sgt_woulds

I work for one of the woodfibre insulation manufacturers we’ve had a couple of similar questions regarding bats in the last few months – hopefully, this means there is an uptick in bat population, but it is awkward to specify a suitable breathable build-up. Below I have copied the relevant parts of some previous conversations FYI: Firstly, unlike spun fibre insulation, such as fibreglass or Rockwool, woodfibre insulation does not pose a direct threat to bats due to entanglement. However, speaking as an ex-roofer - and having seen what guano can do to structural elements, membranes, insulation and electrical cables - I’d recommend keeping them separate wherever practicable. There is a fundamental contradiction when considering the building fabric's breathability and ensuring a safe environment for bats. Breathability is critical for the building fabric, and the only way to achieve this in a risk-free scenario is to use an external layer that ensures water vapour can escape. So a breather membrane or vapour open board. However, the risks associated with long-term exposure to guano should not be underestimated. In volume, it can also pose a significant risk to the wood fibre and the structural timber. The use of a bituminous felt is therefore the recommended approach when roofing to ensure no potential trapping of the bats and to protect the structure. Of course, bituminous felt is non-breathable and hence not ideal for the building fabric. Creating a fully vented cavity below the felt can solve the breathability issues but you also need to vent this at the eaves, and ridge which is not straightforward when trying to ensure that bats can’t access this ventilation space. You could use TLX ‘Bat Safe’ breathable membrane as an alternative to Bitumen F1, but I’d be guided by the bat experts on this. I remember speaking to an ecologist on a job 15-20 years ago and they were critical of the testing procedures used to validate the membranes. This is not a fault of TLX, more that it is hard to test without using real bats! Hopefully, they’ve resolved any issues by now and I'd hope that they have some long-term monitoring data to confirm it's real world performance. You certainly shouldn’t use a standard breather membrane -I’ve stripped it off a roof where it was killing bats that got tangled in the threads and it was a sad sight. I’d still rather use the felt though. My gut feeling is it will stand up to the acid in the droppings better, but I only have personal experience to go on. I have, (unfortunately) dealt with many pigeon infestations where good old F1 felt stood up well to the muck, but on the job I had with bats and the breather membrane you could poke your finger through the membrane where the guano was removed. Going down the ventilated void route would sort breathability, but reduce available insulation depth. In addition, we always recommend a secondary water removal layer below felt as it can degrade over time, which makes the build-up more complicated. A more holistic approach may be to consider a non-vented build-up which allows breathability back to the inside. In this scenario, external ventilation is not critical, but overall performance should always be justified by a long-term hygrothermal analysis of the fabric, (via software such as WUFI which also considers external exposure, rain, shading, occupation and use, etc on a project-specific basis). As an example of a vapour closed approach, please see the build-up below, which may be an option with suitable analysis. This uses a woodfibre sarking board externally and woodfibre flex insulation between the rafters: In this simplified example, the U-value, based on an existing 120mm rafter, is 0.26W/m2K. You will see that there is condensation shown by the software, (U-bakus) - but, with full WUFI analysis, this may well be at a level that is not critical. SIGA, (and other manufacturers who produce moisture vapour-variable control membranes) will undertake a WUFI assessment if their membrane is used, so we have shown their Majrex 200 and would recommend this as an alternative approach which addresses some of the factors discussed above. [not shown in the diagram is the lime or clay plaster on the woodwool panels] Felt does degrade over time, (so do breather membranes) but in my experience, this is exacerbated by their own weight stretching the reinforcing fibres over time and under summer heat. Fully supported over a sarking board this should be less of an issue. Even if the felt does fail in 50-odd years time, then, (if you choose the right product) the woodfibre sarking can act as an additional weatherproofing layer with its hydrophobic surface coating. Using an external sarking board and counter battens as in this example will only raise the overall roof by 60mm which really only shows at the gable ends, and can again be ameliorated with architectural detailing. A conservation officer probably wouldn't even notice it on the finished roof from the ground unless you pointed it out to them. A practicable modification to the existing roof profile that allows for lowering CO2 emissions, protects the building structure, and allows a safe habitat for wildlife it is a compelling argument to use with planning and conservation officers, and ensures the building will be fit for use for many more years with minimal visual difference. Surely this is all they can ask for. In terms of ultimate U-values, this isn't the be-all and end-all in terms of thermal comfort, and building regs with older properties. For existing elements in existing buildings, Part L of the Building regs defines a threshold value of 0.35W/m2K for Roofs in certain conditions where it's not practical to achieve the modern requirements. Worth discussing with your BCO; for an older building, most BCOs are now sympathetic to the argument that breathability is more important than the insulation value. Woodfibre will also provide more decrement delay than unnatural insulations; summer heat protection is probably just as important these days as keeping warm in the short winter months. I suggest speaking to advisors at: Home | spab.org.uk and Historic England - Championing England's heritage | Historic England as they have experience with upgrading the thermal performance of old buildings whilst maintaining their architectural features and may have some case studies you can use. Can you provide links to the information about Batsafe membrane being unsafe for bats? I can only find historic 'concerns'.

