New member to the selfbuild family!

[jimmyharris80]

Hi all,

 

I can’t believe I’ve only just stumbled upon this fabulous resource!

 

A bit of background in terms of our journey so far… my wife and I are embarking on a self build project in Hertfordshire for our family of four.  We currently reside in our hotch potch bungalow on site, it’s had various extensions bolted on over the years and an adjoining garage, there is a fair bit of land that we are looking to make the most of.  We’ve lived here for 5 years now and the building is crumbling at the seams so we’ll be waving goodbye to it and knocking it down, eventually!

We have planning permission for our new dwelling and are at building regs stage now, there is still a fair amount of cost uncertainty given recent price escalations and we’ve not quite yet got to a reliable figure in terms of the build costs, we have a budget of around £500k + contingency for the build. 

We feel like we’re at a bit of a junction in terms of our build approach, we’ve always assumed timer frame but since the design has been refined and some feedback we’ve had from the main contractors we’ve approached we are now having a few doubts, I’m hoping you guys maybe able to allay our concerns and offer some valuable guidance.

I will post up a separate thread in the appropriate section with a bit more detail of where we stand currently but in the meantime here’s a few 3Ds of our dream self build home we are looking to make reality!

 

Thanks

 

[joe90]

Welcome, looks a good project and oodles of knowledge here, we never mind questions, even stupid ones, we have all been there, done that. Remember that you only buy insulation once and with the recent price hikes of all fuels the more the merrier along with airtightness. I look forward to your various threads 👍

Edited March 18, 2022 by joe90

[Bitpipe]

Welcome, beautiful home and I congratulate you on having the courage to demo and re-build (we did similar in Berkshire).

 

Are you building to a particular standard? Building regs are quite unambitious in respect to energy efficiency and you can do much, much better for probably not much impact on the budget. 

[jimmyharris80]

2 hours ago, Bitpipe said:

Welcome, beautiful home and I congratulate you on having the courage to demo and re-build (we did similar in Berkshire).

 

Are you building to a particular standard? Building regs are quite unambitious in respect to energy efficiency and you can do much, much better for probably not much impact on the budget. 

 

Hi joe90 and Bitpipe, we did originally embark on a renovation project of our bungalow and pulled together some designs, but estimated costs were escalating to a point where a knockdown and rebuild made more sense from both a cst and outcome perspective, so here we are!

 

We have instructed our architect to meet the regulations in terms of energy efficiency at this point, we're not looking at passivhaus standards by any stretch but our assumption was that if we wanted to beef up the insulation at a later point we could do that during discussions with any contractors when agreeing the spec, if I'm wrong in this assumption please do shout!  I guess a thing we need to bear in mind is the impact on the rooms in the roof in terms of wall thickness, probably fairly negligaible in the grand schedme of things but things are a little tight up there in the bathrooms so every 5cm counts, but then heat loss/increased heating costs trump that for sure given recent events and price escalation.

 

I've started another thread here on our build approach, this details our elevations, sections and floorplans.

[joe90]

7 minutes ago, jimmyharris80 said:

We have instructed our architect to meet the regulations in terms of energy efficiency

I think you will find we, on this forum, think current regulations are dire which is why most of us instal much more. Who knows where fuel costs are going, the one thing is they will not come down. My build is near passive standards and my heating rarely comes on and the house is very comfortable. I disagree that adding insulation later is easy, far better to plan it from day one.

[JohnMo]

Hi, would agree to add later, even later in the design process will cost you.  Once wall and roof thickness is set so is the installation depth to a large degree.

 

Don't think of passivhaus a distant unachievable thing, a normal build can't do.  Some aspects you may not do, but it worth reading up on, as most things make really good sense and can be added to a design for little or no cost at the design stage.

 

Building regulations insulation is far from ideal and so is their airtightness.  Would look to have a minimum of a 0.15 u value, for walls floor and roof.  If you have UFH go to about 0.1, to save too much downwards heat loss.

 

From your design be wary of overheating from your glazed gable ends.  Extending your roof and walls out similar to the rear, could give some shading, when the sun is low in the west can be as much of a problem as midday sun.  The architect should be able to model it, you need to know what spring, autumn and summer will do to your internal temperature.

 

 

 

 

[jimmyharris80]

Thanks guys, I think this ties in with my other thread on construction method, as depending on whether we go timber frame or blockwork this will determine the make-up of the wall/insulation requirements and thickness.  I have to admit this isn't an area I've given a huge amount of attention and we've gone with the architects view on it up until now, maybe time to pick up the phone!

