Bitpipe

Removing complexity is key to removing cost - you don't need to resign yourself to a featureless box but some architects will include details without much thought on how it will be built. Groundwork is often the biggest unknown cost so get that nailed down first and understand what different options will cost then work forward on slab and frame etc.

Did you get an actual topological survey of the site that can be imported into a cad tool? Our architect insisted on one before starting any work and it was a useful tool thereafter. Anyway, your GF looks over complicated. Why not push the retaining wall to the back of the build and have a contiguous slab and steal some extra space while you're at it? Could be a useful location for a TV/cinema room / plant / gym etc. The step down into dining room looks awkward and will restrict your usage if/when mobility becomes an issue. Easy enough to put ground level light wells back there too We built a passive TF on-top of a basement and it worked well, we just mimicked the passive slab design with SE specced EPS under the slab and on the outside of the concrete walls. Essentially you'd be doing a 3 sided version of this in block, ICF or cast concrete then have TF to the front and for the first floor upwards. Alternatively you could have the retaining wall discrete from the house structure and have a simple slab and TF construction from slab upwards.

It's the gold bars in the hem to weight them down that does it. Or if you buy from John Lewis, diamonds and rubies.

Rollers have gaps between panels too - our cheap tensioned wire and clipped on voile panels work well as the internal backup as they can be moved as the sun does and address glare spots.

Same as ours - saves on cost of curtains also as they give you a lot of privacy even when letting in a lot of light. Always amazed how expensive curtains are!

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)!

I only lifted mine during the recent storm - have never done that due to high winds in the last 6 years.

Interesting - the composite board is only £16/m2 and I'd assume the cross batten material cost and overall labour cost would be equivalent (have you a grip on those yet?) By comparison my render cost is £70/m2 for batten + board and £78/m2 for the topcoat - all ex VAT.

While our blinds are a similar design to @jacks they seem fairly good at blocking most light when tilted to max closure, but not complete blackout. Happy to take a pic if that helps. We though that we'd want to recess them completely during the day but in reality they do not move up and down at all, we just adjust the tilt of the blades depending on time of day and strength of sun. You get complete privacy when they're past 50% closure as there's no line of sight at street level (will still let in light as sun is obv. higher in sky). We did not spec blinds to the west as it faces the garden and we didn't think gain was as problematic here, which is true apart from summer when it still makes a difference at 3/4pm. We initially put up a cheap (£10) tensioned wire from Ikea across each of the 4.5m sliders and clipped on hemmed panels of linen fabric (again, Ikea) which were surprisingly effective at blocking light and heat. We've since added some internal Ikea opaque motorised blinds (with the Ikea smart hub) which can be adjusted to any height to manage glare etc. Looking forward to seeing how they do in summer - there is a few cm gap between each one though but we still have the voile to mitigate.

Lovely. We need to replace our Parex render (MgO carrier board failed, not the Parex part) and are thinking of doing something completely different like dark vertical timber or equivalent composite. What is the per m2 cost of yours and is a regular joiner installing or a specialist?

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

Twin wall timber frame with pumped cellulose insulation? Similar concept as SIPs but back when we built (2015/16) cheaper. We also considered ICF which many here have used and it lends itself to DIY also. No secret that we used MBC who can also do the passive insulated foundation slab (we had a basement so replicated the spec ourselves) so just one contractor to work with for the super structure. They guarantee the airtightness spec (provided you use appropriate windows & doors) and also include all floor decks, stud walls (not just the structural ones) etc.

I left my plant room unfinished on purpose as it's the only place I can still see the cast concrete walls, which I really like. Floor is covered in self levelling compound that was used in rest of basement and it wears reasonable well. Unfinished plasterboard to the interior wall where the door is and ceiling. BC just asked me to fill any gaps with fireproof LE foam which was a 20 min job.

Two different issues at play here - one is insulating from outside noise and the other from internal noise. The first is easier to achieve - well insulated walls (we have the twin wall system) good airtightness, triple glazed windows without trickle vents etc will all minimise noise transmission from outside (traffic etc). Internal noise transmission is much trickier as your rooms are harder to isolate from each other. You may be able to create a quiet room but I have met some self builders who have spent a lot on resilient bars, rubber mats, sound-blocking plasterboard etc and all to little effect. Agree on badly planned glazing - when your house is well insulated this can lead to significant overheating due to solar gain. We have external blinds to east and south glazing which is very effective. In regard to the twin wall, it's a specific timber frame design that allows a relatively deep cavity between inner (load bearing) and outer walls that is filled with pumped cellulose insulation while reducing cold bridging and also ties in with a passive slab which decouples the structural elements from the elements. You can get similar performance from different approaches like ICF or block & beads etc.

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.

Had a lot of hard landscaping works done post build, including two large block paved in/out driveways. Used a guy who's bread & butter is block paving so watched him closely as I'm using the leftover blocks for a small bin store. +1 for the paving expert. The basics seem to be excavating to sufficient depth, especially on sides. Generous bed & haunch for the perimeter blocks as they stop the other blocks moving, very well compacted bed of type 1 for the main block bed, blinding sand and then blocks. Whacker and kiln dried sand to lock it all together. Where it gets complicated is ensuring a sufficient fall for water, drainage (aco) and cleanly cutting blocks when you get to the perimeter. My guy made it look easy but had years of experience. As above, if you're planning to park on it then you need necessary permissions and need to ensure you're building to a sufficient weight standard (deeper excavation and type 1 layer).

Same as us then! 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.

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.

