puntloos Posted October 23, 2020 Author Share Posted October 23, 2020 And one delayed update: Demolition + Removal + Groundworks: 20,000 Digging a massive hole for the basement: 10,000 25m2 basement + 130m2 foundation to 'cover' the entire house footprint: 100,000 To be clear, the above is under the assumption that the soil is 'solid', No unexpected water, or sagging, or unexploded WWII bombs. Yes we'll have to do some investigations. My question is: How much more is this cost (130,0000) than if I were to just clear, groundwork, foundation? I'm trying to separate out the GBP/m2 of the basement Link to comment Share on other sites More sharing options...
Moonshine Posted October 23, 2020 Share Posted October 23, 2020 Sorry I can't help with the costings but following the thread with interest, as I am looking to excavate a basement from a sloping site. The basement is 25m2, and includes and integrated garage and entrance hall, my hope is that the garage won't need significant tanking. Ground investigation works (4 boreholes) were done earlier this week which found dense sand with a sandstone layer 2.5-2.8m below, though will be 3 weeks until we get the formal report and slope stability assessment. Got a SE lined up to do the below dpc calcs. Once we have though calcs and spec it can go out for pricing from ground workers. It will cost us £4k ish + VAT for the SE and ground investigation. My hope is the basement and foundations for the house up to dpc build cost doesn't exceed £30-40k. Time will tell how far off I am going to be on that!!!! Link to comment Share on other sites More sharing options...
Thorfun Posted October 23, 2020 Share Posted October 23, 2020 8 hours ago, puntloos said: And one delayed update: Demolition + Removal + Groundworks: 20,000 Digging a massive hole for the basement: 10,000 25m2 basement + 130m2 foundation to 'cover' the entire house footprint: 100,000 To be clear, the above is under the assumption that the soil is 'solid', No unexpected water, or sagging, or unexploded WWII bombs. Yes we'll have to do some investigations. My question is: How much more is this cost (130,0000) than if I were to just clear, groundwork, foundation? I'm trying to separate out the GBP/m2 of the basement I'd be upfront with the groundworks company that did the quote and ask them! they should be able to break it down for you. I'm very interested in the result if you do as I'm in a similar position in that I should be looking for quotes in the next couple of weeks for our basement and foundations. Link to comment Share on other sites More sharing options...
puntloos Posted October 25, 2020 Author Share Posted October 25, 2020 On 23/10/2020 at 10:08, Thorfun said: I'd be upfront with the groundworks company that did the quote and ask them! they should be able to break it down for you. Sadly not, the groundworks company doesn't do foundations, and the basement company doesn't do foundations-alone. I'm sure I can get more quotes, for example I asked a quote from a timber frame company that will do foundations so perhaps from them I can untangle it. On 23/10/2020 at 10:08, Thorfun said: I'm very interested in the result if you do as I'm in a similar position in that I should be looking for quotes in the next couple of weeks for our basement and foundations. Let's share our notes, shall we? ? 1 Link to comment Share on other sites More sharing options...
puntloos Posted October 25, 2020 Author Share Posted October 25, 2020 On 23/10/2020 at 06:29, Moonshine said: Sorry I can't help with the costings but following the thread with interest, as I am looking to excavate a basement from a sloping site. The basement is 25m2, and includes and integrated garage and entrance hall, my hope is that the garage won't need significant tanking. Ground investigation works (4 boreholes) were done earlier this week which found dense sand with a sandstone layer 2.5-2.8m below, though will be 3 weeks until we get the formal report and slope stability assessment. Got a SE lined up to do the below dpc calcs. Once we have though calcs and spec it can go out for pricing from ground workers. It will cost us £4k ish + VAT for the SE and ground investigation. My hope is the basement and foundations for the house up to dpc build cost doesn't exceed £30-40k. Time will tell how far off I am going to be on that!!!! 40K for a 25m2 basement + foundations? That sounds hugely optimistic, perhaps depending on where you are trying to build.. but if you have any actual quotes I'd love to hear them! Link to comment Share on other sites More sharing options...
Moonshine Posted October 25, 2020 Share Posted October 25, 2020 (edited) 1 hour ago, puntloos said: 40K for a 25m2 basement + foundations? That sounds hugely optimistic, perhaps depending on where you are trying to build.. but if you have any actual quotes I'd love to hear them! QS estimate for excavating, retaining walls, tanking, foundations, and basement floor is £39k. The ground floor (block and beam, screed, insulation) adds on £13k to that. Basement is a 3 sided box dug out of a slope, total retaining wall is 17m. Only 7m of that needs tanking as the rest is garage. Of course this may not be accurate and I won't know until I get proper quotes. Hopefully will be able to get firm prices in a month or so. Edited October 25, 2020 by Moonshine 1 Link to comment Share on other sites More sharing options...
puntloos Posted October 25, 2020 Author Share Posted October 25, 2020 27 minutes ago, Moonshine said: QS estimate for excavating, retaining walls, tanking, foundations, and basement floor is £39k. The ground floor (block and beam, screed, insulation) adds on £13k to that. Basement is a 3 sided box dug out of a slope, total retaining wall is 17m. Only 7m of that needs tanking as the rest is garage. Of course this may not be accurate and I won't know until I get proper quotes. Hopefully will be able to get firm prices in a month or so. Ah ok so this is a QS estimate? Very helpful to know, perhaps the basement team I found was too pricey. Where are you located though, I imagine 'middle of nowhere, Ireland' might be cheaper than my 'commuting distance from london' spot.. Link to comment Share on other sites More sharing options...
