Thin-Joint: Base Course for Cavity Wall Construction

The unique characteristics of aircrete make it ideal for the construction of cavity walls. With its combination of strength and resistance to moisture, it provides superb thermal and sound insulation properties.

When building a cavity wall it is important to get the base course right and to check the level before continuing above this course. Any inaccuracies can be corrected using a mallet. This is the key to the Thin-Joint System, as if you get it right, you will not have to level the blocks again.

Advice on how to achieve this result:

  • Bed the base course into traditional sand cement mortar. This will allow you to even out any unevenness in the floor due to its thickness. Levelling a base course for cavity wall construction is slightly trickier than that of a base course for solid wall construction because the blocks need to be parallel. Once you have mastered this, it is all straight forward from there on.
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  • For cavity separating walls, lay the blocks so that the cavity is at least 75mm wide.
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  • Use Celfix Mortar on the perpendicular joints using the correct sized proprietary scoop or sledge. This will create a 2mm joint rather than the traditional 10mm joint. As a result, this allows the cavity wall construction above to be laid flush to the base course.
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  • Fill the cavity starting from the base course with mineral wool for the best thermal performance. The wool should have a maximum density of 40kg/m3.

To find out more about using the Thin-Joint System for cavity wall construction, watch my demonstration.