Request for Clarification Responses
DBH Olive Ave Roof Replacement and Façade Repairs
Supplemental Information - Not Part of the Contract Documents
The following list is comprised of paraphrased Requests for Clarification (RFC) submitted by potential bidders or sub-bidders in writing via email, letter, and this form:
24-S-08 Request for Clarification Form
Do the CRCs for off-road diesel-fueled fleets need to be submitted with the bid for subcontractors? We will not know who the low selected subcontractor is until bid time. (RFC 24S8-1 submitted 10/9/2024)
Per Bidders Checklist Section 002213, Title 13 CARB Certification (Section 004556), subcontractor certificates will be due no later than 4:00 PM on the fifth (5th) calendar day after the bid opening if not submitted with the bid. Response date: 10/14/2024
Do General Contractors need to be asbestos certified prior to bid opening or just the subcontractor performing the abatement work? (RFC 24S8-2 submitted 10/9/2024)
Per Notice to Bidders Section 0001113, bidders are required to possess asbestos certification from the Contractors State License Board and registration with the Division of Occupational Safety and Health prior to the opening of bids for this project. Response date: 10/14/2024 A General Contractor need not be asbestos certified provided the subcontractor performing the abatement work is asbestos certified. Revised 10/16/2024
Is there a Bid Bond Form to use or can our surety use their own? (RFC 24S8-3 submitted 10/9/2024)
The bid bond itself can be issued by the bond company. The section of the electronic solicitation or hardcopy bid, “Bid Security and Signature,” – Proposal 4 should be filled out with information regarding the bid bond by the bidder. Response date: 10/14/2024
Is professional Liability required for this project? (RFC 24S8-4 submitted 10/9/2024)
Per General Conditions Section 007200, 2.40 B4, if the Contractor is a licensed professional or employs professional staff, (e.g., Architect, Engineer, Surveyor, etc.) in providing services, Professional Liability insurance is required. Response date: 10/14/2024
The commercial General Liability is set at 5M/10M do the subcontractors have to carry the same limits? (RFC 24S8-5 submitted 10/9/2024)
The County will monitor the insurance of the Prime Contractor. Response date: 10/14/2024
Specification No. 75416 KEE Roofing material page 168-169
We noticed for the reroof the only product we can bid with is tremco. Can we bid this project with a GAF 60 Mil PVC product. We believe you will get the same Quality product at a better price. (RFC 24S8-6 submitted 10/14/2024)
While “Tremco, TremPly KEE Single Ply Roof Membrane” is the basis of design product, substitutions are allowed. See Project Manual, Section 012500 for substitution information and format. Response date: 10/14/2024
In regards to the project referenced above, we have warranty eligible contractors interested in providing a competitive bid using Mule-Hide’s PVC KEE HP roof system. Our PVC KEE HP roof system meets or exceeds current ASTM standards and is equal to or superior in all respects to the specified product. Mule-Hide Products can also provide the same system warranty as specified. The formal request, along with supporting documentation, is attached. If you are not familiar with Mule-Hide Products, we are a commercial low-slope roofing manufacturer that has been in business for over 30 years. We offer multiple product lines for commercial roofing applications, including EPDM, TPO, and PVC. Mule-Hide Products also offers full system NDL warranties through our nationwide network of qualified contractors, with over 900 distribution points across the United States and Canada. Please do not hesitate to contact me if you need additional information. Thank you in advance for your consideration. (RFC 24S8-7 submitted 10/14/2024)
Substitution Request and Details RFC #24S8-7(PDF, 6MB)
This substitution is acceptable. Response date: 10/15/2024 This substitution does not meet or exceed the specified requirements as listed in the Project Manual, Section 075416. This substitution is not accepted. Revised 10/16/2024
Specification No. 099113
Sheet A-301, Elevation notes 1 & 2 make mention of a new texcote and new paint finish. Spec section 099113 also makes mention of painting. However, I do not see a painting schedule or color callouts on the exterior elevations of what colors go where. Is anything supposed to receive paint? If so please clarify colors and locations. (RFC 24S8-8 submitted 10/16/2024)
