How
to replace cavity wall ties
Order
and Free Technical Help - 01626 872886 - discuss your wall tie building
problem with a Qualified Dampness Expert (C.R.D.S.)
A borescope,
metal detector, surface thermometer and a 'damp meter' (see www.dampness-info.co.uk/meters.htm)
are useful tools for this diagnosis.
Checking
Cavity Wall Ties - defects
that can occur and some tips:
Cracking
in walls
Horizontal
cracking in the brickwork, blockwork or render: this can indicate wall
tie failure, but might also be connected with other types of movement.
Consult a qualified Structural Engineer. If the cracks are thought to
be a wall tie failure symptom locate the ties with a metal detector
and either insert a borescope through a small, drilled hole (usually
10mm diameter) or remove a brick or block. Check which type of tie you
have - a 'fishtail' tie or a twisted wire tie. Fishtail ties can expand
enough to cause cracks and must be removed, or isolated, after new ties
have been fixed. Twisted wire ties cannot rust enough to cause cracks,
so do not require 'isolation' or removal. In either case visible red
rust or white rust indicates sufficient corrosion to require replacement
(see the BRE guide notes on Wall Tie corrosion categories).
Remedy
- detect the existing ties with a metal detector, mark out a new diamond
pattern and fit replacement ties and then isolate (with a Clan Sleeve,
Rockwool or builder's foam) any 'fishtail' ties.
Bulging walls
Bulging of the wall - danger:
walls with bulges can collapse without warning - cordon off and immediately
consult a qualified Structural Engineer.
Remedy
- if the Engineer considers the bulge to be within the allowable tolerance,
fit replacement ties and then isolate (with a Clan Sleeve, Rockwool
or builder's foam) any 'fishtail' ties. Otherwise, the wall will have
to be taken down and rebuilt. Sometimes the top triangle of a gable
wall bulges because it is single leaf (4.5 inch) - check from inside
the roof).
Bulges that have been cleared
by a qualified Engineer
Sometimes
bulges are due to insufficient tie density - modern Standards require
at least 2.5 ties per square metre.
Remedy
- detect the existing ties with a metal detector, mark out a new diamond
pattern and fit additional ties to meet the Standard.
Replacement Tie types and
limitations
Wall construction
problems: bricks with holes in them (potted) or with big voids each
side (frogged) can be difficult to re-tie with a mechanical expanding
type replacement.
Remedy
- in these cases you may need to use resin fixing ties. (See Price List
below)
Checking the original tie
type fitted - a Tip
Checking
the existing Wall Tie type - a useful tip - if you do not have access
to a Borescope or a Metal Detector you can sometimes view the ties from
the cavity using a torch and small mirror, either in the roof space
at the top of the wall or by taking out an air brick. This also allows
you to measure the cavity width, a dimension needed when ordering remedial
ties.
Quick
Ties - easy
to install, mechanical fix.
Type - Mechanical
Tie PN11FX (with unique Shear Nut).
Sizes - typical -
11mm x 200mm, 11mm x 225mm, 11mm x 250mm
How many do I need
- 2.5 ties per square metre, including doors and windows in the area.
How to calculate size
- outer wall thickness + cavity width + 55mm
Limitations - not
suitable for bricks with multiple holes, large 'frog' cavities or of
very soft material - ask about our Resin fixing Ties for these types
of wall construction.
Mechanical Tie - PN11FX
(with unique Shear Nut)
As used by
the Trade - Quick Ties are inserted into 10mm holes
1. Simple
tool tightens inner and outer sleeve
2. Can be
driven with an electric screwdriver
3. No resins
required
4. Quick
to install - just drill, blow out dust and fix
The speed of fix of the Quick-Fix
tie with a torque set electric drill is probably the fastest currently
available in the UK market
To Purchase replacement
wall ties: prices shown here exclude VAT
Note - we will split boxes,
so you can buy any number of Ties.
Mechanical Wall Ties,
11mm diameter - select your length as calculated above:
200mm - box of 150 ties
- £112 -
225mm - box of 150 ties
- £120 -
250mm - box of 150 ties
- £132 -
Other lengths available -
call 01626 872886 .
Fixing tool - stainless
steel, thin wall socket - to fit an electric drill - £20.00
-
Blow out tool - puffer
pump, to remove dust - £4.99 -
Resin Fixing Wall
Ties - 11mm diameter - select your length as calculated above:
305mm - box of 150 ties -
£150 -
Other lengths available -
call 01626 872886 .
Epoxy Wall Tie Resin
- 300cc - allow one tube per 10 ties, which will fix both ends - £19.36
-
Blow out tool - puffer
pump, to remove dust - £4.99 -
The Quick Fix PN11FX double
expansion remedial wall ties are manufactured from corrosion resistant
Austenetic 304 Grade Stainless Steel tie bars with Neoprene sleeves.
The Quick-Fix
tie features a unique tall-nut which when turned with a
setting tool, rotates the whole tie bar, forcing the inner leaf Neoprene
sleeve to open and grip in the masonry.
The inner fix has now been
created. At a factory set torque level, the end of the tall nut
shears away and the remaining nut is forced down the tie bar to expand
the Neoprene sleeve to grip the outer leaf.
NOTE - Don't forget that,
if you have existing ties called 'fishtails,' you may need to expose
the outer ends of the original ties and 'isolate' them with Rockwool,
builder's foam or similar, to prevent future rusting from causing expansion
inside the mortar joints and horizontal wall cracking.
Click
here for a Product Data Sheet
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Site written by: David
Moore
David Moore, B.A. (Hons.),
C.T.I.S., C.R.D.S. Technical Author
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