ProDave Posted April 24, 2017 Share Posted April 24, 2017 11 hours ago, Adamantium said: We had to resubmit due to an objection from the environment agency because the flood level models were out of date. We are building within 8m of what is classified as a main water way, but the EA is ok as a result of a betterment of the current position.The "river" is imho a brook, but I can't ignore EA modelling and so have considered this in the design. The plot is classed as flood zone 2, but has not flooded in 40 years. The river is about 5 feet wide and ranges between 2 inches and 2 feet deep depending on rainfall, it's about 2 metres below my first floor level, so I'm not losing too much sleep over it. That sounds very much like our burn More like about 3 feet wide when it's in a nice mood like that, but it can come up a lot and then flows very fast. Our house is probably closer than yours will be, and our floor is also bout 2 metres above the water. Plenty of places for it to flood to without causing problems. Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 11 hours ago, PeterW said: Quick one - how have you managed to get CIL exemption without planning..? My understanding is you need the planning permission first and that creates the liability..? Cheers Peter I haven't got it yet, I've applied for the exemption. At the same time as filing the forms to assume liability, I also applied for the self build exemption. Once permission is granted, I intend to dispense with the conditions as early as possible and then apply to confirm that I have started before doing anything that could constitute work. I'm even worried about having a soil sample taken as the amount of machinery might lead people to believe that work has started. I'd also very much like work to start to lock in the planning permission. I need to follow a careful path as the soil sample will allow detaileed design of foundations which then need to be submitted to thames water to allow buildover consent to be granted. That requires £2000 and CCTV footage followed by a wayleave/easement (they already have an easement over the land so I'm not sure if another needs to be created). After that I should be allowed to start digging. Right now I'm praying to be allowed trench foundations as piles could alter the design of the house (have to be slightly further from the sewer - which means narrowing the foot print unless a slab can overhang the end of the piles). I've already learned so much, but also learned that I know practically nothing. Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 ProDave, Similar kind of size yes, but we have masses of foliage lining the banks which are much steeper and concrete reinforced. The other nice thing is that 9 years ago a massive flood defense reservoir/accumulator was installed upstream to protect the village I live in from the minor flooding it used to experience. So far it has worked perfectly even during a few extreme examples of localised rainfall that would previously have created the issues it was installed to prevent. In all times, the water has remained a good two feet below the level of the concrete bank which is still significantly below my floor level and which is about 7.5 metres from the nearest point of my house, with 4 of those metres sloping away. Link to comment Share on other sites More sharing options...
PeterW Posted April 25, 2017 Share Posted April 25, 2017 Out of interest how big is the sewer and how close are you building to it ..?? Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 (edited) 860mm diammeter (strategic trunk sewer). Its invert level is 2m deep. If I use pile foundations they need to be 1.5 from the nearest point on the circumference, and have to be continuous augered piles. Conventional trench foundations can be 1m away and the 45 degree load zone from the bottom of the foundations must not overlap any part of the sewer. Having drawn up the cross section for approval, my foundations would need to be a minimum of 1.5m deep along the 15m flank wall of my house. Given the heavy construction of my house, I'd be surprised if conventional foundations would be shallower than that anyway, Ground investigation quote yielded the following information also: The available information indicates that the geology of the area should be formed of chalk, however there is a ribbon of alluvial deposits (clay, silt, sand, gravel) associated with the neighbouring stream. This alluvium may encroach on to the property but is not anticipated to be very thick. Edited April 25, 2017 by Adamantium Link to comment Share on other sites More sharing options...
