Helical remedial products have been independently and vigorously tested in a wide range of common materials.
Helical remedial ties are stainless steel, corrosion resistant and flexible to accommodate natural building movement. They are easy to install and test in the building under repair, leaving nothing to chance.
Where drilling through the brick face is not acceptable then it will be necessary to consider inserting the remedial ties through the mortar bed. This will be satisfactory where the mortar is strong and in good condition. Angled drilling may also be used in special circumstances.
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Maclennan have been experts in designing, installing and guaranteeing systems for over 30 years.
Using the latest 8mm diameter grade 316 austenitic stainless steel Helical wall tie we can install new ties quickly and easily and still provide you with a guarantee.
If you see horizontal cracking to your property and you have a cavity wall then that would suggest that over time moisture has got into the brickwork and started to corrode the wall ties making them expand and lift the brickwork above giving you the cracking.
The cracking should appear ever 450mm vertically. MacLennan can isolate the old steel ties to stop future movement and install new ties at the recommended pattern, as these ties are stainless steel they are less likely to corrode. With one of these ties we can get between a 1.5kn and 2.5kn pull out to make sure this is the correct tie application. There are a numerous amount of variations of ties we can use to suit all building materials.
Testing and Spacing
Pre-specification testing should be included as a routine part of the building survey. At least one, and preferably two, ties should be inserted into each elevation at different levels to determine the minimum pull out load obtainable from both near and far leaves. This minimum load should be used as the basis for deciding the density of ties to be installed. This testing is carried out by all Maclennan Surveyor’s when contracts are awarded or for a small cost at tender stage. For a small contract at least 10 ties must be tested; on large projects 5% of all ties should be tested. For most applications (buildings under 30m high and areas with a maximum wind speed of less than 46m/sec) the minimum tensile proof load is 1kN based on a tie density of 2.5 per m (900mm x 450mm centres). This excludes cladding form masonry and substrates below 100mm deep.
Independent Testing and Approvals
Helical remedial products have been independently and vigorously tested in a wide range of common materials. The testing programme is on-going and to date has been carried out by the Civil Engineering Department of Oxford Brookes University; the Civil & Structural Engineering Department of Middlesex University; The Transport Research Laboratory, Crowthorne and the Building Research Establishment, Garston
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Other Types of Masonry Repair
This is very common on end gable walls of terraced housing and old properties where the floor joists are running front to back of the property. With the floor joist running parallel to the wall there is no connection of the wall into the rest of the building to complete the structural diaphragm of the property. MacLennan can prepare a quotation where we connect the wall back to floor and ceiling joist and where necessary also connect the wall to internal stud partition walls or spine walls.
Delamination is a form of bowing which happens in large thick solid walls where the internal skin has come away from the external skin leaving the rubble-filled void in the middle of the wall to drop giving you the impression of bulging from the outside but no structural damage to the inside. We can reconnect the external masonry back to the internal masonry avoiding the need for a costly rebuild.
Wall Tie Replacement
Wall ties are an important structural component ensuring the stability of the outer leaf of a cavity wall against wind loads. The condition and number of wall ties in the structure are important and where corrosion has set in or wall ties are missing or broken, then remedial ties will be required. Solid masonry may also delaminate through broken headers or deteriorated mortar and require remedial tying to ensure future stability.