All exposed surfaces of existing exterior concrete wall panels shall be prepped and painted as specified to match existing. Additionally, all exposed exterior flashing shall be prepped and painted as specified. Colors shall match existing unless noted otherwise; for example, cap flashing at concrete wall panel shall match concrete wall panel color and cap flashing at existing brick shall match existing brick color. Response date: 10/16/2024
The existing can lights in the soffits looks to be 12” square recessed lights. Are these to remain as is? If there is a new different style light to be installed later it might be best to install those lights now to avoid patches in the new hardi-board later. Please advise. (RFC 24S8-9 submitted 10/16/2024)
Existing exterior lights, fire sprinkler head, etc. in building soffit shall remain unless otherwise noted on construction documents. Response date: 10/16/2024
There are details for both wood and premanufactured metal HVAC curbs in the details. Please clarify which one we are to use. Pre-manufactured curbs on top of wood levelers would be the recommended as shown on S202 detail 1. (RFC 24S8-10 submitted 10/16/2024)
Contractor shall provide pre-manufactured curbs over leveling blocks as indicated on Structural detail 1/S202. Contractor shall also verify that pre-manufactured curbs are compatible with HVAC equipment specifications as listed on Mechanical drawings (FOR REFERENCE ONLY). Since HVAC equipment is not part of this contract, Contractor shall provide weatherproof galvanized sheet metal covers at new curbs per detail A3/A-802. Detail A3/A-802 also indicates Mechanical platform flashing, and "NEW PRE-MANUFACTURED SHEET METAL CURB" with a reference to the Structural drawings. Response date: 10/23/2024
Drawing No. A-202.0
Per the roof demolition plan all of the existing roof top mechanical equipment and curbs are to be removed from the roof. Please give direction on how existing electrical feed to roof are to be dealt with. Example: is the wire to be pulled back to the interior panels? (RFC 24S8-11 submitted 10/16/2024)
Contractor shall remove items as noted in the Construction Documents only to the extent that they do not interfere with new work unless noted otherwise. Contractor shall cap or otherwise safe-off items to be removed immediately below the roof structure so that they are accessible from below. Safe-off of electrical shall include the disconnect of wiring at the panel source. Contractor shall verify that wires to be removed or abandoned in place are deenergized and disconnected prior to performing work. Qualified Electrical Workers with the required Personal Protective Equipment using lockout tagout procedures are required to verify wiring and equipment are de-energized and disconnected. Response date: 10/23/2024
Drawing No. A-802 Detail A3 and S202 Detail 1
There are 2 different detail in the documents for the new roof curbs for the future A/C units. one is for a wood framed curb and one for a premanufactured metal curb. Please confirm utilization of metal curb per comment at jobwalk (RFC 24S8-12 submitted 10/16/2024)
See response to RFC 24S8-10. Response date: 10/23/2024
Drawing No. A-802
Detail on Drawing A3 depict the new roof system to be installed over a coverboard and new rigid insulation. One detail notes new rigid insulation to be 2" thick. We cannot confirm thickness of batt insulation below the roof deck to ascertain existing R-Value. please confirm new insulation thickness or R-Value required above roof deck (RFC 24S8-13 submitted 10/16/2024)
Typical existing roof structure includes (from top to bottom) roof deck, 2x6 wood framing with R-19 batt insulation, and 5/8" gypsum board. The County Architect confirms the thickness and type of rigid board insulation as designed is appropriate. Install rigid board insulation at thickness and type as indicated in drawings and specifications. See also Project Manual, Section 075416. Response date: 10/23/2024
Specification No. 5213
Page 1 Article 3 of the construction agreement states that the work is to be completed in 137 calendar days. We anticipate that submittals, procurement, and subcontractor coordination will be 45 days leading to 3 months for construction. Working during the winter months we do not see this schedule as viable. please consider extending total duration to 180 calendar days (RFC 24S8-14 submitted 10/16/2024)
Contractors shall provide bids under the current schedule and number of calendar days as identified in the Project Manual. Per Agreement Section 005213, Article III, the completion time is already subject to extension based on a variety of circumstances beyond Contractor control, including "storms and inclement weather" that may occur during winter months. Response date: 10/23/2024