 

We are planning to have UFH throughout, we're off-grid for gas so an ASHP/UFH makes sense in terms of a solution here.

 

In terms of the gable ends, just the SW elevation has the extended canopy as the plot is a little sunken (not obvious from the 3Ds), there are mature trees to the south and west boundaries of the plot that provide shading for a large part of the spring/summer/autumn months (for this reason we've had to discount solar PV for now as we just don't think the payback is there - although current oil/elec prices do alter the calculation somewhat!)

 

Below is what has been specced at the moment in the BR drawings in terms of wall/roof insulation, any views on how much we'd want to beef these up by to get to 0.15u?

 

Apreciate I'm putting a lot of info out there and asking a lot, the more I look a the detail the more I feel a little out of my depth, but I'm here for the education and it's much appreciated 👍

 

[Iceverge]

Welcome welcome. 

 

Be sure to set aside some funds for airconditioning and/or external blinds if you haven't already. 

 

If the house is built as designed I wouldn't be terribly optimistic about small energy bills either.

 

The good news is that you're early enough to do something about it. Looking at your architects drawings they're probably not the best source of advice. 

 

Perhaps query with them the cooling and airtightness strategy to test the water. 

 

[PeterW]

To echo what @Iceverge says… you need to look quickly at that design as it is barely building regs for insulation ..! What is the purpose of this 140mm block with another skin for the render ..? The mix of TF and blockwork doesn’t make sense, and the blockwork insulation is definitely not enough. 
 

Airtightness in this will be a real challenge and there are gaps in the VCL (vapour control layer) that are visible in the plans above. 
 

Roof design makes no sense either - they have specced Kingspan NilVent (clue in the name here ….. ) which is a breather membrane requiring no air space below, and then spec a minimum 50mm air gap. 
 

I would hazard a guess that they also had lunch with the Kingspan rep last week as I’ve never seen it specced so much on a set of plans …. 

 

[Bitpipe]

 

 

On 18/03/2022 at 12:39, jimmyharris80 said:

 

Hi joe90 and Bitpipe, we did originally embark on a renovation project of our bungalow and pulled together some designs, but estimated costs were escalating to a point where a knockdown and rebuild made more sense from both a cst and outcome perspective, so here we are!

 

Same as us then!

 

On 18/03/2022 at 12:39, jimmyharris80 said:

 

We have instructed our architect to meet the regulations in terms of energy efficiency at this point, we're not looking at passivhaus standards by any stretch but our assumption was that if we wanted to beef up the insulation at a later point we could do that during discussions with any contractors when agreeing the spec, if I'm wrong in this assumption please do shout!  I

 

Yes, you are wrong - it needs to be designed in from day one but does not necessarily add much cost, when's all's said and done the structure of your home is about 20% of the overall build cost and making that closer to passive may add on 10-20% to that cost (maybe less). Really it's just more insulation, more focus on airtightness and consideration to over heating etc. 

 

If anyone tries to present it as some hair shirt wearing lifestyle strategy then show them the door. We leave doors and windows open year round when we feel like it but our house is warm in winter, cool in summer and we have relatively low energy bills - that's what it's all about.

 

Take a look at MBC Timberframe as an example of the package approach - we used them as did many others here but there are lots of alternative contractors and build systems to get the same result. Lots of ICF builds here and well insulated block also.

 

 

 

 

[Faz]

Why aren't you insulating the cavity (and making it bigger)? PIR and insulated PB is expensive and 90mm overall is not really that great.

[Adrian Walker]

Depending on your soil conditions I would look at an insulated slab rather than beam and block. 

[SBMS]

@jimmyharris80Looks like a great project! How are you looking at managing the build? Contractor or are you doing work yourselves? Have you got a total square meterage of the size of the build?

 

We are starting our build next week and one of the things I’ve learned is that design considerations in your build can significantly affect the cost of the build. It would be my one piece of advice to those embarking on a self build, to focus on how the design impacts costs. Architects don’t seem to design to minimise build costs (our said 250k for build costs. It’s nearly 200k more than that!) and with current price rises it’s something to consider now whilst you’re early

[SBMS]

19 hours ago, Bitpipe said:

Yes, you are wrong - it needs to be designed in from day one but does not necessarily add much cost,

+1 but it can add costs, nothing significant but things like 150mm lintels instead of 100mm lintels adds costs (they’re bit more scarce at moment). 

