New build with basement Essex/London boarder

[Hyside]

 

Morning, 

 

Based on the East London/Essex border. We had planning agreed 2 years ago to knock down our existing detached property and rebuild a new house with a basement. With all the inevitable delays and second guessing everything, plus the ongoing pandemic fiasco, I can see, if I'm not careful the next year flying by and missing getting it started in the 3 year planning window. So I'm going to take a deep breath and make a start asap. 

 

Although the actual construction side seem to be nearly there - We have the Architect plans and SE calculations, a sort of acceptable pre-cast basement quote and watertight superstructure quote. (Although I've forgotten most of it, I was on the tools myself many moons ago, so I'm going to dust off the Black and Decker workmate and try and do as much as I can internally). 

Some advice on what order everything happens before the works starts. Regarding Party wall agreements, insurance, warranties/NHBC, building control etc. Would be much appreciated.

 

Thanks in advance.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited November 4, 2020 by Hyside
Morning, not Afternoon

[Jilly]

Looks great! Covid only seems to be affecting material supply, not labour. 

 

Your architect should go through this if you intend to keep them onboard. My first one seemed expensive, and I changed, but wished I hadn't as the second one didn't understand the project fully.

 

If its detached, you don't need to worry about party wall agreements, that's only if you are doing something to a shared structural wall, as far as I know, unless you mean something to do with the basement?

 

You need to have Building Control (BC) Drawings done by your architect's technician, called a Full Plans (FP)  application (you submit the SE calculations with this), someone may correct me, but I think a Building Notice (BN) would be too risky for this size of project. FP takes a bit of time and during lockdown BC took 5 months to approve mine. You can even get construction drawings done too if you want more detailed instructions on build detail. (I think architects vary on how they do this?). 

 

Notifying BC, whatever method you are using, and making a start however, activates the planning and so you are ok to then take your time. 

 

Don't forget to read up about CIL  and VAT

 

You can search on here for various Insurance discussions and warranties.

 

 

Edited November 4, 2020 by Jilly

[Hyside]

Thanks for the reply and info Jilly, much appreciated. 

 

I thought I need to get a party wall agreement because the basement and piling for foundations were going to be lower than my neighbours, but perhaps not then. I'll have a chat with the architect to see where we are regarding the BC drawings. 

 

 

 

 

[Jilly]

 

 

5 minutes ago, Hyside said:

I thought I need to get a party wall agreement because the basement and piling for foundations were going to be lower than my neighbours, but perhaps not then. 

 

 

 

 

I know nothing about basements, so check that out properly!

[Bitpipe]

We went through this with our basement, provided you are more than 6m from your neighbours foundation and don't fall foul of the 45^o rule then you won't need a party wall agreement.

 

[Hyside]

Thanks Bitpipe

 

27 minutes ago, Jilly said:

 

 

I know nothing about basements, so check that out properly!

Me neither ?, and so far it been a bit of a rollercoaster. Thanks

 

21 minutes ago, Bitpipe said:

We went through this with our basement, provided you are more than 6m from your neighbours foundation and don't fall foul of the 45^o rule then you won't need a party wall agreement.

 

Thanks Bitpipe - Seems like I'll need to get a PWA then, looking at the diagram we're closer than 6m on one side.

[Mr Punter]

1 hour ago, Hyside said:

Thanks Bitpipe

 

Me neither ?, and so far it been a bit of a rollercoaster. Thanks

 

Thanks Bitpipe - Seems like I'll need to get a PWA then, looking at the diagram we're closer than 6m on one side.

 

It does not matter if you are within 6 metres UNLESS your foundation / walls cut through the imaginary 45 degree line.  Unlikely unless you are piling or within 3 metres of their building.

 

Party Wall matters can be expensive and time consuming, so if you do not have to do it, don't.

[Bitpipe]

9 minutes ago, Mr Punter said:

 

It does not matter if you are within 6 metres UNLESS your foundation / walls cut through the imaginary 45 degree line.  Unlikely unless you are piling or within 3 metres of their building.

 

Party Wall matters can be expensive and time consuming, so if you do not have to do it, don't.

