PhilC

Not a pro as I said but PIR is not breathable so if moisture gets into the frame and you have another non-porous layer VLC/PIR internally then the moisture can't escape anywhere.

Hi Everyone, I am in a bit of a puzzle about how to detail the steelwork to support a 100mm block (rendered) wall (~2.5m height lightweight block). I could put the timber frame lintel or steel beam to carry the external block leaf lower down closer to the main beam but this creates a large thermal bridge in my mind, between the timber frame panel and the flat roof insulation. Raising the lintels up allows the PIR to come in underneath and prevent the thermal bridge. I did speak with my SE about it and in principle he thought this was ok. PIR of flat roof can come up to the frame under the masonry external leaf. Weather tightness, cavity tray etc would be above this to run out to the roof deck. The alternative is to bring the blockwork down to the steel, although this is an issue because the steel is 254mm high as are the metal web joists in the floor, so it takes the full-height plasterboard to T&G deck of the floor level so I cannot have a flat plate weld on it and as said, this seems to create a large thermal bridge even if the cavity is packed out with insulation below the cavity tray. I appreciate thoughts on this one, seems right to try to bring the flat roof insulation under and up to the frame. Render board is an option I guess but I went that route when planning our new 1st floor renovation rather than a new build, it seemed very expensive for the material and work and I think it may be difficult to match up with a rendered block ground floor. Also, I had virtually no interest in quoting for it, part of the reasoning for switching to a new build. Thanks.

Sketchup make 2017 free version

Some pics, work in progress still

Thanks

Great stuff really helpful Liam! Hope the project is going well

Local authority or private?

Will see if i can get a conversation with a local BCO, thanks

Thanks Liam, much appreciated will take a look.

Not a pro but the last one puts a non-breathable layer (external PIR) outside the timber frame so I would avoid that, water won't escape the frame even with a breather sheet on. I am looking to put thick option A in, albeit with differing stud sizes and PIR depths between and internally.

Hi Everyone, Hoping for some advice on submitting a building control application. As background, we got planning permission to convert a detached chalet bungalow to a full house with a new closed panel timber frame 1st floor and rooms-in-roof design. Once we tried to get contractors for the conversion involved and ran the numbers it became clear it would be cheaper and simpler to knock down and do a new closed-panel timber frame build. Thread discussion about that here. We are not changing the footprint and the rebuild would look the same from the outside as the planning permission we obtained. I've spoken to a planning consultant and the officer who did our original planning permission and apart from the detail as to why the need to switch they did not see any particular reason against it. One main difference is we would do this on a self-build mortgage, we have discussed this with a provider and they have done their checks and are ready for us to provide planning/BC. We need a full BC application for financing. I did the original planning application and I have been building a detailed 3D model to provide the various plans, foundation, drainage, structure, plumbing, electrical, fire etc. I have a qualified SE provide me with beam calcs etc. I've never done a BC application and the requirements for the plans seem more opaque than planning and I am wondering if I am over/underworking the detail necessary. The timber frame and steel will all be provided by an STA provider who will validate their design anyway, although they have said my model will reduce any estimation and some design costs from the project. I've laid out most of the structure now apart from the roof, but I am wondering how detailed this really needs to be? I would prefer to complete the BC app independently of a provider as I will save the considerable upfront cost and be able to take the design to multiple parties to compete. Appreciate any experienced thoughts about this, I want to make sure I am employing my time in the right way. Happy to share model pics if you would like, Thanks, Phil

Timber frame people who i have been discussing the project with have a foundations company who they have worked with on their previous builds, will get in contact with them.

Will have a look, should be fine planning portal is public anyway.

👍 looking at most raft designs I don't see a use for the cavity wall, my footings at around 900mm deep. So, I guess I level off and hardcore between my existing sub-ground cavity wall to the bottom of the raft level? if I am not moving the perimeter of the building.

Thanks Insulated raft was what I was thinking