Par. 1. - For the purposes of this section a basement wall shall be construed to include any exterior wall between the ground and the first floor, and any party, fire and bearing walls from the top of foundations to the first floor.

Par. 2. - The thickness of masonry walls shall be in all cases, irrespective of the requirements of this section, sufficient to help the stresses in the masonry within the working stresses prescribed by this act.

Single Family Dwellings

Par. 3. - For single family dwellings not over three stories high with wooden floor beams spanning not more than fifteen feet, all exterior, party, bearing or fire walls shall be not less than twelve inches thick for basement walls and eight inches thick above the basement: provided, however, that the ends of floor timbers on opposite sides of a wall in such buildings shall not be nearer than eight inches to each other.

Dwellings Not More Than Three Stories and Twenty Feet Wide

Par. 4. - For dwellings not over three stories high with floors spanning not more than twenty feet, all exterior walls shall be not less than twelve inches thick for basement walls and eight inches thick above the basement, and all party, fire, and bearing walls shall be not less than twelve inches thick. In case any part of such a building is adapted for any use other than habitation all walls surrounding that part of the building shall be not less than twelve inches thick.

All Other Dwellings, etc

Par. 5. - For all other residences and for hotels, lodging houses, boarding houses, clubs, convents, hospitals, asylums and detention buildings, all exterior, party, fire and bearing walls above foundations shall have the following minimum thickness in inches:

Stories.

Basement.

I.

2.

3.

4.

5.

6.

7.

8.

1story building.....

12

12

             

2 story building.....

12

12

12

           

3 story building.....

12

12

12

12

         

4 story building.....

12

12

12

12

12

       

5 story building.....

16

12

12

12

12

12

     

6 story building.....

16

16

12

12

12

12

12

   

7 story building.....

16

16

16

12

12

12

12

12

 

8 story building.....

20

16

16

16

12

12

12

12

12

Other Than Dwellings

Par. 6. - For all other buildings, exterior, party, fire and bearing walls above foundations shall have the following minimum thickness in inches:

Stories.

Basement.

I.

2.

3.

4.

5.

6.

7.

8.

1 story building.....

12

121

             

2 story building.....

12

12

12

           

3 story building.....

16

12

12

12

         

4 story building.....

16

16

12

12

12

       

5 story building.....

16

16

16

12

12

12

     

6 story building.....

20

16

16

16

12

12

12

   

7 story building.....

20

20

16

16

16

12

12

12

 

8 story building.....

20

20

20

16

16

16

12

12

12

1 In case the floor area is less than 500 square feet, the wall thickness may be 8 inches.

Par. 7. - Provided, however, that if any part of any building is lower than the rest, the lower part may have walls of thicknesses required for a building of height equal to that of the lower part.

Foundation Walls

Par. 8. - The foundation walls shall be at least four inches thicker than the required thickness of the walls of the first story. The thickness herein given shall apply to all masonry walls unless they are reinforced by a frame or skeleton of steel or reinforced concrete.

Mezzanine Floor or Balcony

Par. 9. - For the purposes of this section any balcony or mezzanine floor of more than ten feet span shall be considered as forming a story in fixing the thickness of the walls which support it.

Ashlar

Par. 10. - In reckoning the thickness of walls, ashlar shall not be considered unless the walls are at least sixteen inches thick and the ashlar is at least eight inches thick, or unless alternate courses are at least four and eight inches to allow bonding with the backing. Ashlar shall be held by metal clamps to the backing or be properly bonded to the same.

Non-bearing Walls - Thickness

Par. 11. - Non-bearing walls not used for fire or party walls may be four inches less in thickness than is required by the preceding tables; and such walls supporting stairs or stair landings may be eight inches less: provided, however, that no such non-bearing or stair wall shall be less than eight inches thick nor have a greater height unstayed laterally than thirty times its thickness, except with the approval of the commissioner.

Curtain Walls

Par. 12. - Curtain walls between columns, buttresses or projecting piers may be thinner than is required by the preceding tables: provided, however, that in single family houses not over three stories high such curtain walls shall be not less than four inches thick, and in all other buildings such curtain walls shall be not less than twelve inches thick for fire or party walls nor less than eight inches thick for exterior walls, except that the parts between the top of one window opening and the bottom of the window opening above, if faced with metal, shall be backed by at least four inches of incombustible material. No curtain wall exceeding twenty feet in length shall have a greater height unstayed laterally than thirty times its thickness.

Hollow Block Walls

Par. 13. - Hollow block walls shall have the same minimum thickness as is required for brick walls, but shall not be used for bearing walls in buildings over four stories high. Solid unreinforced concrete walls shall have the same minimum thickness as required for brick walls. Reinforced concrete walls shall be of the thickness and construction required by the commissioner, subject to the requirements of section fifteen.

[1918, Special Acts, c. 179, sect. 11.]