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We have cellars under our house, as do the rest of the houses in the road.
Ours is "unconverted" and used as workshop/bike store/utility room.
Next door's was converted into living space a couple of years back by the previous owners - dug down to increase headroom, then supposedly fully tanked, fitted with pumps etc.
Every time we get a proper full on storm like we had last night - their cellar now floods causing great damage and a big insurance bill (its happened 4, maybe 5 times). We've had the odd trickle come in before but nothing that couldn't be sorted with a mop. (this has only occurred since next door had the cellar done)
Last night we realised we had a solid 2" of water all over the cellar floor. It appeared to be coming in through the shared wall (as we bailed the place out, you could see the flow emanating from that direction. I rang next door to ask if they'd checked their basement - they hadn't - and were somewhat shocked to find the best part of a foot of water in it.
Once we'd bailed our side out, which took a couple of hours, I went round to give them a hand (they're not the most practical types). What seems to happen is that the water builds up between their original cellar walls and the new, tanked, "room within a room" until there's sufficient pressure for it to permeate through to us, plus exploit any weakness in the construction of their inner walls. Their pumps were working - simply couldn't cope with the volume of water.
(It's difficult to see how the water is getting into their cellar as its all nicely decorated in there - but its coming in to the living spaces through the original floor level power sockets - which have been blanked off and the sockets moved further up the wall. I suspect the root cause is that their front yard slopes towards the house - ours goes away from it)
Now we haven't had any substantial damage caused (my collection of MDF offcuts is probably ruined), so I'm not looking for any financial recompense, but it was a complete PITA, and given the increasing regularity of "once in a lifetime" weather events, its only going to get worse - so do we have any way of forcing next door to get their act together and stop flooding us?
I suspect it might be difficult to prove that the water ingress into your cellar is directly caused by the modifications to theirs. At the very least you'd probably need to fork out for a professional survey which would probably need access to their cellar as well as yours. They might be reluctant to grant access if they suspect your motives are to 'force' them to make what will likely be very expensive changes.
Can't they get back on to the builders who did the work to their cellar? Or was it DIY?
I can't see how you can blame them.
The water would be there whether their cellar was tanked or not (obvs it's not tanked very well if they're getting water into it).
They dug deeper to make the headroom, but doing so has put their floor closer to the water table than you.
It simply sounds like last night the water table was high enough to affect your cellar as well.
I agree its difficult to "prove" conclusively. But it didn't happen before the cellar conversion, does happen after it.
Its not a water table thing, as it only happens when there's flash flood storms, not over winter when the water table is high. Pretty sure its the runoff from their front yard draining to the lowest point, which happens to be the cellar
The first time this happened, their newly installed lightwell turned into a swimming pool in minutes (not helped by faulty guttering dumping water straight into it, as is still the case) and the water then pushed the glass of the double glazed window loose. There's now a pump in that, but its still obviously getting in somewhere in quantity.
I don't think it helps that I'm pretty sure the drains are above the new floor level of their cellar - not by much, but pumping uphill is never good. Again, I recall their being grief with some non-return valves.
When we converted our cellar in Sheffield, we upgraded the pump and pipe. The pump that was first installed was just very weak, and the builders also pointed the (small) outflow into the shared ginnel and had dug a gravel French drain under the tanking - again towards ginnel and neighbour downhill from us.
We moved the outflow to the front garden, where the downspout was and I insisted that they change basically garden hose for the 30mm black water main type pipe.
I added a much bigger pump after one winter, and added an override switch - the floating bilge switch was not that reliable.
you may need to demonstrate the water level in their cellar was higher than your basement to justify them as teh cause. This may be popping out in a storm to take a few photos.
It sounds like they need to sort their surface drainage which, while not being cheap, is not that challenging really. they could get a bigger pump and sort the guttering etc for instance. If there is a problem with capacitgy in the sewer in the road then this may be a much bigger issue. however this would probably have been apparent before they built their cellar. although the intensity of storms has got greater in recent years
Id be surprised, if its happened 4 -5 times in a year, that they are insured for it. When my roof was damaged and replaced on insurance they put a 'we wont pay for a replacement for x years' caveat on the payout.
It sounds like they need to sort their surface drainage which, while not being cheap, is not that challenging really. they could get a bigger pump and sort the guttering etc for instance
Yes, absolutely - the problem is that the current and last 2 owners haven't done anything bar cosmetic work. We've been in 11 years now - the first owner was a little old lady who sold up as the house was too big and did absolutely no maintenance. Then there was a 5 person family who had the interior redecorated and converted the cellar, but did nothing about the knackered roof, the lack of insulation, the gutters or the drainage. They left when the parents split up. Current resident is a single middle aged lady who lives alone during the week but has mates over for parties at the weekends (which is a whole other story! My assistance with their clean up was partly political). Neither of the last 2 have been in any way handy or understanding that 100 year old houses don't just work, they need constant looking after.