Have you measured the local grid voltage? In parts of the UK, (Cambridge, Norfolk, Suffolk) grid voltage can be quite high. Back in 1999/2000 before feed-in-tariff and DNO limits came in we had to manually program the SMA inverters to allow them to work outside of normal grid voltage ranges (at the time, a very narrow range which did not reflect reality). There were also a lot of arguments with DNO at the time as they were essentially caught out for having defective regulation of the grid. We found that voltages in Cambridge normally 'floated' at about 250 volts, but in some areas (end of transmission lines) grid voltage could be well over 260volts/ Highest variance I ever recorded was in a cottage in the middle of a field in Devon. Having done 3 return visits from London I eventually persuaded my company to allow me to sit there for two entire days monitoring the grid voltages. At various times of the day, voltage spiked to a constant 278 - 280 volts then dropped down to 230-238 volts the rest of the time. There were specific times of the day that these occurred. TCALST: The cottage was at the end of a very long transmission line, immediately after a clay works. Every time they stopped for a planned break, machines and furnaces turned off and voltages spiked. The homeowner told me she was always having to replace electrical appliances - she thought it was just due to poor build quality and bad luck! Perhaps you have a similar situation in France that is being exaggerated by daisy-chained inverters?

In Europe most sockets don't have switches. Funny old world.

Watch: Burglar caught in Home Alone-style trap On our vans we rigged up starter pistol caps to explode if the side doors were bent down. Same on a shed door at our yard. Judging by the puddle and splashes, when it went off, it caused a very physical reaction from the would-be thief 🙂 Once, after a late night out at the pub, I'd just flopped into bed when I heard my van alarm going off. I dashed outside and chased the little tyke down the street. After about 200 yards I realised it was quite nippy outside. Having a drunk angry man rushing out at you in his birthday suit, screaming blue murder and brandishing a toothbrush with evil intent, (I've no idea why I grabbed that as I shot outside) seems to be a fairly good deterrent.

Unfortunately, part of my compliance role is to conduct due diligence for our timber supply to conform with the UK Timber Regulations. All of the timber used for our products is sourced in Poland from the state forestry within 150 miles of our mills, so the supply chains are fairly clear and simple, but I do know that there is some conflict timber coming into the country via Belarus, and there are possibilities for corruption as anywhere. I tried using Bing Copilot to research corruption and illegality linked to the timber trade for our specific sources and supply chain routes. Pont blank, the results it gave back were total BS. It stated unequivocally that seven of our regular hauliers were directly linked to the transport of illegal timber, but unfortunately, unlike the example above it didn't provide any links for me to check it's sources, which is a vital part of my due diligence. I wasted about 3 hours trying to find evidence using google searches and brought up nothing. I questioned Copilot again referencing its earlier answers and asking for links to sources. After the seventh or eighth rephrased query it finally admitted that it had no information to corroborate its earlier claims. An 'apology for confusion' popped up saying that this Copilot session was to be 'reviewed' All the other searches then started to return results such as below, but no more pop-up apologies: I won't be trusting AI for my research in the future - current evidence is that it is no more truthful, honest, or informed than the average politician. I recently received an e-mail from Inland Revenue boasting that it's new AI customer service gave correct answers 80% of the time in a trial with 1000 people and is now to be rolled out to a capacity of 15,000 real customers. This means that up to 3000 people each year will get the wrong advice regarding their TAX affairs. Superb.

