Hi. I wonder if anyone could shed any light on this. We have a first floor bathroom. Everytime we drain the bath, the bathroom sink (which is about 4 feet from the bath) gurgles and quite often, the bathroom fills up with the smell of sewer gases. The bath, sink and toilet are draining fine. Dynorod have been out and say that there don't seem to be any blockages in the soil pipe. I have Googled it and it looks like our vent pipe may be blocked? It is a new house (six years old) and the vent pipe ends in the roof space and there is a grill at the top of the roof where the gases escape/air comes into the pipe. British Gas sent out one of their plumbers yesterday. He reckoned that he unscrewed the vent in the loft and looked in it and couldn't see an obstruction. He is going to come back with something to fit to the pipework on the bathroom sink to stop gases coming into the bathroom. My question is, could the grill on the roof be obstructed with spider webs maybe reducing ventilation in the vent pipe? The plumber said there was no obstruction, but I don't believe that he actually physically examined it as he didn't get into the roof space (stayed on his ladder throughout). Any advice would be welcome. Thanks.