joshwk

Good tips, thank you @SteamyTea & @Iceverge. @SBMS: 142mm appears to be the standard manufacturing for TEK Kingspan. 172mm is also possible but requires additional work in cutting transition materials down to suit the non standard wall panels width (quoting the images shown above). Per the table, 172mm with no additional insulation is estimated to achieve a 0.16 U/value. To achieve close as close to a 0.1 U/value as possible based on @JohnMo's suggestion, in my personal situation, I think the best route is to use 142mm but upgrade from +25mm to +75/80/90mm to achieve a 0.11 on the walls (in line with the current estimated U-Value for the roof).

Thanks @JohnMo, that's a great callout. Very helpful.

Hi all. We will be constructing our self-build in SIPs and I was curious to understand if there is a school of thought on 'diminishing returns' when it comes to wall thickness and U-value effectiveness. I realise the black and white answer is 'the lowest u-value is the best' and that there is a significant variable in the form of cost, but what I am curious to understand is if there is any general thinking on what a 'sweet spot' might be when it comes to investing into additional PIR vs the incremental gains made from improving u-value? Currently, I am approaching our build on the basis that walls would be 142mm + 25mm PIR to achieve a u-value of 0.15 and roof would be 142mm + 75m PIR to achieve a u-value of 0.11 but am wondering if I should be looking to improve the wall insulation further? Our property is not excessively large (~200sq/m total) so I am also conscious of trying to maximise room sizes. We are not going for Passivhaus but as this will be our 'forever home', I'm keen to ensure I'm building out house with the long term in mind. I have included a table below that we received from our SIPs supplier for visibility in case helpful. Thanks in advance. Walls U-Value Table Roof U-Value Table Walls + Roof Summary

Hi all. New member to the forum (intro post here). Currently looking at MVHR and am trying to determine whether rigid vs flexible ducting is "better" when starting with a new build. So far the school of thought seems to generally be that rigid is more hygienic/longer lasting but comes at the cost of price/slightly harder to install. A salesman was laying on the fact that all Passivhaus certified equipment is tested using a rigid setup (verifying this is the recommend setup), but unclear if this is true and accurate. I don't want to hear it and wondered if rigid was 'quieter' than semi-rigid? Any thoughts or feedback much appreciated.

Thanks all for the warm welcome and @Nick Laslett for the helpful suggestions. At risk of breaking the rules, a few responses/questions to your comments (mods, let me know if I need to move this to individual threads or via PM if you wouldn't mind Nick): 1. Insulated slab foundation. The primary issue for our delayed start date has been structural, due to the elasticity of the soil and close proximity to a very large oak tree (we are building quite far into the root protection zone - surprised we got planning in the first place!). As a result, I'm informed the floor needs to be beam & block so assume insulated slab is not an option? 2. UFH in slab, not screed Same here I assume, for the above reasons? 3. Proper ASHP configuration. People like HeatGeek on YouTube are now advocating this stuff, but back on 2018-2019 BuildHub was already there. I have an insane quote from a Heating company in 2019 pricing my ASHP/UFH set-up @ £40,000+. I would be surprised if my ASHP/UFH install cost me more than £5000. I've watched a lot of the HeatGeek stuff and the computer nerd in myself was really impressed with what they do. Would you recommend going through them direct or shall I head to the ASHP forum to source recommendations in the West Sussex area? 4. Going from resisting MVHR, to embracing it. The sooner you incorporate the MVHR ducting solution into the fabric of your build, the easier things will be. Every structural decision needs to accommodate how the ducts are going to route through the building. Embracing! We're currently going through the technical design of our building so am keen to appoint an MVHR designer so we can do exactly what you suggest. I'm still researching whether rigid vs flexible ducting is "better" when starting with a new build. So far the school of thought seems to generally be that rigid is more hygienic/longer laster but comes at the cost of price/slightly harder to install. A salesman was laying on the fact that all Passivhaus certified equipment needs to be tested in a rigid setup, but please let me know if I'm barking up the wrong tree. 5. Ducting requirements for ground works and in the slab. The insulated ASHP pipe is a particular pita to install. Assume the same issues for the block & beam reasons here. 6. Getting an electrical supply kiosk/water supply as soon as you own the land. All these services can be changed by you later in the build without involving the infrastructure companies. Great advice. I've already had a price to install electricity to the property and RE: water, due to the fact we are off the grid, we pull this from a borehole so am arranging for a tap to be installed on the land. 7. Do your own heatloss calculation using Jeremy Harris’ spreadsheet. There is also a great MVHR calculation spreadsheet, but this might not be as robust. Just downloaded: first thought was a little overwhelming but it appears primarily just entering values into the white boxes. One of the issues I'm experiencing with steel doors is that they don't appear to have an associated U-value, they are all just stated 'Energy Rating B'. I'll take a more detailed look at the spreadsheet though - thank you for the suggestion. 8. Manifold approach for domestic plumbing. Also hot return, if applicable. 10mm pipe for certain outlets. I did all of the plumbing in my build, this was only possible because of the discussions here. The manifold photos are just eye candy to me now. Am estimating that 3 manifolds will be required and have given some thought to where they will be located (one in the kitchen/diner, one in the cupboard on the landing, potentially one in the HWC cupboard). RE: hot water return, does this refer to a hot water circulating pump? I would love to have hot water on demand in all the bathrooms in order to avoid the dreaded 'warming up wait'. Thanks again.

First time self-builder who has recently only discovered the forum - I wish I had sooner! We acquired our plot of land on the stamp duty holiday deadline, 30 June 2021, and it has been a "journey". Our project that started with planning permission on a "full conversion" basis is now a "full demolition and rebuild", due to structural issues. Despite losing most of my hair, I'm pleased that we will now be left with scope for a better building. Currently in the process of drawing up our Building Regulations (for the second time) but will be constructing using TEK SIPs. For anyone curious, floor plan/3D model below/attached. Planning to approach the build on an ASHP, UFH, MVHR + Ground Mounted Solar PV basis (if the budget allows) so have a wealth of questions I would gratefully appreciate support on. We're aesthetically wedded to steel windows, despite knowing the thermal performance of aluminium is better/cheaper, but can't seem to shrug it off. I'll divert questions on these topics to the respective threads imminently but grateful for the wealth of information discovered so far and looking forward to discussing more with you all.