fandyman

Appreciate the input - in this case both the independent expert and FENSA concluded the installation does not meet the standard of reasonable skill and care and is non-compliant with Building Regulations. I understand that in a fully specified project more detail could be agreed upfront, but for a standard domestic installation the expectation is that the installer designs and installs appropriately. The findings here point to installation defects rather than specification issues. Also, if the installation requires the customer to design thermal detailing and specify tolerances to avoid basic defects, it’s probably not being carried out with reasonable skill and care anyway which the reports confirm.

Sorry I said "as well" in the sense it was concluding the same as FENSA did which was basically a defective install. Doors are of poor quality (but doors and glazing meeting build regs themselves) as confirmed by independent expert (pricing of the doors was standard though) but yeah the sole reason for the issues observed was the poor installation resulting from lack of reasonable skill and care from the installer.

Just to update that S75 independent expert concluded that the installation is defective as well: Installation did NOT meet the standard of reasonable skill and care Doors/windows were installed too tightly due to inaccurate measurements Little or no insulation between frame, cill, and masonry This has created thermal bridging, especially at the bottom of the installation Condensation and mould confirmed under normal living conditions (not lifestyle-related) Standing water in the frame due to lack of proper drainage (no weep holes) Evidence of poor sealing, contributing to water and air ingress The recommendation is full removal and replacement of the doors and side panels.

Quick update following the FENSA inspection. An independent inspection has now been carried out, and the installation has been formally assessed as non-compliant with Building Regulations (Part L - thermal performance). The key findings were: The doors/windows were installed with only ~20mm setback from the external brick face, which the assessor states is likely to cause thermal bridging Recommended minimum setback is ~50mm, or use of thermal breaks The frame was not properly centralised in the opening, resulting in insufficient sealing and lack of expanding foam, affecting airtightness Additional issues noted around drainage and water retention within frame Overall conclusion: installation not compliant, with thermal performance concerns validated. At this stage, I’m focusing on understanding the appropriate remediation route based on this, rather than speculating further. I’ll update again once I’ve progressed the next steps on the S75 side.

I guess you must have been thinking about a detail like the below @garrymartin: In terms of the en suite @G and J I have actually made it even less intrusive with the above and also downstairs will have a relocated kitchen (new drainage through the front garden connecting to the existing as a new branch inside the existing chamber on the drive) so it should work all fine.

Thanks for all the great ideas - I think this could work. Will now be checking other aspects of it including the lower floor as well.

@ConorSee the house floor plan as is currently. @G and J Good point with 'part of the main bedroom' suggestion. I like this approach a lot. All in all, if well executed, do you think it wouldn't kill the value? I know think that as long as the new wide bay hallway serve a purpose eg. drawers/ dressing table/window seat it could make the plan work. WDYT?

This is what it would look like @G and J I would have to move the ensuite out of that bedroom and create a new one in a new master bedroom Would it be acceptable or look odd?

It will be a secondary bedroom and the new room added to the right will become a master bedroom with ensuite. The window in the bathroom is a standard wide non-opaque window. Are you suggesting the bay window may be presented as a functional desk space or bench, desk, reading nook? That might be one option that I have not considered yes.

Hi all, looking for opinions on a first-floor side extension layout (UK). I’m considering adding one additional room on the first floor to the side of the house (not rear). I’ve attached the existing first-floor plan with the new hallway marked in red and black. Because of the existing stair position and structure, one option involves forming a short internal corridor that is carved out of the current main bedroom (through existing wardrobe space and en suite), rather than walking directly through the bedroom itself. Important clarification: This would not be a walk-through bedroom The new room would be accessed via a dedicated corridor The corridor would have a full-height window for daylight The sleeping area would remain separated by a door So practically it would be closer to a small internal hallway arrangement, not circulation through the bed space. My questions: Is this type of solution generally considered acceptable in UK extensions if proportioned well? Are there any resale or usability red flags you’d immediately see? Would planners / Building Control typically object to this, assuming room sizes and light are compliant? Happy to hear both professional and homeowner perspectives - especially if you’ve seen similar layouts work (or fail). Thanks in advance.

