Download minimum requirements for permanent / single st~ey houses

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v:
OP.~t
NA'Rotl,
MINIMUM
FOR
PERMANENT
SINGLE
by
REQUIREMENTS
ST~EY
/
HOUSES
,
T.I.~
'f
National Housing and Building Research Unit
MI~STRY OF LANDS t
HOUSING AND URBAN DEVELOPMENT
DAR ES SALAAM 1974
II
PREFACE
The "Minimum Requirements for Permanent Single Sto~y
Housing" given in this pamphlet must be regarded as
guidelines for those who need a definition of the term
"Permanent Housing" in Tanzania.
T~ere are three main reasons why the guidelines are
published:1.
They can be a substitution for the former "Building
Covenants. II
2.
The building regulations .i.n force are limited to
the major towns and are valid only for the most
developed areas of these towns. The existing
regulations are also partly not relevant to
Tanzanian conditions.
3.
Today permanent houses will be built allover
country in both urban and rural areas.
the
The "Minimum Requirements for Permanent Single Stoi'y
Housingrt have been worked out by National Housing and
Building Research Unit. These guidelines were originally
made as a substitution for the former "Building Covenants",
which were used to define the quality of houses to be
built on surveyed plots. The "Building Covenants" gave
figures in Shillings for the minimum value of houses
being built.
During colonial times this method of specifying quality
was a very efficient way of aChieving segregation. The
Building Covenant for some areas was set very high so
that only well-to-be people and mainly europeans could
afford to build houses at the value required. This system
is now abolished.
The existing building regulations are limited to be used
for certain areas of the major towns, city centres and
IILowDensityrt areas, mainly for high cost and medium cost
housing. The "Minimum Requirements for Permanent Single
Story Houses" are not completely consistent with the
3
building regulations in force. The existing regulations
must still be followed in those areas were they are in
use. The discrepancies originates from the fact that the
building regulations are not in all relevant to Tanzanian
conditions. They are based on old British regulations made
for ,a different climate, building materials and skills.
The minimum requirements can be fully applied in areas
where no building regulations or rules are in existance.
A proposal for new Tanzanian Building Regulations are
being worked out by National Ho~sing and Building
Research Unit. Most likely there will be no discrepancies
between the minimum requirements and the future new
regUlations.
t
we hope that these requirements can be of help for those
who are involved in establishing durable and hygienic
housing throughout the entire country.
July 74
Harald Kristiansen,
Director •
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4
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C'O N TENT
O.
GENERAL
7
1.
SITE
7
2.
FOUNDATIONS
10
3.
FLOORS
12
4.
WALLS
14
5.
ROOFS
17
PUBLICATIONS
FROM B.R.U.
19
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5
O.
GENERAL
All sections of these requirenents
parts.
are divided in two
The first part is general and specifies the
performance requirements
which shall be fulfilled.
The
second part gives solutions which will meet these
requirements.
This does not mean that other solutions
can not be used.
For practical
solutions which meet the given requirements
it is also refered to BRU Data Sheets (BRU ab. for
Building Research Unit)!
1.
SITE
Every house shall have an access path.
The path shall be
made with such slopes and of a such surface material
that
it keeps dry and not sticky also after rains.
The site shall be levelled so that it drains off surface
water to avoid flooding of the house, and to avoid water
standing in mosquito breeding pools.
The ground shall
slope away from the house for not less than 2 meters from
the external walls, with a slope of not less than 3cm for
every 100cm.
•
Examples
Three '30lutions are shown.
The first, Fig.1.1 indicate
how the house should be placed.
A house, if possible,
should never be placed in a depression.
how water can be prevented
Fig.1.2 shows
from flooding the house if it
• The purpose of the Data Sheets is to give advice on
appropriate utilization of local materiRls, sound
constructions,
and suitable layouts and furnishing
the field of housing.
Information
about the sheets
can be given by National Housing and Building
Research Unit, P.O. Box 9344, DSM.
7
in
•
is built on a slope.
Fig.1.3 shows how the ground shall
slope away from the house.
(See also data-sheet BRU
C.1.1 "Site Planning and Preparation").
WRONG
RIG
!i~·l.l
H T
The site must have good drainage •
•
FiE·l·2 Make a terrace for the house on
sloping ground.
8
•
,
!ig.l.i
The ground must slope away from the house
on all sides to avoid flooding.
•
9
2.
FOUNDATIONS
The foundation has two main purposes:
(a)
It shall transfer all loads to the ground without
harmful settlements.