Moonshine Posted October 25, 2020 Share Posted October 25, 2020 1 hour ago, puntloos said: Ah ok so this is a QS estimate? Very helpful to know, perhaps the basement team I found was too pricey. Where are you located though, I imagine 'middle of nowhere, Ireland' might be cheaper than my 'commuting distance from london' spot.. Yes, though there coatings didn't include steel rebar and a step beam, so I am expecting some upward movement. Also total floor area of mine in 80m2, so over the basement, there is only 60m2 of foundations needed I am in the south west and likely to be cheaper than London commuting belt, though really need a formal quote to see if the qs is in the right ball park. Have you had quotes from more than one contractor? Link to comment Share on other sites More sharing options...
puntloos Posted October 25, 2020 Author Share Posted October 25, 2020 (edited) 50 minutes ago, Moonshine said: Yes, though there coatings didn't include steel rebar and a step beam, so I am expecting some upward movement. Also total floor area of mine in 80m2, so over the basement, there is only 60m2 of foundations needed I am in the south west and likely to be cheaper than London commuting belt, though really need a formal quote to see if the qs is in the right ball park. Have you had quotes from more than one contractor? Only one for now! Happy to send it over privately, send me a message if interested? Edited October 25, 2020 by puntloos Link to comment Share on other sites More sharing options...
Gus Potter Posted October 26, 2020 Share Posted October 26, 2020 What about getting and SE in right at the beginning even before you ask a builder, employ a QS, get an Architect. SE's know a lot more about this process than the common perception that they just just "provide calcs" A few rakes about on build hub say etc will get you on the ball re your budget. Work out if you have the money, can borrow it etc first . Much of the cost lies in the ground. Then spend £300 - 500 quid on getting an SE. Yes..you maybe don't want to put your money where you mouth is at the moment but it's a bit like site investigation.. if you skimp on this you end up paying for it later and often more. This is a known statistical fact in the industry and you are more vulnerable to this as a domestic client. Maybe it's worth getting and SE in early who will take you under their wing and guide you. A good one (SE) who has experience will do a desk stop study on the QT before they meet you and this can really go along way towards identifying real potential issues that need investigated/ designed around. This will also help you get provisional prices from builders by way say of an A4 spec on a page or two and you can access their contact list. They will also help you prepare a brief for the Architect. Also a lot of "SE's" are pretty good Arctitectural designers themselves so you may not need an Architect at all. You get two birds for one stone. You'll need an SE for a lot of basements so I think you could be missing trick and often wasting your money. It will do you no harm to just ask an SE right at the start? 1 1 Link to comment Share on other sites More sharing options...
Moonshine Posted October 26, 2020 Share Posted October 26, 2020 7 hours ago, puntloos said: Only one for now! Happy to send it over privately, send me a message if interested? I am probably not the best person to review as I am on the learning curve too. However I would definitely advise you to get the ground investigation done and structural design below dpc done, including any bending bar schedule. The ground workers i have spoke to wouldn't even give me an indicative cost and needed the design they would be working too. Do you have planning / building control approval? From here it sounds like the quote you have is built on loads of contingency from the company as they don't know the details of what they are buildings. Also it sounds as your ground conditions are clay which will increase the cost I think. Link to comment Share on other sites More sharing options...
oldkettle Posted October 26, 2020 Share Posted October 26, 2020 (edited) 16 hours ago, Gus Potter said: What about getting and SE in right at the beginning even before you ask a builder, employ a QS, get an Architect. SE's know a lot more about this process than the common perception that they just just "provide calcs" Hi Gus, From your post it seems the SE needs to be local? And what is the deliverable of this exercise - feasibility study, list of surveys to do before any basement or foundation design is possible? Advice - certain number of hours? Basically, I am pretty sure any SE would like to limit the time they spend for a fixed fee which is perfectly reasonable. And I would also want to be clear about what I am asking for. Edited October 26, 2020 by oldkettle Link to comment Share on other sites More sharing options...
