Foundation/Site Work Code Requirements

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1 Q: What is a Foundation Only permit and why did I receive one when I filed for a full Building Permit? All Building Permits for new construction and additions are reviewed for zoning compliance. This review often results in a condition that is placed on the permit application, by the Zoning Enforcement Officer, in accordance with Sect of the Building Zone Regulations. This is commonly referred to as a Proof of Location Survey. After the permit application is reviewed, approved and ready for issuance, the Zoning Enforcement Officer may require a Proof of Location Survey, in which case a Foundation Only permit is released. This allows construction of the foundation ONLY. Once the soil bearing inspection is made and approved, permission to place the concrete is given. After the concrete is placed, the permittee is required to have a CT Licensed Surveyor prepare an A-2 Survey indicating the As-Built location of the foundation. A copy of this is required to be submitted and will be compared to the original survey submitted with the permit application. If the As-Built foundation is in the same location as the original proposed location it will be approved by a Zoning Inspector and a full Building Permit will be issued. Only then does the permittee have permission to start framing.

2 Q: What do I do if concrete footings have been placed and I failed to request the required inspection or failed to get the approval to pour the concrete? If you as contractor or owner either failed to call the Division of Building Inspection to request a soil bearing inspection or requested same but either did not receive or failed the inspection and proceeded to pour the concrete without this inspection and approval, you will be required to do the following: A. Contact a CT licensed PE to inspect the excavated foundation and have him/her file a Soil Bearing Inspection Report on the adequacy of the as-built foundation. This report shall include all of the following: 1. Date, time and site conditions at time of inspection and verify that the perimeter of the foundation had been excavated for inspection. 2. Identification of person(s) who conducted inspection. 3. Soil analysis: description of the soil in the ultimate bearing strata, including sufficient data to establish its character, nature and loadbearing capacity. 4. Soil bearing value: verification of presumed soil bearing value per square foot and actual loads per square foot placed on the soil by the proposed structure. B. A letter from the permittee/builder verifying the following: 1. Person(s) authorizing the placement of the concrete foundation. 2. Explanation of reason(s) the concrete was placed prior to receiving the required soil inspection approval from this office. If you have any questions feel free to contact this office at Instructions for the Soil Bearing Inspection Report form on the following page: Print out form on LEGAL SIZE paper. Fill out and deliver or send the original with live signature and seal of CT Registered P.E. to: Town of Greenwich DPW, Building Inspection Division Town Hall Field Point Road Greenwich, CT

3 Q: What is the minimum footing depth for Greenwich? All footing bottoms shall be placed a minimum of 42 inches below finished grade AND placed on undisturbed soil (Figure 1). Footings can be placed on ledge if they are properly pinned (Figure 2). Grade 42" min. Soil Figure 1 Undisturbed soil Grade no min. Soil Ledge Figure 2 Rods drilled and grouted into ledge

4 Q: What is the load bearing value of different types of soils? Table PRESUMPTIVE LOAD-BEARING VALUES OF FOUNDATION MATERIALS CLASS OF MATERIAL LOAD-BEARING PRESSURE (pounds per square foot) Crystalline bedrock 200,000 Sedimentary rock 50,000 Sandy gravel or gravel 12,000 Sand, silty sand, clayey sand, 8,000 silty gravel and clayey gravel Clay, sandy clay, silty clay 3,000 and clayey silt For SI: 1 psf = kn/m 2.

5 Unreinforced Foundation Wall Design Re Section Masonry and concrete wall construction. Foundation walls using unreinforced masonry or plain concrete are considered acceptable when such walls will not be subjected to more pressure than would be exerted by backfill having an equivalent fluid weight of 30 pounds per cubic foot (480 kg/m 3 ). Required thicknesses are found in Table a of the code. Minimum thickness of unreinforced foundation walls listed in Table a of the code are predicated on the material used in the construction of the foundation wall, the maximum height of unbalanced fill (see figure on next page) and the type of wall system which is to be supported. The tabulated values are based on the assumption that the lateral loads will be carried by the walls through bending in the vertical direction. It should be noted that the actual thickness may be as much as 1/2 inch (12.7 mm) less than the required nominal thickness specified in the table. Table a MINIMUM THICKNESS AND ALLOWABLE DEPTH OF UNBALANCED FILL FOR UNREINFORCED MASONRY AND CONCRETE FOUNDATION WALLS 1, 2 WHERE UNSTABLE SOIL OR GROUNDWATER CONDITIONS DO NOT EXIST IN SEISMIC ZONES 0, 1 OR 2 FOUNDATION WALL CONSTRUCTION NOMINAL THICKNESS 3 MAXIMUM DEPTH OF (inches) UNBALANCED FILL 1 (feet) Masonry of Hollow Units, Ungrouted Masonry of Solid Units Masonry of Hollow or Solid Units, Fully Grouted Plain Concrete Rubble Stone Masonry 16 8 Masonry of hollow units reinforced vertically with No. 4 bars and grout 8 7 at 24 inches on center. Bars located not less than 4 1/2 inches from pressure side of wall. For SI: 1 inch = 25.4 mm, 1 foot = mm. 1 Unbalanced fill is the difference in height of the exterior and interior finish ground levels. Where an interior concrete slab is provided, the unbalanced fill shall be measured from the exterior finish ground level to the top of the interior concrete slab. 2 The height between lateral supports shall not exceed 8 feet. 3 The actual thickness shall not be more than 1/2 inch less than the required nominal thickness specified in the table. 4 Six-inch plain concrete walls shall be formed on both sides. 1

