MM STEP REPAIR MORTAR

MM Stride REPAIR MORTAR – Repair of Worn or Defective Steps.

Stride repairs in the context of this document, are carried out to the existing or original airplane, line and level, not over-coating, that would create a difference in the height of the risers. Steps, going and risers should be consistent, except on a winding staircase where the going will exist wider at the outside of the radius than at the center bespeak, the risers will however still all exist the same summit.

Both the going width and the riser peak on all straight flights should be consistent, if not the steps become a trip hazard. As little as 3mm of variation in the height of a riser in mid flight can cause whatever one to lose residuum and fall.

There are exceptions – non planned, but that have over time created a change in height mostly as a part of pavement levels.  Ofttimes altered by local government and services contractors, the bottom step to a pavement may well change significantly over time, information technology is not how steps heights are calculated at the kickoff, but this frequently ways that the altered height of the lesser footstep just has to exist maintained.

The height of risers between landings must not be contradistinct – over coating all steps can be adequate as long equally this is followed through the entire stair. (Where a full tread repair is required, and the thickness of the repair is at least 15mm a full tread may be carried out but with the starting time layer (10mm minimum) fully bonded with fibres and the cease practical at non less than 5mm wet on moisture. –(Always seek communication on this type of repair equally at that place may exist structural implications)

Step repairs are required when the goings (treads) and risers, become worn through foot traffic, accidental harm and the like.

In areas of foot traffic, the surface repair materials must reach at least 20MPa before a reasonable degree of clothing adequacy is achieved, less than 20MPa will result in wear from common foot traffic.

Step repairs must be carried out in a logical sensible manner, must achieve a sound bond, exist consistent in thickness, applied in layers where required, to achieve even curing and drying. Repairs must end flush with the surrounding going or riser or both and should exist finished such that the line and aeroplane of the repairs leave safe navigable passage without deviation in going (tread) dimension or riser height.

The drawings provided, 1, 2, 3 and SK1a evidence three typical steps from a pavement rising to a landing, commonly supported on support walls in basement areas of tenement buildings. These are probably the about common locations for step repairs subjected to external weathering. Drawing SK1a shows step ends affected by move of, or corrosion of imbedded metal and refers to the issues associated with pen cheque staircases.

From the design phase, the masonry used in the majority of cases is amongst the densest, strongest stone available – seldom if ever are steps wrought from rock of less than 90 – 100 MPa in compression and generally ten MPa or more than flexural strength There are very few repair mortars that tin accomplish these strengths.

The vapour permeability of these types of stone is often very low, but not e'er. Many sandstones that are used for steps and slabs are tightly grained, complimentary stones and generally depression in overall porosity, adding to their durability. The more permeable a stone is, the less probable it volition wear well when used as a slab or a step.

Cartoon 1

Drawing i shows the full general configuration with the vi most common defects and the necessary reference points for ensuring the repairs that are carried out are accurate and properly sized.

Drawing 1

ane.Typical leading-edge impairment to going and riser, deepest in the heart of the stairway where maximum foot traffic occurs, tapering out towards the less frequently trafficked edges. The middle areas are almost always where heavy items are bumped upward, where prams and other wheeled items are pulled up, hence the riser damage is often on a like scale to that of the going.

2.General wear, unremarkably very old steps. Recent improvement in shoe pattern and manufacture, the utilize of trainers and light human foot article of clothing has had a major touch in improving foot health and because of the generally softer more forgiving human being-made materials, vesture characteristics have inverse significantly. Historically Skegs, nails and tackety boots had a major impact on goings in item, the re-soling of boots and shoes was common for the major role of the previous two hundred years, additionally safety wheels replaced iron rims and therefore these forms of habiliment volition be far less mutual in the future, and consequently require repair materials to handle the far less demanding conditions than that of even 30 years agone.

3.Significant smashing, boss, spalled or discrete areas of stone tin can occur where there is rusting of metal railings imbedded either in pb or mortar or epoxy resins.  (Meet cartoon SK1a – Step ends)

4.Generally, rusting imbedded railings causes this course of expansive impairment. One should await to see natural faults such as dries or flaws at the ends of steps. The builders might take stretched their standards when a natural fault was close to the end of the step, rather than having to discard the entire stride. (See cartoon SK1a – Step ends)

5.Full general erosion / wearable that is greater than 3mm can often be left untouched on a staircase that is being carpeted where a fixed runner is being used to center the carpet on the staircase. The repairs, completed inside the tread covered past the stair carpet, are to the original level and airplane. The areas of the pace to the far left & right, may remain untouched.

half-dozen.Landings – ¼, ½ and full, can be subject to more wearable and tear as these are traditional resting areas for heavy loads and manoeuvring of goods & materials before being lifted and carried up a flight of stairs. The principles of repair remain the same for landings, as they do for goings or risers.

