Gus Potter

Appreciate your frustration @Dave Jones Thing is that when the timber was put through the grading machine it may have been ok. Fabricated trusses tend to have their own special grade of timber TR26. Remember that when the timber is tested we work on probablities and normal distribution curves to determine strengths. Here what you have is some splitting timber that could be outside the 95% percentile. But it has been spotted before it got built in.. that is good that you have spotted this as in some ways it shows the system works, awareness from site operatives.. if it looks wrong it probably is. The timber could have dried out after grading and fabrication.. wood is a "living material" and is full of surprises. We design for the odd concrete cube test not being strong enough and say for the odd truss being crap as we know that really one off bad one.. say like you have will hopefully get spotted. If we designed on the basis of everything being perfect houses would cost an awful lot more to build. Options that spring to mind. 1/ Send the photos to the truss folk and say you are concerened about the splitting. Ask them to confirm that the material is still compliant with say TR26 timber / their design and that this may be outside the normal expected strength / material property distibution. 2/ Ask them if one or two can be remediated.. at their expense or how quickly you can get new ones and the old ones taken away also at their expense. Express you preferance. 3/ Say you expect an immediate response and warn you will follow up with more in depth enquiry if not the case.. starting with how this got through their CE marking process, sent to site and that they are now not responding to reasonable enquiry about a safety concern. The key is to state the facts, send photographs and say this is a structural safety issue.. and that it is costing you money due to delay as you can't progress the works due to a safety concern. I think you may find that you have new trusses in two to five days at no cost to yourself. The reason is that when faced with a few photos and technical observation the manufacturer can fast track stuff to head of bigger problems and claims at the pass. The above is the way you start to lay the groundwork for a legal claim if they don't play the game... but that is very remote.

In terms of structural safety, yes. But we all have a civic responsibility and structural safety is paramount.. But let me also appeal to all on these grounds... Why not make sure that you have built something that will really last, maybe a lot longer than it's design life, be proud of it, leave a legacy? Yes I know it's about the money.. but you have put so much work into this.. In terms of your wallet. What happens when you apply for you completion certificate. Who signs to say that the building has been constructed as per the approved plans? If it becomes apparent that you have added undeclared load what then? .. that can develop into a big problem, habitation certificates, lenders not playing the game etc. If it was me signing off your house I would check you are not pulling the wool over my eyes at not just my expense / risk but for the sake of all the folk who may own the house after you. But the other side of the coin is that I would try my best to get it to work for you and prove it and.. that may take a bit of innovation and lateral thinking. I would play this off a straight bat, rest easy and be proud of what you have built without any worries. Cost for a design review. If you have all the calcs and drawings that is a good start. But there is probably manufacture's data missing. So a bit of due dillegance required here, phoning about for the SE and talking to you to tease out what you have really built. Say 3 days work with full disclosure from you and payment on the nail. It carries liability so say £400 a day = 1200. depending on who you get there may be vat on top of that. That will be on the ball park to get you the checks you need. What you won't get for that is any kind of warranty that you can then pass onto a third party. There will be caveats.. for example if the checks reveal that there is a flaw in the original design then it's a different scope of works. Also, if you can't access the joist data in particular lines become blurred. Things like this happen if companies have gone bust. There are ways of tackling this but it takes more time. If you go to a larger SE outfit then a graduate rate is say £85.00 per hour.

Had a very quick spin through the parts of the calcs you have posted. The output is not that clear and to really consider this we need to be able to see all the data that lies behind the the output. In other words to check this we need a lot more transparency and need more info. On the face of it though in terms of the joists themselves it looks like they have spare capacity to take a bit of extra load in terms of strength. But we also need to consider deflection. Looking at the output you may get this to work ok and still be within the limits set by the original designer. It looks like you have about 20% to spare deflection wise and it is deflection that appears to be governing the joist design. There are some vibration checks.. good to see. Adding a bit more dead load should not be a material factor on this relatively short span. However to do this responsibly we need to then trace the extra load all the way down to mother earth and look at how this extra load may impact on the other parts of the structure. For example.. we need to check the joist end supports.. are there lintels below, if so what is their capacity?.. does this extra load cause more bending effects in say the masonry below / above due to the nature of the joist end supports acting possibly at the face of the walls rather than dead centre over the wall. Often all works out ok.. but adding or in fact removing loads from a structure must always be checked. Sometimes if you remove a permenant load it can cause problems.. good example is a basement in water. Remove the ballast and the thing can suddenly float upwards! Another is where you may be relying on weight to stop a roof lifting off. Swap dense masonry blocks for lightweight aerated ones.. often done to reduce heat loss if you can't get the u value calcs to work.. if there is not good communication between the design team this is the sort of thing that gets missed... very easily done! In the round though based on the summary output you have posted it looks like you can add a bit of extra load subject to detailed checking. Advise you proceed with caution. If the joist manufacturer is no longer trading then there are some other avenues / ways a round this with a fair wind but story for another day.