Gus Potter Posted October 27, 2020 Share Posted October 27, 2020 Hi Oldkettle. It's a matter of preferance really as to whether an SE is local or not and at what stage you get one on board. For work that is below ground.. basements, retaining walls etc then a local SE will have a reasonable idea of what may work vs the risk the Client wants to take. At one end some don't want to spend any money on say site investigations or exploring the options of cut and fill, drainage etc. This increase the risk that you will encounter the unforseen. At the other you can spend more, too much, well not often, on investigation and this provides greater certainty. They (local SE) will probably be familiar with the area. Also, they may well have a good rapport with local BC and be sharing knowledge about what is encountered under the ground locally and so on. One thing that can be really useful though is just being able to have a chat with an SE, call it a brain picking excercise. There are some SE's who will come out to site in an informal manner with a pad of paper and pencil, walk you through the various principles of design, do the odd sketch to demonstrate the principles and "chew the fat" with you. At the same time they will give you pointers as to what you need to investigate and how you go about it, who to approach and how you ask (technical jargon) for your particular site. This can pay dividends later on. You can find SE's who take this approach. It can work well as you start to build a relationship, which you can if you wish formalise later on. Try asking some SE's if they will come out on this basis to give some informal advice. Some will be delighted to do so as for an SE it is often much more interesting to be involved all through a project, offer to pay for their time, say by the hour and you may well be pleasantly surprised at the outcome. All the best with the project. 1 Link to comment Share on other sites More sharing options...
Internet Know How Posted January 2, 2021 Share Posted January 2, 2021 On 11/07/2020 at 08:57, Conor said: So, we got final tenders in last week. The winning tender has £39,500 for a 100m² basement. That includes: 200mm ground bearing slab and tanking (ground works done and compacted stones laid already) All steel reinforcement ICF walls up to ground level Tanking for ICF Perimeter drain, backfilling with clean stone Fyi our ground works: site clearance, excavation, main drainage works, muckaway, under slab stoned with 150mm type 3, access road and working areas stoned, is coming in at about £14k. Still waiting for the final bill. That was basically a man with a digger @ £40/hr + materials. What exactly is included in your 40k quote? how did you put your job out to tender? Did you just send out your basement design to local firms after contacting them directly? Link to comment Share on other sites More sharing options...
Internet Know How Posted January 2, 2021 Share Posted January 2, 2021 On 11/07/2020 at 09:05, Thorfun said: my quote for our foundations for the basement came in at £105k without a lid! £30k of that was just dealing with the digging of the hole, £30k for dealing with the muck away and the rest for an insulated slab. 3.1m deep, 130m2, clay on top of sandstone. seems expensive to me. the actual basement walls were reasonable though at about £30k, although no mention of waterproofing was made in the quote so I assume I'll be adding extra on for that. will continue to shop around. When you work out what the materials actually cost then yeah it is expensive. I have done some high level material calcs for my basement. For 230sqm slab, and 210sqm of walls I am getting to around £65k in materials. This includes MOT, sika concrete, rebar, mesh, formwork hire. It does not include removing spoil, machine/scaffold hire. Obviously there are the additionals such as waste pipes, but thats rather inexpensive. Link to comment Share on other sites More sharing options...
Internet Know How Posted January 2, 2021 Share Posted January 2, 2021 On 23/10/2020 at 01:43, puntloos said: And one delayed update: Demolition + Removal + Groundworks: 20,000 Digging a massive hole for the basement: 10,000 25m2 basement + 130m2 foundation to 'cover' the entire house footprint: 100,000 To be clear, the above is under the assumption that the soil is 'solid', No unexpected water, or sagging, or unexploded WWII bombs. Yes we'll have to do some investigations. My question is: How much more is this cost (130,0000) than if I were to just clear, groundwork, foundation? I'm trying to separate out the GBP/m2 of the basement I had demolition quotes ranging from £12k to 21k initially, then one guy came in quoting 7.5k. For the dig, work out how much spoil you have to remove in tonnes (https://www.source4me.co.uk/calculate_excavated_spoil.php), and then work it out to £100-150 per 16 tonne wagon load out. Then figure out how long it will take your guys on the machine to remove it. If your concrete team are expecting a hole ready to start with, why not get one team to do the demo and dig the hole, then another to come in and start the groundworks Link to comment Share on other sites More sharing options...
Conor Posted January 2, 2021 Share Posted January 2, 2021 27 minutes ago, Internet Know How said: how did you put your job out to tender? Did you just send out your basement design to local firms after contacting them directly? We did a Lot for the whole structure (founds, walls, tanking, floors, steels, roof), went out to three builders that I had researched that do ICF and concrete works etc. Went for the cheapest lol Link to comment Share on other sites More sharing options...
Internet Know How Posted January 2, 2021 Share Posted January 2, 2021 7 minutes ago, Conor said: We did a Lot for the whole structure (founds, walls, tanking, floors, steels, roof), went out to three builders that I had researched that do ICF and concrete works etc. Went for the cheapest lol I am pretty much at that stage my self now. Having had the usual surveying and demo quotes its crazy how varying the prices come in! Link to comment Share on other sites More sharing options...
Thorfun Posted January 2, 2021 Share Posted January 2, 2021 1 hour ago, Internet Know How said: It does not include removing spoil, machine/scaffold hire those things aren't cheap Link to comment Share on other sites More sharing options...
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