6 Unreinforced Foundation Wall Design (continued) Finished grade Foundation wall Depth of unbalanced fill Thickness Top of slab (or top of under-floor space) Foundation Wall With Unbalanced Fill 2

7 Crawl Space Ventilation CABO, Section 409 Crawl Space Ventilation. The space between the bottom of the floor joists and the earth under any building (except such space as is occupied by a basement or cellar) shall be provided with ventilation openings through foundation walls or exterior walls. Ventilation openings shall be provided with corrosion-resistant wire mesh, with the least dimension being 1/8 inch (3.2 mm). The minimum net area of ventilation openings shall not be less than 1 square foot for each 150 square feet (0.67 m 2 for each 100 m 2 ) of crawl space area. One such ventilating opening shall be within 3 feet (914 mm) of each corner of said building. Exceptions: 1. Ventilation openings may be vented to the interior of buildings where warranted by climatic conditions. 2. The total area of ventilation openings may be reduced to 1/1,500 of the under-floor area where the ground surface is treated with an approved vapor barrier material and one such ventilation opening is within 3 feet (914 mm) of each corner of said buildings. The vents may have operable louvers. 3. Ventilation openings may be omitted on one side. 4. Under-floor spaces used as supply plenums for distribution of heated and cooled air shall comply with the requirements of Section Ventilation openings may be omitted when continuously operated mechanical ventilation is provided at a rate of 1.0 cfm for each 50 square feet (1.02 L/s for each 10 m 2 ) of crawl space floor area and ground surface is covered with an approved vapor barrier material Access. An access crawl hole 18 inches by 24 inches (457 mm) by 610 mm) shall be provided to the under-floor space Removal of debris. The under-floor grade shall be cleaned of all vegetation and organic material. All wood forms used for placing concrete shall be removed before a building is occupied or used for any purpose. All construction materials shall be removed before a building is occupied or used for any purpose Finished grade. The finished grade of under-floor surface may be located at the bottom of the footings; however, where there is evidence that the groundwater table can rise to within 6 inches (153 mm) of the finished floor at the building perimeter or where there is evidence that the surface water does not readily drain from the building site, the grade in the under-floor space shall be as high as the outside finished grade, unless an approved drainage system is provided. See drawing on next page. 1

8 Crawl Space Ventilation (continued) Re Section Ventilation. To control condensation within crawl space areas and thus reduce the chance of dry rot, natural ventilation of such spaces by reasonably distributed openings through foundation walls of exterior walls is required. Susceptibility to condensation is a function of the geographical location and the climatic conditions and, thus, the dependence upon ventilating openings through the foundation wall or exterior wall may run counter to energy conservation measures. Measures to keep animals such as rodents or vermin from entering the crawl space are stipulated in the form of the installation of a certain size wire mesh over the opening. The figure below illustrates the use of openings through the foundation walls. A number of exceptions are provided to address a variety of conditions wherein openings through the foundation walls or exterior walls are either reduced or eliminated. Alternatives include the ventilation of the space into the interior of the building where climatic conditions warrant such an option, such as areas where the climate is moderate and dry. When the ground surface within the crawl space is provided with an approved vapor barrier, a reduction in the net area of the ventilating openings to one-tenth of that required is permissible. Additionally, when the vapor barrier is installed, the ventilation openings provided into the crawl space can be equipped with operable louvers, allowing additional energy conservation benefits during times of the year when moisture condensation is unlikely. The third exception allows the omission of ventilating openings on one side with the thought that the remaining three sides would provide the necessary cross flow. The remaining three sides, however, must have the total minimum net area as required within the general provisions of Section The fourth and fifth exceptions allow the omission of the ventilation when the space is used as a supply plenum or outside air is mechanically induced and a vapor barrier is provided. Both methods specified prevent the area from becoming wet. 3'0" 3'0" 18" x 24" min. access hole Screened openings (mesh opening 1/8") through foundation wall to crawl space 3'0" max. (typ. from corners) Total net clear area of opening equals the crawl space area divided by 150. Crawl-Space Ventilation 2

9 Q: How close can an underground pipe or conduit be to footings? 45 No pipes Pipes