[SBMS]

On 18/03/2022 at 14:54, jimmyharris80 said:

Below is what has been specced at the moment in the BR drawings in terms of wall/roof insulation, any views on how much we'd want to beef these up by to get to 0.15u?

Our roof makeup is 0.15 and has been specified as 150mm PIR boards between rafters (600mm) and 37.5mm insulated Plasterboard. This is for a second floor which is in the roof. Unventilated roof. 

[Bitpipe]

57 minutes ago, SBMS said:

@jimmyharris80Looks like a great project! How are you looking at managing the build? Contractor or are you doing work yourselves? Have you got a total square meterage of the size of the build?

 

We are starting our build next week and one of the things I’ve learned is that design considerations in your build can significantly affect the cost of the build. It would be my one piece of advice to those embarking on a self build, to focus on how the design impacts costs. Architects don’t seem to design to minimise build costs (our said 250k for build costs. It’s nearly 200k more than that!) and with current price rises it’s something to consider now whilst you’re early

 

I agree that architects can be cost insensitive and design features that look great but end up being expensive - we have two rear bedroom balconies that fall into that category, never used and were a pain in the backside to accommodate plus expensive.

 

The homebuilders bible has some good rules of thumb on how design impacts build cost - ratio of linear wall to volume enclosed (square good, rectangle less good, L shapes and similar less good again), gable vs hip roof, rooms in roof, building on a slope etc etc.

 

However I think it's shortsighted not to maximise insulation and airtightness in the fabric where it will be expensive and likely impossible to improve it post build - the two need to go hand in hand but very few architects will take that approach.

 

Very much a 'here is a pretty and functional dwelling, we'll figure out later how to get it to meet regs' approach.

 

[Thorfun]

welcome, looks an amazing project.

 

On 18/03/2022 at 09:00, jimmyharris80 said:

we’ve always assumed timer frame but since the design has been refined and some feedback we’ve had from the main contractors we’ve approached we are now having a few doubts

 

the problem here is that many contractors out there are very much of the 'it's how we've always done it' mindset and so using timber frame is deemed wrong by some. it also means that, generally, they won't be paid for that as the majority of people use a TF company to erect the superstructure and then hand over to the contractor/client to do the rest.

 

I also whole heartedly agree with all the comments above about insulate now! for a small cost now adding extra insulation will reap the rewards for the rest of your lives living at the house. don't stick to building regs, you need to far exceed them.

 

I also agree to the comments about external blinds. get them in the design now and you can hide them away in the fabric of the building.

 

I recommend spending the next 2 weeks hidden away in a dark room reading as many threads on this forum as you can! 

 

good luck and we look forward to following your journey.

[jimmyharris80]

Hi all,

 

Many thanks for the words of advice, points taken on gables, blinds & insulation and factoring this into our design now.  This is when I start to feel a little out of my comfort zone I must admit!  We have very much been led by our architect to date, the design process up to gaining planning went well, since then the BRs elements have been handed off to a more junior architectural technician where interactions, explanations and guidance through the process has been pretty minimal.  As a result this is where we’ve landed, that maybe as much our fault as it is our architects as we could have been more specific in what we’re trying to achieve.

 

What we seem to have ended up with is a hybrid blockwork/timber frame design that based on the feedback here isn’t optimal in terms of insulation or airtightness, we certainly need to make some remedies and amendments to the design and BR drawings.  However, my wider concern is what type of build system is best suited to our design, I have read up on the various construction methods timber frame, ICF, traditional B&B and the pros and cons of each, but am struggling with what best fits our project.  ICF could work well due to the semi-basement ground floor, traditional block also but need to ensure better insulation factored in, timber frame is what we've always assumed would be the way we'd go (rightly or wrongly).  It’s all a bit of a minefield!

 

We always planned to enlist a main contractor to deliver the build, my wife and I neither have the knowledge or the time to manage the build ourselves (2 kids, dog and busy jobs!).  When we visited BuildIt Live a month or so ago we did discuss with the construction & PM consultant the option of chunking up the build into 1. demo/groundworks/blockwork 2. timber frame 3. Main contractor through to completion.  This keeps interfaces to a minimum and would probably be the limit of what we could manage.

