How many wall ties do I need?
The wall tie density is relative to the cavity wall size, height, apertures and openings.
For 50-75mm cavities, a density of 2.5 per square meter is required, with 900 mm horizontal and 450mm vertical centres. Ties should be evenly spaced except around openings where they should be staggered accordingly.
ACS recommends wall ties achieve a minimum embedment of 62.5mm, this ensures the correct installation of the wall tie and exceeds NHBC requirements.
Timber Frame Ties
Timber frame ties should be installed to a density of 4.4 ties per square meter where wind speed does not exceed 25m/s as outlined in the BS 639902 Code of practice for wind loads. If the building is located in an area which exceeds 25m/s the timer wall tie density must be increased to 7 ties per square meter.
Remedial Wall Ties
ACS recommends following PD 6697 which is to install wall ties at 900mm horizontally and 450mm vertically in a staggered pattern with 300mm vertical centres around openings within 225mm of the aperture.
As of the time of publication, no British standard has been created for the spacing of remedial wall ties.
Article originally published on 30th October 2018