Insurance calls for General Liability to be 5 million per occurrence/ 10 million aggregate. this is obtainable with Umbrella polices. Pleas clarify comment that if General Aggregate limit applies, either the general limit shall apply separately to this project or the limit shall be 3 times the occurrence limit? (RFC 24S8-15 submitted 10/16/2024)
Yes, a $10,000,000 aggregate using an umbrella policy written on a per project basis is acceptable. See Addendum 1. Response date: 10/25/2024
Specification No. General Conditions Section 2.40
Section 2.40-B.2 calls for Automobile Liability with limits of 5 million. This is extremely abnormal. Please confirm this requirement can be obtained by coverage from an Umbrella Policy. (RFC 24S8-16 submitted 10/16/2024)
Yes, the $5,000,000 automobile liability can be obtained under coverage from an umbrella policy. See Addendum 1. Response date: 10/25/2024
Please issue Asbestos report by Addendum for review (RFC 24S8-17 submitted 10/16/2024)
The Asbestos Report has been posted under "Supplemental Information.'" Response date: 10/23/2024
Specification No. 072726 - 1.11
Section 072726 calls for air barrier warranty period to be 30 years. The only locations where new air barrier is required is at the brick wall patches. Tremco will not supply a 30 warranty in a patch back condition. please confirm that the 30 year warranty will not be required. (RFC 24S8-18 submitted 10/16/2024)
A 30 year warranty is required except where manuafacturer warranty limitations and exclusions apply. Response date: 10/23/2024
Drawing No. A-301
Note 3 on Drawing A-301 states to replace broken windows. Please clarify scope including number of windows to be replaced (RFC 24S8-19 submitted 10/16/2024)
Windows repair and/or replacement work has been removed from plans and is excluded from this contract. See plan revisions, delta 4, dated 2024-10-21. Response date: 10/25/2024
Drawing No. A-301
In regards to existing storefront. Scope is unclear on sealant work. Please clarify scope (RFC 24S8-20 submitted 10/16/2024)
See response to RFC 24S8-19. Response date: 10/25/2024
Drawing No. A-301 Specification No. 099653
Section 099653 specifies silicone elastomeric coatings and lists surfaces to receive. On the brick Fascade it only refers to repairs at missing brick locations. is the intent to coat all of the existing brick surfaces with silicone coatings? please review and advise and if not where is this product to be utilized (RFC 24S8-21 submitted 10/16/2024)
Section 099653 only applies to existing concrete wall panels. Existing and new brick shall not be painted or coated. See also response to RFC 24S8-8. Response date: 10/25/2024
Specification No. 088513
Section 088513 specified glazing sealants. please clarify scope of glazing at existing storefront (RFC 24S8-22 submitted 10/16/2024)
See response to RFC 24S8-19. Response date: 10/25/2024
Drawing No. A-202.0
Per note 3 on drawing A202.0 it calls for removal of existing equipment platforms which implies that all existing roof top equipment is to be demolished. Existing chiller units have steel water lines that penetrate through roof deck into interior mechanical equipment room. please give direction on where and how existing lines are to be terminated after equipment demolition. (RFC 24S8-23 submitted 10/17/2024)
Demolition at roof shall include the removal of all roof top equipment unless items are identified to remain in the Construction Documents. Contractor shall cap or otherwise safe-off items to be removed immediately below the roof structure so that they are accessible from below. See also response to RFC 24S8-11. Response date: 10/23/2024
Drawing No. A-202.0
Demolition plan note 3 states to remove existing roof top platforms although it does not reference or note removal of existing roof top equipment/chillers, etc. please confirm that demolition of existing roof top equipment is part of this bid package (RFC 24S8-24 submitted 10/17/2024)
Demolition of equipment platform shall include the removal of all associated roof mounted equipment (HVAC, chillers, exhaust fans, etc.). Response date: 10/23/2024
The plans do not delineate how many square feet of exterior brick veneer are to be demo'd and replaced. We request the County provide a Square Footage as the base bid for all GCs rather than everyone coming in differently subjecting the County to Change Order. (RFC 24S8-25 submitted 10/18/2024)
As the basis of bid, the area of brick to be replaced is now included on sheet A-301. See plan revisions, delta 4, dated 2024-10-21. Response date: 10/25/2024
Drawing No. A-301
All items called out by Gen Notes 2A-E on Sheet A-301 need to be identified on the drawings so that quantities can be obtained for bidding purposes. If not, we would suggest quantities be given by the County for pricing purposes. (RFC 24S8-26 submitted 10/18/2024)
