Construction Pathology: site supervision and inspection for masonry works
The type and amount of construction inspection will vary from project to project. As a minimum the inspectors should closely review the mockup panel. When a mockup is not used (usually an unwise saving), the first section of wall constructed should be considered the test panel.
The masonry inspector's job is to obtain good masonry according to plans and specifications. The inspector, in addition, should explain the reasons for the specified procedure or technique of construction. Sincere mechanics will produce better masonry if they understand the reasons for certain procedures. Sincerity is not enough by itself, as can be seen by jobs where the quality of work was partially ruined by mechanics who laid header courses in the wall or poured grout too stiff; all in the name of a "better job". Masons have remarked that they want to do as good a job as they know how, but they might cut protruding bed joint fins of mortar from the wall into the grout core or delay the puddling of the grout (these are discussed later in the text) because they do not understand that these techniques are detrimental to good results.
A written report should be made and provided to the designers for each day that an inspection is made (ideally the owner/developer should be sufficiently knowledgeable and interested to review these reports as well; this unfortunately is seldom the case). Any deficiencies that are uncovered should be reported to the builders and designers. Corrections to any deficiencies should be noted in subsequent reporting. At the completion of the project the inspector and contractor should make a final report certifying compliance.
For commercial buildings, a program of periodic inspection may be acceptable, while for institutional buildings continuous inspection is probably more appropiate, regardless of code requirements.
In the case of BV/SS construction, in addition to the regular inspections, the designers should make periodic visits to review the general condition system.
When the project was designed using full allowable stresses, it is imperative that the inspector be on site full time. The inspector should regularly check the batching of mortar and grout to assure proper proportions and the laying of units to ensure proper workmanship. The inspector should verify and ensure full compliance with the contract
documents for the placement of reinforcement, grouting and reconsolidation and the protection of the masonry from rain, dirt, cold and/or hot weather.
When the project was designed using one half allowable, it does not mean that there is no inspection required. At the very least, inspect the project on a periodic basis to confirm that the project is proceeding in accordance with the code and contract documents. Generally speaking, it is easy to end up with full allowable stresses (or worse!) if the mortar beds are sloppy or incomplete: full time insppection now would be much cheaper than the nightmare of problems and litigation later! In any case, unit strengths, mortar proportions and grout proportions are required to be verified.
Specifier's Checklist - Site Supervision
Why a "Specifier's Checklist"? Because too often we see specifiers who do not have any clue about masonry! This is a good way to have a project end up in disaster! Ideally, the specifier and inspector should be only one (fully qualified) person.
Material supply: job should not start unless everything is on hand
- masonry units of each type, grade (SW, MW, or NW based on the weathering index and the exposure of the brick), quality, quantity
- special units
- tests required (and their schedule: some require of lead time, i.e. months before breaking ground), with all results tabulated and interpreted! (with many architects and quite a few contractors things such as a very high or low IRA will go unnoticed)
- conformity with samples
- confirm continuity of supply and uniformity from sample to sample
- other materials: ties and anchors of each type/size properly labelled, thimbles, cleanouts, dampers, reinforcement (type, grade, quantity), built-in items
- cold and hot weather procedures in place; limits defined, red flags drawn
- mix design appropiate for the particular job: view standard ready mixes with suspicion
- check aggregate and bagged materials
- tests required (and their schedule: some require of lead time)
- confirm color continuity and uniformity
- confirm mixing proportions continuity; measuring device for uniformity
- confirm use of permitted-only admixtures
- protect from rain and frost
- protect from earth soiling
- protect from damage by others; machines, etc.
- provide dry storage for lime, cement
- protect sand from contamination by earth, debris
- protect sand from frost
Mock-up (sample) panel
- prepare panel sufficiently early to allow drying out. Contrary to what architects usually think, this is important not only for correct color fine tunning. Excessive shrinkage, as well as mortar mix workability, bond, etc. can and should be observed at this stage.
- determine joint size in accord with required laid-up dimensions of masonry
- establish quality of workmanship to be expected
- joints properly tooled and well consolidated.
- care is taken to minimize mortar droppings.
- expansion joints are kept clean of mortar or other material.
- materials are adequately stored.
- correct mortar mix is being used.
- mortar joints are completely filled.
- weep holes are open and free draining.
- unfinished work is protected daily.
- establish human relationship with tradesman to be supervised; hold briefing sessions, especially where reinforcement is required
- confirm accuracy of setting out dimensions
- check vertical dimensions and plumb and level of walls
- check for usage of damaged face units
- protect walls from rain washout of fresh mortar
- protect exposed top of wall from rain and at night by tarpaulins hanging 3.5 ft. down faces of wall, and safely secured
- ensure walls are kept cleaned of mortar splashes
- uniform batching of mortar
- blending of colours of masonry units
- cavities are kept free of mortar droppings especially on shelf angles and cavity flashing
moisture of mortar is adjusted to suction rate of masonry units
- unit is not disturbed after setting mortar in bed joint is sufficiently plastic at time unit is set in place to get a good bond
- full bed and head joints of correct thickness
- fresh mortar is not baked dry by sun before curing can take place
- grout holes in reinforced masonry are kept open
- grout is of proper slump to allow free flow around reinforcement
- mortar in reinforced masonry is mixed to provide designed strength
- solid masonry construction in chimneys and tight joints in flue linings
- caulking by others around openings
Back-up wall: (steel) studs
- proper ties (type, size, material) are being installed.
- anchor tie engages joint reinforcing.
- anchor bracket is fastened to steel stud framing, not sheathing alone.
- anchor tie and bracket connection is within manufacturers accepted adjustment.
- wall anchors are adequately spaced.
- verify anchor embedment.
- size and spacing are correct; twisted or out of plane material should be discarded, not fixed
- welds and other fastenings are adequate and galvanized.
- miscellaneous structural components are correctly installed.
- heaters on hand for cold weather work
- sheathing is in place, correctly fastened, and holes repaired
- flashing is correctly installed
- coatings, where used, completely cover the surfaces intended.
- vapor retarder and air infiltration barrier is installed and adequately sealed.
- expansion joints are adequately caulked.
- brick surface is cleaned and sealed.
Existing masonry problems: find the source
Identifying the problem:
A masonry wall showing efflorescence, spalling, cracking or bulging usually indicates a concern that must be addressed or at least acknowledged.
Do not repair the damage or clean the wall without locating the cause of the problem, or you will likely face the problem again, only more accentuated or damaging.
The cause of damage can be located through:
Then and only then should the necessary adjustments, and/or corrections be made.
- A search to locate the cause
- by opening up the wall to inspect
- that the wall was built as designed
- that the design is functional
- that the cause of the damage is located
- An analysis of the source and its relationship to:
- away from structure tied into the masonry wall
- from lack of deflection spaces, expansion or control joints
- temperature/weather variations
- retention within the wall
- impaired drainage
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Site design by the author himself. Strange hobby, isn't it?