The nuts of step repair require the steps to be reinstated to their original line, level and plane, non always apparent or easy when the surface of the stride is worn, but actually more frequently than not, very uncomplicated in practice.

Finding reference points for setting line, level and airplane.

If all the steps are to be repaired, the problem of determining line, level and aeroplane requires no more than than simple arithmetics. Where possible damage from previous step repairs have obliterated all the actual show of original line, level and plane, the height landing and lesser landing provide the acme of the steps divided past the number of risers, gives the riser dimension. In some instances, the lesser step volition accept altered every bit a result of level changes, peculiarly prevalent where pavements take been re-laid. In these instances, a adding – or best guess as to the likely meridian of the bottom step means the remaining risers will exist accurate for prophylactic admission and egress.

The distance from the top riser face to the bottom riser face, divided by the number of goings (treads) gives the correct going dimensions.

Drawing 1 shows typical areas of failure one-six.  A, B, C and D indicate reference points that will be closest to the original sizes, when the repairs are either isolated or every bit a function of normal tread vesture or corrosion bug.

Position A is normally best to determine the riser height, but it is non always possible to access these areas because of built-in or later alteration, where risers are clearly all dissimilar sizes at all the most common reference points, adding remains the safest selection.

Position B is oftentimes the best location for determining the plane, line and level of the going, equally at that place is almost never whatsoever abrasive article of clothing at these locations. Rusting can cause expansion and bulging so "sounding" the areas earlier measuring to determine that the stone is solid is important. Again, if all reference points provide conflicting information, calculation should be used to determine the going level, line and plane.

Position C and D  – There are two ends on each step, 1 may be worn, the other perfectly OK or ane element from 1 end can be used in conjunction with another chemical element for the other end.

Drawing ii

To ensure the all-time result for repairs, they should be cutting out to form neat, accurate mortises, irrespective of the original shape of the disuse. The very to the lowest degree that is required is to remove all loose, friable and deleterious materials from the repair surface area.

Positions 1 and ii Shows the irregular repair areas properly cut back in various levels in neat accurate straight lines and where practicable, level sections ready for filling with the repair mortar.

Repair mortar in this case is MM STEP REPAIR

Cartoon 3

Reinforcing will be required where the repairs converge at the junction of the riser and going. This is a leading-edge repair and may oftentimes be the deepest repair required on the step. Reinforcing should consist of dowels. These demand not be more than 2mm stainless wire, fixed in 4mm oversized holes with Rapid set, High Bond Crack-fill mortar and should be placed at the everyman level start, at 100mm centres forth the leading-edge angle, as shown. Lacer wires, 3mm-4mm in diameter, are in blue (horizontals).

Dowels tin can be readily bent back over themselves to tie into other dowels to class a bones reinforcing cage. Horizontal members must be stock-still at the leading edge of a tread repair and in any areas where there is more than 40mm in the depth of the repair.

All reinforcing should have at least 10mm cover. Mesh alone is not a suitable means of reinforcing pace repairs.

Reinforcing is fixed by drilling close to or on the inside angle of an internal corner, shown in ruby-red. The drill should be angled such that the it enters at an bending of approximately 45 degrees from horizontal. Low level percussion or non-percussion drills may be required with certain masonry units. Dowels from 1.5mm – 3mm from stainless wire should be left long enough to tie in the centre of the reinforcing area.

The shape of the reinforcing is important. Information technology should, where possible be brought out to a line and level consequent with the line of the leading edges of the repair area, such that when the horizontals are fixed in identify, they run parallel to the leading border of the repair. They need to be at a consistent superlative have a minimum 10mm cover and can be secured sufficiently with fine wire ties without compromising the 10mm cover dominion.

Make full deep repairs more than 40mm in ii or three passes, keep horizontal reinforcing out of the repair expanse until the concluding application to foreclose restricting the working space.

For larger flatter areas such as those shown in a higher place at location 2 in Cartoon 2, it is necessary to carefully scutch or tool the rock to as most as flat as possible to avert pregnant differential thickness of repairs. Repairs of this blazon crave fully bonded repairs; this means the utilise of a bonding span, SBR applied neat to the surface of the stride, with the repair mortar being laid moisture on wet.

