Par. 1. - The foundation loads of every building, except temporary structure, shall be carried down to a satisfactory bearing material by means of properly designed walls, piers, grillages or piling which shall be so designed, located or otherwise disposed as to permit the entire loads which they transmit to be distributed over the bearing area with a unit intensity which shall not exceed the allowable value given in this section. The bearing area of any pile is the area over which it distributes its load.

Par. 2. - The footing of every foundation shall be carried down at least four feet below any adjoining surface exposed to freezing and no footing shall be started on soil which is in a frozen condition. Foundations shall not be laid in freezing weather unless adequate precautions are taken against frost action.

Par. 3. - For the purposes of this section " satisfactory bearing material" shall mean only ledge rock in its natural bed, natural deposits of sand, gravel or clay, and any combination of the foregoing materials which does not contain or does not overlie an appreciable amount of organic material.

Par. 4. - In the absence of satisfactory tests of their sustaining power, the maximum allowable bearing values of the above materials shall be limited by the following unit pressures: -

Par. 5. - Definitions. - (a) Solid ledge: Naturally formed rock, such as the granites and others of similar hardness and soundness, normally requiring blasting for their removal.

Par. 6. - (6) Shale: Laminated slate or clay rocks removable with more or less difficulty by picking.

Par. 7. - (c) Hardpan:Athoroughly cemented mixture of sand and pebbles or of sand, pebbles and clay, with or without a mixture of boulders and difficult to remove by picking.

Par. 8. - (d) Gravel: A natural uncemented mixture of coarse or medium grained sand with a substantial amount of pebbles measuring one fourth of an inch or more in diameter.

Par. 9. - (e) Sand (compact): Requiring picking for its removal.

Par. 10. - (f) Sand (loose): Requiring shovelling only.

Par. 11. - (g) Sand (medium grain): Individual grains readily distinguishable by eye though not of pronounced size.

Par. 12. - (h) Sand (fine grained): Individual grains distinguished by eye only with difficulty.

Par. 13. - (i) Hard clay: Requiring picking for its removal.

Par. 14. - (j) Disintegrated ledge rock: Residual deposits of decomposed ledge.

Par. 15. - (k) Medium clay: Stiff and plastic but capable of being spaded.

Par. 16. - (I) Soft clay: Putty-like in consistency and changing shape readily under relatively slight pressure.

Par. 17. - Note. - The materials described in items c, d, e, f, g, i, j, k, shall be in relatively thick beds, if full loading value is used. Otherwise, if underlaid by a softer material, the value assigned to that material shall be used.

When a Building Rests on a Ledge

Par. 18. Wherever a building or structure is to rest in part only upon solid ledge, the unit intensity of load upon the balance of the bearing area shall be not more than one half of the value given above for the several classes of soil.

Par. 19. - Prior to the issuance of a permit for any permanent building or structure, the owner shall, by means of open pits or by test borings carried at least ten feet into a satisfactory bearing material other than ledge rock, determine the character and depth of the soil underlying the proposed site, and a certified copy of the reports of all borings and tests pit so taken, together with samples, taken dry, of the material selected for a foundation bearing shall be filed with the commissioner for his approval and classification. The number and location of borings taken, together with the method used in making and reporting them shall be as directed by the commissioner.

Par. 20. - Foundations for first and second class buildings may be of brick, stone or concrete. The thickness shall be as stated in section twenty-three with the further provision that all foundation walls below grade shall be figured as retaining walls when they act as such.

Par. 21. - Foundations of stone shall be of square split stone except that rubble stone shall be allowed under buildings outside of the building limits as they existed prior to September twenty-third, nineteen hundred and thirteen, but only when such buildings do not exceed forty-five feet in height and the foundation wall is less than ten feet in depth. No rubble foundation shall be less than twenty inches in thickness. All walls shall be properly bonded by through courses.

Par. 22. - Footings. - The footings of foundation walls or piers shall consist of footing stones, concrete, reinforced concrete construction or steel grillages. Footings of wood construction may be used provided that they are to be entirely below the permanent ground water level.

Par. 23. - Footing Stones. - Footing stones shall be at least ten inches in thickness. They shall be fully bedded upon the bearing soil.

Par. 24. - Concrete Footings. - Concrete footings shall be not less than twelve inches in thickness. They may be either stepped or battered to meet the wall or pier which they support. The offset of each step or the angle of batter shall be such as not to exceed the allowable stresses in the concrete. If battered footings are used there shall be a square shoulder at the base which shall be not less than four inches in height.

Steel Grillage

Par. 25. - Steel grillage foundations shall have at least six inches of concrete below and shall be entirely embedded in and surrounded by concrete at least four inches thick between steel and earth, and the concrete shall be no poorer than one part Portland cement and seven and one half parts aggregate, measured before mixing.

Par. 26. - Footing Loads. - Provision shall be made in determining the required area of footings for safely supporting the full dead loads and the figured live loads on the lowest tier of columns, piers or walls, plus the weight of the footings themselves and such backfilling and overlying basement floor loads as may come vertically over the projecting spread of the footing.

Par. 27. - Foundation Piers and Caissons. - The foundation of any building or structure may be carried down to ledge or other satisfactory bearing material by isolated piers of approved masonry or by open or pneumatic caissons, so designed that the working stresses in the materials and on the soil do not exceed those established by this act.

[1918, c. 179, sect. 8, Special Act.] [1920, c. 91, sect. 2.]