 

The alternative could be an MBC type offering, groundworks + timber frame with a main contractor taking over from there, I would need to check with MBC if the retaining wall/semi-basement we have could be accommodated within their foundation system.

 

A lot to read up on for sure, and we may look at enlisting some independent professional advice as to the best build approach for our circumstances as this decision impacts on the design changes we need to make.

 

On 20/03/2022 at 09:52, SBMS said:

@jimmyharris80Looks like a great project! How are you looking at managing the build? Contractor or are you doing work yourselves? Have you got a total square meterage of the size of the build?

 

We'll be going with a main contractor, we just don't have the time or knowledge to manage ourselves.  Total square meterage is approx 215m2 across the three levels.

 

On 20/03/2022 at 09:39, Adrian Walker said:

Depending on your soil conditions I would look at an insulated slab rather than beam and block. 

 

We're in rural Hertfordshire, soil is clay and pretty heavy, we've had a soil report done and it will fail an infiltration test.

[Bitpipe]

2 hours ago, jimmyharris80 said:

Hi all,

 

Many thanks for the words of advice, points taken on gables, blinds & insulation and factoring this into our design now.  This is when I start to feel a little out of my comfort zone I must admit!  We have very much been led by our architect to date, the design process up to gaining planning went well, since then the BRs elements have been handed off to a more junior architectural technician where interactions, explanations and guidance through the process has been pretty minimal.  As a result this is where we’ve landed, that maybe as much our fault as it is our architects as we could have been more specific in what we’re trying to achieve.

 

What we seem to have ended up with is a hybrid blockwork/timber frame design that based on the feedback here isn’t optimal in terms of insulation or airtightness, we certainly need to make some remedies and amendments to the design and BR drawings.  However, my wider concern is what type of build system is best suited to our design, I have read up on the various construction methods timber frame, ICF, traditional B&B and the pros and cons of each, but am struggling with what best fits our project.  ICF could work well due to the semi-basement ground floor, traditional block also but need to ensure better insulation factored in, timber frame is what we've always assumed would be the way we'd go (rightly or wrongly).  It’s all a bit of a minefield!

 

Pretty much any system can work with any shape / size. When you have below ground elements then timber is out for that part but IFC would be appropriate, or even a block or cast concrete system, with appropriate waterproofing (SE specced) for your ground conditions.

 

The MBC passive slab is not that complex and we replicated it for our basement and ensured that when we got to ground level, the profile matched what their timber frame would have required with their own system - i.e. an EPS insulated perimeter of sufficient thickness to meet the outer leaf (we used 200mm) and a 300mm thick concrete wall (they needed less) to take the soleplate for the load bearing inner leaf - plus structural support for other point loads inside the envelope. Best way to figure that out was to get MBC to design the frame sans slab and hand that design to a SE (or use theirs) to design the sub ground structure.

 

2 hours ago, jimmyharris80 said:

We always planned to enlist a main contractor to deliver the build, my wife and I neither have the knowledge or the time to manage the build ourselves (2 kids, dog and busy jobs!).

 

 

Few home truths here - whatever you think, you will be very involved in the build.

 

Unless you have very deep pockets and very, very detailed drawings speccing the location of every switch, socket etc, you won't just be handing off to a MC and coming back 9 month later to a completed house.

 

There will be a multitude of decisions to be made, some time critical, and some way ahead of when you think (i.e. what's your flooring finish - needed to set ffl through etc.) Many of these will need you on site to make a final call and many won't be obvious until the structure is up around you and you finally see what you're building. There will be alterations, deviations and mistakes (yours and theirs) to deal with.

 

We project managed with all of your constraints above and it's not that hard.

 

1) you know what you want (mostly) or will know when you see it.

2) you know what you can and can't afford.

 

Your contractors will deliver the build but as PM you select them (and you may well use very few in the end) and you tell them what you want.

 

You will likely want to source specific items (sanitary ware, tiles, kitchen, doors, handles, stairs etc) and get the quality / cost you want. I doubt you will just leave it to the GC to use bog standard off the shelf items - you just need to be able to use the internet and pick up the phone now and again.

 

You will not be ordering general building materials - most contractors are supply and fit anyway which is good for your cashflow, VAT reclaim and their sanity).

 

You'll be doing the VAT reclaim at the end as it's inevitable that you'll be buying some bits and pieces.

 

Adding all that up, you're effectively already the PM. Add a bit of tidying up and prep at the weekends and you're there.

