Monty Gerhardy

I’d agree wholeheartedly with that. Reading various comments on this and similar forums it’s fairly obvious that there is a lack of knowledge about fenestration – one bloke I had a discourse with back on ebuild didn’t realise that he had installed alu-clad plastic rather than the alu-clad timber he thought he was buying. To quote Patrick Hislop, Senior Consultant Architect at TRADA - “Although the window is one of the most critical components in any building, it is often the least well specified. “ (Wood Windows: Designing for high performance. ISBN-10: 1900510626) I am happy to offer considered opinion, referenced where appropriate. If somebody disagrees or finds fault then raise the issue and make your case. I’ve never hid my preference for timber – I’ve worked with it in various ways for over 30 years but I’m not punting any brand. I’m not overly impressed by casual assertions and less still by lazy accusations of shilling – where’s the evidence? Put up or shut up. If people don’t care for my style then don’t bother reading my comments.

If that’s what you are flogging then Mandy Rice Davies dictum comes to mind. In the view of TRADA (Wood windows: Designing for high performance) and NHBC (Standards 6.7) drained and ventilated designs (externally beaded) are recommended for areas of severe and very severe exposure to wind driven rain (see map, Standards 6.1) The security issue is a non-sequitur. The AuraPlus window is SBD licensed as are numerous other externally glazed alu-clad timber windows.

Not sure that you are getting the right steer from the drawings that have been put up What you have is probably as illustrated in attached pdf The claddings are a compression fit - the video may give a bit more context. https://www.youtube.com/watch?v=DAlTAH-WHUY auraplus-tgu-windows2.pdf

If you are set on this approach you want to search for glaziers that can supply ‘encapsulated glazing units’. Personally I’m not a fan. Thermally they are usually not great given the narrow cavities, lack of soft-coat LowE and gas filling. I also remain to be convinced about the durability of the perimeter sealing. I would recommend having a standard IGU installed in the window frame in the normal fashion (thus maintaining the integrity of the thermal/physical envelope along with manufacturers warranty) and then have an encapsulated unit framed within an alu U-channel sized to fit in the internal reveal of the frame. Done well it would be barely noticeable. You also mention that the window is on a landing. Without railings or a physical barrier the glazing should be designed to take barrier loadings.

Your ‘quote comparison’ reads like a non to subtle sales pitch. “Are any of the products finger jointed as standard (which is more cost effective versus fixed timber, but not as aesphetically pleasing)….Hinging - Are the hinges concealed or are they exposed?” Somewhat subjective I would have thought Thermal stress – not at all unusual for an annealed middle pane of a triple-glazed unit. “This required the whole sash to be replaced, as the glass was glued into the frame on that particular product.” Q.E.D. I’ve seen IGU’s flex in the region of 20mm – in/out, in/out - like the diaphragm of an amplifier under loads in excess of 3000Pa in a test rig. Deflection of glazing up to 25mm is acceptable. In addition to the inherent flexibility of the glass the spacer bar/sealant will absorb stresses. The wet or dry glazing gasket will absorb stress between IGU and frame. Last but not least there will be a weatherseal gasket between the door leaf and door frame that will also absorb shock. If it’s not thermal stress then a sharp sudden impact like a ball or bird would be far more plausible. Obfuscation – I clearly didn’t quote you or imply anything. Reverse ferret

You make no mention of; · Basic performance testing – watertightness, air permeability, strength. Likewise cyclic-testing or corrosion resistance. · Certification/3rd-party assessment of suitability for UK conditions · Security testing. Glazing. · There is no specific requirement for units taller than 1400mm to have toughened glass. · The doors sold to your customer must have either been rubbish or totally unsuitable for the location if they were vibrating so much that a pane of glass shattered. Incidentally, I regard the vibration theory causing breakage as implausible. Timber · If softwoods are being used - which is the most common timber for windows - the form of preservative treatment is of particular significance. Ug · Not as important as Uw. You also make no mention of g-value – high solar gain with a lack of shading is a problem with large areas of south facing glazing. ‘A’ rated sounds great in theory but can often lead to sauna like conditions in a highly insulated building. Hinges · Function over form. Of far more importance then visibility is the load rating, durability of the hinge finish and potential for adjustment. A few other things to look out for; · Are all the windows and doors from the same factory/manufacturer? If not profiles will vary, as may colours, ironmongery and even glass colour. · Does the warranty come from the manufacturer or the agent/distributer? What happens to the warranty if agent goes bust? · Is the system designed for UK weather/building conditions or Central European climates? · If to be used in areas of severe or very severe exposure (see BRE 262) can the system accommodate a checked reveal as required by NHBC? Is it a drained and ventilated design ? · Has the glazing been sized to accommodate the wind loadings? · Has glazing been sized to accommodate any barrier loading requirement at higher levels ? · Are units being joined together and have these couplings been assessed by an engineer? · Does the product certification cover the size of unit being supplied ? Does the certification relate to all the products being supplied ?

