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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Repairing internal concrete floor membrane
Hi,
sorry - it's another hypothetical question ;- "The Bungalow Project", we've evolved the new plan so that it works much better WRT to where new rooms will be and also WRT to logistics of doing the job. The gotcha compromise is that one of the two bathrooms (well, the other is a bog and shower) has ended up landlocked behind a bedroom[1]. I'd have a toilet 1.2m away from the external wall. So I need to bury a 110mm pipe under the floor and out through the wall. No general problem with any of this, simple straight run under a doorway, the drains outside are fairly deep and no issues with fall. Assuming that the wall footings are deep enough (out of the way, to be determined by digging hold outside) I have one problem to solve: How do I repair the floor membrane after I've cut a trench about 300mm by 1.2m? He http://www.diydoctor.org.uk/projects...roundfloor.htm suggests I need to pour a load of "Structural Epoxy Pouring Grout" in, covering 150mm of the existing membrane on all sides of the cut and backfill with concrete then screed. Assuming I'd need at least 50mm of the epoxy, that's an absolute minimum of 16 litres which is coming in to 240 quit+VAT. I'm aware that diydoctor are trying to sell their goods, so the question is: Are there other acceptable ways to repair the membrane? I would have thought that, after dropping concrete around the pipe level with the existing membrane, that laying new membrane well overlapping the old, taping and pouring more concrete would have been sufficient. But I have no practical experience of DPCs... Thanks for your thoughts Cheers Tim [1] Bathroom being landlocked allows the bedrooms to have proper windows. Previous plans have severely reduced window area in one bedroom. I can live with electric lighting and forced ventilation in one of two bathrooms, but making a bedroom dark will be much worse. |
#2
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Repairing internal concrete floor membrane
Tim S wrote:
Hi, sorry - it's another hypothetical question ;- "The Bungalow Project", we've evolved the new plan so that it works much better WRT to where new rooms will be and also WRT to logistics of doing the job. The gotcha compromise is that one of the two bathrooms (well, the other is a bog and shower) has ended up landlocked behind a bedroom[1]. I'd have a toilet 1.2m away from the external wall. So I need to bury a 110mm pipe under the floor and out through the wall. No general problem with any of this, simple straight run under a doorway, the drains outside are fairly deep and no issues with fall. Assuming that the wall footings are deep enough (out of the way, to be determined by digging hold outside) I have one problem to solve: How do I repair the floor membrane after I've cut a trench about 300mm by 1.2m? He http://www.diydoctor.org.uk/projects...roundfloor.htm suggests I need to pour a load of "Structural Epoxy Pouring Grout" in, covering 150mm of the existing membrane on all sides of the cut and backfill with concrete then screed. Assuming I'd need at least 50mm of the epoxy, that's an absolute minimum of 16 litres which is coming in to 240 quit+VAT. I'm aware that diydoctor are trying to sell their goods, so the question is: Are there other acceptable ways to repair the membrane? I would have thought that, after dropping concrete around the pipe level with the existing membrane, that laying new membrane well overlapping the old, taping and pouring more concrete would have been sufficient. But I have no practical experience of DPCs... Thanks for your thoughts Cheers Tim [1] Bathroom being landlocked allows the bedrooms to have proper windows. Previous plans have severely reduced window area in one bedroom. I can live with electric lighting and forced ventilation in one of two bathrooms, but making a bedroom dark will be much worse. You could get away with not digging any floors up if you used a saniflo. Also, how do you know the existing floor has a membrane already in it? - they were only used from the late seventies onwards......saying that, I wouldn't worry too much about it, they are never completely sealed anyway and are often ripped and punctured several times during the concrete pour - 17st blokes wearing concrete encrusted wellies and pushing 5cwt barrows of concrete aren't very gentle WRT visqueen - it doesn't really matter, so long as you backfill and pack down as tightly as possible, then /try/ to get as much of the ground covered as possible prior to re-concreting -- Phil L RSRL Tipster Of The Year 2008 |
#3
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Repairing internal concrete floor membrane
Phil L coughed up some electrons that declared:
You could get away with not digging any floors up if you used a saniflo. Hi Phil, Valid suggestion, but after reading this group for n-years, I think I'd rather **** in a teacup than use a saniflo ;- Also, how do you know the existing floor has a membrane already in it? - This is of course a very good point. Planning for the worst... they were only used from the late seventies onwards...... 1950's here. That is interesting. No membrane would make the job a no brainer. saying that, I wouldn't worry too much about it, they are never completely sealed anyway and are often ripped and punctured several times during the concrete pour - 17st blokes wearing concrete encrusted wellies and pushing 5cwt barrows of concrete aren't very gentle WRT visqueen - it doesn't really matter, so long as you backfill and pack down as tightly as possible, then /try/ to get as much of the ground covered as possible prior to re-concreting OK - seems reasonable. I knew they're not 100% watertight anyway, but I was talking to a welsh builder on my electrics course yesterday about it and he spooked me a bit. Just one of those things I am utterly clueless about (hence no common sense). Cheers, Tim |
#4
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Repairing internal concrete floor membrane