If there is a problem with capacity in the sewer in the road then this may be a much bigger issue. however this would probably have been apparent before they built their cellar. although the intensity of storms has got greater in recent years
Well the road name includes the word "spring". We're most of the way towards the bottom of a dirty great big hill and the neighbours the other side, who've been there decades say the manhole covers used to blow out in storms, before the sewer was upgraded (maybe 15 years ago?). Last night you could have comfortably kayaked down the street, and this morning some road closed signs have popped up, as the tarmac has lifted in several places. There was a LOT of water. However I could see that our yard was draining into the street quite nicely.
Id be surprised, if its happened 4 -5 times in a year, that they are insured for it.
Its happened 4-5 times in the last 4-5 years. The giveaway is a storm, followed by a skip in the front yard full of laminate flooring and waterstained soft furnishings. Its entirely possible they haven't claimed for the last couple. New resident has only been in a year or so. Apparently she asked the previous one if the cellar flooded when she was buying and was told "no". At which I laughed...
Maybe their cellar had a concrete floor that was dug out that prevented the water ingress ?
We had a terrace house in Sheffield. The prior owners to us had said it had flooded once or twice previously.
It appeared to be coming more frequent than that in our time that we owned the property. This was a house on a row of terraces running top to bottom down the fall line of the hill. Both neighbours had zero water !
Flash flooding has definitely increased in the last few years it could just be this ie an increase in occurrence of water not being absorbed in to the water table
Indeed, I suspect the original floor next door just about kept the water out. Digging that out and a what seems to be a poor tanking job has made their and your situation worse. If water can now flow out of the natural strata under the tanking, flow up the sides and penetrate the party wall. Insurance and legal wrangling is likely on the cards.
if there was that much water on teh street and under teh road to lift tarmac i`m not surprised it flooded.
the spring name thing is also a classic tell for groundwater problems.
if the basement isnt a waterproof box (and is lined internally) then water will use the path of least resistance to collect. usually through the wall. NHBC have a traffic light system for waterproofing of basement depending on the end use. sounds like the previous guys may have done a cheap and cheerful job which is now showing the issues.
if the water is collecting and backing up in the wall void then a bigger pump will defo help. especially if their yard drains towards the road. the aim for them will be to reduce the volume of surface runoff draining towards the basement where feasible.
You could drill some holes in your basement floor to let the water drain out quicker.
You could also replace the concrete with gravel if it's just used for bike storage.
Better outside drainage seems to be the priority though.
Does sound like the sh1t tanking and lowering of their basement has caused the water to be forced through the gaps in your basement wall as well as their tanking. Before they lowered their basement I imagine that the water levels were below the old level/your current level and hence no problem. Now there is less tolerance so it gets forced up and through your wall quicker.
You could drill some holes in your basement floor to let the water drain out quicker.
Drill the holes through the wall to let the water back into their cellar 😉
If it's a major problem for you I'd be looking at tanking my own basement. Doesn't sound like you'll get any joy from your neighbours and going legal will cost more than any building works.
Why not fit a submarine door to your cellar and increase the pressure in your side. Thus keeping the water out. Problem solved. You may need to decompress after doing bike maintenance but I’m sure you could keep yourself busy down there.
if the basement isnt a waterproof box (and is lined internally) then water will use the path of least resistance to collect. usually through the wall. NHBC have a traffic light system for waterproofing of basement depending on the end use. sounds like the previous guys may have done a cheap and cheerful job which is now showing the issues.
This is pretty much what it is. I've just had a scan through the NHBC thing, and I guess whoever did the calcs on the water volumes didn't do their research on the flash flooding potential of the area. It wasn't a "cheap" job, and I don't recall them having people monitoring events at all, let alone the length of time suggested by the doc. It was more "it'll be fine because technology" (where have I heard THAT before...?)
if the water is collecting and backing up in the wall void then a bigger pump will defo help. especially if their yard drains towards the road. the aim for them will be to reduce the volume of surface runoff draining towards the basement where feasible.
Ours slopes away from the house. Neighbours (both sides) towards it. I agree reducing the run off would be the best solution though!
If it’s a major problem for you I’d be looking at tanking my own basement
That's not gonna happen. I'm pretty much of the opinion that the guys who built these places 100 years ago knew what they were doing, and f***ing around with them is the best way to cause problems, especially when it mostly doesn't work (not that we have the cash either). Cellar conversions have been a popular thing up and down the street, so I'm going to be interested to see how many skips appear in the next few days. Next door the other side (detatched from us) also flooded. Again, supposedly tanked with a pump, but overwhelmed. They just use it as utility/storage though, so like us, bar the annoyance no real damage done. Current plan is just to jack everything on the floor up another couple of inches...