EdHat

I find extractor fans in the kitchen and bathroom make the biggest difference and keeping doors to these rooms closed. Consider ones with a humidistat. Activity in these rooms can cause big spikes in relative humidity (RH) and temperature. When the temperature then drops, after cooking and showering finishes or as the air moves to colder parts of the house, the RH raises further. If you have extract fans in the kitchen and bathrooms and still have issues then I too would advise getting a decent dehumidifier. You can set them at say 60% RH and they will turn on when it gets above this, preventing RH getting high enough for condensation and mould growth. Meaco is a good brand and their units are low wattage

@PSC88write a letter making your case, reference policies from the local plan that you are complying with, and give local justification for materials including photos and recent uses. I find planners stipulating materials a bit of a nonsense as it'll likely be permitted development for you to change your roof covering, windows, render afterwards anyway. I had planners tell me they didn't like mono-pitch dormers and wanted traditional pitched dormers. There was a reason I'd included mono-pitch in my design and i wasn't going to back down. I struggled to find local examples, but made the point that policy doesn't forbid them and they'd recently approved flat roof dormers, so if I couldn't have mono-pitch id go for flat, knowing they couldn't object to this. They backed down as they'd obviously rather anything but flat dormers. So what I'm saying is, even if you can't find examples of what you want, sometimes giving examples of something worse works.

@Post and beam Which manufacturer did you end up using out of interest? George Barnsdale do look very good on first impression, they put a lot of information out there on their website which makes incorporating them in a design early on easy.

I'm not sure if i understand your question. Do you want to build right up to the boundary and therefore don't have room for a normal gutter? With a warm roof you can form a gutter in the insulation, you only need to achieve a 1:80 fall. Roof manufacturers will have a standard detail for this. Alternatively is it possible for the roof to fall a different direction and then have a kerb along the boundary side so no need for gutter there?

Just to drive home the point, as others have said, and hopefully provide some clarity, the original post refers to the principal designer (PD) role under the building regulations. This is a separate role to the PD role under CDM, but just to confuse things they decided to use the same titles. CDM principal designer Responsible for ensuring H&S has been considered in the design in terms of construction and future maintenance and any risks are designed out and preparing H&S file at the end of the project. Doesn't necessarily have to have designed anything themselves, as designers have responsibilities under regulations. CDM principal contractor Responsible for H&S onsite during construction phase. Prepare the construction phase plan, provide welfare facilities and coordinate contractors. Basically manage the site, individual contractors still have H&S responsibilities under the regulations. BR principal designer Responsible for ensuring and declaring that the design is compliant with the regs. Architects should really be doing this under there role in completing technical design stage anyway. The only real additional requirement is they must sign a declaration. Again, designers still have responsibility for there own portion. OP there should be no issue in architect continuing to act in this role during the works but you will have to consult with them if there are any changes to the design. BR principal contractor Responsible for ensuring construction is as per the design, and therefore compliant with regs. Has to sign a declaration on completion and therefore assume a lot of risk. PAS 8671:2022 is where to find the full details of the PD role but there is a brief summary of that and PAS 8672:2022 here: https://consultations.hse.gov.uk/bsr/building-safety-competence-information-pc-pd/supporting_documents/Building safety competence information for principal contractors and principal designers.pdf If you are competent you can be the client and fulfill all these roles. PD and PC roles under the building regs don't place any more requirements on the lead designer and main contractor then they would usually have contractually anyway. The purpose is basically to clear up the fact that it is not the building control's responsibility to ensure design and construction comply with the regs and if you manage to get something non-compliant approved and signed off, and it later comes to light, there is someone to be held responsible.

As others have said, as it's a solid wall you want to use vapour permeable materials to allow moisture in the wall to evaporate. Use a humidity variable VCL on the warm side. Tyr-Mawr do some good systems. Don't leave voids, this will encourage interstitial condensation. If you can't lower the external ground level, take the DPM up the wall to 150mm above external ground level and fit a DPC here as well. Dry rods in the mortar bed are probably your best bet. Alternatively, waterproof render over the whole wall inside and then use a standard VCL and PIR internal wall insulation system. You will need make sure you get your VCL completely airtight and get a good seal with the floor membrane as well as introduce adequate ventilation elsewhere to keep humidity levels under control. My preference would be the former.

Proper single ply membranes are often used on large flat roofs without complicated details for speed of insulation or pitch roofs as it presents a very clean look. These are usually PVC or TPO/FPO and are heat welded at laps which makes them very durable. I see some issues with puncturing where people walk on it, but electronic testing can locate punctures and they can be patched. Biggest issue I've seen is with poor installation where it wasn't adhered properly and blew off in a strong wind. EPDM seems to be a more DIY suited product for use on simple small scale roofs i.e. garages, garden buildings. While the membranes seem to have a long life expectancy I'm not convinced the adhesives and trims do. The EPDM trims do not seem durable to me as they sandwich the membrane and rely on foam for creating a seal. Laps do not seem durable either as they use adhesive rather then heat welding. They are especially vulnerable on corners where they often start to open up so belt and braces would definitely be wise. I see a lot of rippling with EPDM that I haven't noticed with other single plys. EPDM is also much more vulnerable to puncturing then other single ply membranes. Note the big manufacturers of single ply membranes, such as Sika, Icopal and Bauder don't produce EPDM membranes. The Alwitra one in featured in the Robin Clevett video is PVC. I very much a fan of bitumen felts for 'out of site' flat roofs for their durability and cost effectiveness. There are a lot of cold applied liquid systems on the market now with BBA certs to rival lifespan of other products which are excellent for complicated details and overcome many of the issues with GRP, but do come at a cost premium.