PeterW Posted April 25, 2017 Share Posted April 25, 2017 So I take it TW aren't letting you connect into that ..!! Is your build within 3m of the sewer then ..? You may want to consider a passive slab as the loading would be less although the SE would need to confirm the 45 degree angle with something like that. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted April 25, 2017 Share Posted April 25, 2017 (edited) I was thinking that a passive slab would be a very good potential solution, at a lower ground works cost, too. Well worth looking into, in my view. My other thoughts were with controlling heat loss and solar gain. Even if the house is only constructed to our (pretty dire) building regs performance requirements, I think those very large areas of glass are going to need some very careful detailing. These sort of windows worked very well to bring light into cold and draughty Georgian houses, but will be both a significant cause of heat loss in winter and a potentially very significant cause of overheating in summer in a house built to modern standards, unless mitigation measure are put in place. My experience is that few architects are really up to speed with this sort of detail, although those who do a fair bit of commercial work often seem to be. Edited April 25, 2017 by JSHarris Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 3 hours ago, PeterW said: So I take it TW aren't letting you connect into that ..!! Is your build within 3m of the sewer then ..? You may want to consider a passive slab as the loading would be less although the SE would need to confirm the 45 degree angle with something like that. I have no desire to connect to that, I was planning on utilising the existing drainage connections with suitable modifications. Yes it's within 3m. Building over is unlikelyh to be permissible when it's a main strategic sewer, but I don't want to take the risk anyway. At least if I build up to a metre of it, the house can stay standing if they need to dig it up one day. Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 (edited) 3 hours ago, JSHarris said: I was thinking that a passive slab would be a very good potential solution, at a lower ground works cost, too. Well worth looking into, in my view. My other thoughts were with controlling heat loss and solar gain. Even if the house is only constructed to our (pretty dire) building regs performance requirements, I think those very large areas of glass are going to need some very careful detailing. These sort of windows worked very well to bring light into cold and draughty Georgian houses, but will be both a significant cause of heat loss in winter and a potentially very significant cause of overheating in summer in a house built to modern standards, unless mitigation measure are put in place. My experience is that few architects are really up to speed with this sort of detail, although those who do a fair bit of commercial work often seem to be. The heat loss is a concern but one that I cannot avoid. The light and appearance is very important to me, so I expect I'll need to subsidise the heating and cooling for eternity. I actually have no idea what a passive slab is, so any quick pointers would be greatly appreciated. I'm guessing its a floating slab of concrete that isn't anchored in deep foundations. This makes me concerned on the run adjacent the sewer as it really does require footings deep enough that the 45 degree load zone is safely beneath the sewer. Is it possible to build a slab that has a strip/trench as well in order to satisfy thames water? Once I'm outside the 3m zone, they don't care what the foundations do. Edited April 25, 2017 by Adamantium Link to comment Share on other sites More sharing options...
joe90 Posted April 25, 2017 Share Posted April 25, 2017 Yes, look at the Golcar passive house foundations. http://www.greenbuildingstore.co.uk/golcar-passivhaus-ground-floor-foundations/. This is what I copied, they are insulated but have strip foundations like you require and you don't have to pay circa £1000 for a structural engineer to design a passive slab for you. Link to comment Share on other sites More sharing options...
Ferdinand Posted April 25, 2017 Share Posted April 25, 2017 (edited) 23 minutes ago, Adamantium said: I actually have no idea what a passive slab is, so any quick pointers would be greatly appreciated. I'm guessing its a floating slab of concrete that isn't anchored in deep foundations. This makes me concerned on the run adjacent the sewer as it really does require footings deep enough that the 45 degree load zone is safely beneath the sewer. Is it possible to build a slab that has a strip/trench as well in order to satisfy thames water? Once I'm outside the 3m zone, they care what the foundations do. This is a passive slab, to be more exact @JSHarris' passive slab (sequence of photos). It is a concrete raft foundation (= less deep digging) incorporating about a foot of insulation such that, when combined with similar walls and roof, your heating bills are approximately zero. It is a shallow hole over the whole house footprint filled with hardcore and blinded (smooth layer on top to be less nobbly) with sand, and insulated under the concrete pour, perhaps with ufh and other bits and bobs poking out (soil pipes etc). Then the house is built on the layer of insulation usually as timber frame, with cladding. In the pic, all the black polythene round the edge is covering special insulation blocks that meet the insulation in the walls. A number of people here have used this (which is from a company called MBC) or similar systems. Edited April 25, 2017 by Ferdinand Link to comment Share on other sites More sharing options...
