One of the reasons for applying for full plans approval under the Building Regulations was to have an "approved drawing" of my house project plans and elevations, including a drainage layout, so that the builder could give me an accurate tender quote and to ensure that all work undertaken with these drawings was Building Regs compliant. The added safeguard was a contract condition that only the client (i.e. me) could make changes to the approved plans. On that basis, all should have gone well...
Unfortunately, like many other aspects of this project, things did not go to plan but the resulting issues didn't come to light straight away. To understand the consequences of the builder's actions, you have to know the history of the build, so here's a quick recap, focussing on drainage issues...
Alarm bells should have sounded back in July 2018, when the foundations were being dug for the side return extension, waste water backed up in the main drain and overflowed out of the old gully. The first occasion when a blockage in the main drain under the house caused a flood. The builder sent someone to sort it out, and I thought no more about it.
The drainage installation was inspected on 19 September 2018. Notes on the Building Control record at the time state: Poor English speaking builders had to use google translate....Roding access on SVP to be installed and also 90 degree bend on existing wall.
Works continued on site. The concrete floor slab was poured on 3 October, leaving the original manhole and old SVP proud of the new slab.
By mid-October, it appears that drain pipes had been laid for the new sink and appliances in the kitchen and the new toilet, wash basin and washing machine in the adjoining toilet/utility room. Floorboards were up in these areas on 18 October, so I'm guessing that's when the new drain runs went in...
Stud partitions to form the new WC/utility room went in on 25 October and by the end of that month all the new walls had been plastered.
Building Control's next visit was on 2 November to view the new purlin in the loft and carry out a routine inspection of progress on the ground floor. The BC record shows no notes taken at this visit, about drainage or anything else for that matter. However, my blog post for that day records
"The Building Inspector has visited and is happy with the replacement purlin in the loft (subject to seeing the structural engineers drawing, which I've asked the man in charge to send on to him) and with the replacement loft windows. Downstairs, he's happy with the padstones which have been installed, including padstones at either end of the steel above the new garden doors which weren't actually specified (that was why the props were there) but hey...better safe than sorry! He's also happy with the "rodding" eye access into the soil vent pipe inserted at his request, even though its not quite where he thought it would be. Next inspections will be when the underfloor ventilation is completed, insulation laid and underfloor heating installed, then screeded over"
There is no record of Building Control being invited back to inspect these stages of the work; the builder ploughed on regardless. The insulation and underfloor heating was installed on 8 November 2018, and the floor screed laid the next day. Building Control was not present at the time. Indeed, they did not return to site until 2020, at my request, due to my concerns about the standard of the work and the man in charge being reluctant to organise a final inspection to get the project signed off. But I'm getting a head of myself...
Drainage works continued on site. The Saniflow in loft and wash basin in the ground floor loo were connected up on 5 December 2018; the downpipe from the extension roof on 2 December; the toilet and wash basin in the loft on 10 December and the ground floor loo on 16 December (but not the cistern, only the drain). The kitchen sink was connected up on 19 December and the shower in the loft on 21 December 2018...my goodness, I'd forgotten what a mad chaotic rush everything was in the week before Christmas - how did I keep sane?
In January 2019, it became apparent that all was not well...I noticed that whenever the kitchen tap was running, air bubbled up in the bottom of the toilet pan next door
Reviewing the approved plans to get to the source of the problem, I noticed that there was supposed to be something called a stub stack installed in the corner cabinet in the ground floor loo, into which drains from the toilet, wash basin and washing machine were supposed to flow before being routed into the original manhole. That stub stack had not been installed and the system was not venting properly, causing air to escape or be drawn in through the nearest outlet - the toilet pan.
The builder's answer was to fit a narrow diameter pipe into the back of the toilet pan, and run it along the back wall of the room, into the corner cupboard and up, terminating in something called a "Durgo" or Air Admittance Valve (AAV).
The AAV lets air into the system by popping up the valve when a vacuum is created by the passage of water through a drain. Then the valve closes to stop drain smells coming into the house. It stopped the air bubbling in the toilet pan but never functioned properly; the vacuum pressure was so strong it blew the top off the valve almost every time a large amount of water went through the drain, so the smells lingered...And its not a proper stub stack, which is supposed to carry waste into the main drain below floor level and incorporate a rodding eye to clear blockages as well as an AAV to ventilate the system. I didn't appreciate the importance of that at the time...I do now!
