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Sorry, unable to edit previous post, was meant to add Regarding IWI and the breathable option of wood fibre batts fitted between battens would you cover this with standard gypsum plasterboard OR wood wool board? Irrespective of which of the above option is chosen the whole idea is to make the insulation breathable so breathable paints will be required for the IWI walls. I can only assume these will be much more costlier than standard wall paints and also there is the question of where to source these from, specialist companies such as mike wye, celtic sustainable etc. I dont think these are available from the likes of your local B and Q, Wickes etc.

General question: Say if a house ground floor with 2 floors above Would there be an issue/compromise if IWI was not applied to ground floor externally facing walls but only applied to 1st and 2nd floor externally facing walls? When I say issue I mean risk of condensation to ground floor externally facing walls as the IWI is not continuous from ground floor to 2nd floor. Ground floor has some beautiful age old coving which other family members want to retain. Thanks

Hi Iceverge Thank you for the video, very informative. Just couple of questions 1) The studs that'll be fixed vertically between the sole plate and top plate, will any insulation go behind these? I suspect not. 2) How are these to be screw fixed to the sole and wall plates? As in I'm trying to visualise where the screws will go from these to the wall and sole plates? Thanks

Hi Iceverge Can you please elaborate a little bit on your method of choice for IWI. Am I correct in thinking all the walls whether internal or external facing have a parge coat of plaster (lime?) and then for externally facing walls CLS stud work is applied to the wall? and filled with a breathabl material. Is the 63mm CLS Stude essentially a 3inch by 2 inch stud? Also what centres would you go for? Would you fit the studs independant of the wall or attached to the wall? If independent is there niot a change that the studs may not be stable? Novice here so apologies for the basic nature of the questions. Thanks

Hi Mike I wonder of you can share how you tackled your project with respect to method of insulating your property internally. Particularly interested in the thicknesses of material use and how it was applied to the walls. I need to go down the breathable insulation route but unsure whether to go down the batten route and installing hemp batts or equivalent product between the products or 'glueing' wood fibre boards to the walls with lime plaster. Thanks

Excellent. Looking for ward to the next read. It's glaringly obvious i'm a bit of a novice, unware of the intricacies but ardent learner. I didnt quite understand the above... am I correct in thinking the wall perimeter essentially needs to be sealed before the application of PIR or am I way off.

A timely response for me. I'm very much interested in your preferred breathable method of IWI. I need to go down this route very very soon but need to decide on the application of the breathable insulaton to the wall- so type of breathable (Inditherm batts, rigid fibre boards) and the method of fixing to the wall- between battens or mechanically fixed with plastic plugs I got lost in the 3,2,1 bit of your explanation. So just to confirm you would parge coat the wall with lime plaster (thickness of coat 6mm ?) then mechanically fix rigid fibre boards to the parge coat. What thickness of rigid boards would you opt for? Theres mention of warm batten method on lime parge aswell. Can you please expand how this would play out- what centres between the batten would you opt for. I suppose this will be largely determined by the size of rigid fibre board? What size of battens would you opt for? In my mind I'm overthinking that the depth of battens should be same depth as the rigid fibre board to create even surface which can be lime plastered finished. Thanks

Thank you RedBeard. Whats your opinion on using NHL 3.5 for parge coating? Have seen this being mentioned by a number of people. Is there a difference between RK38 and NHL 3.5 I dont have muck knowledge of lime plaster products so please overlook my ignorance.

I'm in kind of similar situation and need to get moving have been dithering, thinking and over-thinking the past few months..... type of insulation, having some sort of ventilation system put into the property... PIV or decentralised MHRV etc lots of consequential decisions You maker an interesting point above mechanical ventilation. Are you thinking along the lines of decentralised MHRV or something else e.g a very good extractor fan

Can you please advise on the most appropriate method of insulating this ceiling please. Above and between the horizontal rafters OR underneath the horizontal rafters? Current line of thinking is to have some insulation between the horizontal rafters- rockwool/PIR type and some roll type insulation above the rafters. Total depth of insulation apporx 300mm Worried about how to limit any interstitial condensation that might get trapped on the horizontal rafters and cause decay/dry rot etc. having read recent thread on this forum. There will be plentiful air on top of the insulation to wick away any condensation reaching above insulation level. Thank you for your input

Thank you for the explanation. Are you thinking of going to bare brick or installing the PIR insulation onto existing plaster? I've come across recommendations of applying parge lime coat if bare brick and then having PIR on that to allow for levelling of the wall surface but also any moisture thats travelled through to the wall can be absorbed by the lime plaster. Having said that I suppose its a bit of paradox to have breathable lime parge coat and non breathable PIR board on top. There is so much info available about the breathable vs non breathable insulation options for solid wall IWI that it can make the head spin and create lots of doubts. My main worry is interstitial condensation risk with non breathable insulation and the long term impact on the fabric of the building should the worst case scenario occur. Can I ask what sawayed you to the PIR rather than breathable insulation? Retro-fit insulation can be a conudrum to the point that it can cause paralysis in decision making

Need recommendations for products which will satisfy lime based parge coat requirements for bare bricks on external facing wall upon which breathable insulation will be fixed. Will plasterers who are accustomed with gypsum be able to work with lime or does it require a specific skill set? I have a plasterer in mind , very experienced with gypsum. He mentioned has worked with lime once last year so not sure what to make of this. Thanks for your help

The walls are dry except for some patches of condensation on 1st floor chimney breast area which I think might be due to hydroscopic salts? (not sure if that is the correct phrase) or water ingress from open topped chimney which I'm planning to cap with readily available chimney caps. Walls are mostly lime plastered although it is a bit hollow in places. Couple of walls are bare brick so thinking of getting it parge coated with lime plaster NHL 3.5. Yes with regards the insulation 50mm inditherm or other type breathable batts between timber studs with thin wood fibre board thinking about 20mm so net effect of 70mm insulation. Externally walls are brick only no work done to them. Thanks

Hi Everyone. Been lurking on the forum for a while, extremely useful resource. I'm in the process of applying IWI to externally facing solid walls, Fairly large task. Very conflicted between the natural breathable route and the non breathable route. For the breathable route- Battens filled with breathable batts of approx 50 cm thickness boarded with approx 20mm Woodfibre insulation board and then lime plastered. Confused about what paints then to apply to the lime plaster finish- certainly they have to be breathable (clay paints?) and I suspect will have to be specially sourced. Also unsure if I can applying lining paper to lime plastered walls to hide any imperfections in the plaster Also in rooms where 2 of the walls without IWI intend to use non breathable paints to keep cost down worried that there will be a mismatch of colours? The non breathable route essentially similar to Ankkers method recently posted. Thank you for your guidance

Hi Ankker. I'm in a similar predicament. How are you proposing to attached the 60 mm PIR to the wall? By foam or dot and dab or mechanically fixed? Also the service cavity created by the timber battens am I correct to assume this will be void space except of any services running through the void. What sized batten do you intend to use and are you thinking of going down the route of using tanalised battens? Thanks