bissoejosh

Our frame co have mentioned that engineers have insisted on it in the past for this exact reason, as did TRADA. Exactly what I intended to do. I also like the fact that I would have a nice working deck to build from. It doesn't sound like anyone else was questioned about the compressive strength of the deck board. I think we're going to fall back to the engineer for this and get some point load calcs confirming the board is fit for purpose.

That's really interesting, I had thought it was just the way it was done having spoken to our frame designers and the suppliers/TRADA. The proposal would still use a 45mm sole plate. I hadn't considered the leak issue either which sounds sensible. So just to clarify the sequencing for yours was sole plate, wall, then deck after?

Just to say this worked a treat, not too tricky to learn & all approved by BCO with the 'draft' layer removed. Many thanks!

Bit of an odd one this... Our drawings show the first floor i-stud walls being built on a P5 deck which rests on posi joists. All pretty standard and drawn by the timber frame designers and approved by the frame engineer. Our BCO has apparently never seen a timber frame done this way & is worried about the P5 being strong enough for the wall loading. He wants to see BBA certification or similar that this is OK and won't be crushed. Failing this he he would like the deck to stop short of the walls and be an infill deck which would be tedious. The thing is no one has certification (that I can find) which shows the necessary detail. I've spoken to Norbord & Egger who both recognize it as a standard detail and see no issue. I've also spoken to TRADA who have the same opinion. Any idea how to sway the BCO without upsetting him? In all other elements of the build he has been fantastic and is super approachable - we just have a sticking point with this. My fallback is to ask the engineer to make it a frame requirement but I'd rather not play top trumps with BCO for the reasons mentioned.

I have and may still use a something like marmox if I can't reduce the risk enough without. One of the issues is our sole plate is 245mm so much wider than the standard sizes I think.

thanks, much appreciated. Will see what I can come up with...

This is by far the easiest to understand of all the explanations I've read and certainly represents conditions experienced here in Cornwall. I guess the question I need to answer is whether there is enough thermal resistance with the detail I've drawn or if a cavity wall concept with both the core and external face insulated provides a more robust solution. What method or software would you use to model this?

certainly did - many thanks. I needed to dig out an old windows PC but I've almost completed the basic calculation. I'm going to try your heat loss calc tonight and see how things compare...

Apologies in advance for dragging up an old topic.... A large element of our build requires the use of a beam and block floor on strip footings. In an ideal world this wouldn't be the case but our site dictates it. As mentioned in other posts we are using an i-Stud frame and whilst not expecting passive standards, would like to do the best we can. I've read numerous threads regarding the issue of sole plate decay through condensation when using a cold foundation detail such as ours, and if possible I would like to minimize the risk. I'm happy to consider the use of thermo blocks etc if they are genuinely required but wondered if a simpler solution exists. I've read several comments suggesting running external insulation above and below the sole plate however that isn't possible without significantly increasing our vented cavity. The detail below uses a 215mm block with the 245mm frame overhanging by 30mm (approved by the frame engineer). This would allow space for 40mm of EPS directly below the sole plate and continuing down as far as necessary. I would finish this in a similar way to some of the MBC houses on EPS slabs - fascia board etc. Does anyone think this would be enough to minimize the condensation risk? Another option seen on the touchwood site is a basic cavity wall concept filled with EPS on which the sole plate sits, would this be a better option? Both are viable for us in terms of footing width. As always comments greatly appreciated. DewPointDetail.pdf

Apologies if I'm being daft but how do you actually access the download? All I can find are options to join the Stroma DOCEA scheme...

Thanks for that - very useful. I'll see what our frame designers say...

I hadn't seen that page actually so many thanks. The section I'm struggling with is on beam & block due to level changes and a complex site. The solution on that page is quite similar to the golcar/denby dale solution for a masonry wall which we've done for our basement / lower GF. My current idea for a 245mm wall was a 215 block on the flat with EPS outside to flush with the sheathing board so approx 40mm. However this relied on the outer flange of the stud being mostly non load bearing as only 20mm is sat on block effectively. The insulated cavity option certainly looks like a possibility so I need to do some drawing and speak to our frame guys.

Sorry I realize this is an old post but I'm looking into the sole plate issue myself and came across this thread. We're going for an i-Beam frame as mentioned but currently our sole plate is drawn as a 245mm solid timber - was yours an i-beam laid on its side and if so did you insulated the web? Apologies If I've misunderstood!

