Technical Specifications
TECHNICAL SPECIFICATIONS
WOODEN HOUSE
Jamaica Red Cross Dean Housing
Assistance Program
Page 1/8
Technical Specifications
CONTENT
TECHNICAL SPECIFICATIONS
1. CONCRETE ......................................................................................................................................... 3
1.1.
Foundations: ............................................................................................................................... 3
1.2.
Reinforced Concrete for Belt or Tie Beam (when needed) .............................................. 3
1.3
Reinforced Concrete for Column (when needed) .............................................................. 4
1.4.
Quality of Concrete Work in Footing, Column and Beams ............................................ 4
2. Reinforcement bar and concreting work .......................................................................................... 4
2.1.
Formwork .................................................................................................................................... 4
2.2.
Steel Reinforcement ................................................................................................................. 4
2.3.
Concreting ................................................................................................................................... 5
2.4.
Placement of concrete ............................................................................................................. 6
3. Wooden frame ..................................................................................................................................... 7
3.1.
Lumber .............................................................................................................................. 7
3.2.
Frame ............................................................................................................................................ 7
4. Roof ...................................................................................................................................................... 7
4.1.
Structure ...................................................................................................................................... 7
4.2.
Covering ...................................................................................................................................... 8
5. Windows and doors ............................................................................................................................ 8
5.1.
Windows ...................................................................................................................................... 8
5.2.
Doors ............................................................................................................................................ 8
Page 2/8
Technical Specifications
TECHNICAL SPECIFICATIONS
1. CONCRETE
1.1.
Foundations:
Generally, in the design shown in the attached plans, the foundation
can be described as a continuous strip foundation.
1.1.1. The excavation for the trench must be 18 inches wide and 2 feet deep.
Unless otherwise stated, the foundation consists of a footing, 18” x 9”,
with at least 3 rows of 6” blocks completing the substructure. Each
foundation shall be constructed according to the structural details
provided. The footing shall be constructed in two layers: the first layer
consists of 2 inches thick blinding. The steel reinforcement shall be as
given in the structural details provided in the drawings.
1.1.2. All excavations shall be approved by the JRC/FRC Site Supervisor
before placement of reinforcement.
1.1.3. The substructure shall be constructed with at least 3 rows of 6” blocks
filled with reinforced concrete every 16 inches as shown in the
structural details. The reinforcement should be ½” diameter mild steel
bar and 1:2:4 concrete mix.
1.2.
Reinforced Concrete for Belt or Tie Beam
(when needed)
1.2.1. The concrete shall be reinforced concrete and shall be 6” x 8”. The
steel should be of ½” diameter mild steel bar. The lap joint between
the steel bars should be at least 2 feet. The minimum concrete cover
of all steel reinforcement in the beam shall be 1 inch. Steel
reinforcement shall be as shown in the structural details.
Page 3/8
Technical Specifications
1.3
Reinforced Concrete for Column (when needed)
1.3.1. The column shall be constructed from reinforced concrete and shall
be sized as specified in Drawings. The steel should be ½” diameter
mild steel bar. The lap between the steel bars should be at least @
feet. The minimum concrete cover of all steel reinforcement in the
beam shall be 1 inch. Steel reinforcement shall be as shown in the
structural details. The steel reinforcement for column shall be as
shown in the structural details. The steel reinforcement for column
shall be lapped and tied to the exposed steel reinforcement from the
footing.
1.4.
Quality of Concrete Work in Footing, Column and Beams
1.4.1. All columns shall be constructed to be straight and vertical. All beams
shall be constructed to be straight and horizontal. Formwork shall be
adequately support to prevent twisting or bending.
2. Reinforcement bar and concreting work
2.1.
Formwork
2.1.1. The formwork panels or timber shall be smooth and held with
supports and bracing at close intervals to prevent bending, twisting
and buckling. Removal of the formwork shall be done with care to
prevent chipping of fresh concrete.
2.2.
Steel Reinforcement
2.2.1. All reinforcement bar installed shall be clean, free of rust and oil.
2.2.2. The reinforcement shall be installed in accordance with detailed
drawings. The longitudinal lap between 2 bars shall not be less than 2
feet. The hook bends in bars shall be at least 6” long and in stirrups of
3” long and connection of 2 feet long.
Page 4/8
Technical Specifications
All reinforcement shall be supported in its correct position by
approved bar chairs, spacers or support bars before the pouring of
concrete.
2.3.