I don’t actually disagree with any of that. Identifying causation rigorously is exactly why I’ve moved away from forum debate and toward independent inspection. At this point we’re well past exchanging hypotheses - the issue is persistent, localised, and observable, and the next step is to establish the mechanism formally rather than speculate further. I also agree that trades too often dismiss customer observations until someone “with letters after their name” repeats the same thing. That’s unfortunate, but it’s precisely why independent assessment exists. Whatever the outcome - whether responsibility ultimately sits with the installation detail or the underlying fabric - understanding what’s actually happening is essential before any proper remediation or replacement can be considered. Thanks for taking the time to set that out, and happy new year to you too.

Thanks for taking the time to think this through in detail. Some of the scenarios you describe - frame-to-frame alignment tolerances, bedding of the cill, or concealed gaps masked by sealant - are interesting. However, they all ultimately point back to the same issue: the assembly and detailing of a multi-part door system at the threshold. If any of those conditions exist, they wouldn’t be characteristics of the existing building fabric but of the way the system has been installed and integrated. Small tolerances, hidden voids or misalignment at the base may be common, but they are precisely the kinds of details that affect internal surface temperatures and condensation risk. I also note the suggestion that the glazing units themselves may be allowing air passage around the frame. If that were the case, it would raise a much more fundamental issue with the assembly and sealing of the system rather than with the surrounding structure. Ultimately, the challenge here isn’t identifying ever more hypothetical mechanisms in isolation, but assessing whether the installation, taken as a whole, has resulted in an internal threshold detail that performs acceptably under normal occupied conditions. That’s why I’m seeking an independent assessment rather than relying on conjecture or what might typically be tolerated in practice. I appreciate the input, but at this stage the question isn’t what might possibly explain it, it’s what is actually happening — and whether the installation outcome reflects reasonable care and skill.

I think we’re actually closer in position than it might appear - though perhaps drawing different conclusions from it. You’re right that Section 75 isn’t a forum for debating where industry responsibility ought to sit. That’s precisely why I’m not relying on what is customary, typical, or widely tolerated in the trade, but instead on independent assessment of whether the actual outcome of the service supplied meets the standard of reasonable care and skill. Where I part company is the suggestion that persistent condensation and mould are merely “subjectively unacceptable”. These are objectively observable outcomes, not matters of taste, and they are exactly the kinds of issues that reasonable care and skill are meant to prevent - regardless of how common a particular installation detail may be. You’re also right that an expert will examine whether a competent installer should have identified the sub-threshold detail and either mitigated it or flagged it before installation. That question sits at the heart of the dispute, which is why speculation about how often this is overlooked in practice doesn’t really resolve it. I appreciate the confidence expressed about how an expert might conclude. I’m comfortable letting evidence rather than expectation decide that point. If the conclusion is that the underlying fabric alone is responsible, I’ll accept it. If not, responsibility will follow accordingly. Either way, I agree - it will be interesting to see the outcome, and I’m happy to report back once it’s determined.

That’s fair - we’re clearly coming at this from different perspectives. Where I disagree is that reasonable care is limited only to what a trade chooses to concern itself with. It’s judged on the service actually provided and the outcome it creates, not on whether the installer considers certain aspects “out of scope”. I’m not expecting encyclopaedic knowledge of building regulations or retrofit design - I’m questioning whether an installation outcome that produces persistent condensation and mould under normal conditions is an acceptable result of the service supplied. You’re right that the credit card provider may apply its own logic - which is precisely why I’m comfortable letting an independent process assess it rather than relying on forum consensus. At that point it becomes an evidence-based decision, not a matter of sympathy either way. I appreciate the discussion - I think we’ve probably taken it as far as it can usefully go here.

Reasonable care isn’t limited to what a trade normally chooses to think about - it’s judged on the outcome of the service. If the installation creates a new internal surface that predictably falls below dew point under normal conditions, it’s fair to at least question whether that outcome is acceptable. I didn’t engage a general contractor or an architect, but I also didn’t instruct a detail that would knowingly create condensation and mould. The installer surveyed the opening, specified the product, and executed the threshold detail. Whether that outcome is ultimately deemed acceptable or not is exactly why I’m seeking independent review - not because I expect installers to be “more than a window company”, but because outcomes matter regardless of marketing labels.