All surface repairs should exist filled to a level and line to a higher place the original or desired level. The last repair is and so cut dorsum as the mortar stiffens and hardens upwardly. Surface finishing can exist past scratch or needle float, pairing tools such as forest cutting chisels, trowel edges or past Carborundum sanding when the materials gain some strength. This would commonly be done not more than 24 hours subsequently application but will depend on personal choice and timing. However, finishing can be left for weeks if needed. In these circumstances, the apply of conventional Masons tools and or mechanical buffing & shaping will be required.

Cartoon SK1a

Step ends – Open stringers with handrails, expanding corroding or mechanical damage from imbedded metal in steps.

Impairment around imbedded railings and handrails – oftentimes only detected past resonance testing (sounding)  where initial expansion of the metallic work has generated a very fine crack line – all step ends with imbedded metal should exist checked past resonance testing before determining the full extent of repairs.

Where A – B is the finished line of materials cut out from the body of the tread – this may be dictated past the radial fractures caused by expansion of the imbedded metal piece of work of the bannister, or where the masonry has separate & spalled as a function of weaknesses in the natural bedding plane or both.

Cut out with diamond discs in a serial of parallel lines running from the face up of the riser to the dorsum of the step. Where pencheck's are worked to a diminishing waist – narrow to the dorsum of the step as shown. Seek advice if cutting out will reduce the working thickness of the waist of the pencheck by more than than ¼.

C –  is a twisted wire dowel drilled into the body of the tread on the horizontal and vertical faces.

Drill holes should exist angled into the thickest sections of masonry and never drilled towards thinning masonry or towards an outside face or edge. Holes should be not more than 6mm in diameter and not less than 3.5mm bore and at least 30mm deep but must not exceed 50% of the masonry thickness. ane strand of 16 Approximate stainless or copper wire twisted effectually a 3mm diameter dowel to course an eyelet as shown, should be used for all areas where the repair does not compromise the structural integrity of the masonry. For deeper repairs, the wire may be doubled up and be twisted with eyelets at 20mm bore. Wire dowels should be fixed in identify with high bail fast setting mortar (Rapid set, Loftier Bond Crack-fill mortar)

D  – is the corroded, expanded palling (The vertical component in a banister) that caused the step to fracture in the first place. Wire brushed all around to check the integrity of the metal – afterward descaling and cleaning, retain the imbedded section simply if at least 2/3rds of the metal is sound and corrosion free – otherwise cut and weld a new section of similar textile or supplant entirely. Treat retained cleaned imbedded metallic with an anti-corrosion mortar suitable for marine environs (MMACC) ensuring nothing contaminates the freshly exposed, cutting back masonry.

Reform the footstep using MM STEP REPAIR mortar, over make full the repair and shape back equally the mortar stiffens and hardens (Not less than 6-12 hours after application, depending on temperature).  Course work can often allow the repair to be filled in a single pass. An open stringer allows the use of carpenters clamps to support simple course work. Individual railings should be properly spaced, tied and clamped together to keep them stable and motility free when the mortar is placed, and for at to the lowest degree 48 hours later final curing and finishing. However, a run of railings, need to exist kept secure for at to the lowest degree 7 days. If the piece of work is to be built up, let at least i hr only not more than 2 hours betwixt layers of mortar, up to 60mm can exist placed in a single pass on horizontal surfaces and 40mm on vertical faces.

Total surface covering of rock steps requires unlike materials and a different arroyo.

High strength materials are required to effectively embrace over steps. The repairs are built upwardly in sparse layers to a level and final unmarried application – homogeneously applied over the whole area for a uniform end.

Temporary suspension of the use of steps is essential during the repair process. One choice is to repair half the flight on one side and once fully hardened, repair the other half, in this instance access is continuous even though it may be restricted. In all other instances for repairs to be done successfully, the steps take to be decommissioned and where appropriate, culling access and egress provided. Within certain limits, temporary scaffolding staircases tin can be usefully employed for most entrance ways.

Masons Mortar Ltd guides are provided to our customers for employ with our materials, they are not specifications and are for full general guidance only.

All materials inclusive of graphics are under copyright 2009. Any person, visitor, institution or organisation responsible for unauthorised duplication, replication or copying in any form of this document volition be prosecuted.

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