Full grids that include gutters have 14 columns, as the 2 outside gutters are included as columns.
<LatticeGrid innerGrid={true} fullWidth={true} fullGrid={true} useGutters={true} className={"grid-demo grid-demo--full-grid-gutter"} slug={"full-grid-gutter"}>
<span>1</span>
<span>2</span>
<span>3</span>
<span>4</span>
<span>5</span>
<span>6</span>
<span>7</span>
<span>8</span>
<span>9</span>
<span>10</span>
<span>11</span>
<span>12</span>
<span>13</span>
<span>14</span>
</LatticeGrid>