I'd ask about the warranty as well. Not sure what you'd get if you plan on incorporating 'stained glass' inside an IGU. You might be better of with the stained glass set in it's own frame (independent of the IGU) fitting within the reveal of the window frame.

Without having tested a window (to a recognised standard) it would be difficult to demonstrate that reasonable provision has been made to resist unauthorised entry by way of the window, or door. PAS24:2012 (and even the current 2016 version) is the least demanding of the standards mentioned for manufacturers to meet.

Nothing particularly odd about it - but there are other more effective methods. Part Q doesn’t reference any foreign standards. SBD accepts the (BS) EN 1627 RC2 category for windows prevalent ‘in Europe’ with the simple addition of at least one pane of 6.8mm laminated glass.. and a few more items for RC3 compliant doors. And some of those beads could be 'bumped' from outside if you knew how to do it... I’m surprised anybody building in an area of severe or very severe wind driven rain would choose anything less, particularly if using timber or alu-clad timber windows. NHBC are not keen on anything less in such circumstances. Interesting course of action… as those windows are not designed for a security glazing tape ! It’s clear from the picture that there is an EPDM wedge gasket installed where the tape would be going. You should find out who the manufacturer is and ask them. The clowns supplying the windows are clueless. From the picture I’m assuming that there will be a triple-glazed IGU going into the frame. It would not be un-common for a large unit to be delivered ‘dry-glazed’. This allows the IGU to be temporarily removed from the frame upon delivery to site. The frame can then be easily fitted and fixed and the IGU is then installed and secured. I would assume that in this instance the IGU is secured by a manufacturer specified adhesive mastic in the corners and at regular intermediate points. This would be perfectly acceptable for an SBD compliant window. If you suspect the windows are not as described then contact Secured by Design directly. It’s not unknown for some suppliers to have a relaxed definition of what constitutes an SBD licensed window. Plod runs the scheme and takes a dim view of people taking the piss out of them and customers. have your architect demand the manufacturers SBD schedule and a statement from their SBD recognised 'Certification Authority' that the specific unit in question is licensed. Good luck.

It can. You’d have to be within the building to use a tool. Secured by Design intention is to make it difficult to break in – short of bank like security measures, it’s not possible or economical to make a domestic window totally burglar ‘proof’. The SBD testing is based around the attack methods that the typical UK burglar utilizes. They don’t typically carry glass suction lifters…. or be inside the building trying to remove the glazing.

Indeed. Given the amount of money people are spending on windows it’s surprising that the installation detailing appears to be an afterthought in many instances. IMHO the hierarchy of requirements for a window installation should be 1. robustness of installation - window stays in place 2. robust detailing - it keeps the water out 3. thermal robustness - thermal optimisation This is particularly so in areas of severe and very severe exposure to wind-driven rain ie large parts of the British Isles - http://www.nhbc.co.uk/Builders/ProductsandServices/Standardsplus2016/#135 What I would describe as THERM fetishists spend an inordinate amount of effort ensuring that the window installation is thermally optimised to the detriment of the weathering and physical robustness. All well and good for a Passive House in central Europe where the winters are not only a lot colder but they have less 'horizontal' rain. Pretty isotherms on a computer screen may not look so good in situ on the western seaboard in the middle of January. Furthermore, the simpler the detailing the easier it will be to execute on site. As you’ve pointed out in an earlier post the ‘compressible fill’ underneath the window is daft - as it is in the original Nordan detail. I would only envisage it being effectively used underneath a window to allow for differential movement between a timber frame and a masonry outer-leaf, and even then it would only be between the masonry and the window cill - http://www.gov.scot/Resource/0047/00479931.pdf - detail 3.08 (E3) on page 9

If a supplier gives money off just for the asking then one ought to ask oneself; 1. Why was it 'over-priced' in the first place 2. Could I have got even more off if I pushed a bit harder On reflection neither scenario is particularly edifying.

