How to waterproof a habitable basement

You will need to provide a Grade 3 Habitable basement to comply with BS8102 

You need a 20 year guarantee. The only meaningful guarantees are Products Insurance backed guarantees.

To comply with British Standard’s you should have 2 forms of waterproofing.

From a design point of view. Type C is mandatory to comply with BS 8102 2009 and for common sense reasons. If the waterproofing leaks for any reason you have to be able to resolve the problem with the minimum of disruption to the occupier. You cannot do this with A or B systems.

Type A is an external sheet membrane or coating system which forms a barrier.

Type B is an integrally waterproof structure.

You cannot expect Type A to be installed completely defect free (this is a precedence set in law Outwing Case ) 

Why is waterproof concrete so problematic?

Type B basement construction is notorious for leaking. This cannot be disputed by suppliers as the evidence is over whelming. MacLennan-LSE work for waterproof additive companies, repairing failures with our injection systems and cavity membranes. All of the waterproof additive companies have to employ injection specialists to put right their frequent failures.

Additives do not stop leaks through cracks, honeycombing and joins. The additional reinforcement and joins required by most additive companies add unnecessary cost to the construction.

The additional reinforcement as required by waterproof additive companies is expensive and causes problems for detailing and pokering effectively.

If you have a leak after construction phase the additive companies will not return until fixtures and fittings and even internal walls are removed at the clients’ expense. They will not accept consequential damages.

To inspect or prove a failure with Type A the property needs to be excavated and this leads to more damage.

Type A and waterproof additives should not be used together as type A protection will prevent Autogenous healing if the type A is installed soon after construction.

All of this has to be considered during design and liability does fall on the designer if it is not.

A concrete structure without waterproof additives but with well compacted concrete and no honeycombing and well prepared (scabbled) joins with water bars will provide a Type B structure.

A concrete structure with additives and reinforcement to BS8007 but with less than adequate workmanship in any small area will leak. Honey combing occurs due to lack of accessibility to poker due to the amount of steel. Water bars are difficult to detail and install. surface prep of joins is difficult due to steel.  

 MacLennan-LSE Design

We install internal and external waterproofing.

We would always recommend an external system to protect concrete reduce damp ingress and to provide a dry environment in which the Type C system is a standby system which is installed for peace of mind.

The Type C system has the guarantees and full compliance with British Standards by being a serviceable system.

We cannot guarantee an external system on its own. Guarantees for external systems are not worth anything to the client. Contractors and suppliers will always find reasons for not honouring guarantees.

Product insurance and insurance backed guarantees are not available for external Type A systems. If you are offered one please talk to us and we will demonstrate why it will not give you protection.

We can install several different external systems. Some pre applied onto piles or formwork before concrete is poured. Others are membranes adhered to the finished concrete. We also spray cement based systems and crystalline penetration systems which are partly Type A barrier and Type B structure as they waterproof the concrete.

We can guarantee an internal type C system for 20 years as a standalone system if the concrete is BS8110. The joins need to be well designed and installed and the client has to have a maintenance agreement for sumps and pumps.

Designing this from drawings is a simple matter for us and is easily refined by mail or phone.

We design as many as 600 basements a year from drawings.

We are always happy to attend design finalisation meetings once we have some sort of commitment from the client that we will either win the work or a good percentage of the work we are involved with from this client.

Where we have a track record of winning work with an architect or engineering practice we will if required attend design meetings but normally find that we could have given the same advice and input from our desk by Mail , phone or conference call and saved a day out.

What you should insist on if you are looking for a waterproofing company

• Design, supply and install waterproofing systems. No split responsibility
• Take full responsibility for waterproofing Basement walls, floor and roof
• Accept design liability on our PI (unlike any manufacturer). 
• Give insurance backed guarantees of up to 20 years
• Provide an insurance backed products guarantee for consequential damages (this is critical as it covers consequential loss.)
• The above is not to be confused with Insurance backed or bonded guarantees or Manufacturers guarantees none of which protect the client to the same degree or offer consequential damage cover.
• Ensure compliance with all relevant standards.
• Show evidence and references for a large number of similar installations. We can show hundreds
• Comply with all relevant health and safety requirements.
• Do not use sub- contractors for specialist work. Only own fully  trained staff
• Can prove to be trusted and endorsed by some of the foremost market-leading architects, engineers and building contractors.
• Agree to accommodate project time constraints
• Are very competitive on price taking all of this into account.

Maclennan-LSE does all of the above and takes the worry out of all the financial risks associated with structural waterproofing, protecting contractors, designers and clients with our expert design, supply and installation of the most reliable systems. We also provide the added assurance for clients knowing that we are covered by the most comprehensive and specialist insurances available.

