Visti

Thanks all, these numbers really help to gauge where in the ballpark we stand with the Colorcoat, though prices certainly do seem to have jumped in the last 12-18 months by the looks of things. The main thing for us is the DIY aspect; the more we can do ourselves to drive down the price the better, and this certainly does look to have a lower skill requirement to install that zink. Saying that, I'll also be investigating DIY Zink following the additional information @Alexphd1 PM'd as it does seem viable when DIY'd

We're discouraged by Zink due to the ~£120/m2 (material + labour) cost that we're being told by both our architect and quantity surveyor. We've reached out for actual quotes but are seeking alternatives until they come back, hence the query. Would you mind sharing your supplier with me via PM @Alexphd1?

We were thinking of going the same route following the cost of zink! What sort of £/m2 are you being quoted for materials and labour @Pete? Seperate figures would be great if you've got them

We've been quoting for MVHR's left right and center these past few weeks and have come to several conclusions: We're confident we can DIY the installation We think we can design the layout of the ducting (for a radial system with semi-rigid ducting) We have no idea why spec's (and therefore costs) being quoted to us vary so immensely (suppliers & units below) Calculations for Whole Dwelling Ventilation Rates (Table 5.1b) Calc 1 (# rooms) 4 bedrooms: 25 l/s = 90 m3/hr Calc 2 (internal floor area) 0.3 l/s/m2 * 184m2 = 55.2 l/s = 198.72 m3/hr Calc 3: (max # inhabitants) 14 * 4 l/s = 201.6 m3/hr (given our plans, we can sleep up to 14 people at peak times like Christmas and Easter) That leaves us with a unit requiring a flow rate of at least ~200m3/hr. Clearly we don't wish for the system to run at 100% due to noise and maintenance, so a unit with a capacity greater than this would be ideal. But is 50, 60 or 70% the best measure? And what pressure differential should be be considering? 50, 100, 150 or 200? There seems to be no standard way to compare these units! I'm an aerospace engineer by trade, so I'm certain that we can go ahead with the installation ourselves as well as the design. Then again, the same profession makes it difficult to select THE unit we should go for without thoroughly understanding that is it indeed the correct specification for us. Another compounding factor appears to be that Genvex is highly recommended in previous posts despite the units purchased by @PeterStarck and @JSHarris being almost double the cost of the units above (~£4k). Is this due to the inbuilt heat pump or combi boilers? or am I missing something? Edit: I should add that the total internal volume of the house is about 586m3, larger than the typical volume per m2 which makes the sizing even more tricky!

Welcome to the forum from another recent newcomer! I concur with @Ferdinand and @recoveringacademic: whichever you select will become a pivotal third member of your team. So you've got to not only know that their work is good but that their values are aligned to yours. No good hiring a renowned contemporary architect if you're after a simple extension; their portfolio is a good place to start. Only correction is that the design is from Charlie Luxton, who is also a TV series host for Building the Dream which I also highly recommend. It is less 'grand' and focuses more on Charlies input in helping the self-builders with ideas as he is a certified architect in his own right. Funny enough, we didn't know he had a TV presence until shortly before we signed up with his firm as he'd been giving presentations at nearly every Graven Hill event we'd gone to over the past 4 years. The reason we went ahead with them and we're happy with the fee's (available in that thread) is because: The values they've championed in every public presentation, TV show and private engagement with them was 100% in-line with our own values Our very tight budget for a ~200m2 build was less of an issue and seen as more of a challenge for them to achieve They were brutally honest with what may be achievable with out budget before we started, and have been ever since. They spent a lot of time with us to distill down exactly what elements we wanted and our priorities. This helped to highlight any conflicts we had between the two of us. They are incredibly considerate; James who is heading up our project is very compassionate and Charlie doesn't get any less excitable or personable in real life. p.s. Listen to the folks on here, they have a wealth of knowledge that'll help immensely!

Great breakdown of how to prioritize each of the jobs in FF, that's placed a few more line items into that phase of the plan with lots of important commentary in red so I don't forget!

I'm in the same boat as you in having to figure this out shortly for our double gable vaulted ceilings. I'll hang around to see what others suggest

MBC have offered to place UFH onto the foundation prior to pouring the screed even if they don't do the slab themselves, so we're likely take that option. As for combi's, we've been advised that they don't scale well with fluctuating numbers of people in the house and that their long tern reliability is questionable. We'll certainly be installing the MVHR following everyone's recommendations here. We've estimated $4k cost to be on the safe side (we're awaiting quotes from 6 suppliers), the other £4k you'll see listed in the DIY column so we'd expect to 'save' that. As for the slab on clay... we may need to take that up with the warranty provider again then. Keep getting told one thing by the 'experts' and then another thing in reality from everyone here. Just glad we're able to get that second opinion

Good shout! We've investigated Fermacell but weren't convinced the outlay was worth it. Thanks for the alternative The separate Acoustics line is going into the floor (37m2), not the internal walls. The category could be better named I suppose! 5mm IsoBase R50 PC @ £20/m2 = £1,110 VL-65 Acoustic membrane PC @ £40/m2 = £1,850 Nope, that one is new to us. More research for us I guess! Thanks for the heads up on the UFH issues, we've had the same from our architect and are including mixer units and pumps with weather compensated control to address the issue. We're not hugely concerned with heating other than not going overboard given the Cellulose! The frame is all good, it's just the use of a slab on clay that Premier wouldn't gaurentee!

