Structural Problems

Traditional stone tenements are typically four stories high with stone outer walls and brick inner and party walls. Timber floor joists are often formed in one piece, set into the outer walls but also loading internal walls. The joists help to stabilise the walls and tie the structure together. There is limited tying of the floor joists to party or gable walls. If the gable is weakened because the foundation is undermined, collapse of the tenement can occur.
Tenements may appear massive and solid but many are not particularly robust and they are vulnerable to a number of defects that develop over time, through weathering, use and ground movement.

Walls

External walls can bulge outwards, often at first floor level where the loads are high. If the timbers that bed into the outer walls are rotten, then there is nothing to restrain the stonework. Also, stone walls are not monolithic, they are formed from facing stones and internal rubble stones, with smaller stones and lime filling the voids between.  Bonding stones travel through the wall helping to tie it together, if there aren’t sufficient bonding stones the structure of the wall can open up.
A number of defects in stonework will occur because of weathering and the slenderness of certain areas of construction (see bays and oriels)
Internal walls are usually formed of brick, with lime bedding. They can have low compressive strength and because of their height, can become out of plumb. Timbers such as vertical door frames as well as horizontal wall plates are set within brick walls giving them some added rigidity, but these timbers can fail

Beams and Columns

Cast iron columns as well as cast iron beams can be found embedded in tenements, usually to form shop windows. Large timber beams were also used to create open plan areas for shops. these internal beams would carry the load of the floor joists and walls above.
In some cases, the loads cause the timber beams to deflect or to be crushed where the beam seats on the head of the cast iron column. Such structures may need to be stiffened.

Ground Conditions and Foundations

Tenement foundations might originally have been simply a bed of stones or flagstones, but they would usually spread out wide at foundation level. Brick footings are also commonly found, with concrete foundations becoming common around the 1890s.
Ground conditions vary over Scotland. Provided the whole building settles at a similar rate, it should not cause a problem. It’s where a ground weakness is localised that most problems occur. Mining areas can be problematic as ‘stoop and room’ mines deteriorate with time. Previous remedies to this problem entailed encircling the tenement block with steel beams that would be tied into the floor structure. This was meant to tie the whole structure together. Grouting of old mineworkings has become the preferred solution for such mining areas.
Old drains can leak and wash material away at foundation level, allowing movement of the foundations.

Cracks

Cracks in stone walls will occur for a number of reasons and their structural importance will vary.
Large cracks which carry up a wall structure and pass through stones may suggest differential settlement and an engineer should be informed. Cracks like this can be monitored to assess whether the movement is still active.
Cracks through the centre of lintels need to be repaired. The cracks can occur because of failure in the stone or because there has been an increase of load on the lintel, possibly because there is a rotten timber safe lintel inside.
Other cracks can develop because  of internal forces such as rusting iron or the roots of trees or vegetation.

Basements and Solums

Basements in Victorian tenements were often formed to cope with changes in ground level as well as to provide additional storage space. As the walls can be partly retaining earth, the chances are they will be damp.
Solum areas are small spaces under the ground floor joists, usually finished with a layer of tar or gravel. Small ‘dwarf’ walls help to support the ground floor joists and these should be designed to allow ventilation to flow through the solum area.
In Georgian properties, basement flats were formed, sometimes for the servants, with windows looking into a dunny area formed by a stone retaining wall. There would be a separate stone stair down to the basement level. The retaining walls are sometimes prone to bulging as increased traffic as well as the build up of moisture can affect these walls.