HomeMy WebLinkAbout03603 FLOOR SYSTEM AND SLABS -ON -GRADE
If a basement is constructed the floor would likely be a slab -on- grade. We
judge potential risk of differential movement and associated damage will be low to
moderate for slab -on -grade construction supported by the clay at this site.
Performance of a slab -on -grade basement floor will be enhanced if wetting of the
subsoils is prevented.
The most positive method to mitigate floor movement is the construction of
a structural floor with an air space between the floor and the subgrade soils. The
structural floor is supported by the foundation system and an excellent choice from
a geotechnical viewpoint. Structurally supported floors result in increased
construction costs as compared to slab -on -grade floors.
We recommend the following precautions for slab -on -grade construction at
this site. These precautions will not prevent movement from occurring, they tend to
reduce damage when slab movement occurs.
1. Slabs should be constructed directly on the native clay. Provision of
a sand or gravel layer below the slabs is not recommended because
it increases the possibility of a single source of water wetting the
entire area supporting the slab.
2. Slabs should be separated from exterior walls and interior bearing
members with slip joints which allow free vertical movement of the
slabs.
3. Use of slab bearing partitions should be minimized. Where such
partitions are necessary, a float allowing at least 2 inches of free
vertical slab movement should be used. Doorways and staircases
should be designed to allow vertical movement of slabs. To limit
damage in the event of slab movement, sheetrock should not extend
to the floor.
CHARLOTTE STUART
PARCEL 6, MOUNTAIN SPRINGS RANCH 6
CTLIT JOB NO. GS -3434
-"—
Scale: 1"= 40'
•
7
•
TH -1
•
,
109
;Ion
OF EXPLORATORY BORINGS
Fig. 2