Feel for you. Much will depend on just what stage of the work you are at. Seems like the beam B1 is in place but no extension roof? I had a quick look at the extract of the calculations. I can't see page 7 but the loading used to design the beam looks about the right magnitude holding up a bungalow roof and the load from the flat extension roof. The mention of a second storey is probably just the SE maybe just calling the bungalow roof the second storey? The beam is checked for at least three criteria. Strength checks.. moment capacity Mc 429.9 kNm, buckling strength Mb 145.9 kNm both of which are greater than the design moment applied to the beam = 121.5 kNm Deflection is also checked against a limit of beam span / 360 = 19.6mm, calculated deflection is 10.883mm I get 10.9mm .. close enough. However B1 has plates welded to the top and bottom flange which stiffens the beam quite a lot. Thus you would expect that the beam deflection would be less still and if it is less still why are they (the plates) there? One reason may be that the SE has decoupled the calculations and assumed that as the loads are not over the.. call it centre of gravity of the beam and we are only seeing part of the calculations. This eccentricity causes the beam to twist more and the SE may have designed the plates to resist this extra twisting and left the remainder of the beam to carry the other forces. The main thing here is that I am not casting doubt on the SE's calculations but would ask out of curiosity if this is the reason for the plates. Also the plates are shown as the same width as the beam flange, nominally 173.2mm. To get the plate flush means cutting a long standard flat bar down lengthways.. more expensive and also if the plate is flush your standard fillet welds are not appropriate. You need to use partial penetration welds or similar which are more expensive. Normally I would use a standard 200mm wide plate which give loads of room for the standard fillet weld, especially as we know that not all beams / plates are truly straight. Again I would ask.. why was it done this way and are there other underlying reasons for this design approach that are not immediatly apparent. Now this is really a mute point as the steel is paid for and B1 is in place.. other than it will let your SE know that you are now better informed. It is what it is. It's a great pity that neither the Architect or SE alerted you to this low height much earlier. But what options might be available to raise the soffit of the beam. Well it could maybe go up quite a lot until the bottom is almost level or just above the ceiling of the extension. Here we would do a bit of joinery work to brace the existing roof trusses as we would be disrupting the joint between the existing roof ceiling joist and the rafter. Turning to demolishing and rebuilding the supporting walls. Ideally we want to avoid this as these walls are probably offering sideways (lateral) support to other walls so when rebuilding you have the problem of re tying your new masonry into the old. In other words you risk making matters worse. Under the padstones the inside edge of the wall forming the sides of the opening can flap about and that will be bothering your SE. If you can live with it can you narrow the opening under B1 by say 100mm each side. What you could look at is either introducing some good solid timber posts fixed to the wall or maybe a couple of light steel channel sections, timber is cheeper. Now we have stopped the supporting wall from flapping about and they will carry a lot more load... which means they may not have to be demolished after all. If the builder can give the SE the hand mixed recipe they used for the padstones and the concrete looks well compacted it will probably be the same strength as the existing brick and thus they could just stay in place and put another cut down lintel over the top once you lift the beam. That could be one solution worth exploring. I would aim to keep on good terms with the SE , builder etc.. but start asking a few informed questions. It may be that your SE comes up with some good / other solutions.. free of charge in the interests of good will. Hope this helps and things pan out ok for you.

Hat off to you for giving Enerphit a go. Here is a question. Is it important to you that you reduce your carbon foot print and overall footprint on this earth during your life span? It's a serious question as you clearly know your ins and outs if you have been exploring Enerphit. For me.. a bit of a philstine I have an ex council house that I am insulating as much as I can, experimenting with eco stuff.. but recognise that if I demolished it then the real carbon footprint would be prohibitive unless I put a life cycle of 200 years on the house at least. Stuff like planning fees.. I can get a lot of insulation for that! Keep us posted on your thoughts.

