I used Dublinwaste.ie a couple of years ago when I was in the same position as you, but it has now been closed down and replaced by . My experience was great, I saved a good bit of money on waste disposal and I got rid of a back door and window to a man who was building a shed, a sink-drainer unit to a woman who was turning her garage into a utility room and a full bathroom suite to a man who presumably was putting in or replacing a bathroom. The people volunteered what they wanted the items for and it was actually very nice to know that the items were going on to new, useful lives.
I would highly recommend it. The only thing I would say is do put in good photographs and also put in all the dimensions (height, width and depth, not just one measurement) of each item. Also put each item up separately as it will maximise your chances of coming up in searches of the site. My stuff went very quickly with this kind of ad but I could see similar stuff that was badly described and or not pictured and was languishing on the site for weeks.