	39.04	7.02	11.35	9.64	3.86
per SF	hr	0.023	0.108	0.176	0.032	0.051	0.043	0.017	0.450
901	hr	11.75	124.75	47	27	25.75	23	1.75	261.00
992 SF	%	4.50	47.80	18.01	10.34	9.87	8.81	0.67
per SF	hr	0.012	0.126	0.047	0.027	0.026	0.023	0.002	0.263
3650	hr	16	84	91.85	64.5	35	50.5	17.25	359.10
1118 SF	%	4.46	23.39	25.58	17.96	9.75	14.06	4.80
per SF	hr	0.014	0.075	0.082	0.058	0.031	0.045	0.015	0.321
Average %		7.69	26.21	23.86	10.34	17.04	8.83	6.02	100.00
Average per SF		0.021	0.078	0.079	0.027	0.042	0.027	0.017	0.291

 

The deconstruction process roughly follows the reverse of the construction process. The materials that have been put on last will come off first. Variations occur between whole building sections, for example, an addition will be removed in its entirety separately from the rest of the building. The practice of focusing on each material type in a reverse order of the construction process is more efficient for separating materials for reuse, recycling, and disposal at the time of removal. Additions are an impediment to removing one type of material or whole sections of the original structure, but can provide a working surface for other parts of the building, and be structurally dependent on other parts of the building. For these reasons, additions were typically removed in their entirety, regardless of breaking up the material-by-material consistency of the deconstruction process.

 

Economics

The net cost of the deconstruction is modeled by the expression: (Deconstruction + Disposal + Processing) – (Contract Price + Salvage Value) = Net Deconstruction Costs. The net cost for demolition is: (Demolition + Disposal) – (Contract Price) = Net Demolition Costs. If materials are not resold or redistributed on-site or reused by the deconstruction contractor in new construction, transportation and storage costs may be additional costs for deconstruction. In order for deconstruction to be cost-effective and competitive with traditional demolition and disposal, the sum of the savings from disposal and revenues from resale of materials, must be greater than the incremental increase in labor cost for deconstruction versus demolition.

 There are multiple options for contracts and costs/revenues between a building owner and the deconstruction contractor, such as:

An economic factor for deconstruction on a redevelopment site is the time costs of money in financing and construction loan interests. A large site may allow an unwanted structure to be isolated from the other construction activity and be deconstructed without delaying the site development. In the case of a site where the new construction will take place on the footprint of the existing structure, the time for removal of the existing structure by deconstruction is a significant economic impediment.

 

Permitting

The City of Gainesville has a unique demolition permitting process which allows the City to place a 90-day demolition delay on any residence that may have historic value (older than 45 years). During this 90-day delay, the structure is posted as free to anyone willing to pay the costs of moving. This delay can be waived by demonstrating a financial hardship. There are no historic districts or delays in Alachua County.

 There is no differentiation in Alachua County and the City of Gainesville between a deconstruction and a demolition for permitting purposes. The total costs of permits range from $60 to $100 for single or two-story residential structures. The City of Gainesville charges by the total number of stories of a structure, and Alachua County charges by the estimated value of the demolition work. These permitting factors and low cost are not conducive to encouraging deconstruction.

 A possible incentive for deconstruction under the 90-day delay ordinance is to shorten the delay to 30 days, for example, for a “deconstruction permit”. By shortening the delay for deconstruction, it would be less viable to claim economic hardship posed by the delay, some time is allowed to arrange a building removal, and sufficient time is allowed for deconstruction and still result in a net reduction over the 90-day delay.

 The City of San Jose has been developing a construction demolition debris deposit (CDDD) as a means to encourage reuse and recycling of building materials. This deposit, similar to the bottle deposit, requires an upfront deposit based upon estimated waste generation. Upon completion of the project and documentation of reuse for distribution or transfer to an appropriate recycling option or 50% of the waste generated by the project, the refund is returned. This procedure combines the demolition permit with an economic incentive to reuse and recycle the demolition debris.

 Environmental Issues

For the purposes of maintaining worker health and safety, deconstruction is a distinct activity in EPA and OSHA regulations. Relevant environmental and worker health and safety regulations governing the deconstruction of buildings include: US EPA National Emission Standards for Hazardous Air Pollutants (NESHAPS) Asbestos Regulations (40 CFR 61, Subpart M), Occupational Health and Safety (OSHA) Asbestos Regulations (29 CFR 1910.1001), OSHA Lead Regulations (29 FCR 1926.26) and Classifications of Landfills Florida Statue Rule 62-701.200 (19).

 

Hazardous Materials in Deconstruction

The NESHAPS regulation requires any commercial properties or residential properties greater than 4 units to have a reasonable effort to identify hazardous materials prior to demolition or deconstruction. The NESHAPS regulation also controls the techniques for removal, containment, and transport of asbestos containing materials (ACM).