Probably a bit late for the OP but might save some others going with jerry-built details in a similar situation.... http://www.nordan.no/vindu/vis http://www.nordan.no/vindu/vis/vaeggkonstruktioner It doesn't have to be slavishly copied but if it's good enough for the west coast of Norway the principle should be good enough for anywhere in the UK.

For a comparison of the processes I’d refer you back to BS 8417: 2011+A1:2014 and the footnotes to Table 4 “Preservative recommendations as given in Table 4 are based on penetrating processes (see 6.5.3) for which laboratory and, where appropriate, field tests and service experience provide a high degree of confidence in performance.....Developments in treatment techniques using superficial processes….. might justify the use of such processes” (my italics). Hardly a ringing endorsement for superficial processes such as flow-coating. Further, observations by Joran Jerner of SP Technical Research Institute of Sweden can be found here http://www.svanemerket.no/PageFiles/9770/Background%20_windows_consultation_proposal.pdf… but for a taster he states “ It is naive to think that a high share of heartwood can compensate for permeation.” Regarding desired service life data. You second post referenced BS 8417 in relation to a 60 year service life – “requires at minimum timber classified as durable (class 2)”. This is taken from table 3 and is for untreated timber. Table 4. for timber treated using preservatives in accordance with BS EN 599-1, asserts that permeable wood (softwood& heartwood are indistinguishable) with penetration to class NP3 (6mm lateral, x10 longitudinal) will provide for a 60 desired service life. In other words slightly/moderately durable timber such as Pinus sylvestris is good for 60 years with the appropriate treatment. Without that level of preservative penetration then 15 and 30 year maximum service lives are suggested depending on the treatment. “30 years before maintenance” sounds ridiculously optimistic. Any window or door should be inspected at least annually - and more frequently in exposed environments. At a minimum hinges will need to be lubricated. DVC standards are designed for the Danish market …and Danish conditions. BS Codes of Practice (such as BS 8417 Preservation of wood. Code of practice) have been developed with the specific requirements and experience of the British market and the climate/geography of the British Isles in mind. It’s a similar situation with security testing of windows and doors – the UK maintains a requirement for additional forced entry testing - PAS24 - in addition to the EN 1627 standard to accommodate the techniques typically used by UK burglars. The move towards superficial preservative treatment processes (such as flow coating) has been driven primarily as a cost-cutting exercise (and to a lesser degree by workplace elf n’safety factors). It is a lot quicker (cheaper) to make windows if you eliminate the vacuum impregnation process. With the minimal preservative penetration (≤1mm) achieved by flow-coating the durability and continuing integrity of the surface finish is extremely important. In such circumstances even the sanding of the frame can reduce the preservative depth. As Rationel make very clear in their O&M manual ( http://www.rationel.co.uk/media/1620007/om-manual_2014_sept14_web.pdf ), “Any cracks in the paintwork or timber, will allow moisture to penetrate into the product and over time cause decomposition of the timber” (my italics). I’d treat the Wood Window Alliance claims with a degree of caution. The kernal of their durability claims are based on academic studies conducted on vacuum impregnated windows of a specific design. They have ‘carried over’ the results from these studies – as you have noticed – to any generic window that their (paying) membership produce that complies with some basic guidelines. Those guidelines do not have a requirement for vacuum impregnation. The excellent TRADA book Wood windows: Designing for high performance (Patrick Hislop) notes that there are numerous designs of timber windows never mind the range of constructions that are described as ‘composite’. In the real world the preservative treatment is essentially a safety net. A well designed & constructed window, correctly installed with interface details suitable for its environment should shed the water that will facilitate rotting and have a service life of 60-70 years if not longer. The presence of Pine heartwood is certainly no guarantee against rot – remember at best it is only ‘moderately’ durable. Furthermore, heartwood is difficult to penetrate with preservative treatments. Nordan make good windows (SW Norway actually gets more rain there then we do in here in Ireland, never mind the sepearte arctic climate further north) hence their popularity with our Caledonian cousins. UK manufacturers are moving towards flow-coating on cost grounds. Penetrating processes would still be common amongst Norwegian and Swedish window manufacturers – the rest of continental Europe is flow-coat or dipping. Preservative treatment is just one factor in assessing the quality of a timber window but I would suggest that for anybody considering installing timber windows in areas of severe, or very severe, exposure it would be imprudent not to use a vacuum impregnation preservative. Good luck with whatver you choose. It will look a lot better then plastic and should last a lot longer if looked after.