Digging into this requirement a bit deeper.... Given your location and earlier comments on overheating risk you could consider an insulated slab design where the entire structural ground floor of your home (assuming you don't have a basement) is isolated from the surrounding ground using high density insulation (EPS 200+ grade). The UFH pipes are cast in the slab removing the need for additional layers of insulation and screed and usually run at a fairly low temperature (35o). This works best when the house is highly insulated and airtight, reducing the space heating requirement. If you use a ASHP then in summer this can be run in reverse to cool your slab on warmer days. Given your sunny location I would ensure that solar PV is part of your design as it will be able to make a significant contribution to your power requirements in summer. I'd also make provision (really just ducting & services initially) for split air conditioning should overheating become problematic. MVHR is very effective at delivering fresh air while minimising energy loss but given the intentional low airflow of these systems, it's not an effective means of moving heat (or coolth) around the house. That said, in a very efficient home (approaching passive standard) then it can act as a trim function. Think also on external blinds for east & south facing windows as this prevents heat penetrating the house early in the day. Our building (similar size to your proposed one) has a twin wall timber frame construction with the cavity insulated with pumped cellulose. This delivers great insulation but also has high decrement decay and good soundproofing properties. Your windows will also be key, triple glazing will deliver excellent soundproofing and tend to have the necessary seals and gaskets that help also. Also important to remember that any external facade (brick, stone, render, timber cladding etc..) can be combined with any structural system (block, timber frame, ICF) and the various structural systems all have their own pros and cons wrt speed of construction etc and all tend to balance out cost wise - the structure is usually only 20% of the building cost. I guess the big takeaway here is - design and build using the system and spec that gives you the house and performance you want - don't be confined to only what your builder friend is comfortable with and don't fall for the story that other systems are 'too expensive'. Do your research and understand all the pros and cons. Good luck, you'll get lots of help here - between us we've probably used every type of build system and made every mistake there is to make

Also, +1 to avoiding working with friends. A large refurb a few doors up from us has gone to pot as the 'family friend' builder was obviously taking liberties and was difficult to challenge. We walked past the site daily to see little ever happening whereas ours was always a hive of activity and we did the whole project in just over a year from demolition to moving in. Two years in and theirs is still a shell, family have moved back onsite in a caravan (to save money obv) and a local builder is now trying to catch up.

We demolished and rebuilt. It removes all the risk and uncertainty related to the previous fabric and gives you the opportunity to build a modern, energy efficient and comfortable replacement home. If you get it right, your running costs will be minimal and it will be a very pleasant environment year round. Airtightness and high levels of insulation are key, given you're in the south coast you'll need to focus more on managing summer overheating than winter heating. Sadly a lot of the construction industry, architects included, are still stuck in the past and will design and build to a minimum building regs standard with minimum insulation in walls, trickle vents in the windows, radiators everywhere etc. You can do better so do your research now.

Our landscaper has had more than a few non payers, his bread & butter was block paving and he's now out of that as was not worth the grief. As said above, you're in a civil contractural dispute and need to be very careful with how you persuade the client to pay as it's easy to cross line and end up on the wrong side of criminal law. Also heard of a few 'revenge' tales involving postcrete and the water stopcock but again, does not get the bill paid.

PP on previously undeveloped land is very, very difficult to obtain. Your best option is to find a plot in an established area, however if it has not been snapped up already then it suggests that the plot is challenging to build on and there would not be enough profit in it for a developer - e.g. on a slope or an odd shape etc. You can get a mortgage on most property assets with value however this depends more on your circumstances than the plot itself. Utilities can be extended to any plot but question is at what cost - quotes of £40k for power are not unheard of but usually much less than this. Again, if you're in an established area then access, power, water and sewage are usually close to hand. What many of us here have done is to buy a tired property in an established area, demolish and rebuild. Not every mortgage provider will support this (we had that issue) so you either need cash to finance or use a self build mortgage specialist. Sadly, even though you can build on a budget, you will need access to a significant chunk of cash to get the plot and fund the build. £2000/m2 is not a bad rule of thumb for the build itself unless you can put a reasonable amount of time and work into it.

Because in my case it's a combination of timber battens, carrier board, base render coat, mesh, second base coat and then topcoat finish. As there are multiple elements, sourced from different vendors, it's a system and needs to be designed and installed as such. Simple monocoat render (e.g. cement based) on an existing substrate (eg blocks) would be more straightforward. In my case the carrier board has deformed, warped and cracked. The render on top is fine but it does not look good and at some stage even that may fail. Now looking at a fibre cement board (e.g. Hardi) as an alternative.

At the time the system was approved by BBA, NHBC and the render topcoat supplier, the MgO based board in question has now been quietly removed from sale by its manufacturer and is no longer approved by anyone. However the board manufacturer accepts no liability on the board itself even though it is now notorious in the render industry as prone to failure. I'm deliberately not naming names as have been advised by the contractor that I'm working with to resolve that the board vendor is very active at pursuing defamation on other forums so best keep BH out of the line of fire. As it can't be sourced anymore there's no risk of anyone accidentally using it on their build. Looking at replacing with a different render system based on a Knauf board or doing something completely different such as timber cladding. I'll have to bear the cost of removal and replacement - original render contractor has now ceased trading but to be fair to them they did a cracking job and were not to know. Many similar contractors have been left high and dry by the same issue. Main challenge at moment is getting the works zero rated (given the removal and re-instatement will be a £50k+ job this is not trivial). There is case law and precedent as the original works have failed so this is not refurbishment. Still trying to win that argument with the new contractor's accountant though.