Concreting
2.3.1. Cement Quality: Approved cement for all concrete work shall conform
to Portland Cement P500 (good quality Cement). All cement in bags
shall be fresh when delivered, stored, raised above ground on timber,
kept free from moisture including rain and surface water and kept in a
well-ventilated location. Cement from different deliveries shall be kept
segregated and used in order of age, (old first used). Cement of age
greater than 90 days shall not be used in the works. Cement shall not
be stored outside.
2.3.2. Sand used for producing concrete shall be well graded, clean and
sharp. The range of sand particles size shall be between 2mm and
5mm. The sand shall not contain any clay particles or organic
material.
2.3.3. Gravel used for producing concrete shall be a clean, hard, and
durable stone. The gravel shall be 10mm-25mm in size. No dust
organic matters or fines shall be mixed with the gravel.
2.3.4. The water for the concrete shall be potable water, which is clean, free
of oil and organic matters.
2.3.5. The dosage for a cubic meter of concrete (1:2:4) shall be as follows:
Page 5/8
Technical Specifications
Table 1: Concrete mix proportions (Grade 25 MPa Cube Concrete):
For foundations footing and columns, beams
Item
Unit
Mix by
Quantities per
Volume
Cum of Mix
Quantities per
42.5kg Of bag of
cement
Cement
Kg
1
350
1
Sand (dry)
Cum
2
0.50
0.061
Cum
4
0.75
0.091
Liter
-
200
24.3
10/20mm
Gravel (dry)
Water
Table 2: Concrete mix proportions (Grade 20 MPa Cube Concrete):
For ground floor slab only
Item
Unit
Mix by
Quantities per
Volume
Cum of Mix
Quantities per
42.5kg Of bag of
cement
Cement
Kg
1
250
1
Sand (dry)
Cum
3
0.50
0.071
Cum
6
0.75
0.107
Liter
-
200
24.3
10/20mm
Gravel (dry)
Water
2.4.
Placement of concrete
2.4.1. The concrete shall be mixed as near as possible to its final place.
Horizontal movement of fresh concrete shall be avoided to prevent
separation of aggregates. Concrete shall be placed in uniform
horizontal layer. Each layer shall be vibrated before placement of an
additional layer.
Page 6/8
Technical Specifications
2.4.2. Concrete shall be vibrated (consolidated) to secure good embedding
of reinforcement and filling of all voids in the formwork.
3. Wooden frame
3.1.
Lumber
3.1.1. All the lumber shall be treated lumber. The lumber shall be rough or
dress, square edge or clinker.
The plywood shall be 5/8” groove ply treated for outside use.
3.1.2. The lumber used for the frame shall be not less than 2”x4”.
The cladding shall be clinker board 1”x8”.
3.2.
Frame
3.2.1. The corners shall be made with 4”x4”, 8 feet high. They shall be fixed
in the concrete with a strap as shown in structural details.
3.2.2. The base plate must be bolted into the foundations every 32 inches
with a ½” steel rod as shown in the structural details.
3.2.3. The studs shall be no more than 2 feet apart.
3.2.4. Each corner shall be braced with 2”x4” as shown in structural details.
3.2.5. The studs shall be doubled around openings as shown in the
structural details
4. Roof
4.1.
Structure
4.1.1. The top plates shall be doubled.
The ridge pole and ridge beam shall be made with 2”x6”.
The ridge beam shall be joined with a scalf joint as shown in
structural details when the length of the house exceeds 18 feet.
The rafters shall be no more than 2 feet apart.
The eaves shall be no less than 8” and no more than 12” as shown in
structural details.
Page 7/8
Technical Specifications
4.1.2. Straps must be fixed to connect the different pieces together (rafter
to ridge beam, rafter to plate). The straps shall be made with 1/8”
thick steel painted or galvanized.
4.2.
Covering
4.2.1. A ceiling made with dress plywood 3/8” shall be made above the
rafters.
The laths shall be no more than 2 feet apart. The 2 bottom laths must
be 1 foot apart.
4.2.2. The roof shall be covered with galvanized sheeting 28 gauges. The
galvanized must be fixed into the laths as shown in the structural
details. The galvanized sheeting shall also receive edge caps 4”x 4”
and ridge caps 9”x 9”.
5. Windows and doors
5.1.
Windows
5.1.1. The window sill shall be 1”x6”. The window sill must have a slope and
a weather strip at the bottom and the top.
5.2.
Doors
5.1.1. The doors shall be 36” and 32”, made with metal. The doors shall be
fixed with at least 2 units of 4” butt hinges.
Page 8/8