 

2 hours ago, jimmyharris80 said:

 

When we visited BuildIt Live a month or so ago we did discuss with the construction & PM consultant the option of chunking up the build into 1. demo/groundworks/blockwork 2. timber frame 3. Main contractor through to completion.  This keeps interfaces to a minimum and would probably be the limit of what we could manage.

 

More or less what we did but we just used subs rather than a GC for post frame - what we did was this...

 

1) arrange site toilet, water & power for trades - latter will require an electrician and maybe your DNO if you need to move meter to a temps supply ahead of pulling down bungalow. Are you planning to live on site in a van (or the bungalow) we did the van and it saved a fortune and kept us close to the action, which helps. 

2) one contract to prepare site (demolish existing) excavate and build basement, in ground services (water, power, gas, rainwater) and leave site ready for MBC

3) arrange scaffolding & skips to MBC spec. 

4) MBC come and erect frame on prepared site - on a standard build they would do the slab also, maybe be a bit of a hybrid approach for you if some is sub ground and other areas at ground level.

5) Roofer, window supplier & installer and external facade (render in our case) come and do their bit. Guttering / soffit / fascia firm did their bit next and scaff came down (in our case while guttering man was still on roof but that's another story).

 

From the outside it looks like a finished house but internally just a shell.

 

6) Electrician & plumber get us to first fix. I do the MVHR as no-one will ever see it and it saves a few £k, but maybe you do supply & fit for this also.

7) Joiner comes to box out around services and put in door linings etc

8)) Plastering firm comes to insulate the stud walls and ceilings, 'tack ' (i.e. apply plasterboard) and skim (3mm cost of wet finish plaster to board).

9) Tiler tiles bathrooms and other areas, painters paint, flooring goes down.

10) plumber and electrician come back for second fix (sockets, switches & sanitary ware)

11) joiner returns to hang doors and fix skirting & architrave etc

12) last thing we did was install stairs (used temp MDF ones provided by MBC up to this point) to avoid damage.

13) external landscaping, this tends to be the bare minimum to get BR sign off as funds tend to be low at this point but probably grading organic areas, laying turf and dressing the driveway etc

 

You may well get a contractor to take everything post shell on as a package but you don't need to.

 

2 hours ago, jimmyharris80 said:

The alternative could be an MBC type offering, groundworks + timber frame with a main contractor taking over from there, I would need to check with MBC if the retaining wall/semi-basement we have could be accommodated within their foundation system.

 

They will only do the flat slab but their SE can spec adjacent works for others and ensure it all ties together.

 

2 hours ago, jimmyharris80 said:

A lot to read up on for sure, and we may look at enlisting some independent professional advice as to the best build approach for our circumstances as this decision impacts on the design changes we need to make.

 

 

We'll be going with a main contractor, we just don't have the time or knowledge to manage ourselves.  Total square meterage is approx 215m2 across the three levels.

 

We did 400m2 solo, tbh it's not that much more effort just bigger quotes

 

2 hours ago, jimmyharris80 said:

 

We're in rural Hertfordshire, soil is clay and pretty heavy, we've had a soil report done and it will fail an infiltration test.

 

Edited March 21, 2022 by Bitpipe

[Marvin]

On 18/03/2022 at 13:12, JohnMo said:

Hi, would agree to add later, even later in the design process will cost you. 

+1. 

[Marvin]

Hi @jimmyharris80

 

Something that comes up time and time again is that you only buy insulation once, but you pay for heating or cooling every year, and every year it goes up.

 

Good luck. M

[jimmyharris80]

19 hours ago, Bitpipe said:

 

Pretty much any system can work with any shape / size. When you have below ground elements then timber is out for that part but IFC would be appropriate, or even a block or cast concrete system, with appropriate waterproofing (SE specced) for your ground conditions.

 

The MBC passive slab is not that complex and we replicated it for our basement and ensured that when we got to ground level, the profile matched what their timber frame would have required with their own system - i.e. an EPS insulated perimeter of sufficient thickness to meet the outer leaf (we used 200mm) and a 300mm thick concrete wall (they needed less) to take the soleplate for the load bearing inner leaf - plus structural support for other point loads inside the envelope. Best way to figure that out was to get MBC to design the frame sans slab and hand that design to a SE (or use theirs) to design the sub ground structure.

 

 

Few home truths here - whatever you think, you will be very involved in the build.