Can this software be used for the projected EPC/SAP submitted as part of building regs? I understand that the as built one required for completion needs to be lodged through an approved assessor but I'm unsure on the initial one. I've re-drawn and submitted the majority of my reg documents as part of a redesign but I need to modify our original SAP - If I can do this myself I'm happy to try and learn the software this weekend.

As I thought really. In that case I'll work on screed to match levels and then a battened joist approach rather than a battened finished floor. Many thanks!

The screed will be on 200mm of EPS as a minimum. Makes sense about the P5, I've seen it done both ways but that would certainly help as a control layer. Does the screed offer a significant advantage over a straight floating floor?

Our upper ground floor is unusual in that it sits on both beam and block plus a small section of timber deck on posi joists. I'm quite keen to run a heat pump for UFH and need to make a final decision on floor make up. For the area on joists I'm happy either battening on the joists prior to laying the floor deck and fitting spreader plates or alternatively battening on top of the deck prior to laying the finished floor (engineered timber) again with plates. For the area above the B&B I'm less sure whether it would be beneficial to lay the piping in a screed to match the levels with the decked area or or to simply have a floating floor and spreader plates throughout. For reference the B&B area totals around 75m2 and the other 30m2. I suppose my question is essentially does UFH work significantly better when in a screed compared to a floating floor or are the differences negligible?

I was much the same to begin with and initially planned SIPS for speed. This slowly changed and from researching a variety of different frame options I concluded that I wanted either a twin stud or i-Beam version if at all possible. This was down to several reasons but primarily because I wanted to spend what budget we had on the best building fabric we could afford. I also really dislike celotex/rigid insulation and wanted to hit decent U values whilst avoiding it if possible. If one of our local firms had been able to offer something other than a standard frame we might have taken a different route but they seem to very much like what they know. Having had both preferred choices priced commercially they were outside our budget but a bit of research and a recommendation on here led me to Cullen timber who luckily specialize in this and are happy to work, as discussed with self builders who want to DIY it. I'm also 31 and my partner is younger & we're very much doing this on a shoestring. Luckily I'm self employed and live on site so doing work myself, around the day job, is where we can save money. If anything I've spent too long worrying abut the details, at the end of the day it's fairly likely that a genuine self builder will want something decent for themselves and this alone will probably make the house better than the majority of housing stock. Plan ahead but don't get too bogged down would be my advice!

Wouldn't disagree with any of that. It was always an aim of our build for me to learn as much as possible, particularly with the framing where I have less experience. Getting a fully cut frame helps greatly and eliminates a hefty chunk of work. Having it drawn out in both 2&3D should also make a big difference.

Yep, that's them. Rob & Jordan (our designer) have been superb so far and the 3D modelling has been very helpful for working out other aspects of the build. Refreshing compared to so many of our local TF firms who only seem to understand a standard 140mm stud build.

We've taken a slightly different approach which may be of interest. Our frame is being designed by an independent consultant who will produce a machine file that is sent to a factory for cutting. This is also signed off by a SE to satisfy reg requirements. I believe that this is the same factory supplying at least one of the larger TF outfits. The end result should be a fully precision cut frame, supplied in stick build format for us to assemble ourselves or with local assistance if required. Obviously the big advantage to this method is we don't pay any timber frame company markups. Judging by the quotes we received compared to our factory price these can be substantial, and for us would have taken a significant part of our budget. The consultant is also supplying a full set of assembly instructions including a 3D model that allow us to walk through the structure and take a closer look at joints or components if needed. For reference this is all being done with an i-Stud / Beam construction 245mm on the walls and 300mm for the roof. Happy to provide more details if required / allowed...

Perfect, I'll get some extra EPS ordered.

I've realized we have the available height to add an additional sheet of insulation under our 100mm ground floor slab. Originally I had planned on using 2 x 100mm EPS70 with the DPM underneath as stated by Jabfloor. If I add an additional 100mm sheet on the bottom would there be any issues using it as a blind and sandwiching the DPM above it but below the upper two sheets? Consensus seems to be EPS can get wet - but Jabloor to state DPM first then EPS hence the doubt... Also any additional issues going thicker with EPS70 rather than one of the denser variants? thanks

Sounds interesting, yes although ours isn't a basement in the sense of being below ground it has a lot of similarities. The detail at the join is crucial and already causing a few headaches but I'm confident we can sort it. I'll get in touch with MBC and see what they say.

Excellent, will get in touch with them...