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cellar tanking - is the 'cheap' option worth doing or not?

(7 Posts)
beaglesaresweet Tue 19-May-15 23:24:00

Sorry in advance for the long boring post. Had a thread here few weeks ago about some water/mud in the corner of the cellar. PJ (as well as a builder who had a look without testing) said it's likely to be damage in drainage pipe as the rain water pipe runs near that corner into clay pipe underground.

Well, the original builder didsn't want to do the job as too small for his company, so now (after quite a few no-shows and canellations - argh!) I had semi-retired small builders have a look. They've dug outside and found that there's no damage in rain pipe connection or the clay pipe. Then one of hen had another look in the cellar and said hat now he's sure it's just the ground water table issue, it's risen. I asked why didn't he see it before the digging (what a waste) he said it's usually that issue. Anyway now he says that the only way to deal with it is tank the cellar.

I know it's hugely expensive (3K) and I can't afford it, so I asked whether there is any other way, and he said yes, plastic instead of resin layer and then concrete on top going up a little up the wall but not much.

I need to ask here, how much normally this kind of fhting costs? he quoted but I need to check, as it's hell to get any other builders in or find a good one ho's not busy. Second question how reliable or effective it is. He says very reliable but will last 15 yrs as opposed to 30+ with proper tanking. But where would the water inderneath go? would it not seep into walls around that lowish border?
I'm in a semi and neighbou has got a humidifier there permanently. I assume it's much more expensive to buy that and then run it all the time. Or not? I want to do something but without a layout of still a lot of monmey and then discovering after few months that it's not good enpugh and paying yet more!
I also don't understand why the water table has risen within the last two month yet was ok for the years before. Could he be possibly not right or truthful and it's not to do with it? We are on a hil btw, I thought it won't be an issue and surveyor didn't notice anything bad though the cellar felt a bit damp always. But mud and water is new (in one corner). They did major pipe change work in the area recently (partly on our road but not right in front) - but I think it's started a little before that.

I am tempted to dp the cheap option anyway, so very interested if others have done it and what was the cost? thanks!

beaglesaresweet Tue 19-May-15 23:24:46

by PJ I meant PigletJohn of course!

beaglesaresweet Tue 19-May-15 23:30:12

sorry for endless typos! builders have taken it out of me today with going round in circles discussing this!

PigletJohn Wed 20-May-15 14:44:16

I don't know why the water table might have suddenly changed and why it would affect one corner in particular. Did it happen after a period of heavy rain, or building/paving work uphill?

Are you sure it isn't a watermain? Have you got a water meter? If you actually find pools of water, the water co can test it for chlorine content to see if it is tapwater.

If the water table has risen, then a pit would fill up with water (though it might need to be quite deep). Did water seep into the hole round the drain?

Cheapest option will be to greatly increase ventilation of the cellar so it dries out faster than it gets wet.

Sorry to hear it was not broken drains as we thought.

I do not favour pumping out under the cellar floor as this will pump out the mud/wet soil leaving a cavity.

beaglesaresweet Wed 20-May-15 20:42:07

Thanks, PJ. There were paving works and major street pipe changes in the area as I mentioned, not right in front of house but along the road /(next block) and the main road which our srteet leads to. That's what the builder was saying affected it- but I think the problem started a little earlier and maybe it's just made it worse?
It seems to be worse after rain, but even when not raining for few weeks, there was still mud and wet. These are not pools of water on their own, more like mud with some water around.
So if not the machine, how else can I greatly increase ventilation? there is an air brick, it's not a huge cellar, another builder who had a look (but too important to do the job) said that ventilation is ok, and that another brick wouldn't hugely change things. The cellar is divided in two 'rooms, the larger one on the upper side of the hill (we are sideways on a hill) is where the corner is wet, whereas the smaller room the other end is dry and always felt much drier. So again, can this be the case if it's water table?

PigletJohn Thu 21-May-15 00:04:04

it might be interesting to dig a trench on the wet side of the house, to see if there is any source of water that you can find and deal with. It is possible to lay a french drain to lead water around the house, but it would take rather a lot of digging.

I would be reluctant to try to make the cellar dry by treating the walls and floor, unless you were going to do a through job, which would probably involve digging out the floor, to lay a new, deeper, insulated floor with a false inside wall and a drained cavity taking any water downhill via a gutter round edges of the floor. I fear that a less thorough job would not cure the problem so would be money wasted. Modern approach to cellars is to accept that water will find its way in, and to remove it, rather than to try to make the walls and floor 100% waterproof. Google "cellar drainage tiles" to look at modern systems. It is not cheap.

If you are on a hill there is a chance you can lead water away rather than having to pump it away.

If you want to ventilate a subfloor void, an airbrick every two metres, all the way round the house, is now quite common, and as you have a wet cellar, you may need even more. The idea is to have a good airflow from one side to the other with no stagnant damp air that is not blown away.

Without having found and cured the source of water I would not be confident you can cure the damp.

It sounds like you have already had local builders, who are familiar with local conditions, but have not been able to find the cause, so I don't suppose I can.

beaglesaresweet Thu 21-May-15 00:49:40

thanks, PJ, quite a lot of info for me to think about and research.

The local builder does think that he's found the cause - the raised ground water level, but you don't think it's correct, is that what you mean? I only had one builder who came up with any cause, as previous one thought it's likely tyo be drain pipe damage (as you did yourself), it's hell to find anyone trustworthy who wants to do a 'small job' or if a small builder is good they seem to be permanently busy. So I'm not sure how much can I trust this one opinion. He could be right that local digging may have caused the water rising but I don't trust his advice on the cheap tanking just because he hasn't come up with any other options (hence asking here - and he never mentioned increased vents etc) but also it sounds like he's sticking to his ground water theory without thinking of any other option. Maybe they angling for the expensive tanking job, even though the plastic cheaper option he's quoted at 800-900, but it's a lot of money for one day work even for two - and they are the oldest builders I ve met and probably not getting that many jobs. I'm not against their age at all, but I didn't like that they have domne the digging for which they've charched and then suddenly next day he was adamant that it's the ground water. I asked why did they do the digging or why haven't they looked carefully first time round - we had a row! I paid half of what they quoted for possible drain pipe repair and they were still not happy. It looks like I will need to find yet another one.

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