SBMS

Ah okay thanks @JohnMo I was asking because my wife didn’t want timber internally (chunky) and we’ve had quotes from norrsken, rationel etc that are all more than the pure aluminium system. It seems like a bit of a no brainier for me but wasn’t sure if I was missing something

It’s the Uw. Had the values back from local fabricator.

Have done. Largest privately owned fenestration company in UK turning over 53 million so would hope their claims and testing were robust. What do you think: https://www.seniorarchitectural.co.uk/wp-content/uploads/2023/01/PURe®-Casement-Window-System-Technical-Datasheet-28.10.2024.pdf

Would be interested in why many favour timber alu clad over pure aluminium? Thermal efficiency for us is on a par (0.75 u value eg for aluminium windows). For me the internals of aluminium are preferable to more chunky timber. But would be really interested to know if I am missing something?

Stone slips? Just trying to visualise that.. we are using stone copings on top of the flat roof area..

We are looking at some column and beam casings for some aluminium columns and beams on a canopy. We’ve had a quote from guttercrest which was reasonable. But just struggling with what fixings are needed to attach the square column and beam casings to the steels? Guttercrest weren’t terribly helpful and just pointed us to an installer who wants to charge an arm and a leg. Anyone got any ideas how you’d go about fixing these column/beam casings: https://www.columncasing.co.uk/square-column-casings/

Our architect has designed an open canopy structure that will have a glass/plastic roof and open sides. The beams and column are steel. We’ve had a price to clad these in aluminium which is very expensive. We might have to end up with this as an option but wondered if anyone has any ideas for alternatives? Potentially using composite cladding or anything similar? Be interested if anyone has a similar design. Steel bits numbered in red:

Once plannings approved sort out any pre commencement conditions if you have any - another 10 weeks for us! Depending on your planning this will usually involve getting a drainage design done, construction management plan (ask chatgpt to write one) etc. Depends on your conditions obviously. Whilst this is happening get full building regs compliant drawings done by architect along with any drawings by structural engineer. As part of this you might end up getting a design done for any engineered floors / roof. I would recommend Pasquill for this, they’ve always been good. YMMV. Make sure you get your CIL self build exemption and issue any commencement notices for when ready to start. Next get your SAP and Part l over heating work done. You need to ensure your build is compliant. You’ll need to start thinking about windows, doors etc so you know the u values and thermal bridging details. You’ll need to try and achieve these so your as designed sap aligns with your as built sap. Utilities next. Sort out how you’ll get gigabit internet to property as required for building regs. Easiest is to submit application to openreach. Worst case use starlink. Get quotes for water and electric connections as required. Next step is to organise any self build warranty and site insurance. Then appoint your building control and get your architect to act as principal designer for building regs and submit everything on your behalf. At this stage I think you’d be ready to start although I might have missed something. Obviously you’ve got the appointment of a contractor or if you’re self managing your subbies. Think that’s it!

Sorry @JohnMo I thought you were saying all aluminium units were ‘rubbish’ u value.

Yes this is the Uw value with triple glazed units. Some aluminium units were dreadful - 1.6 Uw and triple not much better. These are Senior’s systems with a polyurethane thermal break.

Our quoted aluminium sliding doors are 0.9 u value. Windows are 0.76 u value. That’s not rubbish?

As someone who went rigid (ahem) with the association attenuators etc, couldn’t agree more. Ridiculous amount of extra kit and complexity for no real benefit in my opinion.

I think the internal 25mm and 75mm insulation will serve as your vapour check layer. Your initial post references this in the Kingspan notes.

Don’t do rigid if it’s a branch system. Was a right pain in our last build. Next build we will use a radial semi system.

When I modelled this it was a diminishing return past 0.15 in the walls. I decided to go 200mm cavity with EPS (traditional masonry) and increasing cavity to 250mm and 300mm made very little difference to overall energy loss per annum. Nowhere near worth the additional cost of the insulation, larger (non standard) lintels etc. Your mileage may vary if using SIPS. Interesting also the comment from Kingspan that their fabric makeup also isn’t SAP compliant which I think from memory was what I discovered. I love the ‘simple application of internal insulation’ - not particularly simple to skin the entire inside of your build with another layer of PIR.. Good wall u values but failing thermal bridging elements hence their recommendation of internal insulation over the timber bridging elements. It was a contributing reason to why I decided traditional construction. That said there are SIPS suppliers that don’t use timber connections and thus avoid that issue.