 

Unless you have very deep pockets and very, very detailed drawings speccing the location of every switch, socket etc, you won't just be handing off to a MC and coming back 9 month later to a completed house.

 

There will be a multitude of decisions to be made, some time critical, and some way ahead of when you think (i.e. what's your flooring finish - needed to set ffl through etc.) Many of these will need you on site to make a final call and many won't be obvious until the structure is up around you and you finally see what you're building. There will be alterations, deviations and mistakes (yours and theirs) to deal with.

 

We project managed with all of your constraints above and it's not that hard.

 

1) you know what you want (mostly) or will know when you see it.

2) you know what you can and can't afford.

 

Your contractors will deliver the build but as PM you select them (and you may well use very few in the end) and you tell them what you want.

 

You will likely want to source specific items (sanitary ware, tiles, kitchen, doors, handles, stairs etc) and get the quality / cost you want. I doubt you will just leave it to the GC to use bog standard off the shelf items - you just need to be able to use the internet and pick up the phone now and again.

 

You will not be ordering general building materials - most contractors are supply and fit anyway which is good for your cashflow, VAT reclaim and their sanity).

 

You'll be doing the VAT reclaim at the end as it's inevitable that you'll be buying some bits and pieces.

 

Adding all that up, you're effectively already the PM. Add a bit of tidying up and prep at the weekends and you're there.

 

 

More or less what we did but we just used subs rather than a GC for post frame - what we did was this...

 

1) arrange site toilet, water & power for trades - latter will require an electrician and maybe your DNO if you need to move meter to a temps supply ahead of pulling down bungalow. Are you planning to live on site in a van (or the bungalow) we did the van and it saved a fortune and kept us close to the action, which helps. 

2) one contract to prepare site (demolish existing) excavate and build basement, in ground services (water, power, gas, rainwater) and leave site ready for MBC

3) arrange scaffolding & skips to MBC spec. 

4) MBC come and erect frame on prepared site - on a standard build they would do the slab also, maybe be a bit of a hybrid approach for you if some is sub ground and other areas at ground level.

5) Roofer, window supplier & installer and external facade (render in our case) come and do their bit. Guttering / soffit / fascia firm did their bit next and scaff came down (in our case while guttering man was still on roof but that's another story).

 

From the outside it looks like a finished house but internally just a shell.

 

6) Electrician & plumber get us to first fix. I do the MVHR as no-one will ever see it and it saves a few £k, but maybe you do supply & fit for this also.

7) Joiner comes to box out around services and put in door linings etc

8)) Plastering firm comes to insulate the stud walls and ceilings, 'tack ' (i.e. apply plasterboard) and skim (3mm cost of wet finish plaster to board).

9) Tiler tiles bathrooms and other areas, painters paint, flooring goes down.

10) plumber and electrician come back for second fix (sockets, switches & sanitary ware)

11) joiner returns to hang doors and fix skirting & architrave etc

12) last thing we did was install stairs (used temp MDF ones provided by MBC up to this point) to avoid damage.

13) external landscaping, this tends to be the bare minimum to get BR sign off as funds tend to be low at this point but probably grading organic areas, laying turf and dressing the driveway etc

 

You may well get a contractor to take everything post shell on as a package but you don't need to.

 

 

They will only do the flat slab but their SE can spec adjacent works for others and ensure it all ties together.

 

 

We did 400m2 solo, tbh it's not that much more effort just bigger quotes

 

 

 

Thanks Bitpipe, very informative, when you put it like that is all sounds so simple!  The more I read and begin to understand, the more I think there are elements we can manage ourselves and it's certainly becoming more appealing, just looking at the wealth of knowledge here and the assistance other self builders in our situation have received it certainly gives me more confidence.

 

We know there will be a lot of decisions to make a long the way and there will be a lot of time required on our part, it's just the management side of it and dealing with the interfaces between trades and ordering/scheduling that we're a little nervous taking on ourselves because it's all new.

 

Taking on some of the management will potentially elongate the timeline, but that's not necessarily an issue as we'll be living here on site in the current bungalow minus garage and a back bedroom which we'll need to demo to make way for the new build.  Taking our time and getting it right is more important than speed, we plan to live in the place for 15-20 years.

 

I had a chat with Keith at MBC yesterday on their slab system and his view was that having the retaining wall pushed back and separate to the slab was the way to go which then works with their slab.  That is not what we have in the design, the retaining wall is incorporated into the structure.  He did give us a contact of a groundworks firm he's worked with previously on a similar setup so I will look to make contact with him to get his view.  I think I'll put a post up in the foundations section to cover this particular element, as it's a significant part of the build that we need to ensure we get right.