"Tim S" wrote in message ... Phil L coughed up some electrons that declared: saying that, I wouldn't worry too much about it, they are never completely sealed anyway and are often ripped and punctured several times during the concrete pour - 17st blokes wearing concrete encrusted wellies and pushing 5cwt barrows of concrete aren't very gentle WRT visqueen - it doesn't really matter, so long as you backfill and pack down as tightly as possible, then /try/ to get as much of the ground covered as possible prior to re-concreting OK - seems reasonable. I knew they're not 100% watertight anyway, but I was talking to a welsh builder on my electrics course yesterday about it and he spooked me a bit. Just one of those things I am utterly clueless about (hence no common sense). Not sure about 1950's, but our 1970's bungalow has a painted on bitumastic layer between the floor slab and the screed, which appears (from recent removal of internal walls) to be both intact and effective - screed appears totally dry everywhere I've been so far. If you do have a membrane of some sort between slab and screed you could consider dropping your new 110mm pipe to below slab level, concreting it in to match, and painting a bitumastic layer over the top. You may have to cut back your existing screed either side to produce a good overlap with whatever is there at present. Finally, new screed over the whole lot. Success is likely to depend on your ground water levels and general dampness as much as anything else - we have well draining soil and a steep bank to one side of the house, which helps! Best of luck with all this. Charles F |
#5
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Repairing internal concrete floor membrane
On 8 Sep, 13:24, Tim S wrote:
Hi, sorry - it's another hypothetical question ;- "The Bungalow Project", we've evolved the new plan so that it works much better WRT to where new rooms will be and also WRT to logistics of doing the job. The gotcha compromise is that one of the two bathrooms (well, the other is a bog and shower) has ended up landlocked behind a bedroom[1]. I'd have a toilet 1.2m away from the external wall. So I need to bury a 110mm pipe under the floor and out through the wall. No general problem with any of this, simple straight run under a doorway, the drains outside are fairly deep and no issues with fall. Assuming that the wall footings are deep enough (out of the way, to be determined by digging hold outside) I have one problem to solve: How do I repair the floor membrane after I've cut a trench about 300mm by 1.2m? Sorry if it's a stupid/granny sucking eggs question, but there's no way of taking the waste out through the bedroom and hiding it under a built-in wardrobe or something? |
#6
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Repairing internal concrete floor membrane
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#7
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Repairing internal concrete floor membrane
Hi,
NO*SPAM coughed up some electrons that declared: Not sure about 1950's, but our 1970's bungalow has a painted on bitumastic layer between the floor slab and the screed, which appears (from recent removal of internal walls) to be both intact and effective - screed appears totally dry everywhere I've been so far. If you do have a membrane of some sort between slab and screed you could consider dropping your new 110mm pipe to below slab level, I was thinking to do something that, partly for the pipe's own good and partly if I;m going to break the dpc, I need to keep the pipe clear of it in order to have a decent chance of making it good (obviously excepting where the pipe comes out of the floor). concreting it in to match, and painting a bitumastic layer over the top. The info on bitumastic is ery interesting. I've used gunky bitumastic paint in the 70's so I know what you mean. You may have to cut back your existing screed either side to produce a good overlap with whatever is there at present. Finally, new screed over the whole lot. I think careful excavation of the first layer of screen is called for. Thanks for the tip - I hadn't considered the possibility that the dpc might be betwen the screen and slab, I was assuming it would always be under the slab. Success is likely to depend on your ground water levels and general dampness as much as anything else - we have well draining soil and a steep bank to one side of the house, which helps! Should be OK. The house is on a diagonal slope, so it's high on one side and low on the other. Might be water running past during rain but it should generally drain away. We're on clay, but there seems to be a reasonable depth of topsoil. Best of luck with all this. Charles F Thanks Cheers Tim |
#8
Posted to uk.d-i-y
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Repairing internal concrete floor membrane
Tim S wrote:
sorry - it's another hypothetical question ;- How do I repair the floor membrane after I've cut a trench about 300mm by 1.2m? Well two things spring to mind (if one ignores the possibility there is no DPM there in the first place!). Usually when using sheet material DPM, the joins are simply overlapped by 350mm or so. Perhaps taped if the builder was feeling posh at the time. The other option is a painted on DPM - there are plenty of products to chose from here. Either approach would seem to solve your problem. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
#9
Posted to uk.d-i-y
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Repairing internal concrete floor membrane
John Rumm coughed up some electrons that declared:
Tim S wrote: sorry - it's another hypothetical question ;- How do I repair the floor membrane after I've cut a trench about 300mm by 1.2m? Well two things spring to mind (if one ignores the possibility there is no DPM there in the first place!). Usually when using sheet material DPM, the joins are simply overlapped by 350mm or so. Perhaps taped if the builder was feeling posh at the time. The other option is a painted on DPM - there are plenty of products to chose from here. Either approach would seem to solve your problem. Thanks John. The job sounds perfectly feasible now Cheers Tim |
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