Glad you have found BH, you'll learn loads here (I do), get the benefit of all sorts of different views and if you stick at it.. will allow you to make informed decisons that suits you best and save money along the way @greenqueen"In your opinion what foundation type is best for sandstone rock and sandy soil" The design process goes a bit like this. Rock / sand .. lets start from experience by looking at strip founds and then work up in levels of complexity = cost. Sandstone = good start. Now lets look at the type of sand, where the water table is and where it may be in the future, how thick the sand layer is and if the site is sloping. Breaking this down. The type of sand is important. Are all the grains of sand roughly the same size (poorly graded) if so they can act a bit like a pile of marbles so the bearing capacity is less or.. is the sand well graded where there are small particles of sand and big ones that all interact, have a larger area of surface contact and thus have a greater bearing capacity. When the sand particles are submersed in water (where the water table is and where it may be in the future) it reduces the effective density of each particle of sand by about half (Archimedes) thus as the bearing capacity of the sand relies mostly on intergranular friction we need to know about the water table. We also need to know about the water table is as when we dig a hole it may flood. You can dewater but one big risk is that you suck out the fine particles and make things worse Also you may have so much water that you can't easily pour concrete. If you have a high and mobile water table this may lead you to look at the raft option early on as you keep it out the water table. Of course if the water table is really high then you need to remember that EPS etc floats! If the site is sloping then ideally we want to found the building on the same soil strata, not half on the rock and half on the sand as this leads to differential settlement which can "break the back" of a house. To conclude this part. I think you need to get a handle on the ground and that will help you focus on the viable options that suit you. Post your ground investigation results if you wish for some feedback. @greenqueen " If we are going to build with a combi oak and sips frame, how does/does this affect the foundation type? " As other have said .. sips is structural @Alan Ambrose so why do two load bearing structures? I think oak frames are brilliant. You mention that you may not want to use them everywhere. But if it was me I would want to have them on full show, no point in hiding any part of them. Yes they do move about a bit when seasoning and later during summer and winter. Funnily they tend to shrink in the winter as we put the heating on and can lower the humidity levels.. a bit counter intuitive? But in reality the movement is not that much different from a timber frame house, probably less so. In summary I would price on standard stuff: strip founds, look at suspended floors or a simple 100- 125mm thick ground bearing insulated slab then add in your extras to mitigate thermal bridging ect to bring the house up to the thermal performance you are seeking. Go for the simple stupid first that local builders can handle.. you'll get more sensible quotes this way. That gives you a benchmark.. then it lets you test each of the bells and whistles options. To try and price this up as a novice I would start on say a standard masonry cavity wall construction or a timber frame for the whole house. Then add in the oak frame as an extra over. Sounds odd but depending on the type of oak frame you go for; acting as a true arch or more portalised (which puts horizontal thrust into the founds of the ground floor or floor slab if a raft) then the hidden extras ( foundation detailng and mitigating cold bridging etc) will be covered by adopting the extra over approach. Later you can start to shave of cost by good design and detailing. Have a look at these.. great idea which works. Turning now to some technical aspects of raft foundations and EPS. This is not "new technology" we have been designing insulated rafts for ages. In the UK they crop up a lot on cold stores and in the USA.. well there is not a lot they don't know about this, and they have to also have deal with permafrost in the northern regions. Be glad we live where we do in the UK! @IanR and @saveasteading You are both correct.. to be difficult I'll add my own interpretation.. all in the best taste.. but I'm going to try and simplify / expand for BH folk.. but may make matters worse.. ! There are many different types of rafts and @George can probably add to my list and chip in. I'll give this a go describing the common types, there are many and they all work in a different ways. 1/ A true raft. This is say a 250 - 350mm thick flat slab that is wrapped in EPS with a two / three story domestic building on top, point loads or intermediate load bearing walls from the second storey and roof load coming down in the middle. By making the slab this thick we reduce the density of rebar which lowers the cost as rebar costs more than increasing the thickness of the concrete. Also by making the slab thick we reduce the punching shear stress that comes from the point loads say from columns to create a big open plan space on the ground floor. In summary you would lay the EPS, turn it up the sides, lay in some rebar and pour the concrete. If doing a basement you probably need starter bars and some stuff to sort out the corners and stop the water coming in. Main thing is that the thick slab reduces the rebar congestion which suits local builders.. keep it simple stupid. An important part is also think about slab shrinkage.. story for another day / later. BH folk.. don't get caught out by trying for the thinnest slab you can as the rebar cost etc can go up drastically and you invite other problems. 2/ A semi flexible raft.. still a flat slab as above. You see this cropping up on BH where the EPS extends beyond the inner load bearing leaf to say the outer wall. Now if you assume the load bearing wall is the inner leaf and the load from that spreads out at 45 degrees the EPS contributes a lot more to supporting the big structural load from the inner leaf. But you often find that the EPS can get over the line. Two main reasons are this: When you look up the EPS spec it gives you a compressive strength of say 200- 300 kPa at 10% compression just say for the sake of arguement. That means that the EPS needs to sink by 20- 30mm before you get your 200- 300 kPa resistance. Now 20- 30mm movement is not going to be acceptable, especially when the ground under may also be sinking. What we do is to say let's limit the amount of load that the EPS can take. I'm not going to tell you this range of values as this is commercially sensitive. If you search about other designers they are not going to give away these values until you cough up a design fee, also you need to know about the ground and the chosen / proposed insulation. To design the semi flexible raft we work out what the EPS can carry and then use the concrete slab to carry the rest of the load. This extra load gets shed back into the slab which acts roughly as a cantilever. But for that to happen we need to design the slab to act like a big reinforced concrete slab. But if you turn the slab into a reinforced concrete slab you have to comply with the design codes that relate to that... and that is very difficult if not inpracticable on a 100 mm thick slab. It can sometimes work on paper until you need detail the rebar anchorage and deal with rebar congestion etc. 3/ The edge thickened raft. Here we have a concrete slab that is attached to what looks like a strip foundation. As above the same principles apply.. the strip found can only carry so much load so we shed the load back into the slab and often reinforce that as the top of the slab is in tension. The edge thickening is often used where we may have point loads from columns. The edge thickening acts as a concrete beam which spreads the load over a longer distance around the slab edge then the remiander back up into the slab. I have to give up here on the various descriptions and way of doing all of this. Suffice to say you there are often loads of different options.. But to add to the complexity we need to consider how big your slab is and how much it will shrink and crack and where can we put movement joints?. When you edge thicken a slab it basically gets anchored at the edges. As the concrete cures it shrinks. A true flat sab can slide a bit but an edge thickened slab is bound into the ground at the edges and thus we often need more steel to resist the shrinkage cracking. Well to finish. Probably the ground conditions are the thing to get your head around, it can be a lot of fun researching your local area, talking to the neighbours, did they build an extension what happened? That basic stuff can save you thousands! And when you move in you already know your neighbours.. that is a good start?

