1 Foundation Water Problems An Overview and Discussion of some Causes and Cures for Water Infiltration into Basements and Foundation Structures
2 This presentation was prepared and presented by Dwight Walker (Technical Services Manager) of DMX Plastics Limited to the Alberta Home Builder Association monthly Breakfast Meeting and Educational Series of Presentations. DMX Plastics Limited would like to thank the AHBA and ANHWP for the opportunity to present our material on Leaky Basements and Repair Solutions. This presentation covers only specific causes of leaks and repair solutions, and should not be misconstrued to be a complete coverage of the topic. There are many different solutions available as shown in the presentation, however there are many more that could not be covered here due to time constraints on the presentation length. For more complete information regarding other causes and solutions you can visit the web sites of other solution providers. We hope that our presentation brings to light the importance of building basements right the first time using quality materials and methods. Our intention during this presentation was to provide a an unbiased view of some of the more typical moisture problems encountered in the construction industry and typical solutions.
3 Some Rain Water Facts for Alberta
4 Moisture Problems Major Causes of Basement Moisture Entry Concrete cracks* - Cracks in a foundation walls of concrete or masonry compromises the structures ability to provide a barrier to water/moisture entry. Causes of cracks are settlement, expansive soils, frost, shrinkage due to natural process of concrete curing. Hydrostatic Pressure* Ground water pressure build up that exerts lateral and vertical pressures on the foundation structure Capillary Action* The movement of liquid moisture through a structure or substrate (concrete) using voids and fissures in the material acting as a path for water travel Vapor Transmission The movement of air borne moisture through a structure or substrate due to vapor pressure equalization (high concentration to low concentration) Condensation The formation of liquid moisture on or within a structure or substrate t due to the airborne moisture concentration ti and temperature t conditions being ideal for water to form Poor Concrete* Improper placement, mix design and field applications of concrete can contribute to physical defects such as honey combing, cold joints, and excessive shrinkage
5 Typical Construction Sequence for Foundations Minimal Wall Protection (Dampproofing) Concrete Wall Loose Backfill Soil Moisture Virgin Soil Floor Slab Footing
6 What do we know about Concrete? All Concrete Cracks The tension stress in concrete during curing often results in a foundation crack, and the orientation is typically vertical in nature Concrete shrinks when it cures, A typical wall longer than 20 feet will have a shrinkage crack Mechanical damage cracks in concrete foundation walls is typically horizontal or diagonal in nature
7 Adfreeze and Frost Heaving can be very destructive ti to a structure t
8 Frost Heave is considered mechanical damage.
9 Let s Review Some Common Causes of Moisture Entry into Basements Concrete Foundation Wall Cracks Minimal Wall Protection WllC Wall Crack Flood Water Water Pocket Water leakage into basements can cause serious damage to interior finishes, can lead to unhealthy conditions, mold and mildew
10 Residential homes are damaged every year because of water.
11 Water can penetrate a concrete wall through a form snap tie, foundation crack, cold joint or honeycombing in the concrete. Water can penetrate a concrete block wall through block mortar joints, and unparged concrete block walls
12 Moisture Intrusion on Unparged Concrete Block Walls Block Wall Joint Defects from Settlement
13 Hydrostatic Pressure Insulation/Vapor Barrier Minimal Wall Protection (Dampproofing) Saturated Wall Assembly Mold & Mildew Water Pocket Dampness on Floor Moisture infiltration results in Unhealthy Air + Dampness + Wall Assembly Damage
14 Hydrostatic Pressure What Affects it has on Your Foundation Pressure Plane Foundation Foundation Wall Hydrostatic Pressure Wall Wall Crack Hydrostatic Pressure Basement Floor Hydrostatic Wall Deflection Lateral Stresses Pressure Stress Cracks and Floor Slab Uplift
15 Capillary Action DEW Point Minimal Wall Protection (Dampproofing) Surface Temperature 37 F 55% RH at 64 F Perched Water Table Condensation DEW Point Condition where temperature t and humidity are ideal to form liquid id moisture
16 Poor Concrete Application Poor Consolidation No Agitation (Vibration) Improper Slump for Conditions Aids to Improve Proper Design Mix for Conditions Admixtures to Enhance Placement and Consolidation (DO NOT ADD WATER) Mechanical Agitation during placement (Vibration or Mixing) Ensure concrete not over mixed on the cement truck before placement (check weigh bills) 300 Turns on truck from Plant (maximum)
17 Let s Consider Some Other Factors that can Cause Basement and Below Grade Foundation Leaks
18 Water may build up under the concrete floor slab causing moisture problems or flooded basements Some causes are: Ground water accumulation (perched water table), a faulty or improperly sized/placed pump and discharge line, leaking gp potable water line, overloaded storm sewer,,plugged weeping tile, improper grading, locations affected by tidal shifts or rivers with flood levels higher than the base of the footings
19 The sewer and water lines are backfilled with loose soil and sand under the concrete floor slabs, which remain permeable.this can act as a conduit for water to back up under floor slabs when storm sewers and streets become flooded due to extreme storm conditions
20 Here the section of weeping tile over the sewer trench is perforated, dumping gallons of water at this location into the pervious layer of bedding for the sewer line, which h can find it way under the floor slab The use of a solid equal sized pipe over this section for 12 beyond the trench, with a tamped clay cap over the trench can significantly reduce the chances of perimeter drainage water being channeled under the floor slab.