The NESHAPS regulations exempt residential structures of 4 dwelling units or less. Residential units demolished as part of larger public or commercial projects such as highway construction and shopping centers are not exempt from NESHAPS even if less than 4 dwellings units. A group of individual residential buildings under the same ownership on a site is considered an installation and is also not exempt from the NESHAPS regulations. Hazardous materials are required to be disposed of in a lined landfill or other disposal facility that is permitted for those materials.

 Worker environmental safety is regulated under OSHA and EPA guidelines regardless of the construction activity. The PCCE utilized a certified LBP and ACM surveyor to perform a lead-based paint (LBP) survey and an asbestos survey when asbestos containing materials (ACM) are visually identified during the building assessment. The building assessment survey also included noting the presence of fluorescent lights, thermostats, or high-density discharge lamps that may contain mercury or PCBs, and containers of suspect chemicals, paint, oil, etc.  A Phase II ESA investigation is conducted with spot testing for LBP for all structures.

 LBP is assumed in any structure built prior to and during the period between 1970 - 1980 and OSHA began ACM regulation in 1970. Between 83% and 86% of all homes built before 1978 in the United States have lead-based paint in them. The older the house, the more likely it is to contain lead-based paint and to have a higher concentration of lead in the paint. Houses built before 1950 pose the greatest hazard to children because they are much more likely to contain lead-based paint than newer houses. (CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC))

 

Samples were taken from all suspect, homogeneous ACM and LBP surfaces on all of the structures in this study. Polarized Light Microscopy with dispersion staining was used to analyze the ACM samples using US EPA Interim Method for the Determination of Asbestos Minerals in Bulk Materials. LBP samples are tested using the NIOSH Method #7082.  Samples were analyzed by EMSL Analytical, Inc., Program, Greensboro, NC. The HUD minimum threshold for the presence of lead is 0.5% Pb. A summary of LBP findings for the structures is provided in Table Five.

 According to the US EPA, regulated ACM (RACM) is:  a) friable asbestos material; b) Category I non-friable that has become friable; c) Category I non-friable that will be subject to sanding, grinding, cutting, abrading; d) Category II non-friable that has a high probability of becoming friable in the course of renovation or demolition activity.

 Removal and disposal of all friable asbestos must be completed prior to demolition by a licensed professional asbestos abatement firm. Category I non-friable ACM (asphalt roofing shingles, floor tiles) and Category II non-friable ACM (asbestos siding shingles, transite board) need to be removed prior to demolition only if they are RACM.

Category I non-friable ACM flooring and shingle materials and Category II non-friable ACM are not RACM and do not have to be abated prior to demolition if they are in good condition and not likely to become friable during demolition. Removal of Category I non-friable ACM is permitted according to the Resilient Floor Covering Institute (RFCI) and the National Roofing Contractors Association (NRCA) aPCCEptable work practices. The NRCA association’s recommendations are to remove asbestos shingles by hand and lower them to the ground. Theoretically, demolition should render all ACM to be regulated since it is comprised of crushing, cutting, and grinding activities. However, Category II non-friable ACM is allowed to be demolished in place using proper wetting and containment techniques during the removal and transport.

 Because deconstruction poses a greater worker exposure than mechanical demolition it is prudent to remove all ACM, both RACM, and ACM that is in good condition. Any materials with asbestos are also not viable for reuse. In effect, all ACM must be abated prior to deconstruction whether it is considered regulated or not, which could add significant costs to a deconstruction project over traditional demolition. Any components that are either intended for reuse with LBP remaining on the material or materials that have been repainted to encapsulate the LBP require notification that the material contains LBP. Salvaged materials are not allowed to sit on exposed soils where there is potential for the LBP to leach into the soil. Salvage materials are either moved off –site to an appropriate storage facility, or stored on 6 mil polyethylene sheeting and a waterproof covering. Wastes materials are placed directly into standard 20, 10 and 8 cubic yard roll-offs.

Table Four -  Lead and Asbestos Sample Results by Location (6 houses)

	Total	Floor	Int. fin.	Roof	Int. trim	Ext. trim	Ext. fin.	Insul.	Duct tape
Suspect ACM	50	27	17	3	0	0	1	1	1
Percentage		54.0%	34.0%	6.0%			2.0%	2.0%	2.0%
ACM	12	9	1	1	0	0	0	0	1
Percentage	24.0%	75.0%	8.3%	8.3%					8.3%
Suspect LBP	35	1	14	0	4	9	7	0	0
Percentage		2.9%	40.0%		11.4%	25.7%	20.0%
LBP	18	0	4	0	1	6	7	0	0
Percentage	51.4%		22.2%		5.6%	33.3%	38.9%