Tag Archives: foundation

Soil Testing When test/water damage

When should you call un a soils engineer ?

Many builders and architects are reluctant to hire engineers perform subsurface investigations, and that’s easy to understand : The cost of a house can go up few thousand dollars . Despite the cost, there are circumstances which consulting soil engineer is a wise investment.

If you wondering how earth you are supposed to build a house on a lot with a steep slope, then you need an engineer to determine the soil properties and to evaluate the stability of the incline.

A local history of the presence of the clay soils that are susceptible to shrinking and swelling with changes in moisture content also requires careful investigation and usually , specialized deign services and the use of an out of the ordinary foundation.

Consult your experience . If you are crossing your fingers and hoping the soil conditions would not cause a problem ,you are probably , right to be uneasy . Call in the specialist

Just like concrete in you basement slab. Failure to compact is what leads to cracking sidewalk uneven slabs.

It is particular important that fill be placed in thin layers so that the densification effect of the compaction equipment is it felt the all the way to the bottom each layer. The maximum thickness for each layer depends on soil type : Ordinarily about 12 inches for sandNS 6 inch to 8 inch for clay. The required degree denisification usually set forth by the local building code and specified as some percentage of maximum dry density as determined by one of several standard methods.

The moisture content of the fill material must also be controlled . If the moisture is too low , it is difficult for individual soil grains to realign themselves into the densest configuration ; adding moisture lubricates the grins and make realignment easier . But if there is too much moisture , the soil becomes unstable under the influence of compaction effort will be the water between the soil grins and result in a water bed like rolling the soil . Granular soils such as sand are most desirable for use as fill because their moisture content can be easily tweaked.

TO prevent settlement problems, soil that is stable and compacted must extend at least half the distance from the base of the footing to the influence depth ( the farthest distance beneath the footing that its weight is felt by soil particles.) Strip foundations ( such as the wall in the drawing below right ) as the pedestal the drawing and thus have greater influence depths.

Stable compacted fill extends half the influence depth. Only soil grains inside this stress bulb feel the weight of the foundation. The formula applied when the length of the foundation is 10 or more times greater than its width.

Stable compacted fill extends half the influence depth , Influence depth is (ID)=4xB

Details for drying Foundation

As a research architect at the Building Research Council of the University of Illinois, I am paid to solve some of the more nagging problems that houses have . Frequently , I visit troubled houses, troubled houses, and the most common problem I encounter is poor drainage away from the foundation .This problem became worse as wetlands were developed ; I know what to expect when the name of the developed : I know what to expect when the name of the development is Frog Hollow .

I was once asked yo looked at a house that had settling problems . An addition , built over a crawl space was moving down the relative to the main house. the dirt floor of the crawl space was even with the bottom of the footing. The soil along the of the footing . The soil along the edge along the edge of the footing was in small clumps, unlike the grainy fruity surface of the rest of the floor . I dug away a little more and found drain and found save that reminded me of a prison escape tunnel . In all, 10 ft. of the footing was under minded.

I call my studies of the zone where the house meets the ground building periodontics. Proper preventative care of this area can avoid a variety of problems, some less obvious and a lot more serious than a damp cellar.

For example , a common problem in basements particular those with block walls, is inward buckling . This usually shows up as a horizontal crack one or two blocks below grade , or at window walls , stepping up or down at the corners . A study I did with Illinois State Geological Survey revealed the cause . Clay soils shrink during spells forming a crevice between the soil and the foundation wall. Wind and light rains carry dirt into this crevice . Then, when seasonal rains come, the soils swells back to original dimension, plus the increment of added soil . Over time , the walls watched inward and eventually buckles. You avoid this problem by keeping the soil next to the foundation dry.

Slabs suffer from water problems , too. Garage floors, for example , commonly crack at the outside corners near where gutters drain. This cracking may be due to upward expansion of water directly below the corner. It can also be due to adhesion lifting of the perimeter wall, a situation occurring when saturated soil freezes fast to the foundation wall . The soil nearest the surface is the first freeze , and as the cold water continues , deeper soil freezes. This saturated soil by 8 percent as it freezes, exerting a tremendous force that lifts the soil frozen to the wall above. The wall lifts and cracks the slab .

Moisture damage around the foundations is not limited to masonry problems . In 1947 , Ralph Briton , the government researcher whose work led to current attic ventilation standards , showed that water vapor traveling upward from damp foundations caused moist attic moisture problems . He colluded that if attics are isolated from wet foundations, the standard 1:300 venting ratio could be reduced to 1:3000 .