Not heard of that term before, ta. Every day is a school day.

That is a really good spot! Hat off to you. Has got me thinking.. The Bresummer is under the window cills above and close to the vulnerable flashings over the bay window. Also it's brick, not rendered so maybe some water penetration from a bit of both. I'm thinking.. have the ends of the Bressumer rotted a bit (assume timber) and dropped. If the floor is resting on the Bressumer then it will have dropped a bit too. Check the floor for level and look at the ceilings below. But there may be a 5" iron beam holding up the outer face of the brickwork over the bay window. If the timber Bressumer is ok then has the iron beam rusted at the supports, expanded at the supports and actually lifted the masonry? Over time an iron beam like this can easily lift the masonry by 5 - 10 mm. There may be an iron beam both on the inside and outside, the outer one has rusted more so lifted. The nature of the crack in the wall is interesting. To make headway on a diagnosis you need to examine it really closely as it will yield clues. Some obvious things are to measure how wide it is and it does taper. Next is how much it has displaced sideways. There seems to be a little sideways displacement and a taper. Next is to see how the windows open and shut, check for verticality and examine the paint on the windows. Also try and age the paint on the walls. Does the paint go into the crack.. helps you date things. Ask.. has anyone been messing with the ground floor bay window and were there any massive trees growing in the front garden, problems with the drains for example! You have to look at loads of stuff if only to rule things out.. like have the water board just put a main sewer in the road or is there not HGV traffic (vibration) where there was not before. You also examine the whole building to see if there are any other signs of distress. Going back to the crack. You see it is wider near the left window when viewed from the inside. That requires more info to get to the bottom of the issue. In terms of buying the place apply common sense, look at the whole building and speak to the neighbours for example. Should you buy it? Can't say just yet but so long as the rest of the house is ok, the roof not sagging and other cracking not apparent then if you put in a bit more work you should be able to get a handle on what it may cost to put this bit right.

