saveasteading

Have checked the effect of cedars. Moderate water demand, and growing to 20m. therefore the house is too close to be unaffected. However you are on chalk. The SE will more likely save you money in the long run.

So ask them for a price. This looks like being standard details so they may not charge much, it may allow a reduction in your warranty (and insurance?) costs, and the SE works for you so will discuss options if you ask.

The calculation of carbon used as extra wood, as against any benefit from the sedum would be interesting. Also allow for plastic trays, if any, and special underlay. If you want the sedum for appearance then fair enough.

As I understand the drawing, the trees that would require deep founds are not near the building. What are the conifers shown as blue circles, as that is crucial? Having the name 'The Willows' is a bad start as they are among the worst water drinkers and the roots spread far. However, I am amazed that you are contemplating not engaging an SE. We are here to help but not do free designs and take any risk off you. The BCO will want drawings and calculations (and/or statements) to justify the proposal. They do not necessarily check very much anyway, and will expect to see expert design. Re construction method. My hunch is that beam and block will cost you a little more, as you need more foundations. Also you have lots of hardcore so that is a saving on an in-situ slab. I don't understand why that may not be suitable. You have chalk and so there is no reason for foundations to go deep. But there are many more factors, and we have not seen the site or drawings.

Well, we wouldn't want them to cut corners, but over-designing should not happen either. But a lot less than big deciduous trees. NHBC tables make it very easy.

Local builders have not bought it as they can't make money at it as a developer. In the UK equivalent position such a building is bought for self-build, where we can put in endless hours, change our minds and argue finer points with builders. At a distance this becomes even more difficult. If the builder or Architect or Mayor doesn't agree with your proposals, then you will have to do everything their way. You will have to use a local Architect, and what if they don't like refurb and only like complete replacement? So you must discuss with Architect, a builder, and probably the Mayor or Clerk at the town hall. And unless you know a lot about construction, speak the language including all its subtleties, and have at least 50% contingency on the price you are told, then it probably is too much of a risk. £10k or £50k? Yes. £10k with me on site all the time and if I could suddenly speak Italian and it was only these beams. £50k more likely...but perhaps £100k if the walls and roof come down on purpose or accidentally. Sorry.

Conifers do not necessarily require deep foundations or suspended floors. What type of trees and what ground do you have? If for example spruce growing at 3m in sand, I don't think there is any extra depth...would have to check though. However , the trees would hang over or near, the house and cast their bits in the gutters, so there could be other reasons to lose them. The Structural Engineer will know what has to be done structurally, but may not consider the aesthetics, health of tree, or gutter clearing onus. We all like to see pictures, and it may help to get the best advice.

Will they know about the benefits of exposing or encasing ducts? | see that their brochure is all with fireplaces, so of course should be insulated all the way in the chimney. Very expensive. What does the extra £600 bring as benefit?

Which goes up the chimney. All of it? My fire goes out when starved of air. I also have an old and clunky woodburner, with vent into an old chimney. That does have problems, which were demonstrated when I put some chipboard in...the smell of the chemicals was noticeable in the room so it must leak smoke at joints. With the modern ducted stove there isn't even a smell of wood burning.

I hadn't realised that...rather kills my argument that the BCO has to assume you might install a gas fire. I can't find that reference quickly but will search later. But did come across the lovely term "Fortuitous ventilation": also known as leaks and draughts. 5kW is quite a lot, especially in a new house, so that should be that.

What interesting responses. Please excuse me challenging or testing some. and argue back of course. For clarity we are talking sealed , high quality stoves here, not open fires/gas fires/ leaky cast iron stoves. I am not proposing that there is no air intake. But if I was: The stove sucks in air, not oxygen then expels dirty, low oxygen air out to the sky. The air in the room remains of the normal gaseous proportions. There is no shortage of oxygen in the room or my brain, unless the room is very small. If it is very small, then the fire is also going to be small. Replacement air is drawn in through vents or gaps at doors etc. If there isn't enough air intake then the fire and I both dim slightly, but not a lot. The air intake on the stove I am referencing is about 100mm x 3mm when fully open. the gap under the nearest door (after allowing brush-strip) is 900 x 1mm. When closed down to normal burning, the air intake is very small indeed. 100 x 0.5? I checked the seals to the glass last week and pushed one back into place. If air is being expelled through the flue then an equivalent amount will be dragged in through gaps unless the room is completely airtight. When I fall asleep in front of an open fire, there might well be a lack of oxygen and a surfeit of nasties. In front of the stove it is just heat....and the intellectual stimulus of this forum. Nobody knows what heating might be installed , so design for gas and then we are safe whatever. I have installed an air vent to an aged family member's house where there was none...and a gas fire. I could sense the unpleasant atmosphere which was sleep-inducing and very dangerous. Have the manufacturer's not considered that their fires will have flues? Every catalogue shows a flue up to the ceiling, almost as a necessary feature. My reference stove has a top chamber to carry fumes away and extract heat from them, and I don't think it is so precise that the same does not continue in the flue. Are these readily available, or a shield? Taking this to extremes, we could build a wall around the stove to keep the heat in and maximise the internal and exhaust temperatures. I am assuming, until further advised, that the upmarket stove manufacturers have tested their stoves twice. Once in a lab for best spec figures for publication. Again for everyday use, with a flue of about 2m, perhaps more.

