sgt_woulds

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...

The flammable vapours released might also play a part depending upon distance and the presence of exposed flames. I used to work on the Goodyear blimp. Once, in France, we had an Avgas spillage - about 80 - 100 litres. I can't remember which airport it was, but it was a fairly major one and their response was extraordinary. They closed the airport and evacuated an enormous area down-wind of the spillage, (at least half a km. Mostly fields although they had to ask a farmer to switch off his tractor and put out his cigarette - for a French farmer this must have been like asking him to chop part of his face off!) Within 15 minutes a team of engineers, diggers, and lorries had arrived, excavated the site of the spillage down to a depth of about 2m and a diameter of about 6m and carted the offending material away. A new team arrived on their heels, filled the hole and laid new turf. All in the whole process took less than one hour from when we reported the spillage to the tower! Seems extreme, but the incident team leader, (possibly the angriest chap I've ever met -quite an achievement as the French are good at simmering resentment) said that another airport in France had had an Avgas fire and the ignition source was outside the airfield boundary!

And the dimensions?

So thetdog666, which build-up description is correct?

Back to the original subject, and regarding the efficiency of the wood burn, (which requires a short, high temperature burn) and the need to remove the combustion process from the internal environment I agree that Iron WB stoves are a non-starter and definitely shouldn't be DIY modified. So we should be installing masonry stoves, (Kachelofen, steinofen, pystyuuni, kakelugn, other names depending on where you are in the world) all of which are easily DIY-able - although the best ones with special ceramic burn chambers and venturi ventilation to boost burn temperatures above 2000°C do require special components. Most of the ones I've seen and used in Hungary had external firing chambers for easy loading and cleaning. Some did have a window inside where you could see the flames but as the burn typically lasts less than 60 to 90 minutes it's not worthwhile. Even the most basic designs will effectively use faggots of thin sticks, (not inefficient logs), leave very little ash and produce very low waste gases and particulates, (and low-temperature exhaust) from the chimney. They have efficiencies heading towards 90%. I have looked in the inspection holes and there doesn't appear to be any tar or other deposits in the chimney and I'm told they rarely need cleaning unless wet fuel or logs are used. Rocket stoves, a combination of a fire barrel, flue and cob - are a poor relation masonry stoves - but are quicker, easier, and cheaper to build. I don't have experience with them, but some say the indoor air is less pleasant due to dust scorching on the barrel, similar to modern iron stoves. I have lived with an iron WBS and although the sight of a simmering fire was soothing on a dark evening, that was pretty much the only plus point I could see. A true masonry stove produces low-temperature radiant heat, and many have in-built seats or day beds so you can snuggle right up. In the depths of winter, our relatives fire their stove twice a day, using two faggots at a time. In the shoulder months, 1 burn a day is sufficient.

According to your drawing, there doesn't appear to be any racking board on the frame. Is that correct? In 'traditional' UK timber frame I would expect to see OSB or plywood fitted external to the timber frame. (You also show a 120mm frame in the drawing but say it is only 90mm? If it is 90mm why not fully fill the space - use two layers of 45mm or 90mm boards - both options available from Celotex?) Is your frame open to the cavity? What protects the insulation and timber frame from the moisture in the external cavity - there should be a breathable membrane external to the frame? This is very important as it determines the 'breathability' of the structure and the type of VCL you need to fit internally. This also creates follow-up questions regarding your insulation choice and fitting methods. Detailing will be critical to ensure no long-term repercussions of 'upgrading' the insulation. Are you insulating the whole house, or is this just a small section?

Too true - too many monkeys not enough craftsmen. The adage 'never do to a customer's house that you wouldn't want done to your own' is one I've always worked to and tried to instil in apprentices, but I've worked with many so-called tradesmen of all types who couldn't give a toss as long as they got paid. Having said that, I've yet to come across any roof that is 100% waterproof but a properly installed and detailed membrane should keep out 99.99% 🙂

A valley is a likely area to leak due to the amount of water it will see. Have they fitted the dry valleys yet? Gable ladders are a strange location for issues unless the undercloak is not in place. As ever, pictures speak a thousand words...

