Floor and wall ties detail information

1. FLOOR AND WALL
TIES
SARAT MISHRA
KEC,IOE,TU
1

2. Floor- In order to sub-divide the portion
between plinth level and roof level, the
solid constructions are carried out.
These constructions are known as the floors
and the exposed top surfaces of floors are
termed as flooring.
Wall- A wall is a structure and a surface that
defines an area, carries a load;
provides security, shelter, or soundproofing;
or is decorative.
FLOOR AND WALL
2

3. • For cavity wall to be effective in it’s purpose,
it is essential that both the leaves of the wall
should not come in contact
with other, except at wall ties.
 Ties are used to hold the
two leaves together.
 The ties used for this purpose
should be sufficiently strong,
non-corrodible and should
shaped that water travelling
through the outer leaf does
not travel along it.
WALL TIES
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4.  These ties must be placed at distances
not exceeding 900mm horizontally and
450mm vertically, and should be
staggered.
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5. 5

6.  A cavity wall consists of two slender,
independent leaves of
brickwork or block work.
If a load is exerted to one
or both if these slender walls
they may buckle or collapse
under the load. If the two
leaves are tied together they
will and they can support more
imposed loadings.
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7.  To tie the two walls together, wall ties are
built into the walls in sufficient numbers and
at strategic positions throughout the wall
area.
 The bricklayer is responsible
for building in the wall ties
in their correct positions.
Care and attention must
be taken when building
them into position, because
poor workmanship may
lead to damp penetration,
distortion of the wall,
cracking or in some cases,
collapse of the wall.
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8. • There are variety of wall ties of different shape
and sizes available on the market.
• Wall ties are usually made of mild steel
thoroughly galvanized or dipped in hot tar
and sanded to protect from rust, also
made of alloys or polypropylene.
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9.  For important buildings or for buildings
near the sea, copper or bronze or similar
durable and highly corrosive resistant
metal is used for ties.
 They are manufactured in various length
to suit different wall cavity widths.
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10. • Fig 9.5(b) shows the wire tie, commonly used; the ends
are twisted and turned down, so that moisture travelling
along it drops down in the cavity.
 Also, the mortar droppings do not readily lodge on it
because of the thinness of the wire. Wires may be of
3-4mm dia.
 Fig 9.5(d) shows a similar tie, made out of flat bar
section twisted at the end. Tie shown in fig 9.5(c) has
forked end made out of flat bar twisted in the middle.
This tie is quite stiff and durable.
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11. • When the cavity is filled with rigid thermal
insulation material such as cavity bats,
they are supported at 450mm intervals by
special wall ties. These ties have a device
incorporated into their design to keep the
bats against the inner leaf of the wall.
Fig : Special wall tie 11

12. Fig: Special wall ties
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13. Fig: Special wall ties
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14. As a guide to placing wall ties effectively the
following points of good workmanship may be
of help:
• For strength, all ties must be bedded at least
50 mm into each wall leaf.
• The ties must be positioned with any drip in
the center of the cavity, and pointing
downward.
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15. 15

16.  Ties should be pressed down in the
mortar bed.
 Ties should never be pushed into a joint
as they will not be effective in tying in the
two leaves together.
 Ties should not be bent to suit courses.
 Use only specified type of tie.
 Use extra ties around the openings if
needed.
 Use extra ties at the top of the gable
walls.
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17. • Ties should be inclined downwards
towards the outer leaf, never to the inner
leaf, as they may provide a bridge for
water. Where partial cavity fill is specified
a special tie incorporating a large plastic
retaining washer should be used
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19.  Ties must be cleared of mortar droppings
which can provide a passage for water
across the cavity.
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20.  One method of keeping cavities clean is to
catch mortar dropping on a rigid board.
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21. • Standard Bowties are used when securing
the wall into joist ends. The Bowtie is inserted
through a clearance hole in the wall and
power-driven into position before being resin
bonded into the masonry. Also restrained
straps can be used.
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22. • Bowtie is a long stainless steel tie used to
stabilize bulging walls, without any
external plates, by securing them into the
ends of internal floor joists.
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23. Installation Procedure
• Mark the position of the joist center on the
external wall and then drill a clearance hole
(normally 12mm) through the wall. Clean out the
hole.
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24. • Fit the Bowtie Support Tool to an rotary
hammer drill, insert the Bowties and drive
it into joist end to the required depth – at
least 75mm
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25. • Fit the plastic sleeve over the Bowtie and use the
support tool to push it to the back of the hole in
the masonry (in the outer leaf in a cavity wall)
• Inject Polypus resin to fill the hole and bond the
Bowtie to the masonry and then make good.
•
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26. Restraint straps are suitable for taking tensile forces
and to tie walls and joist.
Straps should:
 Be detailed in the design, including the size, position
and fixings.
 Be galvanized steel with a 30mm x 5mm cross-
section or be in accordance with Technical
Requirement.
 Have adequate packing between the wall and the joist
 Bear on the center of bricks or blocks and not on
mortar joints.
 Be fixed on the side, top or bottom, as appropriate to
the joist type.
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27. 27

28.  Where joists run parallel to the wall,
straps should be fitted along the joists
with a maximum spacing of 2m, and:
 Be supported on noggings and extend
over at least three joists be fixed with two
screws or nails into each joist
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29. Metal web joists
 Metal web joists should not be
notched and nogging nailed twice to each
joist.
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30. For I Joist
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31. Tie bars and straps
Tie Bars and Straps offer an effective
solution to such problems by tying back
affected walls. The bars and straps are
secured to the internal face of the wall
using Anchors and are then notched into
and securely screwed to the floor joists.
Alternatively, they can be spanned right
across the internal floors and secured to
another stable internal or external wall.
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32. Fig: Tie bars
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33.  Corner straps are designed to
provide a bond between walls
which were either constructed
with no bond, or have de-
bonded due to structural
movements.
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34. Fig: Corner Straps
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35.  The present investigation relates to an
improved method of construction of
building. To assure safety and proper
functioning of building to meet
serviceability requirements; it is
mandatory to provide a tensile connection
between floor and wall element which
when overloaded, fails in a ductile
manner.
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36.  There are two general method of
connection for a tensile connection
between walls and floors. If such
condition are going to fail at all, it is
desirable that the failure be in the tie
element and be a ductile failure.
 In the first method, reinforced bars are
precast in the wall element at bar
regularly spacing adjacent the intended
final position of a floor slab, each bar is
bent out at right angles in the wall and
one end is tied to the floor slab.
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38. 38

39.  The second method incorporates a screw
thread elements attached to reinforced
rod within the wall element. A thread bar
is attached to the screw threaded element
and tied to the floor slab.
Fig: Thread bar with screw threaded element
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40.  This overcomes the difficulty of the first
method but is more expensive method of
connection.
 Further disadvantage is that within the
pressure of screw thread if failure occurs,
one can’t reliably get ductile failure of the
metal element.
 Further with both methods, the strength
is limited by the thickness of wall and
strength of mortar.
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