MORTAR
Mortars of a low cement content, or class III mortars as defined in BS 5628 Part 3 are recommended for use with QUINN lite Blocks due to their ability to accommodate movement.
Recommended types of mortar mix: BELOW D.P.C 1:4 cement: sand + plasticiser/mortar mix ABOVE D.P.C 1:6 cement: sand + plasticiser/mortar mix Ready to use mortars should be of equivalent composition. NB Do not use stronger mixes than those recommended.
CUTTING AND CHASING
Blocks are easily cut using hammer and bolster, hand saw or bench saw. The use of coursing units reduces the need for cutting and keeps waste to a minimum. Vertical chasing must not exceed one third and horizontal chasing one sixth of the wall thickness. Electrical socket boxes should not be placed back to back.
Note: Do not use hammer action or percussion type tools
RENDERING AND PLASTERING
Internal
- Dampen blockwork with a fine water spray to reduce suction.
- Apply scud coat 1:2 sand/cement with waterproofer.
- Alternatively a proprietary bonding agent maybe used, e.g. Evobond, Unibond, or PVA bond .
- Scratch coat 1:6 sand/cement to a depth of 8-12mm.
Dabs with dry lining plasterboard or dry lining insulated plasterboard can be used as an internal finish. Gypsm Bond or proprietary lightweight finishes are compatible with QUINN-lite Thermal Blockwork. Plastering should conform to BS 5492 1991 code of practice for internal plastering. A medium grain sized sand is ideal.
External
External render should be PRAL D by Weber Building Solutions or other equal and approved.
Drying must not be accelerated at any stage during building. The Building should be allowed to dry before plastering begins.
Lintels
Steel Lintels are recommended to avoid cold bridging. If concrete lintels are used, additional insulation should be used locally at the lintel. Expanded metal should be placed across lintel extending past each edge to avoid cracking. Lintels should bear onto a full block and should have 100mm minimum bearing at openings of 1.2m or less and 150mm minimum bearing at openings of greater than 1.2m.
Movement Joints
It is not normally necessary to include movement joints in the internal walls and inner leaf of dwellings unless the walls are longer than about three times their height. In the external leaf of dwellings and the walls of industrial and commercial buildings, movement joints should be inserted in accordance with BS 5628 and IS 325. Generally a vertical joint should be inserted every six meters.
Bed Joint Reinforcement
Austenitic stainless steel mesh should be used above and below openings to avoid cracking. This should extend at least 600mm both sides of opening. Bed joint reinforcement should also be used under concentrated loads, e.g. load bearing beams, and where a wall is supported by a floor subject to deflection.
Wall Ties
Conventional butterfly or double triangle cavity wall ties should be embedded a minimum of 50mm in the mortar bed joints in each leaf. Ties should conform to BS 1234 1978 and EN 845-1.