Perfect and pragmatic approach for the Reverend. Sometimes blindly following NHBC guidance or an inexperienced BC officer's view can do more harm than good. @saveasteading yes that looks like good ground. Well defined layer between the upper nutrient rich and the structural soil below. If you have a big tap root it may go straight down so if it rots (could take 50 - 100 years as no oxygen) then it probably won't have any effect as the soil will act as an arch at those depths. A way of explaining this.. say you have a 2 foot diameter tunnel 50 feet under the ground.. the ground will span over that and at say 4- 5 feet down from the surface you may not see any noticable effect. A 5" tap root going straight down will have even less effect. Also remember that you can only work from one side due to the boundary wall. You don't want to destabalise the wall. Also if you excavate a massive hole on your side then it will extend well into your underbuilding. What kind of floor are you going to use? Ground bearing slab or suspended floor? The first approach here as the Rev and Steamy et al advocate (the bridging concept was not my idea, the drawing was just to translate that into how you may go about detailing something like that) is to assume you won't get all the roots out and that over time you may get some movement and design for that. I would try this first as it is less intrusive and cuases less soil disturbance. I take it this extension is single storey, not two or three and that you don't have transfer beams landing over the tree stump zone? Once you start to investigate then that drawing I did may be quite conservative.

No you were bang on @SteamyTea and yes it was your idea first, so not taking any credit for your concept.

No an SE is not "duty bound". A lot of the NHBC information is for guidance. If you can show that the site conditions require a different approach and you can as an SE justify that then no problem. I made a long post before about the things you need to consider. If it was me and things looked promising I would have a look at something along the lines of the very rough sketch below and start to tweak the design to get it just right. I have not shown the top bars on the plan view. Key ponts are: 1/ The concrete is all cast in the one pour with the same mix of concrete. You pour the deeper trench fill bit under the blue line which is bit of DPM plastic. Smooth that off, go and pour concrete around the rest of the found. 2/ At the same time drop in the A142 mesh over the stump area and the M16 bars. 3/ Finish pouring the found over the stump area dropping in the top bars when you go. By that time the trench fill bit will have taken up a bit. 4/ The DPM decouples to some extent the reinforced part of the found from the deeper "trench fill" looking bit below. This means you don't have to follow for example the rules for steps in founds and if the deeper thicker concrete shrinks more than the rest of the found the shrinkage stress is less likely to be transferred to the strip or vs versa. 5/ Make the bar length so you can cut them from stock lenghts. Here the bar length are base on a stock length of 6.0 m 6/ The short 1.3m top bars are there in case the trench fill bit works too well and creates a hard spot that would cause the found to crack where the trench fill comes up to meet the rest of the strip found. 7/ The found is widened locally a bit just to reduce the bearing stress on the ground below.

Yes loads of folk here on BH will be able to give you pointers.. and maybe save you lots of money. But to get the best out of BH you'll need to give us a lot more info so we can all mull it over and give you targeted feedback that applies to your site.