Jeremy Harris Posted April 25, 2017 Share Posted April 25, 2017 34 minutes ago, Adamantium said: The heat loss is a concern but one that I cannot avoid. The light and appearance is very important to me, so I expect I'll need to subsidise the heating and cooling for eternity. You can't avoid having to deal with the heat loss, even if you only build to the pretty awful building regs minimum requirements. You will have to meet the SAP requirements, and with large areas of glazing you will probably find that you need to go for the highest window spec you can find and uprate the insulation and airtightness of the whole house in order to get a pass. Might be worth doing some research now, and particularly learning how to drive SAP, You can download a version of the software here, that allows you to play about: https://www.stroma.com/software/sap-software-fsap . Just building to the minimum fabric requirements in the current building regulations Part L1a almost certainly won't now get a pass, whereas in the past it often would. This means trading things like glass area (which will always lose a lot of heat, even with the very best triple glazing available) with the insulation and airtightness of the rest of the house. One mitigation that might work for a house with a lot of glazing like this is to opt to make the house far more airtight than the regulation require as a minimum, then fit Mechanical Ventilation Heat Recovery (MVHR). It's relatively cost effective, can reduce the energy used to heat the house by a large factor (so helps meet the SAP requirement) and gives the added benefit of fresh, clean air in every room, with optional pollen filtering if you happen to have allergies or hay fever. A further advantage is that you can opt to fit an active MVHR, with an internal air-to-air heat pump, that can actively cool the incoming filtered fresh air in hot weather. We've opted for such a system, and it's pretty effective. Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 Thanks JSHarris, As regards glazing, you haven't seen the rear of the house which is almost floor to very high ceiling glass across the width. Most likely sliding doors rather than bifolds. The upstairs remains sash. I believe the design brief includes MVHR and air to air heat pumps. The windows are the top rated Bygone collection (fake wood UPVC sash) which are costing me a fortune but they are among the best u value upvc window that looks the part that I could find. I am desperate to avoid having vents on the windows though. I fail to understand why you make a house so airtight and then have to have mechanical vents. I need to determine how to do this to avoid ruining the look of the windows. My plan is certainly to uprate all insulation where possible. It sounds like a passive slab might be a big help in reducing heating bills too. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted April 25, 2017 Share Posted April 25, 2017 My advice would be to completely forget about having any sort of trickle vents in the windows, forget bifold doors as they will leak like sieves within a year of being fitted, and go for the very highest spec 3G glazing you can get, in the very, very best frames. Even then I think you might be really struggling to get a SAP pass, even with MVHR. Architects aren't always the best to do the system engineering work needed to make a house both comply with Part L1a and to ensure that there's no over-heating risk, as traditionally some architects would just chuck that "over the wall" to the engineer doing the detail design. That often doesn't work now that the requirements of Part L1a have been slightly tightened, as you can't just build to the minimum fabric performance standards and get a pass, as you used to in the past. I'd very strongly advise doing a design SAP right now, and seeing what the number are. With lots of glass it can be a real struggle to get the house to pass, which basically means no house, even if you have got planning permission and have built it. You don't want to find out after the design has been finalised that you're not going to be able to get through building regs. Sorry, I missed this earlier: On 24/04/2017 at 16:04, Adamantium said: fixed price contract - I recall reading there was a difference between fixed price and firm price - is that relevant here? In essence, a fixed price contract is not a "fixed price", but a firm price contract is. It's a bit confusing, but a fixed price contract (in English and Welsh contract law) has allowances built in for price variations, caused by things like exchange rate variations, changes in supplier costs etc. A firm price contract has no variation in price as long as the specification remains the same as that originally quoted for (which is another issue, as everyone always changes the specification as they go!). There is another contracting mechanism that I think works very well for expensive projects, and that's to opt to have a target cost incentive fee contract. This has a target cost, agreed by both parties at the start, and backed by a good QS, then an incentive arrangement agreed with the main contractor for any cost saving achieved over the contract duration. For example, you might set a target cost of £500k, and agree a 50% incentive fee. That mean that if the main contractor comes in at, say, £480k, then he gets £490k and you save £10k (the £20k saving is split 50/50 between client and main contractor. Managed carefully, such a contract can be a fairly good way of controlling costs, or even allowing for a higher specification if the main contractor can show a saving early in the build. Link to comment Share on other sites More sharing options...