See response to RFC 24S8-25. Response date: 10/25/2024
Drawing No. A-202.0
General Note #5 on A-202.0 states; “Dashed line denotes areas of demolition. Keynoted items are for additional clarification.” The dashed line does not include the sloped roof areas extending behind the brick façade ‘pop-outs’. Please verify that these areas are to be included in the demolition (and subsequent re-roofing). (RFC 24S8-28 submitted 10/18/2024)
Contractor shall remove all existing built-up roofing for replacement including sloped areas behing the brick facade pop-outs. See plan revisions, sheet A-202.0, delta 3, dated 2024-10-21.Response date: 10/25/2024
Drawing No. A-202.0
Demolition Plan A-202 Keynote #18 states; “Remove existing composition tile flashing along sidewall perimeter. Clean and prepare for installation of new roofing membrane.” The photograph and referenced keynote appear to reference the composition tile shingles above the flashing. Detail A2/A-202.0 indicates only “Remove Existing Base Compo Felt Flashing”. Please confirm that the composition shingles are to be removed as well. (RFC 24S8-29 submitted 10/18/2024)
All composition shingles at vertical roof surfaces shall be removed as part of this contract. Response date: 10/23/2024
Drawing No. A-202.0
During roof inspection of job walk, various mechanical and electrical equipment and conduits were found which do not show up on the demo plan A-202.0. Will this equipment be removed by others? If not, please provide plan showing Existing equipment/utilities/conduit on roof. (RFC 24S8-30 submitted 10/18/2024)
See response to RFC 24S8-24. Response date: 10/23/2024
Drawing No. A-203
The Reflected Ceiling Demolition Plan A-203 includes a note stating, “Existing Building Interiors No Work Proposed.” However, access to the roof structure to install new roof curbs will require demolition of existing interior building items, elements, equipment and/or structures located between the dropped ceiling and roof structure in multiple locations. These existing building items, elements, equipment and/or structures have been neither identified nor qualified, and represent an unforeseen existing condition. These may include acoustical ceiling tiles, runners and hanger wires, light fixtures, conduit & wiring, mechanical ductwork, VAV boxes, valve boxes, supports, threaded rod, fire sprinkler, gas or water piping, valves, controls and support equipment. Please advise if the existing building elements located between the dropped ceiling and roof structure in these locations will be removed under a separate contract prior to commencement of this work or if they will be paid for as a change order once the full scope is quantified. If the work is to be included within this contract, please provide As-Built drawings of the building. (RFC 24S8-31 submitted 10/18/2024)
Existing interior building components are to remain during phase 1 unless noted otherwise. Interior demolition will occur during the phase 2 interior remodel with the following exception: Contractor shall include in the phase 1 bid the removal of an 18'x12' area of acoustical ceiling tiles and ceiling suspension grid below each new roof equipment curb to allow for access from below to the structural modifications required as part of phase 1. Other components such as lights, ductwork, piping, ext. are to be relocated only as required to accomplish phase 1 work. As-Built drawings are provided as supplemental information. Response date: 10/23/2024
Drawing No. S-202
S202 shows the locations of the proposed AC units, and details 2-5 identify the scope of modifications to the existing framing members that will be required to install the new equipment curbs. Please advise if the proposed modifications to the existing roof framing members will require shoring, and if so, who is to provide the engineering for the shoring system. (RFC 24S8-32 submitted 10/18/2024)
Structural modifications should not require shoring. Only the 2x6 roof joists at 2'-0" o.c. shall be cut, modified, or removed during structural upgrades. All other structural components larger than 2x6 shall remain without modification. If, for any reason, shoring becomes necessary, the County or its consultant will provide engineering for the shoring system. Response date: 10/23/2024
Drawing No. A-301
General Notes #3 & #4 shown on A-301 describe replacing broken windows and joint sealant/waterproofing as required. No indication is made on plans to show where condition described in notes apply, leaving ambiguity. Please quantify areas requiring replacement of broken windows/joint sealant/waterproofing as applicable. Alternatively, allow for unit pricing for each condition described. (RFC 24S8-33 submitted 10/18/2024)
