Remedial cavity wall tie for replacement of corroded and failed cavity wall ties
Over the years we have made and installed just about every type of remedial and newbuild wall tie ever made.
it is fair to say that none have been as versatile as the 8mm helical wire tie, this achieve higher pullouts, speed of installation, consistency, and cost benefit thatn any tie we have ever made
- Works in any combination of Brick, Timber, AAC, concrete.
- Smaller pilot holes mean less visible damage to the host materials
- Can be secretly fixed (See below video for instructions)
- Limited opportunities for installer error
- Can be installed by non-skilled operators
- High grade stainless steel, appropriate for coastal regions
- No resin required for fixing
- No mechanical expansion
- The installation process is very much "fire and forget"
- Each tie takes no longer than 10 seconds to fix
- Cavity wall tie for all materials and cavity widths of up to 100mm
- For fixing timber to lightweight concrete block
- The hardened fins of the LocTie mechanically fix into the host material in a similar way you would expect a wood screw to work in timber
- The tie is hammered into a predrilled pilot hole and countersunk beneath the surface of the wall with 1 simple tool attachment fitted to a light SDS type drill.
The length of wall tie required is governed by 3 things
- The thickness of the outer leaf, this is usually 102.5mm if the material is brick, block or stone, but could be thicker if rendered or made up of natural stone.
- The width of the cavity, cavities have become wider as insulation requirements have gone up, older buildings are most commonly 50/70mm wide though can be more or less.
- Modern properties are usually 70mm to 100mm wide though can be wider.
- The thickness of the inner leaf material again this is usually 100mm if brick or block but thinner blocks and bricks are made and used.
the lengths of the tie is typically 30/40mm less than the overall thickness of the wall
Establishing wall thickness by Survey.
Measure the overall thickness of the wall near a door opening or window reveal. this is easiest done using a caliper then measuring the width of the open point in the caliper jaws, take of 30mm from the overall width of the wall and you have your appropriate tie length
Pilot Drill Method
Use a 6mm x 260mm drill bit, from the outside of the wall drill to approximately 110mm depth, you should feel the drill bit pressure drop as it breaks into the cavity. mark or pinch the drill bit at its abutment with the wall, extract the drill bit, measure the distance, this will give you the thickness of the outer leaf material.
Reinsert the drill bit and push it into the wall till you hit resistance. Pinch or mark the drill bit at its abutment with the wall, then extract.
The thickness of the outer leaf measurement taken first, subtracted from the second measurement gives you the thickness of the cavity.
Both of these processes are very simple and quick to complete and give confidence as to which tie length to use.
Note it is really not uncommon for cavity width to vary due to poor construction techniques- on large jobs with multiple walls it is best to check a few walls to be safe.
Tie length Cavity width Wall thickness minimum
195mm 5mm-45mm 210mm
210mm 10mm-60mm 240mm
220mm 15mm 70mm 250mm
240mm 50mm-90mm 270mm
270mm 100mm-120mm 300mm
Minimum embedment in inner leaf 70mm unless tensile proof tested.
What size Pilot hole do I need to drill?
people who tell you one size of pilot hole will do are not being thorough, this can lead to underperforming ties or difficulty in installing ties.
Harder materials need larger pilot drills, softer materials need smaller diameter pilot holes.
drilling through a blue engineering brick might need a 7mm pilot hole for an 8mm diameter tie
fixing into AAC or lightweight block requires no pilot hole, so a pilot drill is only required in the outer leaf.
soft to medium hardness brick inner and outer leaf will probably need a 6mm or 6.5 mm diameter pilot drill in both leaves of the wall.
Wall tie Pull Out Strength
The amount of force required to pull a wall tie out of the wall is relevant as the installed ties are there to prevent failure of the wall due to wind suction loads.
Wind suction loads vary depending on where you are in the county, costal and norther areas, have higher wind loads than sheltered inland areas. This leads to higher capacity requirements from the ties, or increased density of ties.
Taller buildings are more exposed to high winds and need even more resistance to wind suction.
The Strucsol Engineering team has been designing cavity wall ties specifications for everything from Sky scrapers to cottages for more than 30 years, we provide this service free for one off customers of trade contractors and specifiers. just call us for advice.