Am I right in thinking there is a minimum height but no maximum? All of mine are set out 1m above the floor level. So much easier on dodgy knees and back. At my mother's house, one of the rooms has all of the sockets just below the ceiling!

Agreed - see my comment re- common sense... 🙂 My dad's generation would say 'don't lower yourself to their level'. Are they your only neighbour?

For paid workers: The Control of Pollution Act 1974: The general guideline across most parts of the UK is that noisy construction work should be limited to: Monday to Friday: 8:00 am to 6:00 pm Saturday: 8:00 am to 1:00 pm Sundays and Public Holidays: No noisy work is usually allowed In most cases, building work on Sundays is prohibited or heavily restricted to quieter tasks that won’t disturb the peace of residential neighbourhoods. While most noisy construction is banned on Sundays, there are a few exemptions: Emergency repairs: This can be carried out even on a Sunday if work is required to address an immediate safety issue (e.g., fixing a burst pipe or repairing a damaged roof). Essential public works: In rare cases, time-sensitive public works projects may be granted permission to continue on a Sunday. Special permissions: Contractors may apply for a special permit from the council to carry out work on a Sunday, but this is typically only granted under specific circumstances, such as avoiding a major disruption or completing essential repairs. For DIY works: yes, you can do noisy DIY on a Sunday if you are considerate and limit the activity. However, your local authority may take a different view if your DIY is extensive and could fall within the description of construction activity. Only an inconsiderate arsehole would conduct noisy works on a Sunday unless out of dire necessity and of very short duration. If necessary, it also good practice to discuss with neighbours and ensure noisy works don't start until after 10am, (to allow for a lie-in) but consideration for others seems to be as rare as common sense these days.

I believe that is a mandatory requirement now?

I 100% agree that the DC connector types should not be mixed. We always made sure that we knew the exact make and model of the connector and any reputable manufacturer should be able to provide spare connectors and tools if they are an in-house design. However, single module Micro inverters will be working with much lower voltages and amperages than found in a typical DC string scenario. In reality, you are very unlikely ever to get a DC fault condition in the connector, (even if mixed and matched)if they are properly fitted But I've seen some horrors over the years... Including from the MCS 'instructor' who tried to demonstrate the fitting of MC3 connectors to a room full of installers with 'Grandad rights'. We really 'loved' being taught to suck eggs by someone who'd gone on a course himself 1 year prior and had zero roofing experience. MCS always was about making money for the people who ran MCS first, not making installs cheaper and safer for customers. Fires in isolators were definitely a thing back in the day - mostly from cowboy installers using AC isolators for DC, and some manufacturers, (notably ABB) not testing their products adequately for multiple high-current DC switching and IP rating. Electrically, below 50 volts DC an isolator is not required and manual disconnect of the connectors will suffice for replacement purposes, (one-off disconnection and assembly in a blue moon) - and you should always isolate the AC side first anyway so the inverter will not be generating. (Micro inverter lock-offs for DNO requirements are also on the AC side). We found it increasingly hard to swing this by MCS so ended up adding unnecessary kit and customer expense for an easy life. Duel panel Micros were not a thing then, but make more sense in this scenario.

