The subject building was a traditionally built Victorian mid-terrace domestic residence, consisting of three floors below a pitched tiled roof.
Problem
Signs of distortion and distress with localised cracking were noted to
the far external gable wall of the rear addition, along with cracked
and dropped brick arches to first and second floor level. Previous
repairs of old tie bars with patress plates, large steel straps,
rebuilding and re-pointing were noted, indicating a history of
movement.
A significant outward bulge to the side elevation at first floor level
with localised cracking was also noted, as was significant downward
movement at the rear doorway with all brickwork leaning towards that
point.
Causation
The movement noted was attributed to subsidence, which may well be
historic as internal redecoration shows no sign of cracking. Under
these circumstances we did not consider that underpinning was warranted
at this stage. Our pragmatic solution was to reinforce and tie back the
building by using a combination of bed joint reinforcement and lateral
restraints into the first floor construction to reinstate structural
integrity.
Solution
AWT’s remedial scheme was the introduction of bed
joint reinforcement beaming, crack stitching, fenestration lintel
repair, grout tie injection and lateral restraints, adding tensile
strength and restraint and thus reinstating the brickwork’s integrity
and the uniformity of the wall. After installation, pointing was raked
out, reinstated and tinted to match the existing (see coloured remedial
works on our proposal picture).
(Pic 3 )
1. Reinforcement: We introduced two rows of twin 8mm stainless steel corded joint reinforcement to form a deep masonry beam – As indicated with red double dotted lines on our proposal images.
2. Grout tie injection: We drilled into the party wall and bent into the hole one of the grouted 8mm stainless steel cords – As indicated with red stars on our proposal images.
3. Lintel repair:
To the underside of the fenestration openings head we drilled for and
injected grouted 8mm helical stainless steel pins through the brick
arch and passed into the line of the deep masonry beam installed within
the existing masonry – As indicated with green parallel lines on our proposal images.
4. Crack stitching: We stitched localised cracks with the introduction of single 8mm stainless steel corded joint reinforcement – As indicated with red single dotted lines on our proposal images.
5. Lateral restraints:
In conjunction with the beam, we introduced 8mm stainless steel lateral
restraints screwed directly into timber floor joists’ end grain or into
the side grain, all resin bonded to the masonry – As indicated with yellow stars on our proposal images.