Following meetings with nfrc research was undertaken jointly to establish the suitability of some alternative proven mortar mixes for roofing applications.
Nhbc roofing mortar.
General wall area above dpc.
Where traditional mortar pointing is used to bed ridge tiles extend over the ridge continue over hips to form a 150mm minimum lap parallel with the hip rafter at abutments be supported and turned up by a minimum of 100mm be draped to allow water to drain behind the tiling battens.
Mortar designation to bs en 1996 1 1.
A cavity tray should be provided to direct to the outside any water that enters the cavity.
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In cavity walls over openings air bricks and the like.
Clay bricks contain soluble sulfate s1 designations have no limit on their sulfate content and so a suitable mortar should be used.
The mortar should be a mix based on sharp sand with soft sand added to achieve workability.
Chapter 7 2 pitched roofs page 12 s12 b includes the following guidance.
The outcome of this research is that nhbc has up dated the mortar mix for roofing.
Nhbc is authorised by the prudential regulation authority and regulated by the financial conduct authority and the prudential regulation authority.
150mm above adjoining roof surface to link with the roof upstand.
On page 5 specifically addresses mortar placement to verges which nhbc has seen to be susceptible to the effects of freeze thaw action.
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Nhbc s registered address is.
Mortar is vulnerable to deterioration by sulfates especially when masonry is saturated for long periods of time.
The cavity tray should fully protect the opening.
Nhbc s registered address is.
National house building council is registered in england and wales under company number 320784.
To reduce risk sulfate resisting portland cement to bs en 197 1 should be used.
Wet bedded verge tiles or slates should be fully bedded on roofing mortar having a minimum width of 100mm.
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