The reason that MCS guidelines do not advise Micro inverters in the loft is that they run hot, very hot. Surface temperature over 60 degrees... After a couple of years of experience installing various micros, we advised people with hard-to-access roofs to bring the inverters into the roof space. This was a PITTA and reduced the efficiency somewhat, (low voltage DC running through longer cables creates losses) but gave a significant practical advantage. Hopefully things have changed now, but in those days Enphase Micros had a failure rate of 2 per 16 installed (average number of panels per install) within 3 years. Remember that the manufacturer will only provide replacement inverters if they fail, they won't pay for scaffold and labour to replace. If you have a bungalow, then by all means fit them on the roof. Otherwise consider access for replacement. We mounted them on Unistrut in free air and a cage was built around them to prevent accidental touch with large warning signs. We also paid attention to the ventilation in the loft or eaves and added additional vents if required. Cable management becomes is onerous, and you need to consider the larger roof penetration and protection of the cables, (so many installers just slip the DC cables under a tile with no mechanical protection). Remember, MCS like building regs are guidelines, not absolutes. If you can demonstrate that an alternative approach is just as safe, and especially where it has additional benefits, (ease of access, possible cooler running due to more free space around the inverter) then an MCS installer can certify it. With full roof arrays you'd need to justify other things anyway; the panels will be closer to the roof edges which requires uplift calculations and additional fixings/amelioration. One advantage of using PV panels instead of tiles is that the finished roof tends to be lighter, which allows more panels on a truss frame roof, especially if re-roofing one built between 1995 & 2005. I've seen so many roofs with more panels than they should have - how many Solar installers run structural assessments of the roofs before install? For a long while, (after MCS funding suddenly disappeared overnight due to ministerial idiocy) fixing other installer's mistakes kept our company afloat when all of the goldrush boys were going out of business... Happy days

As far as saving and storing reclaimed timber - yes it's not always easy or convenient and you do need to consider what the end use will be. Mine has been denailed and is stored outside and uncovered; they are nearly 7 metres long so I didn't have much choice! They do look grotty, but when I cut through the moisture has only penetrated a few mm and the heartwood is perfectly sound. I roughly cut them to size when needed and leave them to dry out indoors for a while, then a quick run-over with a heavy-duty sander or, (old expendable) planer makes them like new. These were all saved for internal stud work so don't need to be 100% die straight or dimensionally accurate, (still better than the typical wavy wet matchsticks you can pick up at your local DIY store). Getting them ready for use takes slightly longer and requires a bit more care in selection but is very satisfying if you can do it on a DIY basis at your own pace. If I intended them for structural purposes, (which they would be ideally suited too - well above C24 grade) then my storage requirements would change.

It's a reasonable primer but it's a shame that it doesn't cover engineered wood as this will probably have far more bearing going forward If we are to meet the volumes required for construction with the poor quality wood available now - and with an eye to protecting what little old-growth natural forest that is left - then we will probably need to rely on manufactured timber products to provide structural elements. LVL production grades the wood during peeling and uses it more efficiently in the finished product with consistent results. Depending upon the manufacturer, 100% of the tree is used as any waste bark etc can be burned in a CHP to help power the production process. It does however require better storage than sawn timber as it is not so resistant to wetting and drying cycles. It makes better use of fast-growing plantation wood which is what the world needs to rely on now, rather than clear-cutting and converting the prehistoric forest of the world. This will unfortunately remain a more expensive option until supply and demand curves meet in the middle.

"Also i was informed by a Finnish timber merchant manager that their flat land results in straightness and strength." But the slow growth in Finland, (all Scandewegian countries) is actually a problem now. Although they plant trees to replace the forests they cut down, it takes so long for the new trees to grow and demand is so high that they are deforesting virgin woodland at an alarming rate. The new trees can't capture and store carbon at the same rate as mature lichen forests (which take about 1000 years to reach peak capture and storage). Finland's timber sector is now a net producer of Carbon Dioxide and other countries are following similar paths, (e.g. it is estimated that all of Swedens unprotected old growth forests will have been logged within the next 50 years. The average age of trees in all the regions will be less than 100 years old. Couple this with the human rights violations of the Indigenous Sámi people - I would argue that timber from these areas, (Iceland, Norway, Sweden, Finland and Denmark) is just as bad for the planet as hardwood clearcutting in tropical forests, or the Redwood logging devastation in America.

You can certainly re-use the rafters for internal partitioning if the walls are not structural. This is what I've done. Good on you for making the effort 🙂 If the timber is pre-1980's it will undoubtedly be a better grade than any modern timber - although you do have to be careful with softwood timbers from the 50-s to the 60's as there was a shortage of materials after the war and a lot of builders, (from surveying experience, particularly in the Cambridge area for some reason) used whatever they could get, (or made it 'stretch'). There are websites that tell you how to visually stress-grade timber (based on flaws, knots etc), provided the species is known, and you could assume a fairly low-to-mid-strength species of softwood. (Unless you've got something really exotic it's quite likely to be Douglas Fir - sometimes the giveaway would be weeping gum pockets, and you may find dried residues) The Building Inspector ought to have some idea of that already, and - if you seem competent - they should accept your demonstration.

