Basement Waterproofing in Chelsea
Background to Case Study
Timberwise were contacted by Donovan Construction to design and implement a basement waterproofing solution for a new-build basement that was in the process of being constructed.
Prior to Timberwise’s involvement
As the basement is below ground our waterproofing specialists had to assume that it would be affected by ground water penetration and consequently the waterproofing design had to be appropriate and the treatments specified had to protect the basement against the potential risk of water penetration
The structure of the basement was of waterproof reinforced concrete construction with external waterproofing and drainage to the upper deck area. Internal basement waterproofing had also been specified to protect against any ground water ingress that could occur for various reasons.
Timberwise’s solutions and results
The new basement construction was intended for domestic living accommodation so any waterproofing specification had to reflect this.
Our waterproofing design specialists refer to the environmental grades and defining performance levels as set out in British Standard 8102 – Code of Practice for Protection of Structures Against Water from the Ground, set out below:
Grades of waterproofing protection
Following the guidance of BS8102 Timberwise advised that a waterproofing solution capable of delivering a grade3 environment should be allowed for and therefore designed, specified and quoted for such a waterproofing treatment.
Our waterproofing design included:
Flood testing was carried out to the upper concrete screeded deck to establish that the installed drainage falls were effective and that drainage to the sump chamber was operable.
External waterproofing was carried out using Delta Kosher repair mortar, Delta Kosher Ploysill TG500, Delta Kosher NB1 slurry and Delta Kosher Deuxan 2C waterproofing liquid membrane. A Visqueen slip layer was installed along with a cavity drain and protection layer to the Deuxan waterproofing.
Inside the basement flood testing was carried out to the basement floor to establish if the installed floor slab was free from low/high spots. Delta Kosher Polysill TG500 was applied to the concrete floor slab to ensure no future problems of lime-scale blocking up the drainage.
Delta MS500 Cavity Drain Membrane was curtain hung on the walls to full height, along with the installation of Delta drainage channel that was connected to a sump chamber. The drainage channel also included inspection ports to allow for future maintenance of the waterproofing system.
The waterproofing installation was then finished off with fully bonded 90mm Foamglas insulation and Delta MS20 Floor Membrane.