HarPlful settlenents mean in
most cases differential settlements.
settlements can be allowed.
(b)
Small uniform
Uater shall be prevented from penetrating
into the
house and eroding away the soil which supports the
load-bearing
structure or the floors.
All solutions which meet these requirements
can be used.
Examples
Reference
is given to the BRU data-sheets
in group C
"Foundations '!
Two solutions are shown.
The first example is a soil-
cement strip foundation which carry a brick or block wall,
and the second is a soil-cement strip foundation which
carry a mud and pole wall(see also data-sheets BRU C.O.1
"Foundation.
General" and BRU C.4.1 "Stabilized Soil
Foundations.
Soil-cement
f01; one Story Buildings").
A trench which is approximately
2.2) should be dug.
40cm by 30cm (Fig.2.1 and
The depth of the trench will depend
on thickness and properties
of the top soil.
All weak
soil shall be removed before the footing is casted.
The
width will vary with the bearing strength of the soil/but
in most cases a width of 30-35cm is adequate.
of the trench should be smooth and level.
10
The bottom
1)The proper mixture of
soil-cement
for a
footing may be 1
volume part cement to
16 volume parts soil.
(For proper mixing
40
and mix-design
see
data-sheet BRU B.8.2
15
"Soil Stabilization.
~""o+----
Footing
Stabilizer:Cement.")
2)The top surface of
the footing should
!i~.£.l
Strip foundation which
be made rouf>h while
the soil-cement
carry a brick or block wall.
is
fresh.
3)The foundation wall
can be made from the
same soil-cement
as
the footing.
4)The vertical poles
shall be embedde4 by
soil-cement
o-;T'r------r''---- Pole hole
•
in the
holes in the foundation wall.
The
holes shall have a
minimum cross-sectio-
40
-+---'---Foundation
15
wQII
o
nal dimension which
is at least 4-5cm
larger than the
~---Footing
diameter of the poles.
The holes may be
round or square.
!i~.£.£
Strip foundation which
The
depth should be at
least 15cm.
carry a mud and pole wall.
11
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3.
FLOORS
A floor shall meet the follo~ing requirements:
(a)
Moisture from the ground shall be prevented from
destroying the floor or other parts of the house.
TroubLesome amounts of moisture, from a health and
comfort point of view, shall not penetrate the floor.
(b)
A floor shall have a hard and smooth topsurface
resistent to applied loads from the use of the house.
It shall also be easy to clean.
(c)
The level of finished floor shall not be less than
15cm above the level of the nearest ground outside.
All solutions which meet these requirements can be used.
Example
Reference is given to the BRU data-sheets in group D
"Floors". One solution is shown (Fig.3.1). Soft soil
has to be removed. The ground surface should be
relatively smooth and level.
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1)
SUb-top-soil
is filled in and tamped.
The surface
should be as levelled as possible.
2)
A layer of tamped s.and or very sandy soil to a thickness of 10cm.
3)
The structural
slab can be made from soil-cement.
A
mixture of 11 volume parts soil to 1 volume part
cement may be used.
(For proper mixing and mix-design
see data-sheet BRU B.S.2
Stabilizer
Kig.2.1
"Soil Stabilization •.
: Cement")
Soil-cement
floor.
•
4.
WALLS
External walls shall meet the following require~ents:
(a)
Walls shall withstand their own weight and all
applied loads without harmful defornations,
and they
shall be properly bonded tor,ether.
(b)
Walls shall resist penetration by rainwater.
(c)
Water and vapour shall be prevented to rise from the
ground through the walls so that any part of the
house is destroyed by d~~pness or so that health
hazard or discomfort
(d)
is created.
Walls shall be of ~ermanent construction
which means
that, with resonable mElintenance, they shall last
for not less than 25 years.
All solutions which meet these requiements
can be used.
Examples
Reference
is given to the BRU data-sheets
in group E
ll
"Walls
Two satisfactory
solutions are shown (Fig.4.1 and 4.2)
The first example is a block-wall.
wall may be untreated,
A properly made block
but a lime-wash or some other
treatment is an advantaf,e.
The second example is an improved mud and pole wall.
a wall is a traditional
on a foundation
Such
mud and pole structure supported
and plastered on both sides.
•
14
·0
1)
··0.
"; . .
The ends of the vertical poles are embedded in the
foundation-holes.
Small wooden wedges may be used to
keep the poles in the right position during casting.
The poles shall be treated with a wood preservative,
applied by brushin~
2)
A lime-sand
or dippin~.
or a lime-soil plaster.