I agree with ProDave. It is certainly the case that installed PV panel prices are now at least comparable with roofing in concrete tiles and considerably cheaper than slate, but I too would be worried about future replacement. Correctly installed, it is rare for panels on a roof to suffer physical damage, (although with a greater frequency of more powerful storms and tornados, this is no longer a given) but electrically panels do go wrong. More so I think with modern panels that, AFAIC, are not as robust as they used to be. When I began installing PV panels 25+ years ago, PV panels were bright cobalt blue polycrystal with spangly silver frames. Power ranged from 65 to 175w. A typical example would be an Astropower AP-120, (roughly 700mm x 1500mm). When Sanyo HIT panels came on the scene (starting with their 180w panels with the weird proprietary framing) and quickly progressing to 240w after about 4 years it forced other suppliers to up their game and with the introduction of FiT the market became flooded with 'all-black' monocrystaline panels all around the same wattage, (although nowhere near the same performance in real life). Average dimensions mid-tweenies were then about 850 x 1600mm. Solar farms were not really a thing at this stage, so panel sizes were more to do with mono cell cutting and manual handling, which fitted well with UK roofs. Smaller panels allow more flexibility in fitting, and the sizes then, (especially the early Sanyo panels) fitted well with the typical UK roof lengths. Now PV panels are being optimised for large-scale solar farms using mechanical assistance for installation. They don't fit UK roof sizes half as well, and finding new unused stock of older panels sizes is not easy. 60 cell panels average 1000 x 1650mm (300 - 400 watts) 72 cell panels average 1000 x 2000mm (350 - 450 watts) These newer panels seem to use thinner glass, back sheets and framing and consequently seem to suffer more from hailstorms and wind events. I personally doubt that PV panels installed today will last as long as the old stock early 2000's panels I have on my garage. (Including an unbranded 35w panel from the early 80's that still outputs 80+% of its original power). I suppose the lesson is, don't expect panels to stay the same shape, colour, performance, (or quality). I'd buy a stock of spare panels just in case. Also budget for at least 3 inverter replacements in 30 years of operation - modern electronic transformer inverters are nowhere near as robust, (or heavy!) as the old Iron core SMA and Sputnik of yore. On the plus side, you don't have to program them with country parameters using dodgy power line coms either - so some things have improved...

True, I should have said 'may need' not 'will need'... This can be determined with a holistic WUFI assessment as no two houses are the same - you need to take into account the location, exposure, construction, state-of-repair, air-tightness, occupancy, and ventilation. IWI requires careful consideration; the breathability and condition of the walls and pointing should always be assessed before specifying the insulation solution; the external brickwork, pointing, roof condition and guttering all need to be assessed and repaired if in poor order to reduce the passage of moisture into - what will become - a colder wall when the insulation is added. No membrane, or insulation, (natural or unnatural) should ever be added until any underlying damp issues have been resolved. Plasterboard and gypsum plaster are - despite what some might claim - breathable, but they are more restrictive than clay or lime and don't work the same way. Natural-fibre insulations and plasters, (e.g. STEICOinternal with a lime plaster) have sorbative qualities that actively absorb and release moisture. This can help where humidity spikes occur, with natural breathable IWI contributing to indoor air quality and comfort. When internal water vapour passes through plasterboard and into natural insulation fibres it can be stored and built up over time. When internal conditions allow drying out, the more restrictive vapour path presented by plasterboards can cause high moisture conditions on the back of the boards - all of which can be exacerbated by any underlying damp issues in building the structure). This moisture will eventually find a way out, but in the meantime in concert with warmer temperatures could cause mould growth and staining. This is why STEICO always recommends V-VCL membranes where its insulation is used behind plasterboards. Admittedly, this moisture could be controlled by the use of MVHR or dehumidifiers to prevent it from entering the insulation in the first place, but this is a less robust approach.

