Thermal movement is a fairly new cause of concern within the construction industry as the use of new modern materials are utilised within construction, the speed of which buildings are erected and the requirement for stronger materials that we can work faster with have been required in the industry as technology has advanced.
Thermal movement doesn’t pose serious threat to the structural integrity in the first instance but over time the damage caused can become very serious. Bricks and mortar are extremely strong and able to resist high compressive forces but offers very poor performance when subject to tensile forces.
Thermal movement is basically caused by the expansion and contraction of the fabric of the building due to hot and cold weather. When it’s hot the masonry expands causing compressive forces which the masonry can cope with due to its high compression strength but once it’s cold the material shrinks with tensile forces causing cracking. This cycle is repeated and small cracks eventually turn into large cracks.
Period properties rarely suffer from Thermal movement as many were constructed using soft lime mortars which allow movement slight movement usually accompanying thermal movement.
Modern structures are sometimes built without any expansion joints so the thermal movement cannot be accompanied within the masonry so cracking occurs.
Remedial measures are required in order to prevent further cracking and this should only be carried out by a specialist. Expansion joints are usually a 20mm wide cut which creates a separation in the masonry allowing each panel to accommodate the movement without cracking occurring.
Newman’s use the unique Twistfix system which incorporates specialist slip ties and the patented CD drivefix tie combined with a backing cord and flexible mastic creating an expansion joint.
We can guarantee all works for up to ten years and have carried out many projects requiring expansion joints to prevent further cracking.
Bulging walls in period properties are a common defect that are often seen along the gable and flank elevations of a property. This defect is especially common in Edwardian and Victorian properties but is also evident in properties of all ages.
Bowing walls should not be regarded as ‘just the way it was built’ this is a serious structural defect that will require a structural repair solution in order to prevent further movement or complete failure.
If the bowing in the wall is only at the levels where the floor joists run either into or alongside then this is more than likely to indicate that lateral movement also known as outward movement has occurred.
Lateral movement occurs when there is no connection between the masonry and the floor joists or stair case allowing the masonry to move independently. In order to prevent further outward movement you must provide a connection between the two.
Newman’s utilise Twistfix lateral restraint ties which are an 8mm stainless steel tie which are installed externally through a 12mm hole in the masonry into the floor joist. With a concealed resin fix to the masonry we are able to tie the masonry to the floor joist which restrains any further movement.
In modern properties or buildings constructed with a cavity wall then the bowing if not confined to the floor joist levels only could indicate that there are other structural defects such as wall tie failure which will need to be assessed.
Out lateral restraint schemes for bowing walls can be guaranteed for ten years covered by an IGL insurance backed guarantee. Contact us today if your property is showing signs of outward movement.
Diagonal cracks above window openings and door openings are common structural defects that show signs of movement which will need to be rectified.
Diagonal stepped cracking often indicates that the lintel that supports the masonry above the opening has failed. There are many types of lintels available and in use such as brick arch and soldier course lintels commonly found in period properties. Newer lintels are normally steel Catnic type lintels which can also fail showing signs of diagonal cracking above the opening.
In many instances the threat of collapse is over looked and simply ignored, in some cases cracks are raked out and repointed but if further movement was to occur the already compromised lintel could in theory collapse bringing the masonry above it crashing down as well.
Lintel Failure often occurs upon the removal of hardwood windows that were originally designed to bear a substantial load without distorting and are replaced with standard uPVC windows which are non-load bearing allowing the lintel to drop or bow causing sagging of the lintel which is shown by the diagonal stepped cracking.
Traditional methods are to remove the lintel and rebuild it, this is an intrusive method of repair and a slow process typically taking around a day to properly remove and replace a lintel.
Lintels can now be repaired using the Twistfix Helical System by using their Bed Joint Reinforcement which effectively creates a new lintel within the existing masonry by remove the mortar within two bed joints above the lintel and inserting helical rods encompassed in grout to create a load bearing lintel which spreads the structural loads across the length of the bars preventing further sagging of the lintel.
With the patented Twistfix 9mm CD helical tie we are able to install 450mm long ties vertically through the masonry in the lintel and pin it into the masonry above. This method is a vast improvement on previous pinning methods which often required 16mm holes drilled through the lintel. We can now install these ties through just 6 or 7mm pilot holes.
This type of repair is a fast and effective method of repair which has been tried and tested with BRE approval. Newman’s can guarantee this type of repair for ten years as we are a member of IGL insurance which covers the consumer in the event that we cease trading.