Building a House Extension London

Building a House Extension London

Drawings. All dimensions for fabrication to be taken from site by the Builder unless otherwise specified on the drawings. All setting out to be to Architects drawings. Any inaccuracies to be reported immediately by the Builder to the Engineer.Foundations are designed on an assumed ground bearing pressure of 100kN/m2 to be agreed on site with the Building Inspector.

All ground for foundations and ground bearing slabs must be inspected and approved by the London Building Inspector before being build upon. Mass concrete for foundations to be grade C20 with maximum 40 mm aggregate size. Use sulphate resistant mix in accordance with Building Inspectors requirements.

The floor for the new house extension , is to be a compactable well granded granular material, free from timber, vegetable matter, steel or other deleterious materials. It may include broken bricks or crushed concrete but may not contain general demolition material.  All damp proofing treatment is to be carried out to the Architects requirements. All internal steelwork to be wire brushed to remove all loose rust and scale and painted with high build zinc primer with touch up on site after installation.

Concrete for the pad stones to be 1:11/2:3 nominal mix with 12 mm maximum aggregate size. Load bearing masonry to be laid using 1:1:6 mortar. Cavity wall ties to be stainless steel at 900c/c horizontally, 450c/c  vertically and at 225c/c around all openings. New masonry for the home extension is to be tied to existing building or house using steel wall starter, plugged and screwed to the existing masonry. Seal and joint with flexible joint sealant internally, mastic sealant externally.

All new timber in works to be grade C16 or better in accordance with BS5268 and to be pressure impregnated with cuts ends treated before fixing. Ply used structurally to be WBP fixed No12 x 65 long improved nails. All temporary works and stability of the building and house extension during construction work is the responsibility of the Builder. Working loads are provided however , sizing of any needles, props or other temporary works must be provided by the Builder. Structural work is to be carried out to the satisfaction of the Building Inspector and to be relevant to British Standard regulations.  

 

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