…Damage from floods,hurricanes,tornadoes and earthquakes.
http://geosurvey.state.co.us/Default.aspx?tabid=392
Few pics of basement wall damage etc, Amherst NY
http://www.lrb.usace.army.mil/AmherstSoilStudy/photos/photos.html
-Lateral pressure causing typical 45 degree stair-step crack in block basement wall. Last set of images posted of inside system you can see stair-step cracks at corner which inside dorks did NOTHING about,only installed an inside water-diverting system.
-Lateral pressure causing vertical mid-span crack in basement wall
-Lateral pressure causing top of basement wall to bow inward 9 inches
(pilasters failed to brace wall).
Needed to relieve,lessen exterior pressure by removing soil,any roots etc
Once a basement wall bowed in,cracked then it has LOST x-amount of its lateral resistance. Sometimes its lost a lil,sometimes alot.But WHY leave the CAUSE(s) against the outside dumb wall which can,could cause FURTHER damage. Installing carbon fiber straps,beams,pilasters etc does not remove exterior pressure(s),doesn`t remove cause…lordy.Block walls will have cracks on the OUTSIDE,why leave them open?
‘Buck’ in Alabamie gets alot of this stuff
http://house-inspector.com/BulgedBasementFoundationWalls.html
…‘basement walls are laterally supported along top and bottom edges’
And so many of these Inside Co`s/systems will REMOVE part, the edge of the basement floor to install silly system and then many will leave a GAP,a space between wall and floor where before they came in and played around the floor WAS up against the basement wall.
…'the backfill of choice is sand or gravel.Unfortunately,most builders backfill w/original soil that was excavated…generally silty clay or clay.
This article pretty good too
http://www.servicemagic.com/rfs/smpros/printArticle.jsp?edOID=13696
…'builders in some parts of country are installing drains on the interior of footings under the basement floor,instead of outside…even though that violates code in most localities…
-Basement Wall Damage, Cause and Resolution
http://www.fairfaxcounty.gov/DPWES/publications/marineclay.htm
-Why Foundations Fail
http://www.bobvila.com/HowTo_Library/Why_Foundations_Fail-Foundation-A2095.html
http://theconinconstruction.com/land.html
…‘it is standard practice by many builders to DENY there are expansive soil problems w/their new construction.They will repeatedly PATCH the cracks in walls…treating the symptoms and not the cause of the problem…builder knows exactly what problem is’… Not so sure most builders actually do,got milk?
‘Today, damage from expansive soils is more costly than damage caused by earthquakes,floods,tornadoes and hurricanes combined’.
U S Army Corps Engineers Soil Study
http://www.lrb.usace.army.mil/AmherstSoilStudy/reports/Amherst-2005-01.pdf
3.1 Overview
…suggests foundation movement may result from a wide range of factors,which can include
- compression of a soft layer in the ground as a result of the applied foundation or perimeter loads
- shrinkage and swelling of clays caused by changes in moisture content
- soil softening
- compression of filled ground
- frost heave
- variations in groundwater level
- erosion
8 nearby construction or excavation - chemical attack on foundation
10)collapse of mine workings or natural cavities
11)vibration
3.2 Lateral Wall Pressure
Four sources likely contributed to lateral wall pressures on basement walls in Amherst
- pressure from soil weight
- pressure from soil swell
- hydrostatic pressure
- pressure from frost
3.4.5 Backfill
…lateral pressure problems are exasperated by using unsuitable backfill material,usually from on-site excavation…all backfill soil analyzed in this study are classified as being expansive which is generally NOT recommended for backfill material.
3.4.11.1 Modeling Results
…the modeling results demonstrate that 1) granular backfills can REDUCE lateral pressures…
http://www.army.mil/USAPA/eng/DR_pubs/dr_a/pdf/tm5_818_7.pdf
-Foundations in Expansive Soils
Occurrance of Damages
‘damages can occur within a few months following construction,may develop slowly over a period of about 5 years or may not appear for many years until some activity occurs to disturb the soil moisture…’
http://dwightyoderbuilders.com/concrete.cfm …6th paragraph
CDC, Foundation
http://www.cdc.gov/nceh/publications/books/housing/cha06.htm#Foundation