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BASEMENT WATERPROOFING

CONVERSIONS

Some of the most satisfying work we undertake is the upgrading of inhospitable, dank, damp basements, cellars and vaults into dry welcoming and useable spaces. Stonehouse regularly convert existing under-utilised areas to home offices, playrooms, wine cellars, gymnasiums and large kitchen/living spaces. The potential is huge and often at relatively low cost and upheaval.

 

We first inspect the area and through a detailed report recommend the correct method of waterproofing. For most conversions we can act as a specialist sub-contractor to a main-contractor or we can complete the works with our own directly employed specialist team of operatives, 
plasterers and carpenters.

 

NEW BUILDS

For relatively little additional cost at construction stage, a new property can benefit from the extra dimension a basement provides, be it a functional plant room or versatile entertainment space.

OUR PROCESS

The inclusion of basements in new-build design is an area of rapid growth. It makes absolute sense with the high cost of land that developers are keen to maximise space in this way. Within the rapidly growing market of waterproofing basements, we have completed new-build projects for both main contractors and self-builders.

 

The main consideration when embarking on the construction of a new-build basement is that the structure should be watertight. For this reason, STONEHOUSE provides specialist advice from the initial concept phase (with PI liability of £10,000,000) and are pleased to accept design responsibility (Example of a technical drawing). Our experienced CSSW qualified surveyors are also registered Waterproofing Design Experts as recommended by BS8102:2009.  Uniquely, several of our operatives are also qualified to CSSW level ensuring on-site decisions are technically informed and considered. Our experience includes domestic projects through to multi-unit commercial enterprises. 

 

FAILED BASEMENTS

Sadly, a significant proportion of our work is to investigate failed basements and correct poorly specified and badly installed waterproofing systems. Over one third of our annual turnover is a result of correcting failed waterproofing systems - our services often directly commissioned by insurance companies. These have usually not been designed in accordance with BS8102:2009. It cannot be stressed enough to clients whether designers, builders or homeowners that the installers of a waterproofing system should be specialists and industry-approved.

 

There are a whole host of reasons why extra stress can build up on basements and cause them to fail. Recent extreme weather conditions mean that systems have to cope with extra water pressure and some areas are susceptible to rapid flooding. We have, through these corrective works, gained a great deal of experience in repairing and re-designing systems to protect vulnerable properties. This has allowed us to compare the strengths and weaknesses of individual systems and we use a range of manufacturers who are technically innovative and value our feedback in the ongoing process of improving their ranges.

 

Stonehouse are fully accredited members of the PCA and the BSWA (British Structural and Waterproofing Association) and importantly all our works can be insurance backed by the GPI. We are experienced at working alongside consultants and leading technical figures in the industry to resolve disputes and agree solutions to some of the most complicated of failures. 

WATER MANAGEMENT

Often, full waterproofing systems are not required or necessary. Sometimes water entry is isolated to one identifiable point and can be simply guided to a sump chamber. Equally, there are some situations where waterproofing is not possible and it is better to allow water to enter at a point of least disruption and in a controlled manner, so its disposal can be managed without affecting the remainder of the property. The following case studies include examples of systems which offer a targeted, less intrusive solution while still complying with BS8102:2009.

 

In other situations where properties are vulnerable to extreme conditions, considered water management is required to avoid water ingress. When flooding happens, the system must be designed to react immediately and effectively and to have ample capacity to remove the water rapidly without strain.

 
 

LIQUID WATERPROOFING

Basements are often designed to extend beyond the footprint of a building and as a result we waterproof the associated concrete roofs and podiums decks using a ‘Type A’ external system. We choose to use a method which is directly applied, fully bonded, flexible and reinforced. We will only bond directly to the sound, prepared concrete substrate and have experience of a range of applications.

 

Our works are often integrated with internal basement waterproofing. This confidently allows us to issue a long-term guarantee which covers and protects the whole envelope of the basement from water ingress.

 

SUMP & PUMP SERVICING

Regular maintenance of a Type C cavity drain membrane installation is essential to ensure efficient, reliable performance. Servicing gives us the opportunity to monitor your installation and also discuss any recent upgrades that would benefit your system.

 

Stonehouse will only offer an annual service to systems which we have designed and installed. As standard there are two pumps to every chamber with a battery back-up. This requires annual servicing which we strongly advise and are delighted to offer via our team of Stonehouse engineers who have advanced and current technical training. This regular appointment allows us to:

 

• Clean - the pumps and ensure they are in excellent working order.

• Remove - limescale build up from the chambers.