The tiles and flashing form the primary waterproofing layer. In older houses this is also the only waterproofing, which is why traditional buildings have slates or plain tiles, both of which have greater overlaps and can resist wind-driven rain quite well. Wooden sarking boards were introduced in high exposure zones to prevent wind from blowing through one side of the roof and lifting tiles on tiles on the other. These were gradually replaced with paper and bituminous membranes that performed the same function but were cheaper and quicker to fix. As modern interlocking tiles were introduced, wind-driven rain became more of an issue, and the membranes became important as a secondary weathertight barrier. They became standard fit in all situations, but gradually changed to the breathable types. The membrane should provide good weather tightness until the roof proper is on but are not 100 % proof thanks to nail holes etc. The better types will have tape at the overlaps and a conscientious roofer will ensure there is a slight 'droop' between the rafters to ensure good runoff and tape penetrations and abutments if leaving exposed. In certain situations the membrane can be deleted, e.g. wood fibre insulating sarking boards above the rafters on a warm roof. Tiles still provide primary weatherproofing and the hydrophobic coating on the woodfibre is the secondary waterproofing layer. In any case, whatever is under the tiles is only ever a backup.

www.paintzero.com Make breathable paints that come as bags of powder - mix with water and off you go. Seems quite a good idea as unused paint powder can be stored easily until it's needed again, unlike large tins of paint that can go wrong. Crown were making bold claims, (probably still are) in their literature and website to push people to use their contract trade paints over freshly plastered walls as the paint was 'more breathable'. I couldn't find anything in the datasheets or the tins that gave the Sd or mu values. After a lot of back and forth they finally said: "We don’t measure the Sd value on our Trade paints as the paint will always have a low Sd value due to the nature of the paints. A couple of years ago we measured the Sd value on Covermatt and Crown Trade Matt and both of these had a Sd value of approx. 0.060. The measurements were carried out in our R&D lab. Please see table below for Sd value and the classifications Sd 0.060 Classification v 1 HIGH Classification Sd 1 HIGH The Covermatt, Trade Matt and Contract Matt are similar types of paints so I would expect the Contract Matt to have similar Sd value and classification as the other two paints." (sic)

If you are looking at building a house with natural materials like straw bales I assume you are happy to trade the low(ish) cost and complexity of the materials against the sheer amount of extra labour required? In which case, have you considered Cobbauge which would be similarly hands-on but not subject to the vagaries of straw bale quality and procurement?

That's not oversight, it's incompetence. It's about a lack of fundamental knowledge of how a PV system works. Any solar installer would check the system requirements before wiring the system. To complete the work they need to update the schematics of the system, (displayed at both inverter and mains incomer locations) to show how the panels and inverter are wired. If you've paid them on the basis of their alleged knowledge then they should be liable for the cost of scaffolding and rewiring to remove the redundant lengths of DC cable, (which will affect the performance of the system by a negligible amount, but the principle remains). They should also ensure that the inverter wiring and labelling are compliant with the wiring regs and MCS requirements and the grid regulations, (at least the ones in place when the system was first installed - G83 I think -G98 came in around 2020 from memory). I'm unsure if there are any additional requirements under the 18th edition WR - I've been out of the game for quite a while - but I'm sure there are some up to date electricians on here who can advise further...

Don't forget to check that your clamps will fall within the clamping zones specified by the panel manufacturer too. Clamps outside these zones may invalidate any warranty and may stress the cells/glass, and the frame may not provide the necessary uplift resistance. Not all solar panels can be clamped on the short sides - best to check. One thing to factor in when installing direct to the gutter - water rushes quicker down non-stick glass than other roofing materials and a large PV array can cause undersized gutters to overflow. Based on my own experience - and pessimism about future weather patterns - I would recommend deep flow gutters in general but certainly in this scenario.

If it were my panel on my roof I'd connect the two strings in series, then connect to one inverter. I'd have a bit of extra inefficiency from the additional cable length, but if I couldn't get on the roof to re-string it'd be the easiest option. However, I'm stating ON RECORD that I DO NOT recommend that you do this. It appears neither you nor your installer are competent enough to install panels or connect high-voltage DC to a grid-connected inverter. My recommendation is to have a suitable qualified PV installer commission the system for you.

You don't necessarily need a new inverter or more panels. 6 panels should fire up a single SB1200. Whether it will make the most efficient use of the panels, who can say. For maximum returns, a PV system should be designed, not just thrown together.