Natural insulations will always cost more in the UK as it is such a small market and buyers have to absorb the increased costs of production, shipping and Brexit red tape. Unlike many countries in the EU, there are no local political forces to drive wider adoption. In most of Europe, there is price parity due to the scale of sales; in France and Italy for instance it is very hard to specify unnatural insulations due to building regulations. In the UK, the best we can say is that prices are on par with mineral wools and have better availability - rockwool costs a bomb to manufacture as it requires huge amounts of heat, and recently it needs to be ordered weeks in advance to ensure supply. There are many advantages to natural breathable insulations, especially for internal insulation. Regarding the OP's specific question, Steico should be cut roughly 5-10mm oversize between the battens. I wouldn't compress the surface more than 3-5mm behind plasterboard - any more than this and you will get bowing. 400 centres on your battens should work well, but I'd add 10mm strips to the face as you suggest. Installation info can be found here: STEICOflex_handling_instructions_en.pdf It is important to note that STEICO does not generally recommend achieving high U-values with IWI due to the condensation risk to the structure. There is, generally, a sweet spot between 40-100mm of woodfibre that balances the energy savings, cost, and condensation risk. If it’s of interest, their Technical Director took part in a webinar that covers some of these points: Rethinking IWI with Natural Fibre Insulation Useful advice can also be found in the following links: Insulation and retrofit - Finding the sweet spot - The Alliance for Sustainable Building Products (asbp.org.uk) The-use-of-natural-insulation-materials-in-retrofit.pdf (stbauk.org) If used behind plasterboard, you will need a moisture vapour variable membrane, (e.g. STEICOmulti renova or SIGA Majrex® or PRO CLIMA intello plus). These ‘smart’ membranes will limit the amount of water vapour entering the fabric but still allow the wall to ‘breathe’ during warmer periods. Correct installation of the membrane, and sealing connections to all surrounding elements is the critical factor with this approach. The best advice is to have the external walls assessed via hygrothermal software - such as WUFI - which will take all of the site variables into account. Internal wall insulation is more complicated than external due to the way it moves the dew point within the construction. In addition, standard U-value calculations will not correctly account for the sorption properties of wood fibres nor their ability to pass on liquid water through capillary action. WUFI purely considers moisture issues and how the various elements of the building fabric will deal with the volumes based on site-specific conditions. STEICO doesn't offer this additional calculation service on a site-by-site basis, but one of their distribution partners, Back to Earth, does. Chris is a great font of knowledge regarding renovation and upgrading of older properties and is a good first point of contact when specifying IWI. Siga & Pro climba with also provide free WUFI assessments if their V-VCL membranes are specified and used in a batten and board approach.

True, but once you have the experience and know that there is a risk you have a moral duty to protect your customers from the consequences of your error. Unfortunately, moral compasses all point due profit these days...

If there have been changes to the installation requirements since early units were sent out - and if this is due to safety-related changes - shouldn't Sun Amp be contacting all of their customers to have their system checked? Especially if they sent out early models without full installation instructions or adequate testing! There should also be a prominent notice on their website. They have a duty of care 'in-principle' and probably a legal obligation too - I'm sure the OPSS would take a view on this. I remember 25+ years ago installing some of the first Sunny Boy inverters in the UK. They were IP65 rated for use externally, but, crucially, not if they were laid on their backs. A lot were fitted beneath solar panel A-frames on flat roofs. The first we knew were multiple reports of failure and we realised the problem when one of our lads took the lid off to see inside. The resulting explosion of flame singed his eyebrows off - but we could then see 2 inches of water sloshing in the case. We replaced affected inverters on all sites and proactively contacted customers to switch off their systems until we could get to them. This was before the manufacturer confirmed the issue and agreed to replace every damaged unit. They reprinted their manuals and issued extra ones to wholesalers with old stocks, so I can't fault them. I wasn't happy about carrying multiple Iron-core inverters up and down stairs for the next few weeks though - those old SB2500 models needed two people to carry! The point is there shouldn't be stories like yours on here - Sun Amp should issue a recall notice as other responsible companies do.

