Zak S

Thanks for the great pieces of advice ?. It seems that a structural engineer is a must at this stage to decide most cost effective design option (remodel/extend v rebuild) which should determine the foundation options, I could go down to. This seems very sensible. PS: reading my comments in italics; a bit shocked at my spelling/typing errors. Apologies

Thanks for such a thorough helpful advice. Greatly appreciated. Can I please check the followings: Does this mean given its currenlty a banglow I will be limited to banglow (no build upward) option unless I go down the underpinning option which is a not an option at the moment. So I had two full bore holes and third extended via with dynamic probe with two trial pits as marked on the plan. If I need to do more trial holes I would need to get ot sorted via a professional but what is it I am looking for which could not be done previously. Sorry just trying to clarify my understanding. So that is 4tonne per sqm. Would this be enough for a banglow only or traditional block and brick two and half (loft) storey house? Definitely, I would consider that if it's possible and a cost effective solution. I had a chat with Hilliard Tanner (Ireland) as @joe90 suggested and he was to going to look at it but he mention thin steel cases concrete beam with raft ok top among one option so I am keeping fingers crossed. I had a chat with a guy from Helical screw piles and he said the raft on it's own (without insulation) costs 150 per sqm so for 330 sqm it would be c50k plus insulation and screed on top to sub floor level. Does that seem right?

Thanks @Roundtuit and @saveasteading

Hi. Thanks. What was the cost per pile? Given the ground is very soft to 9/10m I suppose it would be easy to drive it down?

So I had a quote from local guy he has done lots in the area and also did house opposite. He said 60k (30k for 55 piles and 30k for ring beam) for foot print of 300sqm which included one out building. Bullivant said £38k for 55 piles so slightly expensive and including ring and beam it was coming to 65k. Abby Pynford said 75k uninsulated Raft invoiced and 90k for with void. All are VAT exclusive. Another local company West Midlands piling said £52k. With block and beam included cost would reach to 75k easily without insulation.

I am currently speaking with RB, Abby Pynford (way too expensive for piled slab option), Van Elle and some others for innovative piling options to see if I can find cost effective options. Current conversation seems to be pointing to that due to ground condition Auger Piling wity ring and beam might the way to go unless some trade marked solution can be found. Ground conditon is just very soft clayey with high water table and low significant sheer strenght does not help. Slab without piling on it's own for 330sqm would be c45k without insulation. Adding piling and insulation the cost would be around 85-100k at which point project becomes unfeasible.

Thanks. I will speak with him to see if he has any tricks which dont involve piling in building the slab. Issue is Abby Pynford quoted me 90k for piled voided slab as due to poor ground conditions piling seems must. But I will chat with William. Thanks. Much appreciated.

Would building control be willing to go against recommendation if SI report even if I change the build method?

Bullivant is saying they need to go 5m below the depth of pile to provide the warranty. What is it I need in the report which is not there which would confirm that there is nothing under the sand stone which caused the Refusal. Is it drilling a new bore with different equipment. I really want having to pay for the GI report twice. I have not yet settled the invoice but the current GI covered by stating the Refusal in the quote and me being not technical did not understand the implication. Any thoughts?

Thats makes sense.

I provided the detail about 'Refusal' of rig to go any further and he very helpfully stated: The rationale is that they have stopped the investigation at 11.45m as soon as the SPT’s have become greater than 50 blows for 300mm or less. They have not continued using a core sample and hence the strata they have refused on could simply be a hard band of clay with softer deposits lying beneath which could cause potential issues of “punching”. I personally think given the two house opposite only went to 10/11m for their piles we might be ok but this means RB would be a bit reluctant to accept this SI report. Nothing in life is simple...?

My guess is that this is specifically for forecast piles which may go to only certain depth but I might be wrong.

Thanks. Please do.