 

Completely agree - do all you can to avoid it. Here's the more complete view.

 

 

Lots of resources on line to help you understand if you're likely to need it. 

 

What are your neighbours like?

 

[Alan]

Does it make any difference if the nearest part of your neighbours house is their garage? In this case my neighbour's garage is connected to their house.

[Bitpipe]

On 04/11/2020 at 11:37, Hyside said:

 

Morning, 

 

Based on the East London/Essex border. We had planning agreed 2 years ago to knock down our existing detached property and rebuild a new house with a basement. With all the inevitable delays and second guessing everything, plus the ongoing pandemic fiasco, I can see, if I'm not careful the next year flying by and missing getting it started in the 3 year planning window. So I'm going to take a deep breath and make a start asap. 

 

Although the actual construction side seem to be nearly there - We have the Architect plans and SE calculations, a sort of acceptable pre-cast basement quote and watertight superstructure quote. (Although I've forgotten most of it, I was on the tools myself many moons ago, so I'm going to dust off the Black and Decker workmate and try and do as much as I can internally). 

Some advice on what order everything happens before the works starts. Regarding Party wall agreements, insurance, warranties/NHBC, building control etc. Would be much appreciated.

 

Thanks in advance.

 

 

Welcome - very nice build you've proposed. We built a passive house in 2016 (timber frame) over a full footprint basement after demolishing the existing so can share some steps we went through.

 

I'm assuming you've done the necessary ground investigation to get the SE design of your basement complete? That will also help inform your waterproofing requirements etc.

 

Precast panels for basement can be an expensive way to go - what will the rest of the house be constructed from? Is there a specific reason you are going for that system or is it just a working quote for budgeting?

 

We cast in situ which was cheaper but does take more time on site and needs a bit more access for concrete pumps etc. Others here have used ICF, which can then be used for the whole house build) and others use hollow blocks with concrete infill.

 

Next steps (in no particular order) are to get a building control company involved, private can be more responsive than LA, they work to the same rules at the end of the day.

 

Our BC recommended that we do some notifiable work pre-demolition (was related to relocating some fouls to support caravan and future dwelling) and that started the clock and locked in the PP.

 

LA will likely need a slew of planning conditions satisfied before construction can commence, one of which is usually a demolition plan & access/traffic plan.

 

You then need to deal with the demolition, requires notification to LA and you'll need to address asbestos etc.

 

Pre-demo -services will need to be terminated (gas) and re-routed (water, electric, telco) before you can demolish. You'll need to use the DNO and Open Reach to do the latter two steps, you'll need power, water and welfare (porta loo, tea hut) on site for workers during the build plus some secure storage for materials. You'll also need adequate site safety (fencing etc), signs etc.

 

You may need to improve site access and get hard standing down before serious work starts (demo, excavation etc..)

 

Site insurance needs to precede all of this and you also need a H&S plan.

 

Build warranty is more debatable  - they are expensive and historically hard to claim against but are required if you plan to raise a mortgage or sell within 10 years. 

 

Bit of a random list but hopefully it all helps!

 

 

 

[Hyside]

Thanks for the replies and brilliant information! All really appreciated 

 

In answer to your questions. 

 

We seem to get on quite well with the neighbours both sides but we'll see how long that lasts when we start crushing concrete on-site. 

 

Although one of the most exciting things for me is having a basement, I'm finding the whole process a bit daunting. Especially with the different methods of construction to consider. I think I went with Precast because it was sold to me as the most watertight and least likely to have problems later. Seem lots of people have issues with leaky basements. Could really do with reducing the basement budget though if there's another way.

 

Going for traditional brick and block construction, only because I've worked with it in the past and understand it a bit better. Really considered ICF otherwise, but was told as it was non standard construction it might be difficult to get a mortgage. Happy to be corrected if that's incorrect.

 

How would I find out the depth of the neighbours foundations, is it just digging a hole and having a look? Might be a bit tricky as its all paved. Its around 1930s built

 

Thanks again.

 

 

[Gus Potter]

As a general point maybe to get started assume neighbour's founds are 18" (~ 450mm below finished ground level) and formed in stepped brick - corbelled. Draw your line of ground pressure influence from there. If the neighbours founds are deeper then it can be your lucky day. If you have SE calcs then they will probably have considered this already.