That I certainly can! In fact, there are a couple of articles on NaCSBA which cover GH planning in general. Another article on NaCSBA covers the tax implications specifically surrounding serviced plots where they cover the approach GH has taken. It's complicated and not ideal, but I believe that is more down to Government Policy not having adapted to this sort of scheme as opposed to the council trying to make a quick dime. Same for us; about £22k for the passive slab and £43k for the frame and then various upgrade packages for the insulation. The substructure estimate above is for a beam and block foundation however as we couldn't go with MBC for that in the end. The only restriction we've had in place in this regard is the type of foundation that needs to be applied due to the local ground conditions that GH surveyed prior to our plot reservation. It was defined in the 'Plot Passport'... the document that defines the minimum requirements of the build in line with the GH Design Code / LDO. More details in the first article linked above! "Type of Ground Floor Slab: The proposed form of suspended ground floor slab; e.g. precast concrete beam and block, cast in situ reinforced concrete, etc. (NB: the ground floor slabs will need to be suspended to allow for heave and the expansive, shrink / heave of the highly plastic underlying Oxford Clay)." Otherwise we were free to pick and chose. We were keen on having MBC do the foundation as well as it would ensure continuous insulation between that and the frame. GH worked quite hard to help us make it work in so far as to offering to hire MBC direct to do the work and looking into alternative structural warranty providers who may accept them (Premier Guarantee didn't, who are the ones included in the Golden Brick). Ultimately it was the latter that caused us to throw in the towel as the administrative faff of getting another provider and the outlay of a couple extra thousand quid wasn't worth the delay. We know that this is far from the typical self-build experience, but unfortunately there's little other choice in Oxfordshire unless we're stupidly lucky in finding land (failed at that for 4 years) or win the lottery! Financially this is the best opportunity we have to build near where we want to stay. Biggest difference is the £36k of DIY we've identified as potential savings which is really a big factor in cutting down the labor cost which is high here in Oxfordshire. Primarially in the Superstructure, Finishes and Services Areas cut down: -£5k Drainage (dependent on Golden Brick though!) -£2.5k Service Connections (dependent on Golden Brick though!) -£9k Heating (simplified from ASHP to Gas Boiler) -£8k Electricals (removed solar voltaics) -£7K Drive (can wait until we move in) -£6k Veranda (can wait until we move in) -£3.5k Landscaping (can wait until we move in) -£3k Tiling and Joinery (out! can wait until we move in) Areas that went up: +£7 Roof (upgraded corrugated steel to zink cladding) +£10k Frame (Cellulose insulation) +£5k Kitchen (I believe people were right in that we were specking too low. Can always get a temporary IKEA one though!) That'd be the double layer of plasterboard (£5 - 6.5/m2) and the inner wall acoustics (£4/m2). We may halve this later, but given I'm of the large and accident prone persuasion I do like the idea of walls with a bit more of a sturdy feel to them. About 50%+ of this we plan to save via DIY

So! Thanks to you all the cost estimates have been revisited following the suggestions here and we've managed to plug some line items with quotes. We're now in a position whereby we're confident we can continue with the self build without compromising the key elements of the house nor going bankrupt. It ought to allow us to potentially take some knocks on the way if (when!) they occur. It isn't perfect by a long shot, though it feels a lot more realistic than the Quantity Surveyor and will be a good baseline for moving forwards. It'll probably creep up by ~£100/m2 through discretionary spending, but at least that wont be hidden! If anyone wants access to the excel model they're welcome to a redacted copy placed on Google Drive here. It could use some additional functionality for identifying estimates vs quotes vs actual's which I'm sure will be built in in time.

I've been continually astounded by the fantastic level of input from the community on here; creating an account here is the best decision I've made in this self-build process to date! I'll defiantly be taking up offers of visiting your builds/completed homes and to take on any advice you'd be willing to impart. I'll PM those of you who've already offered shortly. Same offer goes for me: anyone who wants to visit our build when it gets underway in March/April are very welcome. I'll also share the cost modelling so people can poke at the details and use it for themselves.

