Thorfun

oooh....ooh...I know! you had some correctly sized walk-on glazing and @pocster came and stole it?

drive by shooting leaving bullet holes?

be careful about sizing the tank too big though as I was told by 2 separate RWH suppliers that the tank needs to overflow to get rid of 'stale' (if that's the correct word) water from at the top of the tank. if the tank is too big then it may never fill and never overflow. Rob @ rainwater harvesting did the calculations for me and suggested a 5000l tank for our roof size fitted the bill.

this is where it gets a little confusing as when the SE was designing the basement we were going for an internal type waterproofing membrane and waterproof concrete. but after I chose the groundworker to do the work their chosen basement contractor used an external tanking system and waterproof concrete so the wording on the SE drawings is slightly wrong. but there is definitely a membrane there (it's faded from red to white over time) but that will eventually be covered in 100mm PIR and then rendered anyway to add an extra layer of protection to it all. as a picture speaks a thousand words here's one that should explain it. 🙂 areas surrounded by grey are waterproof concrete (with the waterproof additive) and the areas surrounded in red have the external tanking membrane. products used were FIS Maxiprufe Plus (http://www. fisproducts .co.uk/product/maxiprufe-plus-2/) and also FIS waterproof concrete additive here's a better photo showing the membrane and lack of such in the courtyard. there's loads more info about our basement build in our blog showing the entire journey! should you wish some light reading and watching Timelapse footage and here's the entry after the basement was completed.

Cool. Will check it out. Thanks.

I thought multiple spot temperature readings was just on the Flir ONE Pro camera?

while I await a response from the SE I thought it'd be interesting to post a photo of our lovely warm (and dry!) floor in the basement taken with my new FLIR ONE Gen 3. 🙂

yep, permeable clean hardcore all around the basement to allow for free flowing of water. it was basically done to the SE drawings I'm glad I asked for the sump to be made deeper (it's 1500mm now) as the 600mm deep sump would be constantly overflowing if I hadn't and I'd be in real trouble! I've been through my old emails and the Civil engineers did originally design the sump to only take the ACO water from the courtyard. Also, originally the SE specified the land drain to be near the ground level but I asked if it would be better at the basement slab level and they said yes if the water was going to be diverted to the sump and pumped out but they originally specified at ground level so as to utilise gravity. so, tbh, this was all done at my request and I am to blame. but, I am planning on speaking to the SE to ask what ramifications could occur if I block up the 2 x 110mm pipes feeding in to the sump and just let the water gather around the basement. I will also ask if there's a potential solution out of this mess as I would love to not have to worry about the quantity of water entering in to the sump! if I can close it off as you've suggested then I will be one very happy chappy. I'll update on the outcome of those conversations.

the basement area of the house has 2 forms of waterproofing. waterproof concrete and an external membrane. the external membrane does not enclose the courtyard but the courtyard is built with waterproof concrete. I have not seen any water coming in through the courtyard walls. maybe I am over-worrying and I could easily speak to the SE about my hydrostatic pressure concerns. I do remember talking about the land drain location with them but can't remember the details so will need to go through my communication history. I could very easily get to your solution by bunging up the 110mm pipes that come in to the sump from the land drain as the sump is also made from waterproof concrete. then all the water will stay outside of the basement and courtyard. you've definitely given me something to think about here. for now my pump solution is working and I will take a step back from any plans I had for a 50mm pipe until I've investigated what you're talking about.

thanks, and I understand what you're saying. leaving the water sitting around the basement still worries me and worries me what the effect of hydrostatic pressure might be but I now get what you're talking about. I will go back through the original drawings and communications with each of the designers as I do wonder if the sump in the courtyard was only supposed to be for courtyard water but I made the decision to put the land drain in to it as I thought that is what it was for. I will definitely look in to this some more and your solution is possible and something I could definitely look in to at a later date but, tbh, I just want to get the house finished and move in! money is running out and time is moving very quickly and I feel I have other priorities, especially if I can fix this with pumps in the meantime. I very much appreciate you input on this.

is that in the same way you did when ordering walk on glazing?

fair enough but we built the basement in the summer so I'm sure it could've been done. still, this makes me feel better about only using 32mm as maybe using the 63mm would've been a real pain. even more so that me simply running 50mm PVCu pipe.