 

All the best, proposals look great.

[Mr Punter]

I like the design.  Have you looked at doing a blog on here?

[Hyside]

2 hours ago, Gus Potter said:

As a general point maybe to get started assume neighbour's founds are 18" (~ 450mm below finished ground level) and formed in stepped brick - corbelled. Draw your line of ground pressure influence from there. If the neighbours founds are deeper then it can be your lucky day. If you have SE calcs then they will probably have considered this already.

 

All the best, proposals look great.

 

Thanks for the info Gus - just crept out with digital measure to double check the distance to the neighbours. Its over 3m actually about 4.3m, but I have to pile over there for the foundations. So if my neighbours foundations are 450mm then I'll have to serve a PWA.  I'm going to ask them if I can dig a trial pit to check.

 

 

 

56 minutes ago, Mr Punter said:

I like the design.  Have you looked at doing a blog on here?

 

Thanks - The Architect has been brilliant, he's made loads of changes without it being a problem and worked really well with us.

 

I hadn't really considered a blog, but I'll give it a go. 

 

Next question: Is that set up on here or done independently?

 

 

[tonyshouse]

How much water is there in the ground, have you done investigations?

 

I built a basement , use no tanking or waterproofing - brave, yes, but that was eleven years ago 

[Bitpipe]

4 hours ago, Hyside said:

Although one of the most exciting things for me is having a basement, I'm finding the whole process a bit daunting. Especially with the different methods of construction to consider. I think I went with Precast because it was sold to me as the most watertight and least likely to have problems later. Seem lots of people have issues with leaky basements. Could really do with reducing the basement budget though if there's another way.

 

You're going for the most expensive method to be honest. I don't know anyone with a leaky basement and I've met quite a few fellow basement builders since doing ours.

 

Cast in situ concrete or IFC should be much cheaper, the latter has the advantage that you can DIY some of the construction (block placement) if you're able.

 

Any basement can be waterproof if properly constructed. Lots of discussions this week on BH about that.

 

External membrane is probably the most risky as it can be mis applied or get damaged on backfill. Warrantied waterproof concrete is good (we used that, Sika, 20 year insurance backed warranty) and an internal membrane with sump and pump is also well established. All depends on your ground conditions and location of water table.

 

I visited Tony's basement and it's great, however he is an experienced builder and I was not as brave as him

 

4 hours ago, Hyside said:

Going for traditional brick and block construction, only because I've worked with it in the past and understand it a bit better. Really considered ICF otherwise, but was told as it was non standard construction it might be difficult to get a mortgage. Happy to be corrected if that's incorrect.

 

Not anymore - our house is twin walled timber frame, passive construction on a basement and we got warranty, mortgage and annual buildings insurance with no issues.

 

Note that any build method can get you to the necessary insulation and airtightness standard but some will require more attention to detail than others.

 

This is the time to explore options and be creative - the savings can be considerable.

 

if you have a structural design for your basement (i.e. rebar and wall spec) and a ground survey, take it to local groundworkers and get a quote. They will likely sub out the concrete works to specialists but take care of all the excavation, cart away and re-instatement (this will be the same for any basement construction method).

 

Get a few quotes from SIPs and timber frame vendors - they can usually do a good job from your planning drawings. Big advantage of this method is that it goes up very quickly and you can pre-order windows etc as all dimensions are fixed. Talk to ICF contractors too.

 

We started on 1st Aug 2015, demo and site cleared in 2 weeks and basement works completed mid October. Frame erection started Nov 13th and scaff came down first week of Jan. We had a completed exterior  - slated roof, rendered walls, windows installed, all fascia, soffit & rainwater goods done. Looked complete from the street. Internals took another 6+ months and we moved in end of August 2016.

[Hyside]

11 hours ago, tonyshouse said:

How much water is there in the ground, have you done investigations?

 

I built a basement , use no tanking or waterproofing - brave, yes, but that was eleven years ago 

 

That does sound brave. The whole basement thing does make me a bit nervous. 