This is a difficult subject to get your head round to say the least. Hope these general comments help shed some light. You want to do a loft conversion that turns you house from a two storey into a three and you have non rated doors, say traditional 6 panel timber doors with fielded panels. Timber and in particular hardwood doors (the timber is denser) can resist fire quite (talking 30 minutes here) well as the timber chars on the fire side and the charring provides an insulating layer which keeps the remaining timber cooler and thus intact. But you need a sufficient thickness of timber so you can get enough char to do the job. 32mm thick look a bit thin to me, if all other factors work in your favour then the Institution of Fire Engineers mention a figure of 35mm thick if the door has that thickness all over.. in other words a solid door. For me I would look at this as a possible practical / cost effective option for a non period house if the doors were 45mm thick or more and solid. A fielded panel is much thinner, that is a problem. Now it gets more complicated.. you can protect the fielded panels but you need to understand how the panels are rebated into the styles, rails and muntins. Next you need to examine each door for distortion, splitting and so on. Next we need to look at how we are going to install cold smoke seals and heat (intumescent heat) seals... do we fit them to the doors or the frame? Onto the door frame now. Do we have enough meat in the timber to fit hinges and closers in accordance with the manufacturer's instruction? How thick is the door frame, is there a gap behind it and how thick are the door facings protecting the masonry frame interface? The above covers some things we need to think about. In the old days we used to fit hardwood stops screwed and glued to the existing frame, maybe upgrade the fielded panels a bit and pretty much go to the pub. Changed days now as this sort of stuff is well scrutinsed, rightly so. To get this over the line with BC you need to do your research, develop the upgrade strategy, make the case, make sure your case will stand up to test by say the Institute of Fire Engineers and then hope that BC will agree. Anyone doing this type of design / upgrade carries the can liability wise so the days of doing ten minutes work and scooping up are over. Now the above can be challenging and exciting.. but it comes at a cost. The objective is to provide a passage way (protected route) to allow people on the ground and first floor (if not too high above the ground to jump out a window, it's the height to ground level) to escape. On the third floor they escape by way of the stair case. Thus for now assume you need fire doors on all the rooms (sometimes not all rooms but that is for another day) connecting to the staircase so that if a fire starts in one room the smoke and heat can't get into the stair well. Another thing we need to think about is this. When we create a third storey in the attic the attic floor becomes a structural floor.. that needs a 30 min fire resistance from below. If the ceiling joists are thin then sometimes you can't show that 12.5mm plasterboard directly fixed to say prefabricated truss bottom chords (89 x 38) gives the 30 min fire protection. But if your house was built with future proofed attic trusses the bottom chords may be 195 x 45 which usually gives you 30 min fire protection. It's not just the plasterboard alone that gives the 30 min it's also what it is fixed to and whether the plasterboard is skim coated or not. You can get round this by beefing up the ceiling joists if they are thin.. but you need to check the strengthening nailing pattern etc. If you have lath and plaster ceilings that BC query there is a fairly cheep fire emulsion paint that you can apply to upgrade a lath and plaster ceiling to 30 min or more. The above all sounds a bit doom and gloom.. but here a few ideas. Often when doing a loft conversion folk also want to make things open plan on the ground floor.. in new build you may have open plan ground floor also... both play havoc with the protected stair concept. But now we have misting fire sprinklers! The price has dropped a lot and they don't need huge tanks in the loft or a "special" water supply. Yes they do need maintained so there is a cost there. Hope this helps a bit.

You raise a lot of interesting and important concepts here. I'm thinking ICF, rafts and a bit of chemistry. Will mull this over as it needs a cogent response and a worthy response.. will take me a few days and sleeping on it.

Hope this helps. First thing to do is to take a step back and do NOT identify yourself here by posting plans etc that could reveal your location. The reason is that it could impact on the validity of any indemnity insurance. Do NOT contact BC or Planning as this can make the indemnity policy invalid... check the wording. Next is to take several steps back an understand what you have on your plate, maybe you already have done this. I would look at the PD regs in force in 2019. Then see if what you have complies, get that nutted out. Then see if what you propose falls within the PD. You'll need to do a bit of work, spend a few nights reading, measuring your garden for curtilage etc, the heights of the extension, over shaddowing, daylight etc. This is the best way as you get to understand the issues and can make informed decisions. If it does then I would be inclined to submit an application showing the house without the side storey rear extension, a plan showing the side storey rear extension and a plan with your proposals. This would be accompanied by a written explanation of when the side storey extension was assumed constructed. Honesty is the best policy if you can back it up with a sensible argument. If your research indicates all is well then you can regularize it all. If this does not work then you'll get lot's more help here on BH.

Hope all well at your end Steamy. .. but how do you know that they don't loose their elasticity over time for example. There was a few posts a while back on how PIR / EPS will maintain it's integrity.. in terms of load bearing capacity and elasticity. Looking ahead.. in SE Terms.. what happens if the PIR / EPS under all the rafts say we have been designing start to fail in 30 - 40 years time? Well if we are still alive we will be very worried that we have a major safety issue. Now what legacy are we leaving? But if it all starts to compress evenly then then it may just be a case of re levelling the ground and sorting the drains.

