Construction of wall cavities has been in use since the beginning of the Nineteenth Century and became part of building construction practices in the end of the 1800’s to the today.
The primary benefits of the construction of cavity walls are:
Insulation for thermal energy
Blocks water from the outside.
For structural strength and stability.
to allow the removal of water from the structure
Although the construction materials and techniques of cavity walls be different, all methods depend on a tying system to join the outer and inner leaves and to give the wall solidity and stability. Thus, cavity wall ties constitute the most important structural component within the cavity wall.
The past was when a wide variety of materials were used in wall ties. This included in some regions slate and wood. The most commonly used materials from the late Victorian period were mild steel or iron as well as the corrosion-prone characteristics of these tie which have caused the most trouble.
There is a common misconception that homes built after 1981 aren’t at risk of the threat of corrosion in wall ties and related issues. This is due to the fact that after this date, wall tie wires were of higher quality, generally galvanised wire or stainless steel While this lowers the likelihood of failure but it doesn’t completely eliminate the possibility.
The older kinds of tie usually do not have a protection coating, or may are coated with a bituminous, or thin Zinc coating. Whatever the case, they are extremely susceptible to rust in environments with moisture or oxygen. The degree and speed of corrosion will depend on a number of aspects, including
Exposure to weather patterns
The type of mortar is Black Ash and weak mixes, as well as porous lime mixes
The condition of pointing
Inadequate design, construction and layout, blockage of cavities, no DPC’s or membranes
Environmental issues, such as costal sites.
Wall tie corrosion could cause a problem that ranges in severity, from a future maintenance of ace to a massive crumble of the building. When ties corrode, they expand, and this corrosion can cause distinctive horizontal cracks in those mortar bed joint generally, but not limited on the leaf’s exterior. The problems usually occur with the heavier metal and Fishtail types of ties.
Wire ties as well as other thin metallic ties will not expand enough to cause horizontal cracks as long as the joints in mortar beds are exceptionally tight(thin) and mortars are extremely hard. Cracks that are horizontal could seriously weaken properties’ structure as well as increase erosion increasing the exposure of the ties to moisture.
Wall tie density:
The structure of the wall ties found in the majority of older homes is usually observed to be uneven and the overall density of the ties is often insufficient. This causes regions of great concerns and weak spots within these types of structures These areas are typically
Windows’ sides and doors
Eaves and Verge levels
In the past, there was no tie allowance for these areas, and as stated, this could cause weakness in the structure.
Wall tie survey:
The most important elements of this wall tie study are:
The location and the approximate age of the property’s location and approximate age
Choose the method of construction. cavity or brick construction. Materials for the outer and inner leaf. The shape of the construction may be altered even in the walls of the same building for instance, in north-easterly areas. North East it is common for walls at ground level to be converted into cavities at the 1st floor. Also, cavity brick walls are able to be converted to solid walls on eaves level on a gable-end peak.
Mortar type and condition , and the general state of the pointed
The width of the cavity
Wall insulation in the cavity?
Check for cracks and other obvious indications of movement, bowing or bulging walls
Be particularly attentive to horizontal cracks which have been fixed and repaired and
Determine the pattern and the density of existing tie-ups
Determine the condition of the existing ties as well as the severity and extent of any corrosion
Do the locations of the damaged ties coincide with the site of any cracking not yet noted?
It is important to distinguish between cracks that are caused by corroded tie ties and those caused by other damaged metals like cast iron lintels, steel down pipes etc.
Wall tie embedment Are the wall ties sufficiently long to fit the width of the cavity and are they in the correct position
The surveyor has many of the necessary equipment for an exhaustive survey and investigation.
Metal detector to locate ties
A hammer drill that is cordless for inspection holes
EndoscopeOr Boroscope to study ties at-situ
Mortar or mastic to make excellent drill holes
NB Cavity wall insulation is another issue in homes that have cavity insulation. It is essential to remove the brick in order to check the wall ties. This will cost £60.00 plus VAT at the rate of the moment.
Wall tie stabilisation:
When all the outcomes of the inspection are analyzed, it will be time to move on to the next step which could vary from taking no action to ensuring that the ties are not corrosive and functional, all the way to the total reconstruction of walls that are structurally sound. The most cost effective treatment is generally somewhere in between the two extremes.
When considering wall tie replacement near me make sure you check out northwestwallties.co.uk
Specific recommendations are provided in Building Research Establishment (BRE) Digests 329 and 402 and British Standards Institute (BSI) the DD140.
The most frequently used treatments for remediation are:
Complete replacement of the wall tie is suggested if the ties exhibit signs of significant corrosion and where visible corrosion in the course of inspection
For walls that are mostly used, the suggested fixed density of 2.5 tie/m2 and additional ties of 300mm at vertically centred at the edges of the openings and at the top the verges
If the ties in place are made of thin steel or wire butterfly type that might cause horizontal cracks It is normal to keep them in their place
When the corrosion of ties has caused cracks to the leaf’s exterior the ties must be removed or separated structurally from the leaf. This is only possible following an installation process of repair tie and is generally the most costly and disruptive element of stabilisation of the wall tie.
It could be that the wall tie is in good condition but aren’t very dense It could be in instances like this that additional ties could be installed to complement and reinforce the existing tie.
Installation of a wall tie for a second time:
A variety of remedial ties is readily available, and it is essential that to choose the correct tie for each property. The choice should take into account the findings of the survey, and specifically the leaf’s outer and inner cavities and the thickness of the substrate.
A single product of standardization cannot cover all scenarios and, even with the advantage of an accurate survey the installation team will be prepared to handle a range of construction changes
In certain instances, ties could be placed on the outside of the building if significant changes or renovations are being carried out. This is a great option since there aren’t any visible signs of replacement until the work is completed.
When holes are made through the middle of bricks that are surrounded by leafs, it is essential to get the closest match possible using dyeing mortars on the job. Our employees are highly skilled and trained in this particular aspect of remedial work.
The experience of the operator and their supervision is essential to ensure that tie-ups are correctly installed and the job is finished on time and effective.
Treating existing relationships:
When the repair demands an alteration to the existing ties they must be identified generally using the use of a metal detector or an oboscope
Removal of all tie is required when there is a significant amount of damage to the inner and the outer leaves. This requires taking out and replacing the individual bricks. This is slow and labor intensive, and could result in a significant cost.
If the damage is restricted to the leaf’s outer surface, the best option is to isolate structurally the bonds away from mortar bed joint. Many methods are possible for this, including isolation sleeves, either made of with foam or plastic.
NB If a home requires general repointing, it’s beneficial visually and financially to carry out these tasks simultaneously as treatments for existing wall ties.
The installation of a wall tie is a solution that’s technical to a frequent issue with durability and structural strength that is commonly encountered with cavity wall constructions. It shouldn’t be attempted by anyone who is not a specialist for DIY solution. As with other remedial procedures like mold, damp or woodworm elimination. One of the main aspects that the customer pays for is security and peace of mind knowing that the job was completed by experts , and that the home is secure to live in and will keep its market value.