21 If unchecked this trenched area exterior to the foundation can have structural implications to the building by undermining the footings via soil particle migration into the stone bedding and causing excessive settlement of the bearing elements The result could be excessive cracks in the foundation walls which extend up into the superstructure of the building such as shifting drywall joints, leaks around windows, leaks around seals of penetrations ti through h the foundation walls, and damage to exterior cladding due to shifting of building elements
22 In cases where the local soils might be sensitive to moisture (expansive soils), accumulation of excess water under the footings of the structure could cause upward movement in the superstructure due to these soil properties Controlling the flow of perimeter ground and drainage water is paramount in these situations to protect the structure from undue stressesnot accounted for in the initial design of the building and it s materials
23 Damage is not limited to the foundation
24 As much as 25% of homes (new & old) develop complications because of water pooling under the floor L l il d it diti t i t f t th t t ib t t Local soil and site conditions are two prominent factors that contribute to this problem, and a proper understanding of these factors and their relationship to the problem is all too often over looked at the building stage and may not be properly detailed to alleviate these problems
25 Improper Grading Effects Surface Water Accumulates at Foundation Saturates Fill Soils increasing lateral loads Increases the effects of Expanding Soils Creates Hydrostatic Pressure Causes Excessive Settlement of soils causing (sink holes) Causes adfreezing to foundations in cold climate areas, causing frost uplift damage Can cause undermining i (washout) under footings Increases the chances of plugging perimeter drainage tile due to hydraulic loads on soil to separate fines from local soil
26 Proper surface grading is essential for adequate control of surface water run off
27 Effects of negative drainage When the soil becomes saturated with water, a Hanging deck can create too much stress for the wall to withstand and t d it cracks
28 Rain water leaders must direct water away from the building and not on to adjacent properties Ice dams obstruct normal surface drainage Ice will also temporarily plug window well drains Could a French Drain have helped in this situation?
29 Improper location of sump pump discharges can surcharge the soils around the perimeter of the foundation Water that pools can build hydrostatic pressure and cause ice lenses to form causing lateral pressure on foundation walls
30 Moisture intrusion between the footing/wall/floor of a basement via wicking action at the footing, a sign of exterior problems with drainage and ground water control around the footing Someone tried to repair a leak with parging, when this didn t work they tried caulking and covering it with plywood.the wrong approach hto the problem?
31 Cold joints in concrete walls can be damaged by lateral pressures caused by mechanical damage from machines during backfilling, hydrostatic and ice jacking pressures Very expensive remedial work in some cases has to be put in place to structurally reinforce the foundation walls with the added costs of repairing any leaking sources in the walls after the structural repairs are completed Drainage on the outside of this wall, proper control of surface water, proper backfilling practices and controlled concrete placement together could have prevented much of the damage here
32 You think I have a problem? Proper treatment of form snap ties and other voids in concrete walls is not only Code required, it helps stop unnecessary leaks from becoming a sore spot for homeowners
33 These guys removed the window wells and filled the area with concrete. They were trying to prevent water from getting in through the basement windows.
34 And yes, these guys were professionals? y, g y p The installation of a window well, clear cover and a drain pipe to the stone layer at the drainage tile elevation would have worked here when properly installed for much less cost and much more success..
35 Solutions to Typical Foundation Leakage Issues and Long Term System Protection
36 A second sump can be installed to drain water beneath the basement floor It s even more effective with interior tile, filter fabric and washed gravel, the use of a drain solution above the slab isn t recommended In areas prone to water table issues and expansive soils it is recommended practice to install a second under slab water control system and stem don t forget the filter cloth to confine soil particles from being transported to the sump via the tile system which can cause erosion of soil under the floor slab and excessive cracking in the concrete slab
37 A crack up to ¼ inch thick can be repaired using an epoxy or urethane injection system
38 Typical Interior Foundation Crack Repair A crack up to ¼ inch thick can be repaired using an epoxy or urethane Epoxy works best when applied to a dry surface, urethane being water based will work on damp concrete Honeycombs and snap-ties can also be repaired from the interior using these same methods The use of quick set grouts over Honeycombs prior to the application of dampproof or waterproof coatings on the exterior is best during construction prior to backfill
39 The wall is pressure injected with an epoxy or urethane. This process completely fills the voids, one section at a time
40 Urethane is a alternative to using epoxy. This crack was repaired using urethane, which re- cracked. Urethane is a fill-gap measure which adds no structural strength. It should only be used in a stable structure (shrinkage cracks)
41 Honeycomb Repair Solution A waterproof membrane can be applied to the area Honeycombs, cracks and ties can also be repaired from the exterior.
42 Installation of Dimple Sheet Products Protect Foundations from Water Damage Capillary Break and Negative Side Drainage Void Dimple Sheet Dimple Sheet Capillary Break Water Pocket Basement Interior Water Pocket Foundation
43 How can Dimple Sheet Drainage Products Protect you from Water Damage Positive Side Ground Water Control Dimple SheetDrain Waterproofing Drainage Core Fabric Basement Interior Water Pocket Water Pocket Foundation
44 Conditions When You Should Consider Positive Side Drainage Hill Side Construction High Ground Water Table (with mechanical pumping system) Perched Water Table Poor Draining Soils (Clay & Silt, Sand w/high fines content) Building in Flood Plain areas (with mechanical pumping system) Building near steep up sloped lands
45 What Does all of This Information Mean to You The Builder The Homeowner? The Builder/Contractor The Homeowner Dissatisfied Customer Costly Call Backs Tainted Reputation Cost Increases in Repairs Potential for Legal Problems Operational Headaches Decreased Pleasure with New Home Difficulties Finishing off Home Decreased Equity of Home Difficulty in Resale of Home Increased Home Maintenance Potential for Increased Medical Costs The Solution Build It Right The First Time and Choose Your Repair Methods Wisely from a Technical and Cost Perspective
46 Building It Right The First Time has many Benefits, Mainly.. The Enjoyment of your Home and Protection for your Investment