Good question. I'm very supportive of the Passivhaus principles and when I get a chance use that as a benchmark. I don't think I said that I was disagreeing with the principles was just pointing out how you may suffer disappointment.. with a bit of "drama" at my end. Hope the following helps you see where I'm coming from as discussion is healthy. I can see why you are asking and probing my argument. I'm always wary about accreditation schemes, not that they are wrong but they often attract cost. An example here would be the CE marking of structural steel products. There were plenty great fabricators in the UK who could turn out safe buildings.. they got lumbered (mixing materials here) with a lot of cost ( I know as I helped set up the CE marking scheme for a steel fabricator) and all this was passed onto the consumer. In some ways the CE marking for steel is good as it it to do with structural safety.. but a Passivhuas does not pose a structural risk.. of death. If you want an accredited Passivhuas then you have to comply. The earlier schemes and accreditation process was confining and carried additional cost.. part of the cost coming from the suppliers and all this was passed onto the consumer. That was a pity as the concept and intent was and still is admirable... but the reality was that only the well off could afford to be environmentally friendly. Also, the earlier schemes did not really consider embodied carbon, whole life cycle ( BS requires 50 years.. lenders often use 60 years as a benchmark, maintenance cost.. also a biggy.. and a massive elephant in the room) , loss of material performance.. and how homes are used by say a family of two adults, two or three kids..a dog /cat.. then by say an elderly gent.. and then by another owner.. long list. The Passivhuas Trust publish plenty papers but one from last year (May 2022) lets you see how they are dealing with and advancing on the "environmentally cost neutral house" rather than one which is just cost neutral to heat and keep at an even temperature. But also.. as Build Hubbers we would be a bit unchuffed if we thought what we are building is only going to be seviceable for 50 years.. where is your pride folks? The biggy here for me is that when I design a house I try and think.. yes we want it to be environment friendly / not fall down.. keep the bils / running costs down but we also need to design in such a way that the house holds it's value, is it easy to and cheep to maintain (can we source parts, can local folk fix things that go wrong) , can it be heated up if old folk visit, it snows and the kids are opening the doors. OR do we want to spend all that money just so the house can get some kind of accreditation or just look good on paper? @IanR I can see I may have rubbed you up the wrong way here, sorry for that. But if we design for say "difficult me" to make it a home it means that we need to over design and right there is where I think we are of a different view. If you over design a boiler the system is not efficient for example... but what price are do we pay for that luxury and how can we offset that intermittant price? What about those big ticket items.. 3g glazing.. have you checked the guarentee on the glazed units.. maybe they are under warranty for 7 -10 years? What then? I could go on at length but I summarise below and look forward with encouragement. Have you checked the roof warranty.. zinc cladding in a coastal zone? Now if the roof has to be redone that is NOT "Passive" in Cornish etc terms. The building regs are changing a lot in the wording. Previously they used to be along the lines of .. you must do this.. now it is.. well there are opprotunities to innovate and here are the targets you have to meet.. the future looks exciting as we can put forward all sorts of designs and ideas! @IanR I don't doubt your house suits you and if you are getting that stable temperature then well done.. you have made a good job. But please recognise that you may not be the only occupant.. in fact.. you have probaly built a house that will stand for well over a 100 -150 years.. yes you own it now but be proud of your hard work and the legacy you will leave.

Lots of good information here. Agree no reason not to adopt masonry constrcution with beam and block floors. It's that attention to detail, good workmanship. A good thing to do is to try and build up you air tightness in layers.. by that I mean don't rely on the final air layer as the last line of defense. All buildings shrink and move as they dry out, settle in so if you can get the underlying layers of construction reasonably air tight they can serve you well as they at least provide some resistance to passage of air. Bit of lateral thinking here. If you have an oriface (a hole / gap) then you can sqeeze quite a lot of air / water gas through that. But if you have a series of orifices they offer much more resistance. For me it's about also trying to get the building staying airtight for say 50 years (it's design life). In some ways you get less movement with masonry / beam and block construction compared with a TF that moves about a bit more.

Thanks for the guidance. Think you also mentioned Schluter ditra.. a while ago.. you can deduce I'm making slow progress with my bathroom.

Like have you have formed the posts supporting the canopy.. elegant.. accentuates the height and slenderness... I think.