See response to RFC 24S8-19. Response date: 10/25/2024
Drawing No. A-301
General Notes #2 & #5 shown on A-301 describes replacing broken/damaged concrete panel caulking and components as required. No indication is made on plans to show where conditions described in notes apply, leaving ambiguity. Please quantify areas requiring replacement of broken/damaged components as applicable. Alternatively, allow for unit pricing for each condition described. (RFC 24S8-34 submitted 10/18/2024)
Contractor shall assume that all exposed major vertical joints between adjacent concrete wall panels shall be removed and replaced. Concrete wall system joints are indicated in As-Built drawings provided as supplemental information. Response date: 10/23/2024
Drawing No. A-803
Detail A7/A-803 shows both existing (and not noted as “typical”) framing at the exterior soffits. Other members appear to be new. Additionally, the second bullet point in the same detail states “ADDITIONAL FRAMING MAY BE NEEDED TO ENSURE PROPER FASTENING”. Quantity of additional framing, if needed is ambiguous. Please provide As-Builts to determine if additional framing is required. (RFC 24S8-35 submitted 10/18/2024)
Existing soffit framing is 2x4 wood joists at 24" o.c. Contractor shall install HARDIESOFFIT panels as indicated on drawings perpendicular to existing framing; this includes continuous new 2x4 blocking at all otherwise unsupported soffit panel edges. As-Built drawings are provided as supplemental information. Response date: 10/25/2024
Drawing No. A-202.0, A-401, A-802
Conflict exists between details regarding top plate at parapet walls. Per A2/A-202.0, Top 2x Wood Plate is shown as existing. Per details A2,A7/A-401, and details H1,H3,H10/A-802, top plate is indicated as new. (RFC 24S8-36 submitted 10/18/2024)
Contractor shall provide all new top plates as indicated on sheets A-401 and A-802. Response date: 10/23/2024
Drawing No. A-802, A-803
As referenced on the job walk, Please verify metal roof curbs are to be installed and remove conflicting details showing wood curbs (A3/A802 & A3/A803). (RFC 24S8-37 submitted 10/18/2024)
See response to RFC 24S8-10. Response date: 10/23/2024
Drawing No. A-803
Future pipe penetrations in roof mentioned on job walk are not represented on plan sheets. Detail D1/A803 shows penetration flashing. No locations are shown. Please confirm these penetrations do not exist under the scope of work of this contract. (RFC 24S8-38 submitted 10/18/2024)
Unless otherwise noted on plans, all future pipe penetrations from phase 2 equipment (vents, flues, exhaust, etc.) are not part of this Contract and will be installed as part of phase 2. Response date: 10/23/2024
No detail is given to describe how roof openings/curbs are to be covered/protected. Please clarify requirements to cover/protect roof openings/curbs and provide any applicable details. (RFC 24S8-39 submitted 10/18/2024)
Contractor shall provide new weather-proof caps at all new equipment curbs as indicated on detail A3/A-802 including but not limited to "20 GA. GSM PAN OVER BUILDING PAPER & BASE FELT OVER 5/8" PLYWOOD PLATFORM". Response date: 10/23/2024
Drawing No. A-202.1
Regarding Roof note #5/A-202.1, per our observation and from the information contained in the abatement report, we believe these vents mastic containing asbestos and are unable to be reused. Please confirm vents do not contain asbestos (RFC 24S8-40 submitted 10/18/2024)
Contractor shall assume that the roof mastic at all vent curbs, jacks, etc. include non-hazardous non-friable ACM per abatement report unless specifically noted otherwise. Existing vents not indicated to be replaced, shall be abated, removed and reinstalled as indicated on drawings (e.g., see detail A7/A-802). Response date: 10/23/2024
Drawing No. A-202.1
Regarding roof plan Keynote #4 on sheet A-202.1, Please identify extent of work pertaining to both the roof drain and overflow. (RFC 24S8-41 submitted 10/18/2024)
Existing roof drain and overflow shall be removed, retained, and reinstalled as indicated on drawings. Contractor shall assume that every roof drain and overflow will require removal and reinstallation as detailed. Response date: 10/23/2024
Drawing No. A-202.1
We believe Roof plan keynote 14 on Roof plan A-202.1 is an error. Please confirm. (RFC 24S8-42 submitted 10/18/2024)
Drawing No. S-202
Please confirm sheet S-202 depicts the full scope of the framing work to be completed at the roof. (RFC 24S8-43 submitted 10/21/2024)
