MASONRY & CONCRETE STANDARDS
Background
Masonry and concrete work in residential construction provides the base structure upon which the house is built and a permanent fire-proof construction and weatherproof exterior. The work is performed with quarried natural materials or with products manufactured by relatively simple processes, which have been selected for they’re wearing qualities. As such, they are subject to the same weathering phenomena as in their natural state, such as erosion, freezing and thawing, chipping, natural color variations and non-uniformity of size. Masonry work can be performed with an almost infinite variety of materials, methods of application and techniques of installation. This permits the owner an almost infinite range of personal choice but at the same time, creating, once that choice has been made a situation that can never be exactly duplicated. Masonry, more than any other trade, is dependent upon the variation of the product and the techniques of the individual workman.
Masonry and concrete work consists of four primary divisions:
1. The construction of a basement which may be either cast-in-place (poured) concrete or concrete block masonry installed on footings.
2. The placing (pouring) of flat slab areas consisting of footings, basement and garage floors, stoops, patios, walks or drives.
3. The veneering of the exterior of some structures with brick, stone or other masonry products.
4. The construction of fireplaces and chimneys.
Concrete is subject to several natural changes. The first is shrinkage in the hardening process, which creates shrinkage cracks, the type most common in concrete work, especially in flat slabs. Shrinkage cracks themselves do not affect the integrity of the surface. Concrete is subject to the elements and is attacked by certain chemicals. Pitting, scaling or spalling can develop under unusual conditions or when certain salt or chemicals are placed on a slab in winter for ice removal or drop from a car onto a garage slab and/or drive. A certain amount of surface dusting is normal. Proper owner maintenance can alleviate most of these situations. A sealer can be applied by the homeowner to the concrete to minimize dusting and sapling and effects from chemicals.
Cracking is characteristic of concrete, and cracks in concrete walls or mortar joints of block foundations generally do not affect the structural strength of the home. Cracks are caused by settling of the house, shrinkage of concrete, and expansion and contraction and may occur continually throughout the life of the house.
Settling is a natural phenomenon in the construction of a new home and concrete slabs are subject to the settling process. For this reason it is recommended that wherever possible, the construction of floating slabs, such as patios, walks and drives, be postponed until at least the end of the first year of occupancy or even longer so that a more stabilized soil condition will be available prior to actually doing the work.
Masonry and concrete work is also subject to color and texture variations due to the nature of the materials. Repairs, when made, seldom, match in color and some variation is to be expected by the owner.
When selecting a veneer material, predominantly a matter of owner preference, many factors enter in, such as: the bond or pattern to be used for the brick or stone; the selection of the type of mortar joint (whether struck, raked or weeping pattern); the color of the mortar and the shading variation from batch to batch; the shades of the material involved and their relative contrast with the mortar chosen; the choice of material size, standard or king size brick or the type of stone chosen; and, finally, the individual workmanship of the mason. All of these variables set up a distinctive situation within the masonry field.
Common Defects or Problems:
- Leaks in basement or wet basement
- Cracked basement walls
- Cracking of basement floor
- Cracking of garage slab
- Cracks in patio, walks and drives
- Pitting, scaling or sapling, and chert pops of concrete work
- Powdering or chalking of concrete work
- Low spots in concrete slabs, except for stoops with foundations.
- Cracking of stoops with foundations
- Water stands on stoops with foundations
- Settling, heaving, or separating of stoops, steps or garage floors
- Basement floor does not pitch to floor drain.
- Cracks in mortar joints of brick or other masonry veneer walls.
- Brick is different color than what was selected or colors vary
1. Common Defect or Problem – Leaks in basement or wet basement.
Performance Standard – No leaks or flow of water are acceptable, except when caused by an improper ground pitch away from the foundation (a proper pitch is 6″down for every 10′ out from the foundation and must be maintained by the owner), or improper landscaping or subterranean problems where the responsibility is defined as the owner’s by the building contract. Leaking conditions should not be confused with dampness or moisture, which can be expected by the owner during the first year of the settling process, or with condensation during the summer months. If the basement had an engineered waterproofing system on it, then the owner should refer to the manufacturer’s warranty.
Builder Repair Responsibility – Builder should correct as required. After correction, any openings made in order to correct should be repaired. Color variations in repairs are to be expected.
