waterproof guarantee basement construction build manage
  waterproof guarantee basement construction build manage

Client Frequently Asked Questions.

  1. Feasibility?

  2. Excavation? Structure? Electrical and Mechanical? Finishing?

  3. Cost?

  4. Where will we work?

  5. How are we certain the basement will not leak?

  6. How do clients insulate their basements?

1.  Feasibility.

Will go ahead Will often go ahead Might go ahead
Those prospective clients who call to say they included a basement in their planning permission and are going ahead probably have the budget. Those who would like a basement beneath a new extension behind their detached property, at least 3m from their boundaries, will often go ahead. Underpinning your back wall and piling along the boundaries to build a basement in your terraced house back garden is expensive. It only makes economic sense despite the cost in Central London. But with stamp duty very high over a million pounds, even there could be in doubt.

2.  Design, Structural Calculations, Excavation, Construction, Electrical and Mechanical, Finishing.

Would you like your contractor to just build your basement structure or take on your whole basement project?

We are waterproof basement construction specialist civil engineers. We are best suited as just your structure contractor.

We can project manage for you as well should you wish, from inception to completion. But we would usually only be your contractor for the basement structure. This is because your building contractor needs to build the walls, put on the roof and put in the windows before the basement can be pumped free of rain water and fitted out.

3.  Cost.

We do not find extras to bill you for at the end.

You choose from the list above. We give you our price. If you accept it, that is what you pay.

We are the experts. We will include all that is usual whether it has occurred to you or not.

4.  Where?

We operate more or less throughout London and the Home Counties. But without going inside the North or South Circular Roads.

where we will build your basement in the home counties and London

5.  How are we certain your basement will not leak?
  • First, we will get evidence that the concrete used in your project is completely impermeable.

    The only proper test for this is to BS EN 12390 section 8. Our waterproof concrete business has some sample certification here.

  • We will do all the concreting work to BS 8007, which basically means we will make sure that
    1. the concrete is properly reinforced to restrict cracking,
    2. We deliver the concrete properly,
    3. We get the concrete past all the steel properly,
    4. We compact the concrete properly and
    5. We cure the concrete properly.

  • We have learned, because we have taken responsibility for leaks for so many years, how to build formwork that makes the 5 points above very easy to achieve.

    Please do not be impressed by anyone who will fill a wall in a single day. That saves them time and money but leaves you a load of problems later.

6.  How do clients insulate their basements?.

We are often asked how people insulate a basement.

There is no clear winner. Every way is used.

However, you might bear in mind
  • A basement is buried, almost a cave, surrounded by ground always about 10°C.

    Therefore a basement will not absorb much heat from the ground if it is cooler, and neither will it lose much heat to the ground if it is warmer.

  • Ground is insulation because it takes excess energy a very long time to find its way to the open air.

  • Basements only benefit greatly from solar gain if the sun gets in, not if the basement has little window area.

  • If you want to maximise thermal mass, why not use the ground surrounding the basement?

    Or, why not use the basement structure to even greater effect by storing heat from the roof in the base slab concrete?

In 2012 we built a basement near Southampton, in wet ground and only two thirds buried.

These clients have achieved zero energy bills for their new home with U Values around 0.20 rather than 0.10.

See a video, made in 2014, explaining this basement and its heating here.


We have a number of other pages with information.

waterproof basement construction   You Must Have a Soil Report Before Design Starts   Please Ask Your Architect To Read This Page   Please Ask Your Structural Engineer To Read This Page   construction contract

Guarantees Available   Floor Construction Over Your Basement   client faqs   Return to Home Page   waterproof basement construction

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