Foundation Guidelines

STANDARD

The standard concrete foundation is typically made by digging into the ground and creating a finished pad that is flush to the surrounding ground. Typically this pad will be larger than your building dimension by at least 150mm each way, to ensure the structure will fit. It is ultimately the most straightforward solution. Easy to install and great if your structure is just to house the lawn-mower or give some ground maintenance equipment some security and escape from the weather.

Pros:

• Cheapest and easiest solution;

• Requires little technical skill;

• Simple connection to access roads/driveways (as no raised entrance).

Cons:

• Often results in at least one area of the pad being below ground level, as the ground will typically slope into the pad in at least one corner;

• The structure will likely not be watertight (unless you take further steps to make the structure so);

• May require the removal/relocation of soil from the site;

• Can require expensive/complex/time-consuming drainage solutions to divert runoff.

RAISED STANDARD

A raised concrete foundation is made by making a raised shuttering for your slab area, so your concrete pad sits proud of ground level when finished. The pad is typically made larger than your building by at least 150mm each way, to ensure an easy fit of your structure, on the slab. The solution can be inverted – in the sense that the same result is achieved by excavating the ground around your slab, which may provide a good solution should you wish doorway entrances to remain at ground level.

Pros:

• Reduces the amount of material that will need to be relocated. The ground will often still require levelling but not excavating.

• Produces a simple and solid solution to waterproof your structure. If your slab is power floated when combined with our water ingress protection system this solution has a good likelihood of producing a water-tight solution.

• Full waterproofing can be guaranteed with the addition of an additional base flashing that directs water over the edges of the concrete.

Cons:

• Will typically require more concrete than a standard pad;

• Will require a degree of technical expertise to build the shuttering;

• Additional materials required for the shuttering;

• Can require extra work or thought over access as entrances may require ramps to be built.

PRECISION PAD

The precision concrete pad foundation is made in much the same way as the raised concrete pad with the exception that the size of the pad is made to the perfect dimensions of the building. Laying this pad will require a foundation dimension drawing from us, so the foundation will not be able to be laid until this is provided. Please allow up to two weeks for this drawing as we do not produce these until we have finalised the full production CAD model of the structure.

Pros:

• As with the raised concrete pad however with the addition that as the pad is made so that the wall cladding will overlay the edge of the slab, ensuring that the building is completely waterproof;

• Guaranteed waterproofing.

Cons:

• This choice of foundation will potentially delay your project by 3-4 weeks as the groundworks won’t be able to get underway until you have our drawing confirming pad size;

• Pad has to be laid with a high degree of accuracy as there is a very small tolerance to be met.

BRICK SKIRT

Placing a brick skirt around your building waterproofs your building in much the same way as the raised concrete pad does – it creates a barricade that a base flashing can overlay, thereby directing water out of your building. Typically this solution is only considered on insulated structures or where there is a desire to tie the building’s aesthetics with another structure (such as an existing house).

Pros:

• Guaranteed waterproofing;

• Better aesthetics;

• Ensures conformity to the recommended installation protocols for insulated panels.

Cons:

• Cost;

• Extra trades;

• Timely;

• Door openings need to be considered – perhaps with inset drains.

UPSTAND BEAM

An upstand beam is a technical term for a raised (in our case) concrete beam or wall around the perimeter of the concrete pad. This solution is produced typically by either a separate shuttered concrete pour – forming a cast concrete wall or by building the wall using hollow 9” concrete blocks over vertically set rebar which has been inlaid into the base concrete slab, so as the wall is tied into the slab and producing a structural bond. The intended outcome of this method is that the building structure can sit atop the upstand beam either with the cladding overlaying the edge or by using a base flashing to direct water over the edge and away from the beam. This solution is typically only considered on insulated buildings and those which (loosely) will be habitable spaces including areas occupied regularly by staff for long periods. This design of foundation however can also offer a solution to height planning restrictions, as a lower external eave height can be maintained whilst keeping internal ceilings height by lowering the internal floor level.

Pros:

• Guaranteed waterproofing;

• Reduction in steel dimensions can reduce structure cost;

• Engineered solution which produces great aesthetics;

• Ensures conformity to the recommended installation protocols for insulated panels;

• Maintains ceiling heights;

• Good solution if underfloor heating is considered when combined with a later floor screed.

Cons:

• Costly;

• Extra trades;

• Complex and timely to install, as it’s a multi-stage process;

• Door openings need to be considered – perhaps with inset drains and excavation;

• This is an engineered solution that will require separate structural engineers’ advice.

SECONDARY SCREED

A secondary screed is where a new floor is laid inside the building after the building has been erected. This option can be considered as a remediate solution where the user is unhappy with the performance or quality of the original slab. This is a solution for water ingress under the cladding of a building. A screed is also commonly installed where underfloor heating is to be utilised for example.

Pros:

• Relatively cheap, albeit additional expense.

Cons:

• Doorway thresholds/lintels may require adjustments.