| 9.14.4. |
Granular Drainage Layer |
| 9.14.4.1. |
Type of Granular Material
- Granular material used to drain the bottom of a foundation shall consist of a continuous layer of crushed stone or other coarse clean granular material containing
- not more than 10% of material that will pass a 4 mm sieve, and
- no pyritic material in a concentration that will damage the building to a degree that would adversely affect its stability or the performance of assemblies (see Note A-9.4.4.4.(1)).
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| 9.14.4.2. |
Installation
- Granular material described in Article 9.14.4.1. shall be laid on undisturbed or compacted soil to a minimum depth of not less than 125 mm beneath the footing of the building and extend not less than 300 mm beyond the outside edge of the footings.
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| 9.14.4.3. |
Grading
- The bottom of an excavation drained by a granular layer shall be graded so that the entire area described in Article 9.14.4.2. is drained to a sump conforming to Article 9.14.5.2.
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| 9.14.4.4. |
Wet Site Conditions
- Where because of wet site conditions soil becomes mixed with the granular drainage material, sufficient additional granular material shall be provided so that the top 125 mm are kept free of soil.
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