We have been willing since the beginning to pay a bit more for a architect both for their design input as well as for the helping hand; we agreed 13% based on a fixed budget hence the higher than expected expenditure there. We knew they weren't cheap, particularly as Charlie himself has his own TV programme, but they were one of the few that we contacted who had a similar philosophy to what a home should be and appeared to be genuinely interested given our limited budget. That cost is firmly our call and can be adjusted downwards if we chose to manage more of the build down the line (which is likely... there's a chance that maternity leave will coincide with the build!). Heaven forbid, burning bridges doesn't ever work well in the long term and rarely does in the short term either! No, we'll engage as you've said; reiterate our shock, outline the areas where we (the collective we on here!) consider the quantity surveyor was off and then our plan going forward. If anything, this has motivated us to take a lot more on board ourselves which is good. We both love powertools and I've a stack of IOU's to cash-in!

You're not wrong there! These replies are amazing and way beyond what I'd imagined! The missus and I are deeply grateful! I fully realize that I came into the industry with SUCKER painted in massive red letters across my forehead however we'd chosen our architects specifically for the fact that we felt we could trust them to help us in that regard. We've certainly had a rude awaking this week with these figures, and much of the feedback here is eroding our confidence in the surveyor and trust in our architect given how clear we were on the budgeting message from the very beginning. I'm going to incorporate everyone's feedback into a new iteration of the pricing and then get back to the architect and surveyor to 'have some polite words'. Once that's done I'll hope to get back to everyone on specifics and show the new estimate! If work isn't too mental that should be by sunday!

Whilst we've been maintaining a budget and a rough cost plan since engaging with out Architects, it's only in the last week we completed a detailed breakdown of our build costs via a quantity surveyor. We'd budgeted ~£250k to build this house (£225k with contingency) and yet we were quite stunned (as was our architect) when the surveyor estimated a whopping £400k! We were expecting ~£1500/m2, not an extra You can see a breakdown of this below: I've been over every line item like a mad-man since and have been pulling out all unnecessary elements and identifying area's where we can do the DIY ourselves so that it looks more like this, cutting down the total by about £50k. Focus is on improving the superstructure and cutting down everywhere else. Another £50k is feasible if we're willing to move into a 'technically finished' house with at least several years DIY work to complete which we'd ideally like to avoid! I'd appreciate an experienced eye on where this looks bloated or under-committed! happy to provide the spreadsheet on request For those interested, the plans for the house (184m2) are shown in this post here:

Not yet, we've asked for clarification as to exactly what needs to be in place for the structural warranty to be signed off and the build considered complete by the Graven Hill team. Once we have that we'll prioritize those activities to move in asap. Once in, we have the luxury of doing DIY on areas where we possibly can.

Labour and margin I suppose. They're still cheaper than some of the other quotes we've had by far. We don't have the luxury of a lot of time given the 2 year limit to finish the house, and the extra spend to finish quickly may pay off given the £1500 in rent we're forking out until we do.... a delay of 4-5 months doing it ourselves could erode those savings entirely.

Thanks all for the input though unfortunately the matter is hardly settled! We're dead keen on cellulose following all the feedback but we've just had a quantity surveyor estimate a whopping £400k for a 184m2 build, a good £150k over our original estimate of £250k (~£1400-1500 /m2). Hence the need to explore cost cutting options. I'll let you know which route we take following some alternative cost models! Correct, it isn't planning; this is a requirement from Cherwell District Council on the plots being sold at Graven Hill as ProDave pointed out. It doesn't affect us as we're keen on good insulation anyway! Given the £10k difference between the two options, the blue acoustic plasterboard may be a far more cost effective option to keep the sound levels down. Given how much we're looking to shave off the above cost estimate we'll be seriously looking into that. Thanks for the spec ProDave, we'll look into that as an option as the bare frame with no insulation is only £43k, shaving £20k off the MBC's installation of the mineral wool spec and £30k off the cellulose spec. Obviously the raw materials will cost, but the DIY element would help us retain some of those savings.

Not excessively fussed though it would be nice. I've got an alternative layout for the bins/bikes that ought to improve the car coverage in the car port, the number of bikes and gets the bins facing the inside. Just got to draw it all out and try it. Hah! Laura giggled when she read that. Told her I don't know how many times but it's always 'after the build'... It may not be too late now that you've helped hammer that wedge in just a tad more! We do have PD in Graven Hill despite the usual rules surrounding the development, hence the lack of any detailing of sheds or workshops yet. I like the idea of extending the car port to the back of the plot. Agree with the bike storage, tried to get that enlarged a few times but it keeps getting lost in the revisions. Try, try and try again! We hadn't even thought about the valley until this post and your additional points really highlights that there's a lot still to do here. A raised industrial mesh to give a flat surface would be a good start, then there's the ladders and accessability to consider. Good thing the next meeting with the Architect is this Friday! Thanks for the heads up, I was aware of the Housing Act, but not that specific part on overcrouding! I've quoted the paragraph below for the benefit of others if this ever pops up on their search radar. 325 The room standard. (1)The room standard is contravened when the number of persons sleeping in a dwelling and the number of rooms available as sleeping accommodation is such that two persons of opposite sexes who are not living together as husband and wife must sleep in the same room. (2)For this purpose— (a)children under the age of ten shall be left out of account, and (b)a room is available as sleeping accommodation if it is of a type normally used in the locality either as a bedroom or as a living room. Exactly our thoughts too. Bedroom 2 & 3 are provisioned for a mezzanine, either for moving the beds up or for storage. As a kid I loved the mezzanine in my room. Two are mandated, and we'll have space for a third car down the front side to the right if needed where we're having wild flowers. There's nothing stipulating the orientation of the cars or the need for a T drive... I may need to do some more digging in the requirements there! Agreed, yet another change that keeps disappearing with each of the revisions. I'll be a bit more stern this time with the Architect. Not sure I follow?