I concur with DevilDamo and would add, you should seek an surveyor/ technician/ engineer to produce the detailed drawings for a full plans submission. Ask that the drawings give a sufficient level of information to allow builders to quote. You will also need to consider whether you will want someone to tender the works for you and oversee the construction works as it will be worth getting a fee quote at that stage. It will likely require planning. The Local Authority won't necessarily get back to you to confirm whether it needs planning, they are under no obligation to. Have a read through the Permitted Development Rights guidance on the .gov site and see if any applies.

You'll need 140mm or 150mm depending weather it's refurbishment of an existing element or a new thermal element. When I've needed to keep the height down I've been able to reduce the 140mm down to 90mm by using a multi-foil insulation over the joists first. You could also look at Recticel Deck VQ which has a lambda of 0.008 and I believe you can meet the regs with 90mm but I expect it is expensive.

If the porch is not within the thermal envelope of the building, i.e. external door between house and porch and porch is unheated, then building regs application wouldn't be required.

Fill the footings then you're ok. The PWA only applies to the footing works so it will be too late once they're complete.

PIR overcomes that but won't have the same acoustic performance as the mineral wool. How important is sound performance? I would probably go PIR and an acoustic plasterboard. If you keep the r-value of the inner insulation layer lower then the outer layer (and have a good VCL) you generally overcome the interstitial condensation risk. But that will limit you to about 90mm mineral wool depending on exact lambda. If you are confident you can get the install the VCL completely airtight and their aren't any high humidity rooms directly below, then the risk of interstitial condensation is going to be very low even if you fill it with mineral wool. You could add a layer of multifoil insulations beneath the mineral wool which will improve thermal properties and double up the VCL, but it will be expensive.

I know of a similar situation so I can comment as to what my LA planners agreed. - Had PD for a ground floor extension. - Applied for PP for a part single storey part two storey extension which would breach the 45degree rule. - The single storey portion was the same as that approved under PD. - Planners understood that if the ground floor portion was constructed under PD then the two storey portion would get PP and the result would be the same, although with a lot more work finishing the ground floor only to add a first floor. They agreed to include the ground floor in the application and waive the 45 degree rule There exact words were "The ground floor extension would require planning permission if it is not fully completed before the first floor works start. Obviously it would not be reasonable to require the ground floor extension to be fully roofed etc to allow the first floor to be built, and as such, I take the view that although the ground floor extension should be included in this application for planning permission, it would not cause any additional harm whether it is built by itself (under permitted development) or with a first floor addition. As such, I would not be looking to refuse the application on the basis that the ground floor breaks the 45 degree rule, as long as the first floor extension is compliant." At the moment you have two separate permissions, not one for the combined structure. You should resubmit but mention you have PD for a portion and make the point that if you complete the PD and then applied for PP for the extra, the result is the same, so it would be unreasonable to enforce the 45 degree rule.

Although it is not unusual to see slates laid onto the barge board with no undercloak and mortar, you should bed all tiles or slates on an undercloak or use a dry system. I agree dry verges made up of individual caps do not look nice. A wet bedded verge isn't that much maintainance if done correctly. Make sure the undercloak is bedded, projects the right amount and tiles are bedded on a min 100mm wide bed of mortar. Often tiles are bedded and mortar is left recessed and pointed up after, and then that falls out. If done right, by the time it needs looking at plastic dry verges would be faded and looking poor. Bear in mind if, you are considering interlocking tiles each will need to be clipped at the verge which effects the aesthetics of a bedded verge. 1. There are continuous dry verges available for tiles. I would avoid darker plastics to delay the fading. 2. With slate, if you don't want to bed them just use a continuous dry verge, they look very neat imo. 3. At the eaves? Why don't you want weight on the fascia? You can use an over fascia vent to provide ventilation between the fascia and tile/slate. Some roofers still use tilt fillets with 5u felt but eaves support trays are generally more popular now. This is to support the underlay not the tiles/slates though. If you don't have a fascia you would need a tilt fillet to support the tiles/slates.

That looks poor in the photo. The bond is not uniform in the corner with large gaps between bricks. The corner of a bay is a crucial point to do right, as it is often subject to point loads around openings and ties the sides with the front. The brickwork also protrudes into the cavity which is going to cause cold bridging and be vulnerable to moisture bridging the cavity. Regarding the messy/lack of mortar to joints and snots in the cavity, just because it's common doesn't mean it is acceptable. I would be particularly concerned with open joints as it has a full fill insulation. Does your insurance cover allow you to appoint your own surveyor to specify and oversee the works?