I would check with your SE because.. and lets assume the inner leaf of masonry is load bearing. It looks like that is working as a raft, hence the A393 mesh top and bottom. Often the EPS alone is not able to resist the concentrated load at the edge of the slab so you use the slab to resist some of the loads (common in raft design) and this means the top rebar in the slab is in tension. But for the rebar to work it needs to be anchored at the ends properly. To get the rebar anchorage you can either bend the mesh down at the ends (can be hard to do, fiddly or needs special detailing) or extend the slab. Hence KORE's recommendation. But if you extend the slab you start to lose the benefit of the perimeter insulation. Speak to your SE before progressing as this is very important! But well done you for spotting this what seems to be a minor change.. but could have serious implications.

Good question. Can you post a detail or make a rough sketch on what you expect to end up with? The beam looks like it is on the inner leaf? What is the wall makeup?

Err no. I understand the principles... and the challenges you face integrating that with structural design. But also, understand the need to recognise how you need to balance that with how people live from day to day and what makes a home a home.

Oh what an "interesting" thing you have there. Good points made by all so far, make for good reading. Yes, you have a special case. I'll throw a bit into the mix here and come at this from a maybe different angle, excuse the spelling and grammer please. Bit of context first. Let's look at the tree and the old wall. Yes looks dead. But here are things I would like to know about it's life, the ground and the old wall. 1/ What kind of ground do you have, clay, compact glacial till or a post glacial material (~younger than 100 k) years.. low nutriant/ higher nutriant.. harder / easier for roots to penetrate respectively with a topping of garden nutriant rich soil. . Also you may find the roots have grown up the sides of the wall where the ground has been disturbed. Do you have sandy or gravelly type soil, chalk or thin soil with bedrock below? Reason for this is to try and determine where the secondary and tertiary roots will might be. 2/ Which way does the prevailing wind blow from. Trees need structural stability and will aim to grab a hold of a chunk of soil to enable them to stay stable, call that ballast. Some trees have a big tap root and that also contributes to the stability. Reason for this is to try and gather info on where the roots may be going. They may be prevelant towards you neighbours and less so on your side... good news. 3/ What do you know about the ground water level. Do you live up north.. more rain or down south where you get more water stress. If in a water stress area roots can be deeper. 4/ What can you observe in the old wall. Does it look like it has uplifted, been repointed, leaning over. Again this provides information about what impact the tree has had. The old wall will yield clues as to what effect the tree had . All good stuff to know. The above is intended to allow you to understand this particular case and gather information to enable you to look at the other options. Lets say that the stump falls somewhere along the side wall and not at the corner for the moment. One downside of the trench fill is that it needs a big hole that could destabalise the wall as other poster have mentioned. But what if it turns out that once we know more about the roots it turns out that we have just a potential soft spot in the ground that could settle.. as the main stump / primary roots rots away over time. As it has been dead for a good couple of years the ground has probably recovered a good bit ( swelled back up).. Ok maybe settlement is the governing design factor. Let's recognise that we have a single story building (low loading) with a soft spot somewhere along the side wall but not too close to the corner. Can we just do a strip found here but make it say 250 - 300 mm thick and chuck in some 16 - 20mm diameter rebar to make a reinforced concrete beam that will span over the soft spot. Or if the roots are a bit deeper, put in a little trench fill and cast a heavier type beam to span a larger distance. This may need extra what we call steel rebar links which are much more like a reinforced concrete beam you may see in a carpark. The above options may mean you can avoid deep excavation near the boundary wall and all the problems that go with that. Also in some ways you want a foundation that moves about eavenly. Trench fill can create hard spots and that causes unwanted stresses. Last, what about the existing house.. if you start digging deep founds next to that then old house may be moving up and down while your extension is anchored solid. This leads to differential movement that can be undesirable. If you can get handle on these things you can put together a design that BC and all will be happy with. Once you see it all laid out you may think.. how simple is that!.. and if you think that then you probably have a good cost effective and sound solution. Now if the stump is near the corner you can deploy the same concepts but here you have a cantilever found and that is more complex. How complex you need to establish and then compare with trench fill.. but the trench fill might not have to go all the way round as you can do a bit of mix and match.. the bridging and maybe trench fill running perpendicular to the boundary wall. Hope this helps you a bit.

What a good idea, yes that would be a good bit of data to have.