That would be my conclusion too, other than the benefits to the environment in not using oil-based unnatural insulation. IWI requires careful consideration and should be carefully assessed before specifying the insulation solution. When using natural, breathable insulation for some impermeable walls, (e.g. concrete rendered/pointed or granite, flint faced) it may be more appropriate to incorporate a framed system which allows the addition of a moisture vapour variable membrane, (e.g. STEICOmulti renova or SIGA Majrex® or PRO CLIMA intello plus). These ‘smart’ membranes will limit the amount of water vapour entering the fabric but still allow the wall to ‘breathe’ during warmer periods. Correct installation of the membrane, and sealing connections to all surrounding elements is the critical factor with this approach. Ideally, this would be fitted behind an additional service void to guard against accidental penetrations later, for example, when hanging pictures. Plus your follow-on trades will love you. The best advice is to have the external walls assessed via hygrothermal software - such as WUFI - which will take all of the site variables into account. Internal wall insulation is more complicated than external due to the way it moves the dew point within the construction. In addition, standard U-value calculations will not correctly account for the sorption properties of wood fibres nor their ability to pass on liquid water through capillary action. WUFI purely considers moisture issues and how the various elements of the building fabric will deal with the volumes based on site-specific conditions. Back to Earth offers WUFI assessments. Chris is a great font of knowledge regarding the renovation and upgrading of older properties and is a good first point of contact when specifying IWI. Siga & Pro climba also provide free WUFI assessments if their V-VCL membranes are specified and used in a batten and board approach.

Even if breathability didn't matter, internal humidity regulation would, and natural materials like directly, (clay or lime) plastered wood fibre or hemp help with this in properties where effective internal ventilation is hard to achieve. Will you be fitting MVHR?

Or, more discretely as it's not your problem, just inform the neighbour and allow him to take it up with the BCO. I'm not saying it's good, but I've seen far worse from 'brick technicians' laying overhand. An old-fashioned time-served craftsman 'brickie' would find this unacceptable, but there can't be more than a handful of breeding pairs left in the country... probably extinct by the end of this year!

Don't discuss this with your architect - it's very rare that they will have the technical knowledge of woodfibre insulation to be able to advise you correctly. Speak directly to the technical department at STEICO - you can send a message via their website. The STEICO technical team is incredibly busy at the moment and it might take a while for a reply, but they will get back to you as soon as possible. You can also speak to one of the STEICO distribution partners who have their own technical departments; they will be able to help with specification advice, U-values, and compatible components: Mike Wye 01409 281 644 sales@mikewye.co.uk Back to Earth 01392 861 763 Chris@backtoearth.co.uk Ultimate Insulations 01786 447 997 Technical@ultimate-insulation.co.uk Ecomerchant 01793 847 445 info@steicoinsulations.co.uk As stated by others, you cannot fix directly into the boards - you will need battens and counter battens. You need to maintain a minimum of 40mm ventilation over the insulation to allow it to 'breathe' moisture away - ridge and eaves ventilation is required. This is still the case if you fit the sarking boards directly over the sarking insulation as Russell suggests. It 'might' be possible to specify this as a moisture-restricted construction with the correct build-up of membranes inside and out. This has been used a couple of times in difficult cases such as mansard roofs where ventilation is hard to arrange, but it does require a WUFI assessment to confirm that the specification won't cause any long-term issues. STEICOuniversal sarking insulation comes in 22mm thickness - so with 50mm of battens the overall roof raise would be 72mm. This has been approved in some properties in conservation areas by arguing that the raise is only truly visible at the gable ends; this can sometimes be further disguised with architectural detailing. Worth discussing with your conservation officer as external insulation, even a tiny amount with produce much better thermal performance, and, in combination with insulation between the rafters creates a warm roof construction that lowers the risk of moisture damage to the rafters. It helps to create a building that will be more comfortable for the occupants, will be better protected from the elements, (excess summer heat as well as winter cold and rain) and is likely to last long into the future as a result. N.B STEICO external insulation is treated with a hydrophobic surface coating which provides an extra element of waterproofing, (in most circumstances an external breather membrane is not required).

My dad worked at Shellhaven in the mid 60's just before the fire. One of his jobs was to climb into the tanks to inspect them - hold his breath an in he went. H&S would have a fit now! Especially as his foreman used to stand out of the wind nearby smoking his pipe till they finished...