 

According to the SI they did three trial holes down to between 8 and 15 metres and didn't hit water and the holes didn't collapse. However they left a well on-site and found that there is "perched" water - Which I believe to be surface water that's drained through and is sitting in pockets of clay.... I fink.

[Hyside]

Thanks again Bitpipe for your reply.

 

11 hours ago, Bitpipe said:

You're going for the most expensive method to be honest. I don't know anyone with a leaky basement and I've met quite a few fellow basement builders since doing ours.

 

Thats good to hear. Maybe I've focused too much on the horror stories. 

 

Considering what you've mentioned - I've had a rethink on the ICF approach as I have the time to be very hands on. I've been looking around the forum this morning and found "Tom's Barn" posts regarding his ICF build and it looks very impressive. 

 

If I changed the build method to ICF would that have any inpact on the planning permission?

[Gone West]

16 hours ago, Hyside said:

Next question: Is that set up on here or done independently?

PM Admin and ask to set up a blog.

[Bitpipe]

6 hours ago, Hyside said:

Thanks again Bitpipe for your reply.

 

 

Thats good to hear. Maybe I've focused too much on the horror stories. 

 

Considering what you've mentioned - I've had a rethink on the ICF approach as I have the time to be very hands on. I've been looking around the forum this morning and found "Tom's Barn" posts regarding his ICF build and it looks very impressive. 

 

If I changed the build method to ICF would that have any inpact on the planning permission?

 

The vendors of those systems do tend to emphasise what can go wrong with other systems but providing they are properly designed and built you should have no issues.

 

Nope, planning is not concerned with how you build it  - just what it looks like, how big it is, where it is and what it is being used for.

 

Building Regs will dictate the regulations it needs to meet but does not specify the construction method.

 

Plenty on here have self built with ICF - @ToughButterCup has done a lot and learned a lot.

 

The question remains, have you commissioned a full ground investigation, ideally against a spec issued by the SE who is designing your basement?

 

If not, you'll struggle to move forward with the costing as you won't know what's required and what waterproofing measures are required.

 

[Hyside]

Yep - Had a very good SI done, according to people who've seen it. Actually I've had two done, but didn't realise I needed to get the soil tested the first time, and they only did one trial hole.(You get what you pay for), but the second one was very thorough.

 

Thanks - I'll have a look at Toughbuttercup's posts. See if I can get some pointers. (How do you do that thing so it's linked to their name in the post?) 

 

 

3 hours ago, PeterStarck said:

PM Admin and ask to set up a blog.

 

Thanks Peter.

[Thorfun]

1 hour ago, Hyside said:

(How do you do that thing so it's linked to their name in the post?) 

 

start typing an @ symbol and then it will filter after that as you start to type names. @Hyside

[Thorfun]

2 hours ago, Hyside said:

Yep - Had a very good SI done, according to people who've seen it. Actually I've had two done, but didn't realise I needed to get the soil tested the first time, and they only did one trial hole.(You get what you pay for), but the second one was very thorough.

my ground investigation report gave advice for the foundations and basement construction which I then passed on to the structural engineer and he has designed it all. just waiting for the few final pieces to be put in place before I get those final drawings.

[Hyside]

Thanks @Thorfun 

 

The SI gave lots of recommendations for the basement construction but my SE just wrote "basement to be designed by specialist basement contractor" on his drawings - Starting to think he wasn't the best man for the job, although his calcs for above ground seem ok. Having looked on here I'm very much considering an ICF basement, so I suppose I'd need someone with ICF experience to design that.  

[Thorfun]

33 minutes ago, Hyside said:

SE just wrote "basement to be designed by specialist basement contractor"

 

this just seems wrong to me! the SE needs to calculate the load on the walls of the basement etc to make sure it can take the load of the house and hold back the earth around it. so it really should be the structural engineer who designs the basement. I understand getting a waterproofing expert as per BS 8102:2009 involved to design the waterproofing but it really should be the SE who designs the basement.

 

when I sent my plans to SEs for quotes the basement was on it and I made sure that the basement design was included in their remit of work and costs. I'm really surprised by the response of yours.

 

but that's just my opinion and hopefully someone who knows what they're talking about will be along soon.