Laura had her eye on it for two years, so we're very glad we got it even thought it cost us more than expected. There'll eventually be some south facing gardens along the edge, but it'll take many years before they exhaust the northern and eastern segments and go for the south, unfortunately. The large veranda to the' 'front' of the house is to compensate for that very fact. If you need any info from the inline track then throw me a message on here. Thanks for the comments Peter! A 2nd unlabled bathroom on the ground floor. But you're right, no en-suite. It's been pointed out to us many times but we're not convinced that it is worth the added meterage or loss of space elsewhere. We realise it's a very unusual design, so we've designed an alternative plan for the bunk / multi function room that has a more conventional layout of two bedrooms and an additional bathroom between the two. Then, bedrooms 2 & 3 can be joined for a decent master bedroom with an en-suite. That's all for if we decide to sell and make it more conventional, which we hope not to have to do for a long while! Detailed plans are around the corner, but I'll keep in mind to raise this with our architect this Friday. Perhaps one or two down through the corner of the utility room. Thanks! Haha, good ideas, but none quite on the mark! Not far behind every spanish woman is their family, and extended family and so on... easter and christmas are usually packed affairs at 15-20 people. That doesn't even include my side of the family. Space is a premium, not just beds but also a quiet space to hide away for a moments quiet! Nick was not far off though as the kids aren't far behind either! Thanks all!

I'm looking for the advice from those who've gone with MBC for their builds with regards to the insulation that was chosen and how you feel it is performing? We're undecided between MBC's options where the U value is 0.15 W/m2k or better (there is a condition of a maximum of 0.15, so that's the minimum spec we can go with. The goal is to have a balance between performance and cost, so a passive standard isn't on our set of objectives. However, we are mainly concerned with several other factors: Longjevity Sound Insulation Air tightness Cellulose appears to have the advantage in all three areas over mineral wool and PIR from the reading we've done. PIR appears to suffer from shrinkage, off-gassing (low u-value gases leaking, reducing the performance of the insulation overall) and doesn't appear as foolproof to install (inaccurately cut and fitted they leave gaps). The main disadvantage is the cost of the cellulose option at+£10k on-top of our initial option of the U=0.15 mineral wool spec. Any advice / experience would be really helpful! Thanks Mineral Wool (MBC Upgrade to U=0.15) PIR (MBC Upgrade to U=0.11) Cellulose (MBC Passive Standard)

Hi Alex, from one newbie to the other, welcome! We seriously considered ICF/Nudura for a long time before setteling on timber frame, so I'm excited to see how you're applying it! Concur with TheMtchells; photos/drawings please

Hi all! Following a short stint lurking and reading some very informative posts on this forum I thought I'd sign-up and introduce myself. The name is Oliver and my partner and I have been looking to self-build for at least 5 years. We did all the courses (free and paid) on finding land, obtaining planning permission, exploring settlement boundaries, meeting with the local parish councils, searching the land registries, looking up rail and utility sales, talking directly potential neighbours, handing out filers at local pubs... you name it, we've tried it all in the name of finding a plot. We just didn't account for the south east, let alone oxfordshire. Does our naivety and inexperience show though? The time wasn't wasted however. We kept our eyes on the Graven Hill project since 2014 and were finally successful in reserving plot 156 earlier this year. We're at the Developed Design phase of the build and are currently assessing all the structural quotes with a fine tooth comb before settling on a supplier and the technical design. We are using Charlie Luxton for the design of the build and have many positive words to say about them as an architectural firm. Many of you will be glad to hear that MBC are in the running for this, included specifically after so many positive reviews from this board. The fact they turned around a 2nd quote for their passive standard within a few hours is a great indication of their professionalism. Now just to figure out which supplier/structure/insulation to go for... hopefully you'll see a few of my posts around asking about those very things. 3D Render: 156 outlined in red (centre) Site Plan w/ Ground Floor First Floor Section: