Experts in designing, installing and guaranteeing systems
for over 30 years
Compare Internal vs External Basement Waterproofing
Internal drainage systems will still require pumps to remove any water that may enter the structure but the size of pumps is much easier to determine.
The size of pumps will be dramatically smaller and more efficient because of the smaller volume of water they will be expected to remove. The pumps will be operating much less than in an external waterproofing system and so power consumption and pump replacement will be significantly less with an internal waterproofing system.
Which Basement Waterproofing system is easier to repair?
In an event of failure of the waterproofing systems, repair of an external system is not possible.
BS8102 also states that the designer should consider the form and feasibility of remedial words in the event of failure of the waterproofing system. Repair of an external system is in many cases just not possible. Where it is possible to excavate to show the system, identification of the problem and repair is almost just as difficult, especially if the ground is, as is often the case, wet and muddy.
Repair of an internal cavity drainage system is much less of a problem, as in the main, the problem will be with the drainage system. Inspection ports make the identification and cleaning of the system quick and easy.
We believe the arguments for using an internal drainage system as opposed to an external waterproofing system are conclusive. If you require assistance in designing an internal Cavity Drain waterproofing system please contact our in-house technical department MACLENNAN Waterproofing Design on 0845 658 7777 and we will be happy to assist you in the design of your waterproofing system.
The Life Expectancy of Basement Waterproofing Systems Compared
The life expectancy of pumps is dramatically reduced and extremely costly. If the designer is asked how much water he expects to have to remove, the honest answer is that it is not possible to accurately determine the volume. Therefore, what size pumps do you need?
It is difficult to determine the capacity of the drainage system that will be required. Natural drainage is only a safe means of drainage providing it is impossible for the drainage to back up. Therefore unless the drainage or soak-away are below the level of the basement floor, pumps will be required. If natural drainage is available further downhill from the property, the question still has to be asked as to how much water is to be removed by the system, and the same vague answers will result. Without knowing how much water is to be removed, it is difficult to determine the capacity of the drainage system that will be required.
External drainage systems uses geotextile membranes which may eventually block up and can no longer remove water from the areas that surround the structure. The potentially large volumes of water being removed by the system can bring relatively large amounts of fines from the ground into the system. External drainage systems utilize geotextile membranes as a filter to prevent the fines blocking the perforated pipe. However, like all filters they will eventually block up, and once the geotextile is completely blocked it will no longer remove water from around the structure. It is not possible to determine how long this process could take but evidence of complete blockage on external drainage systems within months has been documented.
As well as having the potential to block the drainage system, the removal of fines can undermine surrounding structures. It is vitally important that a geological engineer assesses the design of an external system to determine that neighbouring structures will not be undermined by the system.
It is difficult for any designer to guarantee that the external drainage system will remain in working operation for the whole of the life expectancy of the building and in our opinion it is not a viable option for these reasons.
Internal waterproofing of new build structures is in our opinion a much safer option. It is possible to design the system that will outlive the life expectancy of the structure, without having the problems that are associated with external drainage systems.
Internal Basement Waterproofing is a safer option
The internal waterproofing system makes sure leaks are prevented and stopped.
It is likely that the new structure will be built to BS 8110, or possibly to BS 8007. These structures are very strong and will only leak at joints within the construction. Measures to prevent leakage at the construction joints should be taken using hydrophobic or hydrophilic water stops, leaving a structure that should not leak. However, we should assume that the structure would leak if subjected to a head of water pressure because of the possibility of less than adequate workmanship.
This may be a slightly leaking water stop at a construction joint, for example, but wherever the weakest point of the structure lies, the amount of water entering the structure will be minimal, and significantly less than the amount of water removed by the external waterproofing system. Therefore, the internal waterproofing system is only dealing with relatively small amounts of water, and so the system can work well within its designed performance.
Water entering a strong structure is virtually crystal clear, as the structure filters out the fines. Because the movement of water through the structure is massively smaller than the amount of water potentially being moved by an external system, the volume of fines being removed from the ground is also much less. However, because the structure filters the fines they are not actually being removed at all and so in a worst-case scenario you have small volumes of fines being moved towards, but not removed from the structure.
Resin Injection for Leaks
Leaking joints in concrete and masonry is a very common problem. MACLENNAN often attend site where basements are constructed with supposedly waterproof concrete or external systems and water is running in through the kicker or other construction joins.
MACLENNAN has a range of Acrylic and Polyurethane products that can be employed to stop even the most aggressive water penetration through joins.
The problem is water leaking through structures.
The cure is the injection of the right material to permanently seal the join.
The materials we use have been successfully employed to stop leaks in: Dams, Basements, Reservoirs, tunnels etc all over the world.
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Want to know more about our 30 years of experience visit About Us , looking for a company that is so confident is our basement waterproofing that we have a Waterproof Guarantee call us on 0845 658 777 or send us an email at enquiries@maclennan-lse.co.uk