Adamantium Posted April 25, 2017 Author Share Posted April 25, 2017 Really helpful advice - just as I was hoping for. I'm a patent attorney by trade so I have a fair amount of experience when it comes to contracts and if I can't cope, I know thousands who can. As for a design SAP right now, because of the complexity of the planning permission process so far, I'd rather get it through then look at the numbers. It's easier to apply for an amendment to the design once granted than to try to get the entire design through. You do have me wondering how all the similar yet much bigger houses around me manage to be built. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted April 25, 2017 Share Posted April 25, 2017 The building regs changed slightly for the most recent iteration, nowhere near as much as they need to, IMHO, as they are still crap in terms of energy performance, but the requirements of Part L1a has become a little more challenging to meet with way that heat loss is now determined. In the past you could just build to the fabric minimum standards (which haven't changed in the latest iteration, they are still poor) and be reasonably sure that you'd get a pass. Doing that now probably won't get a pass. For a large house, lack of airtightness will be the biggest heat loss, in all probability, so improving this can reap a really big benefit. The air leakage requirements in Part L1a are not great, 10m3/m2/hr at 50 Pa pressure differential, which isn't very airtight at all. It's easy to get better than 3m3/m2/hr with decent detailing - our house achieved a reasonable figure of 1.22m3/m2/hr, for example. In all probability, ventilation heat loss (with poor airtightness and no MVHR) will be the lion's share of your total heat loss, so designing for good airtighness from the very start (which means selecting a build method that is intrinsically easy to make airtight) will both reduce build cost (in terms of reducing the time taken to tape and seal to get the required air test figure) and make it easier to both meet the requirements of Part L1a and make the house a great deal more comfortable and cheaper to run. Link to comment Share on other sites More sharing options...
Adamantium Posted June 1, 2017 Author Share Posted June 1, 2017 Bit of a follow up - planning permission was granted in committee last thursday - one of the worst days of my life. Horrific interaction with my neighbour who blanked me as I walked into the proceedings. I know it is contentious but it has never been personal, and I wouldn't have held their view against them had I lost. I'm not sure the same can be said for how it has worked out. I am annoyed however, that they've seen fit to remove my category E permitted development rights so I will be appealing. In addition, I now cannot get confirmation that I am allowed to perform a soil investigation as no one can assure me that the machinery won't be considered as starting work for the purposes of the CIL. As a result, I need to discharge the conditions before we can start on the detailed plans! Link to comment Share on other sites More sharing options...
Pete Posted June 1, 2017 Share Posted June 1, 2017 These things happen. Before we approached planning we decided to contact the neighbours to inform them of our intentions and provide them with a copy of the elevation drawings to see if there was anything that they considered contentious. When I contacted one neighbour she just snatched them out my hand and never spoke to me again.She then tried to object at the planning stage by saying all sorts of things including saying that our development would cast shadow on her house even though her house was positioned east of our plot. Another neighbour was adamant that we should not be allowed to build even though she was waiting for planning to build at the bottom of her extremely large garden. Link to comment Share on other sites More sharing options...
jamiehamy Posted June 1, 2017 Share Posted June 1, 2017 Well done! In terms of revoking permitted development rights, it's quite common. In the grand scheme of what you have ahead of you is it a battle worth starting just now? When we did ours, the planning officer stated he would likely remove the permitted development rights as we were in a country park but they never appeared in the report or approval Now the fun begins! Link to comment Share on other sites More sharing options...