A 1:6 mix may be
used.
!ig.~.~
Plastered mud and pole wall.
•
15
,!i,g.'±.l
Untreated
block
waLI .
«
•
5.
ROOF
The roof shall meet the following requirements:
(a)
A roof shall be water-proof.
(b)
A r06f shall withstand its own weight and all applied
loads without harmful deformations. Precautions
against wind load shall include effective anchoring
s6 that the whole roof or partm of the roofing cannot
be torn off by wind. The roof shall sustain a point
load of 100kgf so that persons can walk on the roof
for maintenance.
(c)
A roof shall keep rainwater away from walls and
contribute to the shading of walls, which normally
required an overhang of 50cm or more.
(d)
The space under a roof shall be well ventilated.
All solutions which meet these requirements can be used.
Examples.
Reference is given to the BRU data-sheets in group F
"Roofs".
The roof structure shown is supported by internal loadbearing cross-walls.
Fig.5.1 shows an ordinary roof construction.
Fig.5.2 shows a section through the roof at a load-bearing
interior wall where sound insulation is important. This
may be a wall between family units in a row-house.
17
•
60
Kig.2.1
Simple roof
structure.
Ki,g'2'£
Detail of wall roof
connection where sound insulaion is important.
SECTION
1)
A- A
Timber wall plates are put on top of each cross wall.
The roof is anchored to the hearing structure throuf,h
these.
On places with little wind it is sufficient
to nail the wall plates to the walls.
2)
The open space is filled with morter.
The space
between the wall plates(1) and the corrugated
sheets is kept open for ventilation.
iron
This solution
can only be used where sound insulation
is not im-
portant.
3)
If the wall-plates
are nailed down to the blocks, the
cut (bevel) has to be of a size which prevents the
bricks from cracking.
4)
30 gauge galvanized
corrugated iron sheets.
5) Boards are nailed to wall plates and purlins.
6)
Mortar is filled in between the boards (5).
The C.I. sheets should be pressed into the mortor.
18
PUBLIC~TIONS
FROM BRU
Reports
Rural Housing in Tanzania
Knut I. Edvardsen
Report on a Prestudy
Hegdal.Report
Lateritic Soil-Cement
as a
Materials.
No.1
1972
J .F. I'loriartyand O.
Building Material.
Economic Comparison
and B.
Therbildsen.Report
1973.
of Building
Survey of
J.F.Moriarty
& O.
Therbildsen.Report
Dar es Salaam.
No.2
No.3
1973.
Pamphlets
T.I. Svare.Technical
Better Burnt Bricks.
Pamphlet No. 1
Minimum Requirements
1974
T.I. Svare.Technical
for
Per,;'anentSingle Story Houses
Pamphlet No.2
1974
Data Sheets
BRU A.1.1. BRU-Data Sheets.
Purpose, Preparation,
B. Hegdal, 1973
use etc
BRU A.2.1 Climate in Tanzania.
K.I. Edvardeen,
1973
K.I. Edvardsen,
1973
Simple Advice on Housing
Construction
BRU B.5.1 Burnt Clay Bricks.
Hand Production-Burning
in
Field Kiln
BRU B.8.1 Soil Stabilization.
Tolo Svare, 1974
General
BRU B.8.2 Soil Stabilization.
Stabilizer:
T.l. Svare, 1974
Cement
Tol. Svare, 1974
BRU C.O.1 Foundation.
General
BRU C.1.1 Site Planning
Kol. Edvardsen,
and
Preparation
19
1973
BRU C.4.1. Stabilized Soil
Foundations.Soil-Cement for one
Soty Buildings
T.l. Svare, 1974
BRU H.1.1. Smoke Evacuation from
Fireplaces.Simple lmpraved
Devices~?himneys
B. Hegdal, 1974
BRU H.1.2 Fireplaces in Houses.
Simple Devices for CookingFrying Purposes
B. Hegdal, 1974
BRU J.1.1 Household Requirements.
Main Household Activities and
Facility Needs
B.
BRU J.2.1 House Layout.
Three sectioned House, Total
Area 7G, 9m2
B. Hegdal, 1973
BRU J.2.2 House Layout.
Three Sectioned House, Total
Area 123, 1m2
B. Hegdal, 1973
BRU J.2.3 House Layout.
Total Area 70, 2m2
B. Hegdal, 1973
Hee;dal, 1973
BRU J.2.4 House Layout.
Three Sectioned House, Total
Area 95, 2m2
20
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