 

Right, back to reading some more posts on here, it's what i'm doing in every spare moment I have!

[Bitpipe]

12 minutes ago, jimmyharris80 said:

 

Thanks Bitpipe, very informative, when you put it like that is all sounds so simple!  The more I read and begin to understand, the more I think there are elements we can manage ourselves and it's certainly becoming more appealing, just looking at the wealth of knowledge here and the assistance other self builders in our situation have received it certainly gives me more confidence.

 

We know there will be a lot of decisions to make a long the way and there will be a lot of time required on our part, it's just the management side of it and dealing with the interfaces between trades and ordering/scheduling that we're a little nervous taking on ourselves because it's all new.

 

Taking on some of the management will potentially elongate the timeline, but that's not necessarily an issue as we'll be living here on site in the current bungalow minus garage and a back bedroom which we'll need to demo to make way for the new build.  Taking our time and getting it right is more important than speed, we plan to live in the place for 15-20 years.

 

I had a chat with Keith at MBC yesterday on their slab system and his view was that having the retaining wall pushed back and separate to the slab was the way to go which then works with their slab.  That is not what we have in the design, the retaining wall is incorporated into the structure.  He did give us a contact of a groundworks firm he's worked with previously on a similar setup so I will look to make contact with him to get his view.  I think I'll put a post up in the foundations section to cover this particular element, as it's a significant part of the build that we need to ensure we get right.

 

Right, back to reading some more posts on here, it's what i'm doing in every spare moment I have!

 

No problem, this is the stage where you can get real world advice and costs from contractors etc which is useful to counterbalance the ideas of the architect which sometimes can be complicated to realise before you commit to any course of action. 

 

Also, super important, never feel pressurised continuing down a path that you're not comfortable with just because you find yourself on it. It's not the end of the world to tweak an approved planning app  - we did it twice after our initial PP, one full app and one NMA.

 

I think you're ideally set up to be honest, being on site is a massive advantage as you can see what's going on and are there to be consulted on a 'how do you want this done' conversation. 

 

Most trades will take care of sourcing their own materials, inherent in a supply and fit arrangement, but you will want to be involved when it's something higher value or aesthetic - sanitary ware for example. Don't expect trades to spend all evening on the web finding the best price for a nice Hans Grohe rainforest shower for example.

 

All you're doing really is taking the responsibility to co-ordinate, plan ahead and find trades that a general contractor would do on your behalf and charge you 20% overhead for. Most decent subs are self contained businesses and will come, quote, give you some free advice maybe and then want to be booked in with reasonable notice. Payment by invoice and make sure you're not charged VAT for anything - if you buy materials in your name then you pay VAT and claim it back at end of project.

 

Keep the questions coming, we've all been there and are only knowledgable by standing on the shoulders of others and our own experiences (and mistakes)!

 

Edited March 22, 2022 by Bitpipe

[JohnMo]

To give you an idea of a normal (ish) foundation on sand (although is really an old sand dune, which is now 10 miles from the sea).

 

First photo strip foundations, the front wide ones are all reinforced.

 

Second photo has insulated retaining walls up to DPC and stub walls where structural walls are going. Everything is thermally broken using thermolite blocks

 

Following this ground leveled, then DPC, two layers of rebar, 160mm concrete.  Then 200mm of PIR, then DPC and UFH pipes then another 100mm of fibre reinforced concrete.

 

A passive slab would have been way less work.

 

[jimmyharris80]

2 hours ago, Bitpipe said:

 

No problem, this is the stage where you can get real world advice and costs from contractors etc which is useful to counterbalance the ideas of the architect which sometimes can be complicated to realise before you commit to any course of action. 

 

Also, super important, never feel pressurised continuing down a path that you're not comfortable with just because you find yourself on it. It's not the end of the world to tweak an approved planning app  - we did it twice after our initial PP, one full app and one NMA.

 

Great shout, we are keen to move forward but only when we know what we're proposing is achievable within the constraints we have and the risks we're willing to carry.  I'm starting to question whether the current design is doable within our budget, but I'll keep plugging away researching and informing myself as much as possible to establish this one way or another.

 

I've put a post up on the foundations section for people to give their views on what the art of the possible is.