This is actually a great point. All our floors will be counter battened in this manner by the builder for a bit of a service gap and for plaster boarding. This isn’t accounted for in deflection though, so I wonder how much of an impact regarding deflection this would have? Ie if I keep the 600mm at 10mm deflection I wonder if the counter battening brings this down to 8mm anyway?

Thanks Russell. Well the best is 0mm deflection - where do you stop?

Getting our posi joist floor design done. The initial design targeted around 13.5mm deflection in the joists. I asked the engineer to quote for a 10mm and 8mm deflection. 10mm can be done with a wider top chord and at 600mm centers. 8mm requires 480mm centres. 8mm deflection across two floors is about £1600 more plus probably some additional labour time as there are more joists (they are being hung). Our current build I never thought about this and probably ended up with 13.5mm deflection. It’s a bit bouncy in some rooms. I feel 10mm is significantly better and my gut says 8mm will be overboard and I won’t detect the difference. I think it’ll probably be over £2k more for the 8mm deflection. Can anyone comment on if they have 10mm deflection - is it enough?

Thanks @Mr Punter am I right in thinking they’re self supporting? No need to secure anywhere other than at the top and bottom and not through the stringers? This is for a set that goes from the first to second floor so don’t bear onto the floor and just connect to the floor trimmers.

I get you. How do you specify chunkier materials with Stairbox or was this just their standard 32mm pine?

Thanks @Mr Punter just seen this! That’s great. out of interest, what is ‘commercial spec’?

Our floor joist designer has asked for the point load for a set of stairs where they attach to the landing, for calculating the engineered trimmer. This landing corner floats where the stairs attach and the joists cantilever over another wall to provide the landing so I assume the flooring engineer needs the load to ensure the joists are sufficiently strapped down. We are going to use Stairbox for our stairs - who tell us that they are self supporting and only need attaching at the bottom and top (no drilling through stringers needed). I asked Stairbox if they can provide the point load but they said they don’t provide this. I asked our structural engineer who said he can calculate it but needs the self weight of the stairs - is that just the total weight of the stairs or something else? Has anyone had any experience getting any of this info from Stairbox? Currently I have a conversation with ‘sales’ and am wondering if there’s more technical Support that can give better answers to engineering or structural questions?

Seems expensive. We were at about 11 for similar amount of windows.

We had the same issue about 8 weeks ago. At the last minute the council panicked because the planners had all been on a BNG course and were not clear as to how to approach this with self builds. Our planning consultant played a blinder here. The council basically said the ‘easiest’ thing would be to prove a 10% gain on our site as we actually clearly have it. Planning consultant stood his ground and said no, that would incur additional cost for us in assessing and undue delays. He drafted this condition which satisfied the council and I believe is now standard for most self builds in the borough to protect against submitting as a self build without any intention to build as a self build and then avoiding BNG. Can you suggest the following as a condition? It’s nice and simple and I think works for both parties “The dwelling hereby approved shall be constructed as a self-build dwelling within the definition of self-build and custom build housing in the 2015 Self-Build and Custom Housebuilding Act (as amended by the 2016 Housing and planning Act): i) The first occupation of the dwelling hereby approved shall be by a person or persons who had a primary input into the design and layout of the dwelling and who intends to live in the unit for at least 3 years; ii) The Council shall be notified of the persons who intend to take up first occupation of the dwelling hereby approved at least 2 months prior to first occupation.” note that as our planning consultant pointed out its drafted in such a way that we only have to have the intention to live it in for 3 years… not actually live in it for 3 years…

We used these on our last build. Much cheaper than residence - probably not as good quality but I would say better value for money than residence. Outside I reckon you couldn’t tell the difference between residence. Inside you could as they are not flush. Very happy with them, they’ve been quiet, good seal and look decent quality