infaddict Posted October 23, 2023 Share Posted October 23, 2023 Hi, I live in an 11 year old detached bungalow that has a concrete floor throughout, with all services (except drainage) going upwards into loft. We are remodelling the kitchen and my wife wants an island so investigating options for drainage from the sink on the island to an existing gully or sewer just outside the existing walls. The challenge I have is, I am unsure of exact construction method for the floor. It could be block and beam with a screen on top (if so, depth of screed is unknown) or it could be a deeper concrete slab. I have contacted the original housing company to ask for any plans or technical information they have on the floor structure, but as its 11 years ago I don't hold out much hope. Any ideas on how to confirm the structure? Could I drill a test hole and use an inspection camera to try and find out if there is a cavity under block and beam? If I do that, I will have likely broken the DPM so not sure thats a good idea (unless I come in from side of house under the DPM perhaps). If it ends up being block and beam, my guess is its a very bad idea to cut the blocks and beams in any way as it will damage the structural integrity of the floor. What other options for new drainage do I have? If its not block and beam and is a deeper slab, then that might work as I don't need much fall and its a fairly short run. As always, any comments, thoughts, tips much appreciated and thanks in advance. Link to comment Share on other sites More sharing options...
Mr Punter Posted October 23, 2023 Share Posted October 23, 2023 If it is beam and block there should be several air vents externally about DPC level. Link to comment Share on other sites More sharing options...
ETC Posted October 23, 2023 Share Posted October 23, 2023 Ask Building Control. Their inspections will show the construction of the floor. Link to comment Share on other sites More sharing options...
infaddict Posted October 23, 2023 Author Share Posted October 23, 2023 2 hours ago, Mr Punter said: If it is beam and block there should be several air vents externally about DPC level. Yep there are several air vents on all 4 external wall aspects. The DPC appears to sit on top of them. I wonder if these are ducted as they appear to be slightly above floor level. Does the presence of air vents mean its beam and block then? Link to comment Share on other sites More sharing options...
infaddict Posted October 23, 2023 Author Share Posted October 23, 2023 1 hour ago, ETC said: Ask Building Control. Their inspections will show the construction of the floor. I will ask specifically about the floor but when I previously asked building control about their inspection of sewers/drains, they said an external company/partner was used for my site and they do not have the records. I could ask them who would have the records as surely they should be kept! Link to comment Share on other sites More sharing options...
ETC Posted October 23, 2023 Share Posted October 23, 2023 17 minutes ago, infaddict said: I will ask specifically about the floor but when I previously asked building control about their inspection of sewers/drains, they said an external company/partner was used for my site and they do not have the records. I could ask them who would have the records as surely they should be kept! Yes - there should be records - even if kept by another company. Link to comment Share on other sites More sharing options...
Mr Punter Posted October 23, 2023 Share Posted October 23, 2023 33 minutes ago, infaddict said: Yep there are several air vents on all 4 external wall aspects. The DPC appears to sit on top of them. I wonder if these are ducted as they appear to be slightly above floor level. Does the presence of air vents mean its beam and block then? Yes the vents have a plastic periscope that goes below the beam and block. With beam and block you can smash out a block with no issues, but the beams need to be left intact. The beams may have intermediate support dwarf walls which could be in your way. On the upside, they should have at least 150mm space under. Is it far from the outside wall to the proposed sink waste? Link to comment Share on other sites More sharing options...
infaddict Posted October 23, 2023 Author Share Posted October 23, 2023 23 minutes ago, Mr Punter said: Yes the vents have a plastic periscope that goes below the beam and block. With beam and block you can smash out a block with no issues, but the beams need to be left intact. The beams may have intermediate support dwarf walls which could be in your way. On the upside, they should have at least 150mm space under. Is it far from the outside wall to the proposed sink waste? Interesting. So option 1 is a diagonal run of about 1.7m to a gully that is used for the current kitchen sink. Option 2 is a 4.5m straight run to an existing private sewer where I would install a new IC to take this new connection. Clearly option 2 is a much longer run, but at least it is straight. But I don't know if its straight in line with the beams or perpendicular to the beams! The final option is ditching the sink on the island and just running power (for a hob or socket to charge phones) which requires much less depth (level conduit only). The Mrs wouldn't be happy and means we'd have to find another home for the sink and redesign our proposals. I wonder if its possible to get a wired inspection camera through the air vent and around the periscope to see whats going on under there. Or I could drill a pilot hole anywhere on the kitchen floor to do the same, but risk hitting a beam and that will of course puncture the DPC which would need repairing. Am I right to say the block and beam would normally have some rigid insulation on top, then a screed of concrete? If so any usual depths for both the insulation and the screed? Thanks for all the help. Link to comment Share on other sites More sharing options...
Mr Punter Posted October 23, 2023 Share Posted October 23, 2023 Normally insulation then screed. Don't worry about a small hole in the DPM. The beam and block is not in contact with the ground. Link to comment Share on other sites More sharing options...
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