I'm just gutted I didn't do my research earlier in the whole process as if I'd known that a 50mm pipe would be required I'd have asked the groundworkers to run a 63mm MDPE pipe instead of the 32mm MDPE pipe. would've cost an extra couple of hundred pounds in material at the time and saved a LOT of faffing around now. such is life and maybe someone else in the future can learn from my mistakes by reading this thread!

according to the Zoeller website sumpsandpumps are the UK branch of Zoeller. https://www.zoellerpumps.com/press-room/contact-us/international/united-kingdom/ I'll give them a call tomorrow.

sometimes I do. keeps me sane. very good point.

ok @pocster and @Nickfromwales if I'm going to get a Zoeller or two can you please tell me how to calculate the total dynamic head when taking into consideration horizontal runs as well as vertical? because, the pumps are going to be approx 4.3m (will measure accurately in daylight) below ground level. plus it will need to go horizontal approx 3m once up out of the sump and then approx 15m horizontal to outlet to the ditch. so, from pump to ditch it is (approx) 1.4m vertical -> 3m horizontal -> 2.9m vertical -> 15m horizontal. my options from Zoeller (https://www.sumpsandpumpsdirect.co.uk/acatalog/Cellar-Sump-Pumps.html) are 5m, 5.2m, 5.5m or 10m head pumps and looking at how the rate of water discharge falls off as you get to the limit of the pump it's looking like I would need the 10m head pump.

yep. I know, I know. 😂

so, another thought on our pumps. I wonder if I swapped the pumps for a tube float type pump that starts sooner if the 32mm pipe will be enough? the current pumps start at 305mm depth of water but they do a version with a tube float that starts pumping at 170mm so, that would mean that there's less chance of the pump being able to cope as it starts pumping sooner, right? I'm still thinking of doing the 50mm pipework but I thought maybe for now if I got one of the tube float pumps and swapped out the first pump I have and then monitored it all it might be better.

I'd take it as a positive sign that the company actually care about airtightness! I know MBC specify a max 2ACH for their standard timber frame product so maybe this company has taken a leaf out of their books and is now offering it as standard. an airtight house is a good thing but it will mean that you will need MVHR which might be an expense you weren't planning on. but if you want to reduce your bills during your occupancy of the property then airtightness and MVHR are a step in the right direction.

yeah. exactly. so if I have to do that I might as well just lay the patio of a standard sand/cement mix to fall correctly. then it's solid underneath the patio and no water should get through.

I have thought about this as we have this same solution on our balcony but my concern is that the slab underneath is not level and so the water that goes through between the patio slabs will just pool under the patio. if I were to use pedestals then I'd need to get the slab to fall towards the sump first so that it and the patio all drain their surface water in to the slab. maybe there is a solution that I'm unaware of though!

we chose to build a basement, the architect just drew it for us. the basement is completely waterproof (with 2 forms of waterproofing) and no water has ever got in through the walls. building regulations required a secondary exit from the basement for fire regulations and so we chose to make that a sliding door out to a courtyard to make use of the outdoor space. these are all our decisions. no one forced us to have a basement or a courtyard. the only thing we were forced to do is have an egress. so maybe I should blame building control? I understand where you're coming from and I appreciate you're trying to find someone to blame for our flood but I am to blame. I only had a single pump with no backup or alarm. I didn't hire a professional to design and install a pump station to deal with the water. Also, the water has to go somewhere. the bottom of the basement is approx. 3.5m below ground level. where do you suggest we re-route that water? we're not on a steep slope to allow it to come above ground and so the only option is to keep it around the basement. but that's a really bad idea surely due to hydrostatic pressure. so we need to get rid of the water around the basement. the only solution is to feed it in to a sump and pump it out. so it's designed correctly, I just didn't install it properly. if I'd paid for someone to design the pump station and we then had a flood I would most definitely be speaking to them and making a claim. but that's not what happened.

so actually I can answer my own questions here. I've checked the architect's drawings and they state 150mm step down to the courtyard. so I'm taking that as conforming to Building regs and so will crack on with laying a 50mm directly on the slab and then can lay the patio around it. I also need to fit a drainage channel/ACO to take patio surface water to the sump so should end up ok with levels etc.

well, the basement was designed by the structural engineer (from the architect's plans) and the drainage by the civil engineers but their drawings just say 'pump station by others'. there is no way to get the water from 3m down from ground level off the plot without a pump so I'm stuck with a pump solution and so will have to make it work.

cheers. think that's something I can handle on my own. will pop down to City Plumbing next week and see what they have to save paying postage from JTM