I just noted from the report that they only went to c11m when the brief was to go to 15m depth. I just re read the quote and it said as follows: "Geology for the site is likely to be a mixture of Clays, Sand and Gravel with the quote being based on the excavation of up to 2no hand dug trial pits to expose foundations to the existing dwelling, maximum pit depth 1.20m and for 2no combined sampling boreholes utilising dynamic and rotary augur drilling equipment with provisional borehole depths of 15.0m or refusal*, whichever is the shallower, being included. Refusal* is achieved when >50no blows produces <300mm penetration during a standard penetration test" It's the "refusal" bit I am not sure about. Is that standard? Bullovant saying given he did not go to 15m they will not accept the boreholes and it's likely building regs/warranty provider will say the same and would ask the new investigation. That's means that SI was not properly done. Please could you help? Thanks.

Thanks. You confirm the reservation I had which is much appreciated. I have asked Bullivant and they said in the email "With ground conditions not getting to anything significant until 8/9m then this may not be enough to warrant a pile design." well if piles is not an option then have I run out of options ??

I have been speaking with a company and they say that they are approved by warranty providers and there solution get approval for building regs buy apart from warranty (which only last for ten year), there is a question of impact on insurance as well ability to sell and longevity of screw pile play an important part in it. Given the ground spoils ph is seems to be within acceptable range meaning the corrosion will be not material. Any view on this?

Hi @JohnMo thanks. Just to clarify did you mean to say that screw piles would NOT last over the life of the property hence not allowed?

To me rebuild could only be justified if I build a standard 2 storey plus a loft kind of house. Given the foot print it could easily reach 600sqm but I onky need 450-500 sqm. But want to have decent size ground floor.

Yes. Thanks @Mr Punter the plan is to demolish and rebuild but it would depend all ok the costing hence trying to investigate the cheapest option for foundation for the new build using traditional or helical screw piles. The quote from Abby Pynford was 65-75k for 250sqm voided slab foundation (with no insulation inside the raft). For 330sqm would it be proportionally higher? Not sure if screw piled foundation will be any cheaper but I am getting a view from a specialist company in that respect. Ring beam with 55/60 concrete piles was quoted at 52-60k. Any views on these numbers? Is there no option at all to salvage the existing building for building on top by strengthening the existing foundation (via piles/underpinning etc) Also what would be your advice on soakways as council insist to create soakways. If water table is high and soakways is not recommended does it mean it's a good thing I.e. cost can be avoided or would the council insist on alternative to soakway (I am not sure if there is an alternative). Thanks.

I am thinking foundation for about c330sqm foot print. I have received the GI report which is not encouraging and points to the need for piled foundation. there are multiple options e.g. piles with voided raft, piled with ring and beam, screw piled foundation. What do you think would be the cheapest options? Please is the GI report and property expected foot print (yellow border). Also if any one has experience of screw piling existing foundation (are they cheaper than new foundation?) Also the GI report mention that given the high water table the storm soakways is not recommended. What other option I am left with to divert rainwater away from main drainage system? Thanks all in advance. GI Investigation Report.pdf

Any one with experience of taking the risk of self building while on a standard mortgage with usual high street lender (disclaimer: I am not in way encouraging this risk taking ?). It would be good to know hopefully not too stressful stories.

One option could be to market it as attractive 'Option to buy' where a developer buys the right to buy the property in future at much higher price post a development milestone. Normally the developers will identify these sort of lands and approach the owners. I am not sure how the other way round would work where the land owner approach the developer.

No need for teenagers as these days there are dead quite with headphones on. I can provide the services of my 4.5 year old as a tester. Actually, I might pay to get some peace. Cant wait for schools to open ?

I used res bars for a conversion HMO. Looking at online resources, there various additional steps recommended like using the sound proofing sealants, sound proof membrane and doubling the plasterboard etc. I only used Res bars and RWA 45 insulation and the effect compared to my own house (newly built house by a developer in 2003) was highly noticable. Unless one is creating a cinema/studio, even 70-80% reduction in noise is a great deal. That extra 30-20% might only be worth if there a commercial need (in my personal view).

@harry_angel In 2019 I was in a situation where due to bank pulling their remortgage offer on a BTL property, a purchase from Auction was at risk after having paid a deposit. The only thing that helped in that very stressful situation were friends and family as I was 70k short while remortgaging a different property took few months. So I do value the importance of reliable real friends and family.