Gaps are completely unacceptable. Building Inspector will understand and agree, but may not wish to be involved in your contract dispute. Damage is careless and a concern re standards throughout, but barely affects the insulation level. If you allow the use of foam spray fill, will you trust them to get it to full thickness yet not fill the void? I would be concerned re their attitude and attention to detail. There is no reason to expect that your builder will understand the science of insulation. Sometimes they just have to be told. I have many a story on this, but not now.

I can understand this rule as oxygen is good for us, and we can't ensure the skill set of the inhabitants. However , for your own house, with a lot of understanding of these things, the open one might perchance change to a shuttered one?

Interesting, and currently counter-intuitive...but I am here to learn. I can't see how 2m of exposed flue before it is insulated for the rest of the journey can not provide spare heat...otherwise it is flying wasted to the sky. The early stage fire chucks flame and smoke up the chimney which would be wasted but heats the flue then room. The later stage fire sits and glows very happily, and a lot of the heat inevitably goes up and away. Best capture some. As long as there is enough heat and gas flowing up (to waste) the fire will burn well. Now for the real-time example: I am looking at ours now. Started with tree prunings from last year, an hour ago, and about to put the first proper log on. The flue is 1.5m long exposed before it is insulated (rockwool in plasterboard) and then goes into a chimney (stuffed with rockwool) The heat coming off the flue feels like 2kW to me (and I did remember to mask off the heat rising from the stove). The enclosed length of flue does not feel warm at all, which is just as well as it goes through a wardrobe. The room temperature has risen from 17 to 21 in an hour.

I hoped you might know.

We have had this discussion before. I think the conclusion was that a metallic foil face onto an air gap is good, but not as good as the figures allowed in the calculations. ie in time the foil is not so shiny (even in the dark) and the effect reduces towards that to any other surface. So to some extent you can use it to tick the box on the U value calculation and improve the rating considerably, and get some real benefit, but the reality will be slightly ;less. Therefore probably the pir performs a lot better than the air gap. BUT that service void is very practical. It allows the services to pass unseen, but also means that sockets etc that are under 30mm will not break the VCL. Conclusion: we will go for the shiny membrane because we might as well and it takes up no thickness, and the void will help in the reduction of accidental draughts that the electrician /plumber might not be interested in.

And if you are happy then I am happy that you are happy. Re the efficiencies, yes we know the difference between lab test and real life, in many fields. I would intuitively say that our burner is probably 70% at best and 60% when not working efficiently, including the many kW noticeably coming from the metal flue. And before this fire we used 4kW of electric heat, nearly 24/7 and it took days instead of hours to find the 5C rise we were looking for. Does anyone know if it is working well when all a mass of orange glow, and no smoke to be seen?

I think our room of that size (with very poor insulation and a lot of cold thermal mass, heats by 4C in an hour, at full blast with dry oak. That would be 5 big logs of 1kg each? After that the fire is turned down to minimum air or it gets too hot, and it is a log per hour.

A modern burner is declared at about 80-85% efficient. Then if you keep a large area of a metal flue exposed in the room, there is a lot of heat from that. Presumably in real life it is less than that. Meanwhile, "more than 60% of energy used for electricity generation is lost". ie 40% efficiency from carbon fuel to kW output at end-user.

I think there are some very all-encompassing exclusions and get-outs in the sign-off. It covers what the BCO has seen (which is snapshots) and does not include all the work or all the quality. The checking Engineer does not know all the context either. For example if a concrete footing was laid on ice and on a frosty day, the BCO would not know if it was understrength. If some reinforcement was missing? If some of the timbers were ungraded instead of C24? And so on. Not only accidental or through ignorance but, from tales I have heard from BCO, of deliberate deception. If the BCO was a Clerk of Works then we would all have to allow for the costs and delays for full-time attendance, and a heavy insurance premium

Not good. The width appears to be cut very neatly, so why not the length as well? I consider expanding foam to be for emergency use (and window fitting) only. it is uncontrollable and will expand from where you want it into other voids. In this case it will likely link the PIR to the sarking: not that anyone will see it but it is not meant to be there and could cause problems.. Meanwhile in a steading in the highlands this has been happening. Self-built with time and care, but there are unavoidable tiny gaps. The cut-outs for the ties will be filled with mineral wool. I will start a new thread on thoughts and progress.

Thanks to your comments I now revise my counting to 15 for and 9 against. Some of the 'againsts' could be legitimate vetoes depending on circumstances. Contrary to that is the over-riding expectation of a wood-burner in a forested rural area. On the draught and heat-loss that will occur without much control, through the flues, my attitude is that 1. there is a pragmatic approach that 'very good' will suffice. 2. insulation and airtightness first, then add controlled (or reasonably controlled) ventilation. 3. How much heat loss through a flue compared to doors opening?....I especially value porches for this. 4. As the power was off for 80,000 people for 8 hours yesterday, how much should we depend on electricity?

Simplest yes, but not the long term solution. Silicon degenerates and goes hard. Then you will have to scrape it out and replace it. The boss of a good window company will despair at this (and be glad you told them), and get it remade at their own expense.

I don't agree. They are avoidable and it might take weeks to dry out. If this is new build then it is unacceptable and should be remedied, and not by patching. What does the design say the slope should be? Whatever, the fact appears to be that part of your roof has negative slope, and cannot drain until the water is 15mm deep.

can we see the trial hole results please?