Fast forward through 2019 - after 9 months of living in a building site, I couldn't wait to get away so took myself off traveling to Morocco (twice), Bruges, Ostende, Guernsey and Jersey (work), Bolivia, France, Antwerp and Scotland. With trips abroad and weekends away in the UK, I wasn't around much at home from March-December 2019 so the drains didn't get used a great deal for 9 months.
The first sign of trouble came at the end of December 2019, when sewage overflowed out of the open gully on the deck, just outside the kitchen diner doors, due to a blockage in the main drain. That was the first time it happened. Since then it's happened four more times. Believe me, that's not good news!
On each occasion, the drain clearing people have warned that solid debris in the main drain - even a small bit of rubble - causes natural waste to build up behind and eventually it comes out of the nearest opening...The problem is compounded by the drain layout under the deck with its right angle bend (noted by the Building Control Officer back in 2018 and never addressed it seems). The bend is too tight to use conventional rods to clear blockages so they have to bring water jet hoses through the house as there's no manhole at the front. Its a dirty, wet and disruptive business even when they are being careful - not to mention the cost!
It also became apparent in June 2020 when the deckboards were lifted and re-laid, that the drain layout under the deck had been altered since it was inspected by Building Control in September 2018. The main drain now runs into the corner of the deck to pick up the down pipe from the extension roof which discharges into the open gulley where sewage keeps overflowing...(top right in the photo below).
The change in drainage layout, blockages, smells and lack of stub stack were drawn to the Building Control officer's attention when I requested a visit in August this year. It's a different officer to the chap who came in 2018, so he had to get up to speed. Having looked at the photos and drainage "timeline" I had drawn up, his response was to ask to meet myself and the builder on site to discuss drainage and other Building Regs non-compliance issues.
In spite of four or five requests to let me know his availability to meet Building Control on site, the man in charge failed to respond by the deadline of 9 October 2020. I ended up asking a drainage expert to help me sort out the mess they had made with the drains, get to the root of the repetitive blockages and find a solution to make the installation Building Regs compliant - hopefully without digging up the floor in the kitchen diner!!
A comprehensive camera survey was carried out and a report identified the cause of the blockages - building debris in the pipe...you could see bits of solid material being pushed along by the camera as it snaked its way along the main drain towards the public sewer. The survey also identified that the ground floor loo is drained directly into the main drain at Y junction with no manhole/rodding eye and there are multiple fractures in the length just below the kitchen sink. Because of the small diameter of the pipes serving the kitchen sink and wash basin, it wasn't possible to follow the line of these drains.
In the meantime, while waiting for the drain report, Building Control decided to start prosecution proceedings against the builder for failing to carry out work in accordance with the Building Regs full plans approval. However, I was advised that before they could put the matter before the magistrate, they would have to give the builder one last opportunity to put everything right. Although I wasn't happy about having them anywhere near the house after the problems they had caused, I didn't have much choice.
The builder agreed and the meeting took place on Thursday, 12 October 2020. The builder claimed the changes they had made to the drainage had been agreed with the previous Building Control Officer (even though there's no record to that effect on the file). They couldn't explain why I had not been informed or asked to agree these changes (under the contract, only I can make changes) and couldn't say exactly where the new pipes ran, only that they didn't go into the original manhole and that other elements shown on the approved plan (the stub stack and a back inlet gulley had not been installed).
However, they did agree to carry out additional works which the Building Control officer said would make the drainage acceptable under the Building Regs. This involves
- simplifying the drain layout under the deck to get rid of the right angle bend where the drain goes under the house
- putting a rodding eye in the nearest planting bed so that any future blockages could be rodded through rather than having to bring jetting hoses through the house
- replacing the bottle trap under the basin in the ground floor loo with a chrome "anti vac" trap to deal with smells
- replacing the small 32mm pipe and AAV attached to the toilet pan in the downstairs loo with a 100mm pipe and AAV (the right size of a WC) and boxing in the new pipe to make good
- doing something to the drain serving the kitchen sink and dishwasher (but I’m not clear what that involves so have asked Building Control to clarify)
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