The worlds longest bridge, the Jiaozhou Bay Bridge in north-eastern Shandong Province, China made the Forbes list of the worlds 11 most incredible bridges in 2011.

Construction of the Jiaozhou Bay Bridge (also known as Qingdao Haiwan Bridge) officially started on June 30th 2007.  At 26.4 miles long the bridge is the longest sea spanning bridge in the world, connecting Qingdao and Huangdao.  Chinese officials said the bridge was designed to be strong enough to withstand a magnitude 8 earthquake, typhoons, or the impact of a 300,000 ton vessel and according to the judges, 'Construction of the bridge is a technological miracle', hailing China's advanced level of architecture and technological development.

The bridge was completed on June 28th 2011.  The design lifetime is 100 years, which requires not only durable concrete technology but also high performance protective coatings.  After a long period of survey and investigation, pure polyurea became the best choice for this protective aim.  The bridge was actually coated with polyurea coating during construction.  The polyurea was provided by Qingdao Shamu International Trade Co. Ltd.

The application was completed successfully under the supervision of Dr Weibo Huan, a professor at Qingdao Technological University, who is a pathfinder of polyurea technology and the chief scientist on the Beijing - Shanghai High Speed Railway polyurea protective project.  

The Jiaozhou Bay Bridge is located in North China, where there are 50-60 days of frozen-thawed time per year.  The bridge required:

• A versatile coating with fast cure against high humidity.
• High thick film building, high tensile strength.
• High elongation at break.
• High impact resistance.
• High abrasion resistance.
• UV stable with 100 years durability.

All of the above criteria were achieved with the use of polyurea

Congratulations to Jay Rana a Director at GAP Ltd for completing the Bournemouth Bay Run 2012 in 2 hours and 30 minutes - and with a twisted knee as well! 

Jay is a Director at Consulting Civil & Structural Engineering firm GAP Ltd and did the Bay Run in aid of Talbot Combined School (Bournemouth) and JJ Mehta School (India)

Apparently the plan next year is to complete it in under 2 hours! Good luck with that Jay and we are pleased to have been able to support you in your fundraising efforts.

MacLennan-LSE have carried out another Polyurea tank lining installation this one in Salisbury , Wiltshire. The GRP Tank was leaking. The Polyurea tank lining system was chosen under advice from Maclennan –LSE THE Polyprufe Polyurea can completely replace the existing tank without having to remove it.

The MacLennan-LSE team are all trained in working in confined spaces. The tank was accessed through lifting gear and ventilated with extraction units. The join between the tank and the concrete base was lined. The tank was primed and then sprayed with the Polyprufe Polyurea tank lining system.

The system was dried in 10 seconds and could be filled with water almost immediately

The system is more durable and flexible than epoxy tank lining systems  and GRP Tank liners and can be installed in one day meaning very little down time.

The result was a tank lining installed in a day and guaranteed for 10 years.

MacLenna-LSE carry out injected concrete repairs and waterproofing to Carparks, Basement, Tunnels and any other concrete structure. Working closely with world market leading companies we are able to provide solutions for repairs and waterproofing of concrete.

MacLennan-LSE carried out the insulation on a small barn conversion using there Polythermal sprayed insulation system.

The sprayed insulation systems have been used inappropriately in the past as roof repair systems. They are in fact excellent insulation systems which prevent draughts and offer very good thermal insulation.

• The system is quick to install.
• Easy to detail.
• Completely seamless.
• Does not require storage of bulky insulation boards.
• Makes complying with part L so much easier
• Completely stops draughts which are the biggest cause of heat loss.
• The system does not support the spread of flame

Sprayed Polyurethane Insulation

MacLennan-LSE carried out the insulation on a small barn conversion using there Polythermal sprayed insulation system.
ermal sprayed insulation system.

Yet another very professional Polyprufe installation by MacLennan-LSE

MacLennan-LSE have just completed a Gas and waterproofing installation in Pewsey Wiltshire. 

Working with Acorn Construction and the project architect and Engineer Price Myers MacLennan-LSE designed and installed a water proofing system and Prestige Air installed the gas system and pressure tested the membrane. A Poitive pressure system was installed behind the membrane which forces the gas out of the building from behind the membrane system.

What do you have to do to comply with BS8102

Design Team
4.2 You should have a design team. It should include:

• A geotechnical engineer.
• A waterproofing specialist capable of devising solutions.
• All design decisions should be bought to the attention of the waterproofing specialist.

The specialist can be a manufacturer but only if they have experience in all of the aspects of waterproofing. In reality they will not be able to give unbiased advice. You must take into account the repair ability of the chosen system and the feasibility of remedial measures must be assessed.