Craig’s Comments: The first sentence should read “No leaks or flow of water are acceptable.” Period. The exception should be that it will not be the builder’s responsibility if the owner caused an improper ground pithc, but the improper ground pitch is still unacceptable and should be corrected. We have good basement waterproofing systems. They work well when installed properly. BUT roof water and surface water should still be kept from the foundation as much as possible, and drainage systems must be kept open and working. Basements are ususally the coolest place in the house in the summer. Condensation can easily form on cool basement walls and floors. Keep the humidity low by properly sizing the air conditioner or running an auxiliarry dehumidifier.
2. Common Defect or Problem – Cracked basement walls.
Performance Standard – Hairline cracks in mortar joints or cast-in-place concrete not exceeding 1/8″ average width or hairline cracks in a single isolated block not extending to any adjacent blocks, providing these cracks do not cause a leaking problem are acceptable. If the cracks are caused by an improper pitch away from the foundation or owner landscaping, it is the responsibility of the owner to repair.
Builder Repair Responsibility – Builder to repair any cracks in mortar joints or poured walls exceeding 1/8″ average width. Unless structural danger exists, repairs should be made approximately a year after occupancy to permit normal settling through the stabilization period. Broken blocks should be removed from the inside and refused with a 4″ block. Grout colors should be matched as closely as possible, but color variations should be expected by the owner. Exterior repairs will not be made except in the case of major structural damage.
Craig’s Comments: Improper pitch of the ground near the foundation can cause excess pressure on a wall, causing it to crack. Long horizontal cracks are an indication of excess soil pressure on the wall, either from improper pitch or improper backfilling. Pay attention to these even if they are less than 1/8″ wide. Vertical cracks can indicate foundation settlement or sometimes normal concrete shrinkage. I recommend a poured, reinforced concrete wall with a minimum of 3500 psi concrete. No backfill for 28 days.
3. Common Defect or Problem – Cracking of basement floor.
Performance Standard – Shrinkage cracking is to be expected and requires no repair unless one or both of the following conditions exist:
a. If the two surfaces of the crack are mismatched in height by more than 3/16″.
b. If the shrinkage occurs non-uniformly (e.g. all in one crack rather than several) and exceeds 3/16 average width.
Builder Repair Responsibility – Builder should correct using a latex filler, surface patching or other methods as required, grinding surfaces smooth in case of mismatch. Owner is cautioned repair will not match in color and a hairline crack may reappear.
Craig’s Comments: We can make typical residential concrete slabs not crack. Soil compaction, concrete mixture, reinforcing materials, placement techniques, and curing techniques all play a part, but in the interest of time and money, some short cuts are taken. See the ACI standards for more information. Saw cut or formed control joints will help control where the cracks do develop. I recommend filling the control joints with a urethane caulk (before any framing or flooring is installed in the basement.)
4. Common Defect or Problem – Cracking of garage slab.
Performance Standard – Cracks in garage slabs in excess of 5/16″ in width or 5/16 ” in vertical displacement shall be repaired.
Builder Repair Responsibility – Builder will repair cracks exceeding maximum tolerances by surface patching or other methods as required. See repair method for #3.
Craig’s Comments: See the comments for #3 above. Backfill compaction is critical in garages
5. Common Defect or Problem – Cracks in patio, walks and drives.
Performance Standard – Except as may be otherwise covered by contract, no warranty against settling can be extended for floating slabs installed on soil, which is less than 95% compacted. Cracks in excess of 5/16″ in width or 5/16″ vertical displacement on a surface which is 95% compacted shall be repaired. It should be noted that floating slab type concrete should not be installed until at least the end of the first year, if possible.
Builder Repair Responsibility – Builder to repair to meet performance standard. If replacement of a section is required, the minimum section should be removed from the walk, drive or patio at the blind or open joint.
Craig’s Comments: Compaction of the underlying soil or base is critical.
6.Common Defect or Problem – Pitting, scaling or sapling, and chert pops of concrete work.
Performance Standard – The aggregate in concrete work should not be exposed unless it is caused by a concentration of water, freezing and thawing, use of salt or other chemicals and mechanical implements, and other factors beyond the builder’s control. Owner should consider sealing the concrete.