• Reverse - the primary and secondary pumps.

• Check - the battery back-up system. 

 

Our installations are always fitted with alarms and if your alarm should sound we offer prompt assistance. Uniquely in our industry, we operate a 24hour call out facility for your peace of mind and our servicing charge includes the cost of all labour and parts within the contract.

 

Please note that regular maintenance of your system is essential for maintaining the 10 Year insurance-backed guarantee issued on completion of works. At the end of the 10 Year warranty period Stonehouse provides the opportunity to extend (with an additional cost) the guarantee period for a further 10 years and so on.

Stonehouse Sump & Pump Maintenance Programme

 

EXTENDING UNDERGROUND

New basements are often formed below existing properties, providing valuable added living space and an alternative to moving home. Stonehouse provides the waterproofing skills and experience to ensure that your new space remains dry. Among our large portfolio of works we give examples of Edwardian and Victorian properties which demonstrate perfectly the advantages of retrofit works.

Stonehouse does not carry out excavation works, we prefer to leave the structural work to the builder. We do however act as a specialist sub-contractor, working very closely with architects, structural engineers, main contractors and groundworkers.

This ensures the planning of the basement installation runs smoothly and efficiently bearing in mind head heights, drainage, light sources and ventilation. An efficient installation is cost saving for our clients and is reassurance against the trauma of water ingress following completion. 

 

LISTED BUILDINGS

Many listed buildings have extensive cellar and basement systems which are damp and have historically been neglected except perhaps for the family wine collection! The conversion of these cellars is now possible to offer dry storage and attractive extra living space.

Owning a listed property greatly reduces the methods available for waterproofing. To satisfy the conservation officer, any works should be reversible, with the potential of returning the structure exactly to its original condition. Equally, these works should not add any new stresses to the building as a whole.

By lining the original structures internally with a cavity drain system we can drain water harmlessly away without the need to apply cement to the structure, a technique reminiscent of that employed centuries ago by the Romans. The flexibility of this system allows us to follow the contours of the underground spaces retaining magnificent archways, unique features and complex detailing.

Stonehouse has a wide reputation and an absolute respect for the listed buildings which have been entrusted to us. We have a large portfolio of Grade I, Grade II*, and Grade II Listed properties across the UK. Please browse our website for case studies which confirms the diversity of our work.

 

VAULTS & TUNNELS

Curved surfaces offer more challenges to waterproof successfully – fixings have to be perfect and detailing of curved joints is not easy. The finished plastered result needs to be absolutely symmetrical to be aesthetically correct and pleasing to the eye.

 

We usually use a meshed cavity drain membrane system which allows for flexing and movement. By far the best way of demonstrating our experience is by viewing our case studies which includes projects which range in size from the tunnels of Gibraltar to the dining vaults of Covent Garden and a sunken kitchen wine cellar.

 

EXTERNAL WATERPROOFING

When a structure has no integral resistance to water pressure or when waterproofing protection has to as robust as possible, we use Type A external waterproofing. This is compliant to the British Standard code of practice BS8102:2009, providing a secondary (or tertiary) barrier to the entry of water. The important word is ‘barrier’ because external waterproofing protects against water ingress by applying an impermeable barrier to the external / internal or both faces of the structure.

 

We are able to select from a range of Type A waterproofing materials available from different manufacturers according to their suitability for the project. Since the face of the wall cannot usually be accessed after waterproofing, the water proofing build-up has to be carefully scheduled with contract managers and site foremen as the structure is formed. We have to be flexible and reactive to prevent delays on site, we are proud to have an unrivalled reputation for co-operation and ease to work with.

 

RADON CONTROL

Radon is an odourless, colourless radioactive gas emitted from rocks through soil; a map of areas in the UK particularly affected is available online. Radon is found naturally in very low concentrations in the air we breathe but is drawn indoors by lower air pressure through gaps in floors and concrete structures. This results in greaters levels within homes which can become a risk to health. Radon is heavier than air making basements particularly vulnerable to higher becquerel levels.

 

In a one-step solution, we are able to very neatly tie in our waterproofing technology with making basement areas most at risk to high Radon concentrations gas-proof. Stonehouse install the Newton PAC 500 cavity drain membrane system together with a Prestige Air positive pressure air delivery system. This significantly reduces Radon levels as well as other potentially harmful ground gases.

 

As part of the waterproofing system installation, the joints and special fixings are also tracer gas-tested to provide a gas-tight barrier. This complies with BRE Guidance Paper 211 (Radon Protection for new Buildings).

 

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