Jeremy Harris Posted June 1, 2017 Share Posted June 1, 2017 I agree, I'd not worry now about the PD rights being removed, the chances are that you will stand a better chance of getting them re-instated later, I suspect. Our original recommendation from the planning officer included removing PD rights, for several good reasons, including being opposite a listed building, being within an AONB etc. Between the recommendation and the decision notice I managed to persuade him to not include the condition revoking PD, but this was mainly because we ended up with no objections (there had been loads of objections to previous applications on the same plot). I'm convinced that the planning officer only changed his mind because all the previous objections had disappeared. In terms of neighbours, I think they'll probably come around in the end. All our neighbours had objected to the previous applications, some of them pretty vociferously. Now we get on well with all of them. Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 1, 2017 Share Posted June 1, 2017 53 minutes ago, Adamantium said: [...] Horrific interaction with my neighbour who blanked me as I walked into the proceedings. [...] My sympathy is entirely with you: I have had exactly the same experience, and it's not funny. People and systems show themselves for what they are when things go wrong- usually as a result of a contest for resources of some sort. So, your neighbours weren't any different before this episode: they were always like that. Their true nature was simply hidden. Here, have a laugh on us: read this Oh, and before I forget, welcome! Ian Link to comment Share on other sites More sharing options...
Adamantium Posted June 1, 2017 Author Share Posted June 1, 2017 The issue for me is that our plans result in the demolition of our two garages and removal of our three sheds. I have no objection to being prevented from adding a conservatory or extension etc. but I object to requiring planning to put a shed at the bottom of a large garden. They can keep their class A to D restrictions, but class E really bothers me, it feels like an arbitrary punishment because they didn't want to grant the application but had to due to officer support, precedent and it ticking all the boxes. My planning officer tells me that an appeal has no bearing on the rest of the planning granted, and I can still continue to dispense with the conditions to keep the ball rolling. Link to comment Share on other sites More sharing options...
Ferdinand Posted June 1, 2017 Share Posted June 1, 2017 (edited) What is stopping you adding your new sheds now under the PD rights for the existing dwelling, and then just not demolishing them when you remove the old ones? I am not sure when the removal of PD rights takes effect, but it cannot be before development starts. I guess it will be at the point you demolish. One problem might be if you have something like 'all existing sheds to be demolished' in your PP? What does it say? Edited June 1, 2017 by Ferdinand 1 Link to comment Share on other sites More sharing options...
Adamantium Posted June 1, 2017 Author Share Posted June 1, 2017 My planning doesn't mention the sheds only the garages. I asked about when PD rights change and the officer said she wasn't sure of the law. I assumed that it would be once the planning permission was in place, not necessarily once it had been started. My planning also shows demolition of one of my garages which doesn't overlap the new footprint. I was planning to retain it for site storage until the very end. I believe there's no legal implement to force me to complete the construction and hence demolish the garage at the end. Moot point really as the garage has to go - it's falling down anyway and is totally out of keeping the design and position of the new house. Link to comment Share on other sites More sharing options...
Ferdinand Posted June 1, 2017 Share Posted June 1, 2017 (edited) 6 minutes ago, Adamantium said: My planning doesn't mention the sheds only the garages. I asked about when PD rights change and the officer said she wasn't sure of the law. I assumed that it would be once the planning permission was in place, not necessarily once it had been started. My planning also shows demolition of one of my garages which doesn't overlap the new footprint. I was planning to retain it for site storage until the very end. I believe there's no legal implement to force me to complete the construction and hence demolish the garage at the end. Moot point really as the garage has to go - it's falling down anyway and is totally out of keeping the design and position of the new house. Personally I would just build the sheds you want now, provided they are not ridiculously prominent or painted germoline pink with cartoons of Homer Simpson mooning at the neighbour, document it, and just leave them there. Given your size of plot, I would expect to get away with it and afaics they would have no basis for enforcement anyway. I would still do the same even if appealing on a point of principle. Edited June 1, 2017 by Ferdinand Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now