Builder Repair Responsibility – Correct using a latex filler or grind to remove defect to meet acceptable tolerance. Owner is cautioned latex repair will not match in color.
Craig’s Comments: The concrete finishing process is critical in addressing pitting,scaling and chert pops in concrete. Finishing pushes the aggregate downward while forming a surface layer of the finer materials. Improper finishing can also cause excess water in the surface layer, which will eventually cause the surface layer to break loose. Sometimes you can hear a hollow sound where the surface layer has come loose but not broken free yet.
7.Common Defect or Problem – Powdering or chalking of concrete work.
Performance Standard – Powdering or chalking may occur. Builder should advise owner to seal the surface with a concrete sealing compound.
Builder Repair Responsibility – None. However, only if the surface is soft, other repairs may be required- these are rare and severe instances in which builder would then be required to correct.
Craig’s Comments: None
8.Common Defect or Problem – Low spots in concrete slabs, except for stoops with foundations.
Performance Standard – No water pockets exceeding 5/16″ depth shall exist in any slab, which is pitched. Where a level slab has been requested by the owner or in basements, water pockets may appear.
Builder Repair Responsibility – Correct to meet performance standards by filling with a latex or equivalent filler or grind as necessary. Finished repair should be feathered and smoothed. Minor color variations are to be expected.
Craig’s Comments: This is another situation where the choice of subcontractor plays a big role. Some subs can and will get the slab very close to flat, or to the performance standard that you specify in your contract. You should expect some low spots, but 5/16″ is excessive to me. 1/8″ is more like it.
9.Common Defect or Problem – Cracking of stoops with foundations.
Performance Standard – The effects of cracks or settling with inadequate drainage on stoops make acceptable tolerances much lower than for other slab forms. All cracks, except hairline cracks with no settling, require repair. Minor chips and cracks just beyond the acceptable tolerance should be corrected with a latex filler and beyond that point when complicated by settling.
Builder Repair Responsibility – Correct to meet performance standard.
Craig’s Comments: None
10. Common Defect or Problem – Water stands on stoops with foundations.
Performance Standard – No measurable water depth exceeding 1/16′ is permissible on stoops.
Builder Repair Responsibility – Correct to meet performance standards by filling with a latex filler or grinding. If the defect becomes qualified under item #9 on stoops, it shall be replaced as stated in that item.
Craig’s Comments: None.
11.Common Defect or Problem – Settling, heaving, or separating of stoops, steps or garage floors.
Performance Standard – Stoops, steps or garage floors shall not settle, heave or separate in excess of 1 inch from the house structures.
Builder Repair Responsibility – Builder will take whatever corrective action is required to meet the Performance Standard.
Craig’s Comments: If the settlement or separation occurs so that water will now run to the building rather than away, the situation should be corrected regardless of the 1″ standard.
112. Common Defect or Problem – Basement floor does not pitch to floor drain.
Performance Standard – Basement floors are only pitched in the immediate area of the floor drain. When there is to be a finished floor area around the drain, floors will not be pitched.
Builder Repair Responsibility – None, if the floor meets the Performance Standard.
Craig’s Comments: If, for example, a basement laundry room contains a floor drain, the entire room should pitch towards the drain. In this case, the floor could be finished with sheet goods or tiled. If you want a particular area to pitch towards the drain, regardless of room size or floor finish, specify it in your contract.
13. Common Defect or Problem – Cracks in mortar joints of brick or other masonry veneer walls.
Performance Standard – Small hairline cracks due to shrinkage are common in mortar joints in masonry veneer construction as long as they don’t exceed 1/8 ” width.
Builder Repair Responsibility – Builder will repair cracks in excess of Performance Standards by pointing or patching. These repairs shall be made at the end of the first year of the warranty period. Owner should note that there will be a color variation between old and new mortar.
Craig’s Comments: Cracks in veneers may indicate a foundation problem, especially if they exceed 1/8″
14. Common Defect or Problem – Brick is different color than what was selected or colors vary.
Performance Standard – Due to the natural materials used to make brick, there will be color lot variations. Even within a lot, brick may vary in color.
Builder Repair Responsibility – None.
Craig’s Comments: Make sure the builder used the brick that you specified. In this case, checking the brick after delivery but before installation is a good precaution.
