Window sills are shown here using two profiles, straight face and bullnose. Different type lugs are detailed. Where sills project, lugs are set back from the face of the sill to line up the brickwork. Heights of lugs are figured to match brick coursing minus one joint. The top of the lug may not always match the top of the sill upset in height. The relationship varies due to changing sash heights which alter the elevation of the sill upset. The lug height is fixed to match brick coursing.
Slip sills have no lugs and the lengths are figured 1/2″ less than the brick masonry opening. This allows for a 1/4″ joint at each end of the sill when pointing is desired.
Figure sill lengths 3/4″ less than masonry opening when sealants are desired. This provides 3/8″ joint for gun-in of sealant. Always prime joints prior to application of sealant.
Only the ends of lugged sills shall be embedded in mortar; balance of bed joint is left open and tuck pointed later. This prevents cracking of sills from future wall settlement.