My parents bought a ground-floor apartment last year in a 40-year-old, four-storey building. There is an 8 inch step up onto a ledge ( a few inches wide) and then the same drop down onto the balcony/terrace. They had always planned to get it taken out and lower the door frame so that the floor inside was flush/flowed out onto the terrace. However, a builder has told them this is a ring beam and cannot be altered in any way… that seems extraordinary to me. Is he correct and is this a common building feature?
Balconies come in all shapes and sizes and they can be formed in many different ways. From bolted on Juliette-style metal balconies to reinforced concrete structures. Designers have always strived to make an easy connection to the outdoors from our homes and in particular from apartments where private amenity space can be limited. With the added benefit of this open space there are some risks, one of these being the potential for water ingress. The details used to eliminate dampness and to prevent the entry of water from balconies to the inside have challenged designers and builders alike for centuries.
The desire to have a level threshold allowing an easy flow of people from the inside to the outside can regrettably also lead to a flow of water in the opposite direction. For this reason it is common to have an upstand at the door opening similar to the one you describe. This upstand forms a backing for flashings and allows the “turning up” of waterproofing used on the balcony floor. It is therefore not uncommon to have to step out across a raised threshold at the entrance to a balcony.
The case you describe is somewhat different. In your parents’ case the doors in question lead to a ground-floor terrace. There may be potential to remove the upstand and to drop the position of the doors as you describe but this work would need to be carried out following a more thorough inspection of the existing details used. The situation you describe suggests that the terrace is around 200mm below the upstand and floor and ground level are equal. The fact that floor level and ground level are equal makes the potential for water ingress more acute.
If lowered, the base of the new doors would be positioned below damp proof course level, which is typically 150mm above the terrace surface, again posing a task to eliminate water.
These challenges are not insurmountable and there may be scope for applying a waterproofing system to the lowered door reveals to help seal this weak point. The particular door proposed and threshold arrangement would need to be reviewed.
Perhaps the structural base or level of the terrace could be lowered and a permeable finish placed on top of this to match floor level. Water would be collected below the upper permeable layer preventing direct transition of water across the threshold. The position of the rainwater outlet would also need to be lowered.
The narrow upstand you describe is unlikely to be structural as suggested but it is possible. It is however more than likely a method of preventing direct water ingress from the terrace. This would need to be assessed by opening up and studying the construction methods used.
An inspection by a chartered building surveyor will quickly identify the various issues to be addressed. The surveyor’s knowledge of the practicalities and limitations of the various elements should lead to a workable solution. Your surveyor should also be able to recommend some good builders that will be well used to dealing with this type of tricky work.
Any proposed work to the terrace or alterations to elevations should be agreed in advance with the Owners Management Company and all necessary permits and permissions should be put in place. Again your surveyor will be able to assist in this regard.
Finding the perfect balance between an awkward step with good flashings and a level threshold with increased potential for water ingress is not easy and will undoubtedly continue to challenge apartment owners, designers and builders for the foreseeable future.
Noel Larkin is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland, scsi.ie
