Due to building an extension on the back of our house the garden floodlighting is being revised. I need to fit a light to illuminate a small are in front of the shed, and the most convenient place to fix to would be the UPVC soffit board as most of the wall is taken up by the study window. My question is, is it OK to do this or are they not strong enough? If I need to use inserts of some sort I will as I wouldn't be daft enough to just mash in a couple of 11/4 No.8's and expect that to do the job.