Confirmed. Sheet S-202 depicts the full scope of structural framing to be completed and shall be interpreted in conjunction with all other contract documents. Response date: 10/23/2024
Drawing No. A-100 Specification No. 013100
Currently there is a temp fence around the building. Will this temp fence stay up during construction? If so, will owner pay for the cost? (RFC 24S8-44 submitted 10/22/2024)
The existing temporary fencing is being provided under a separate contract and will be removed prior to the start of this contract. Contractor shall include and provide temporary fencing to the same extent as existing. Response date: 10/25/2024
Drawing No. A-100 Specification No. 013100
Please confirm that no SWPP and erosion control will be required. (RFC 24S8-45 submitted 10/22/2024)
Confirmed. No SWPPP and erosion control will not be required. Response date: 10/23/2024
Drawing No. A-100 Specification No. 013100
Where will the temporary power hookup be located? (RFC 24S8-46 submitted 10/22/2024)
The existing electrical service entrance is located on the northeast corner of the building and building power is currently active and available for use. Contractor shall note that AT&T equipment inside the building is currently operating and any disruptions in power due to construction shall be coordinated with the Owner and AT&T. Response date: 10/25/2024
Drawing No. A-100 Specification No. 013100
On A-202.0 Roof Demo Plan, keynote 10 says to remove existing curbs. Will the HVAC mechanical units already be removed, or do we also have to remove the units? (RFC 24S8-47 submitted 10/22/2024)
All existing roof mounted equipment including HVAC mechanical units shall be removed by the Contractor unless noted otherwise. See also response to RFC 24S8-24. Response date: 10/23/2024
Drawing No. A202.1
On A202.1 Proposed Roof Plan Keynote 8 states proposed New Air Conditioner Direct Drive Package Roof type unit. Is furnishing and installing this New Air Conditioner Direct Drive Package Roof unit part of this contract? (RFC 24S8-48 submitted 10/22/2024)
All new mechanical and HVAC equipment shall be installed as part of phase 2 and are not included in this contract. Any reference to "MECHANICAL" plans, drawings, or sheets is for information and coordination only. Response date: 10/23/2024
Is a field job trailer mandatory for the GC? Is a field job trailer mandatory for the inspector? (RFC 24S8-49 submitted 10/22/2024)
Field job trailers for the GC or inspector are not mandatory. The existing building is unoccupied and may be used as the field office for this project. Response date: 10/23/2024
On the Silicone elastomeric coatings specs, it references Exterior insulation finish system (EIFS), but none was shown on the plans. Please clarify? (RFC 24S8-50 submitted 10/23/2024)
This project does not include the following: Concrete unit masonry, Stucco or Exterior insulation finish system (EIFS). Contractor shall disregard items 2, 4 and 5 as listed in Section 099653, 1.1.A. SUMMARY. Additionally, existing face brick shall not be painted or coated, so Contractor shall also disregard item 3 as listed in Section 099653, 1.1.A. SUMMARY. Response date: 10/23/2024
Specification No. Insurance
Is the builders risk insurance policy intent to only cover the construction portion of the building or does the policy need to cover the total existing building? What would the limit / value be if we need to cover the whole building? (RFC 24S8-51 submitted 10/23/2024)
The builder’s risk insurance is intended to cover the new construction as the County would seek to recover property damage losses to the existing building under the contractor’s commercial general liability policy. Response date: 10/25/2024
Drawing No. A-803
Detail K1 & G1 show batt insulation underneath the expansion joint. Is the batt insulation infill part of this contract? (RFC 24S8-52 submitted 10/24/2024)
Contractor shall install batt insulation as shown at expansion joint details as necessary to maintain insulation continuity at building envelope. Response date: 10/25/2024
Drawing No. A-803
On Detail K1, there is something that is in between the Wood blocking and batt insulation but nothing is called out. What are the screws anchoring to that will hold the blocking in place? (RFC 24S8-53 submitted 10/24/2024)
Drawing No. A-803
Detail G1 Horizontal to vertical expansion joint is not called out on the plans. Is this detail applicable to this project? (RFC 24S8-54 submitted 10/24/2024)
Drawing No. 099653
There is a specification for Silicone Elastomeric Coatings, which is a waterproofing material, but this is not called out on the plans. Will Silicone Elastomeric Coatings be part on this contract? (RFC 24S8-55 submitted 10/25/2024)
See response to RFC 24S8-21. Response date: 01/00/1900