inputFolder = "/home/usr/Desktop/BufferFolder/"
outputFolder = "/home/usr/Desktop//BufferFolder/Addition"
template = gdal.Open("/home/usr/Desktop//BufferFolder/Template.tif")
rows = template.RasterYSize
cols = template.RasterXSize
if template is None:
print 'Unable to open template file'
    sys.exit(1)
templateArray = np.array(template.GetRasterBand(1).ReadAsArray())
mainArray = 0 * templateArray

os.chdir(inputFolder)

def findRasters(path, filter):
    for root, dirs, files in os.walk(path, filter):
        for file in fnmatch.filter(files, filter):
            yield os.path.join(root, file)

count = 0
for raster in findRasters(inputFolder, '*.tif'):
    (infilepath, infilename) = os.path.split(raster)
    openraster = gdal.Open(infilename)
    rasterToArray = np.array(openraster.GetRasterBand(1).ReadAsArray())
    mainArray = mainArray + rasterToArray
    count = count + 1