As part of our Pre-construction Exposed segment, Barry Quon, National Technical and Training Manager for Termseal, looks at the best methods for preventing moisture and termite ingress in back-filled walls. 


With the availability of flat land becoming scarce in some areas of Australia, and the desire for custom-built split-level or multi story homes, there is an increase use of back-filled wall construction in modern day Australian houses. These can be in the form of basements, wine cellars, rumpus rooms and garages. This below ground construction not only adds to the complexity of termite management, but also introduces the need to prevent moisture ingress into these homes.

Leaking basements and termite entry to below ground construction are common, and there is only one effective way to permanently resolve these issues for masonry (concrete) retaining walls. The most effective solution to stop termites and water leaks to below ground walls – either cement block retaining walls, masonry or besser block – is to do the job right, and that means using the correct below grade system. The consequences of basement leaks and termite access can be expensive and time consuming.

Termseal products are well known for providing termite management solutions – from pipe penetration collars to all types of perimeter systems – but did you know there is a Termseal product that can termite proof and waterproof back filled (retaining) walls in one application?

Termseal Multi-Purpose Active is a compound which is a highly engineered acrylic polymer that forms a seamless, flexible, termite resistant and waterproof membrane, and when used in conjunction with Termseal Prime Coat and Termseal Reo-Band FG, waterproofing – inclusive of hydrostatic water pressure – can be achieved.


Any construction joints are repaired with Termseal Sealant Active and Termseal Reo-Band FG


Meticulous preparation, a detailed clean and dry wall is the first step and one of the most important steps in creating a termite and waterproofed back lled wall. This stage is often left out and not performed to standard. Any imperfections in the blocks or mortar joints should be repaired with either Termseal Sealant Active and Termseal Reo-Band FG or, if a large repair is required, a sand cement and Bondcrete mix or non- shrink grout should be considered. This mix should be applied to all the blockwork joints and any holes, etc. to create a surface for the Termseal Multi-Purpose Active membrane application. It is also critical to treat the top of the wall after it has been concrete core filled, especially if an exterior wall, to prevent water penetration through the centre of the block and thus eventually finding its way to the interior of the structure.


Core Filled Wall Preparation with Termseal Multipurpose Active and Termseal Reo-Band FG


Termseal Multi-Purpose active must only be applied to the “positive” or back filled side of the wall if being used as a termite and waterproofing barrier system. It’s fine to treat the negative side of the wall, i.e. the inner side, for termite proofing only using Termseal Multi-Purpose Active, however the wall must be waterproofed by the builder on the positive side or applied over a specialised negative side waterproofing compound.


Always protect the Termseal Multi-Purpose Active membrane with core ute or similar before back filling. There is also a market for remedial waterproofing and termite management to existing walls where waterproofing and/or termite proofing has been overlooked. Positive termite and waterproofing – on the external surface – is always the best option.


Barry Quon, National Technical and Training Manager, Termseal