Cavity Wall Tie Treatments
These are metal ties, which connect at regular intervals the outer and inner leaves of a cavity wall.
Early types are of thick ungalvanised metal, often in fishtail pattern shape.
These can rust and expand in the outer leaf of a masonry wall. This will cause the masonry to bulge out and eventually and become detached from the rest of the wall.
High winds can then cause considerable damage to walls, especially in exposed conditions in buildings over two storeys high. This is accentuated in coastal areas where high salt content of air accelerates corrosion.
The remedy is to locate the existing ties in the mortar joints with a metal detector, expose the end and isolate it with quick-setting plastic foam then repoint the joint.
New ties are then installed to the manufacturer’s specifications (usually around 2.5 per square metre and increased around window and door openings). They are usually installed through the centre of the brick then coloured mortar is used to disguise the entry hole.
The cavity wall is regarded as the best form of damp protection due to the fact that water cannot connect from across a void. As most brickwork and masonry is porous to some degree, sooner or later it will allow water to penetrate. The insertion of a cavity barrier ensures that water ingress is halted at the first step.
In order to keep the cavity walls stable we insert wall ties which connect and secure the both halves of the wall together. This ensures one cannot move independently of the other.
All ties must comply with BS 5628 1978 the specification for metal ties for cavity walls excepting conditions where severe exposure may occur.
The majority of ties are made from stainless steel or galvanised metal and are placed at 900mm horizontally, and 450mm vertically.
Endoscope inspection within a cavity wall
Cavity walls are constructed with metal ties linking the external and inner leaves to maintain structural stability. Some old buildings have untreated steel ties, which corrode. This may break the structural link between the two leaves. Additionally, corroding steel can expand within the brickwork mortar beds and joints and may cause structural movement and damage.
More modern buildings are constructed with galvanised steel ties, which, initially, do not corrode, but corrosion may eventually take place. Since 1981 buildings should have been constructed with stainless steel ties where corrosion is virtually non-existent.
Our Endoscope operates through a small hole drilled through a mortar joint within the external leaf brickwork enabling us to view the interior via a miniature camera and take photographs.
Additionally, the Endoscope inspection will reveal the existence of cavity wall insulation. Many purchasers are particularly concerned about energy use and heat loss. We are able to report that cavity walls either require insulation or have been insulated in the past.
Endoscope inspection beneath timber floors
One of the areas of difficulty when inspecting older property is the condition of concealed timbers. Vendors often refuse permission for invasive inspections.
Our inspection with an Endoscope provides additional information so that we may report more fully on the condition of the floors or concealed ceiling timbers in older and historic buildings with the minimum of disruption.