Outer skin to comprise 103mm thick matching facing brickwork with a 100mm wide cavity and a 100mm thick Thermailite Turbo blockwork inner skin.
Cavity to be closed at all windows, door junctions and at eaves level with a proprietary cavity closure 'Thermabate' or equal, installed by manufacturers instructions. Maintain a continuous cavity between new and existing walls.
Skins to be tied together with 225mm long vertical twist wall ties spaced at maximum 750mm centres horizontally and 450mm centres vertically and at 225mm centres at window and door reveals. Provide additional ties within 225mm of side openings at no more than 300mm centres. Blocks to be laid in a 1:1:6 cement:lime: sand mortar with struck joints. Ensure that cavities are kept free from debris by employing the use of timber cavity battens pulled up as work proceeds.
Vertical damp-proof courses to be provided at all un-bonded jambs: (note proprietary cavity closer at jambs and cills).
At all low roof abutments i.e. porches, and conservatories ensure stepped D.P.C.'s cavity tray with stop end is provided and linked to code 4 lead flashings and soakers.
Code 4 lead dressed beneath cavity trays and over roof slopes with alternate perpends left open for weep holes all as necessary to form a weatherproof junction.
Provide polythene lapped and continuous cavity trays with stop-ends, above all lintels and over short piers between closely spaced openings.
Provide open perpends or PVCu proprietary at 300mm centres, min. 2 no per opening.
Bond new blockwork to existing walls with stainless steel masonry connectors and ties raw bolted to existing walls.
Floor finish to client's requirements.
100mm Concrete (GEN 3) floor slab with a 25mm insulation upstand at the perimeter.
100mm Kingspan insulation.
1200mm Gauge damp proof membrane to PIFA Standard 6/83A:1995.
150mm Sand blinded hard-core mechanically compacted in 150mm layers. (floor slab to be suspended where the depth of fill exceeds 600mm deep).
Super Strength Grade (Celcon or similar) concrete
foundation blocks to BS EN 772-2:1998 and
BS EN 771-3:2003. laid centrally below the load
Concrete foundation 600mm wide. Minimum 225mm thick GEN 1 mix.
New and existing drains around the extension
are to be surrounded by granular material
Where new foundations abut existing footings which are sited at a different level, it is necessary to ensure no permanent undermining occurs. This is overcome by raising the depth of the foundation concrete to the underside of the existing foundation.
Foundation depth according to site conditions.
Note: This is a standard detail in ordinary ground conditions and no trees are present.