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The Nine Stages of Work - Inspection Process

Stage 1 - Commencement of Work
Stage 2 - Foundation excavations
Stage 3 - Foundation constructed
Stage 4 - Damp proof course laid
Stage 5 - Oversite ready for concreting
Stage 6 - Before covering any structural timbers, steelwork or concrete
Stage 7 - Drains laid
Stage 8 - Testing drains after backfill
Stage 9 - Before occupation

The Nine Stages of Work Are

Commencement is the first of up to nine mandatory notices ( not all nine are relevant to some jobs ). The stages of work where notice is statutory are listed below :-

Stage 1

Commencement of Work . Please return the Commencement of Works Notice ( Blue coloured form ) either issued with your Approval Notice ( For Full Plans Applications ) or issued with our acknowledgement letter ( For Building Notice Applications ), at least 48 hours before the work commences.

We normally visit when the work commences. However, in certain circumstances we may decide not to inspect the site until a further notice is received such as excavations for foundations or drainage.

Stage 2

Foundation excavations, relates to site preparation for those parts of the building which will be in contact with the ground. This includes the concrete strip footings, boring for piles and ground preparation for a raft.

Building near trees causes particular problems in clay subsoils. You should inform the Building Control Surveyor as soon as possible if there are trees on or near your site.

The trench should be dug, levelled and cleaned to remove ground water before asking for an inspection.

For a raft foundation, we will be looking to see that vegetable matter has been removed over the area of the site. Soft loose material, particularly excavated material, particularly excavated material, must not be used to form a base for the raft or its hard-core under layer.

If piled foundations are to be provided, please contact us in advance to agree an inspection programme before the piling work starts.

If the foundation incorporates steel reinforcement, for example in a raft or ground beams, you must tell us before the steelwork is covered by concrete so that we can inspect it.

Stage 3

Foundation constructed e.g. concrete poured. Notice must be given when the concrete has been placed. It is advisable to have the corners of the building marked out to show the position of the walls on the foundations.

The Building Control Surveyor will be looking to see that the concrete is of satisfactory quality, that its thickness is adequate, that it is properly lapped at any changes in level and that the walls will be positioned correctly on the concrete. It may be possible to commence the building of walls prior to this inspection, but please discuss this with the Building Control Surveyor.

Stage 4

Damp proof course laid. You must tell Building Control before any DPC is covered up. This includes those in the walls near ground level and vertical DPC's and membranes to retaining walls.

The Building Control Surveyor will be checking to ensure that the DPC being used is of a suitable material, that the horizontal DPC is laid on an even bed and that provision has been made for lapping with the floor membrane if one is to be laid.

DPC's must always be adequately lapped ( 150mm whenever possible ) and when lapped with a polythene floor membrane they must be directly lapped together. A mortar bed must not be laid between the membrane and DPC.

Polythene floor membranes will often be seen when the oversite hardcore is inspected. It will be checked to ensure adequate thickness ( not less than 250 microns 1000 gauge ), that it is on a smooth bed with no sharp stones or other materials which could puncture it and adjoining sheets are adequately lapped and sealed.

DPC's at openings must not be bridged by mortar at any point. At reveals the DPC should be positioned behind door or window frames so that the wall plaster will not bridge it. To prevent ' cold bridging ' DPC's around openings will usually need to be of the insul;ated type.

Upstand DPC's such as those forming cavity trays should have a clear upstand of at least 150mm.

Stage 5

Oversite ready for concreting ( with damp proof membrane laid ). In the case of suspended timber floors it is the ground below the oversite concrete that willl require inspection before it is covered by the floor. This concrete must generally be above the adjoining finished ground level and therefore usually needs raising by providing hardcore beneath it. It must however be low enough to provide an adequate ventilation void beneath the timber joists.

For solid ground bearing floor slabs, it is the hardcore which will require inspection. If a polythene membrane is to be laid the hardcore should be adequately sand blinded before inspection.

The hardcore will be examined to ensure it is a material of suitable quality, that it has been firmly compacted and that its upper surface is suitable to receive the material to be placed on it. Hardcore should be compacted in layers not exceeding 150mm in thickness, preferably by mechanical means. Excessive thickness of hardcore should be avoided. If more than 600mm of hardcore is needed, an alternative should be considered, such as a suspended floor.

The Building Control Surveyor will also check that sufficient room has been allowed for the required floor construction to be incorporated.

Stage 6

Before covering any structural timbers, steelwork or concrete.

Stage 7

Drains laid and visible for checking layout and construction before covering. All drainage work should be inspected. This includes foul drainage, surface/ rainwater drainage to the building, and any drains to retaining walls which have a direct affect on the building.

Clay drain pipes require an even bed. Usuallly a suitable granular layer is spread in the trench bottom with a similar material placed and hand compacted to the side and above.

Plastic pipies require a granular surround of at least 100mm all round and for the full width of the drain trench.

Granular material should be ' pea gravel ' or shingle size 9-18mm aggregate. Sand, rough sand and graded all-in aggregate are not normally suitable.

Common faults to be avoided include failing to provide a flexible joint on rigid pipes wthin 150mm of points where they pass through masonry, and not using the full length of the main channel in preformed inspection chambers.

Drains should be laid, bedded and ready for covering or backfilling, but not covered, when notification is given for inspection. Bases for manhole and inspection chambers should be in position.

You are advised to test the drains before you backfill them.

Stage 8

Testing drains after backfill. When the building is complete, we may ask you to test the drains while we watch to check that they are watertight.

Stage 9

Before occupation ( if phased completion takes place ) and completion of the whole job.

If the building is to be occupied before it is completed, notice must be given at least 5 days before occupation takes place.

PLEASE Also Remember !!!

An incomplete building should only be occupied if the principal health and safety works have been completed.

You should request a final inspection when the building work is fully complete ( except for decorations ). Notice must be given not more than 5 days after completion.

A Completion Certificate will be issued to the applicant following satisfactory completion of the work concerned.

If you have any doubts or queries, please ask one of the Building Control Surveyors for further advice.

Sometimes it is necessary to carry out work in phases. If this applies, it is essential that notice is given every time any of the above stages are reached.

Some jobs will also require further specific inspections of particular items, your Building Control Surveyor will inform you of these. This may also include routine inspections to check on the progress of the work.