MLSE comment:
1.We always work with the engineer on the design team.
2. Reparability is not possible with Type A Systems. Reparability is only possible with Type B waterproof concrete during construction phase.
3. It is for these reasons that you should not have Type A and Type B together but can have A&C or B&C

Risk Assessment
5.1.2 You have to carry out a risk assessment. Taking into account the effects of climate change, burst water mains and sewers, adjacent trees, Sulphates , Radon, Methane and other ground gases. Where external drainage is proposed the effects of drawdown, Silting, and Biofouling even in permeable subsoil groundwater needs time to drain away and this can result in limited pressure periodically coming to bear on the structure.

MLSE comment:
Taking the above into account you can never consider anything less than full waterproofing from ground level down.

Two Forms of waterproofing
6.2.2  Two Waterproofing systems combined should be considered where

• The assessed risks are deemed to be high.
• The consequence of failure to achieve a dry environment is not acceptable.
• Additional vapour checks are necessary for a system where unacceptable water vapour transmission can occur.

MLSE Comment:
Consequence of failure Is always unacceptable in a grade 3 Habitable basement.

Your design
Taking into account the requirements of BS8102 and need for a grade 3 basement.
An external system with type B waterproof concrete cannot comply because. · In the event of a leak neither can be repaired. And so do not comply fully with BS8102 requirements for reparability and feasibility of remedial measures.
Type A

• An external system must have a fully serviceable external drainage system around the perimeter below the internal floor slab level. This must drain to a soakaway that will work in all groundwater conditions or to pumped drainage. This is also a requirement of Building regulations 2000 basements for dwellings.
• Failure to have a fully serviceable drainage system can lead to water pressure build up.
• A system without drainage would fall foul of The Outwing Case 1999 and would bring liability for failure to the designer.
• It is proven in law that an applied membrane system cannot be detailed defect free. Therefore water pressure has to be removed.

Type B

• Leaks in type B frequently occur through cracks, honeycombing and joints ( even with Hydrophilic strips )
• Waterproof concrete companies employ teams or engage sub contractors ( often MLSE ) to repair these leaks with resin injection, because they happen so frequently.
• Once the structure is fitted out and internal finishes are complete. If a leak occurs it cannot be repaired.
• Waterproof concrete company guarantees to not extend to consequential damages incurred by the necessity to strip out finishes to carry out repairs.

Failures in the above systems are common place and cost hundreds of thousands a year in litigation and disrupted contracts.
The worst combination of systems is Type A and Type B
In the event of a failure the argument from the type B supplier will be that the hydrophilic strips or some other element was not correctly installed. They will also say that the installation of the Type A prevented autogenous healing of the concrete.

The Type A supplier will not accept any liability for failure. They will also point out that damage could have occurred during backfilling and also rely on the Outwing Case to blame design. Which they are right to do as the design should accept that the Type A cannot be defect free.

Final note Hydrophilic strips.
Hydrophilic strips are not permanent. Manufacturers cannot prove that they work beyond a few years. High content Bentonite systems have a finite amount of Bentonite in them which will stop reacting at some stage. High rubber content strips do not react as much as Bentonite. The safest Hydrophilic strip has a small hose in the Hydrophilic strip and it creates a fully serviceable and repairable hydrophilic joint. These can be supplied and serviced by MacLennan-LSE

Type C system

• Complies fully with BS8102 and with Grade 3 construction.
• Fully serviceable.
• Guarantees do cover consequential damage.
• In 20 years and thousands of designs and installations MLSE have only had 3-4 very minor leaks.
• MacLennan-LSE accept design liability on our PI for waterproofing design.
• If the construction is well compacted poured concrete, MLSE will advise the cavity drain as a standalone system with no requirement for additional Type A or Type B
• If the construction does show signs of leakage prior to installation of Cavity drain then it can be dealt with locally by injection or applied coatings over the kicker or defects externally.
• The cavity drain system can be designed into any existing proposal without any changes to existing design.
• Unlike type A the Type C system can be installed in any weather conditions and so would not affect programme in foul weather or cold conditions.

The Polyprufe System
MacLennan-LSE sprayed the Polyprufe system over this failed Asphalt roof in central London saving the contractor thousands of pounds and weeks of work. The Asphalt remained in place and was covered with 2mm of indestructible elastomeric Polyprufe. The UV stable coating is guaranteed for 25 years and will accommodate any movement is finished and can be tracked over in seconds. Can be applied over Asphalt , single ply, concrete , wood, metal, Polyprufe supply any colour .

For information on roof refurbishment click here

How to cure leaking decks

Spraying Polyprufe is the most effective method for deck waterproofing whatever the deck construction. Waterproofing fails at seams and joins. Polyprufe doesn't have seams and joins and is easy to install around details like gullies and services.