ab12

Did a soft fill in the cavity between engineers and inner block leaf consisting of 1 cement to 8 ballast after some google research. Is this the right mix? Know have done further research and the recommendations are to use 1:3:6 ratio of cement:sand: 20mm stone to make C10/M10/Gen1 (all 3 are equivalent) grade of concrete for the soft fill. Is this equivalent to 1 cement:8 ballast? Also what is the ratio of sand to stone in ballast, cant seem to find the answer on the net. Finally what type of read mix do I need for the floor please above sand blinding layer. Is it C20/Gen3/ST1 (all 3 are equivalent).? Many thanks

Hi JohnMo I have had a good read but can't see anu U values stipulated for UFH for solid ground floor slabs. What is the best way to lay 2 layers of PIR boards e.g 100mm followed by 50 mm or vice versa. Would it be better to lay 100mm first and then 50mm on top.

Quick question- what is the recommended practice for the OSB shuttering around the concrete foundation slab- should it be left in place or taken out. Brickie/builder wants to put put soil above and compact the floor in the perimeter around external leaf of engineering bricks. My worry is over time OSB will decay and may cause little bit of the ground above and surrounding it to shrink. Therefore is it best of its taken out or am I over thinking this? Pictures below, red arrow pointing to OSB shuttering boards, from Memory I think depth was 60cm so approx 50 cm or probably a bit less remains below ground. Thanks

Is the new building Reg U value for floor UFH 0.18 Or 0.15? Just done a google search and its coming up as 0.15.

In the middle of having a kitchen extension. Brickie has nearly built up to damp. I have opted for the following floor make: 150mm hardcore 50mm sand blinding 2000 g (500 mu) DPM 100mm concrete slab 1200g (300 mu) DPM 100mm OR 130mm OR 150mm insulation DPM unsure about the g or mu value may choose 1200g or even thinner? 75mm non liquid screed over UFH to reach finish floor level I'm confused about the insulation part. Need to reach U value 0.18. walls, all exposed to outside with Cavity of 150mm between outer and inner walls. Dimensions of internal leaf walls are 5.6m by 3.49m , Area to be insulated: 19.54 m2. Exposed perimeter is 14.69m. PA ratio is 0.75.....can get U value 0.17 with 100m Cellotex U of 0.14 with 130mm Celltotex U 0f 0.12 with 15omm Cellotex I have already purchased 6 sheets 2400mm by 1200mm Cellotex. Is it worth going the extra mile and have extra insulation so either 130mm or 150mm laid in 2 layers, so 100mm sheets laid first followed by 30/50mm sheets OR 30/50mm sheets first followed by 100 mm sheets. Please let me know your thoughts. Workers coming and laying hardcore and sand, I may need to dig a little bit more of the floor if go for 150 mm insulation OR I can sacrifice on sand blinding layer by choosing 30mm sand blinding instead of 50mm sand blinding without needing to dig any more floor.

In the middle of having a kitchen extension. Brickie has nearly built up to damp. I have opted for the following floor make: 150mm hardcore 50mm sand blinding 2000 g (500 mu) DPM 100mm concrete slab 1200g (300 mu) DPM 100mm OR 130mm OR 150mm insulation DPM unsure about the g or mu value may choose 1200g or even thinner? 75mm non liquid screed over UFH to reach finish floor level I'm confused about the insulation part. Need to reach U value 0.18. walls, all exposed to outside with Cavity of 150mm between outer and inner walls. Dimensions of internal leaf walls are 5.6m by 3.49m , Area to be insulated: 19.54 m2. Exposed perimeter is 14.69m. PA ratio is 0.75.....can get U value 0.17 with 100m Cellotex U of 0.14 with 130mm Celltotex U 0f 0.12 with 15omm Cellotex I have already purchased 6 sheets 2400mm by 1200mm Cellotex. Is it worth going the extra mile and have extra insulation so either 130mm or 150mm laid in 2 layers, so 100mm sheets laid first followed by 30/50mm sheets OR 30/50mm sheets first followed by 100 mm sheets. Please let me know your thoughts. Workers coming and laying hardcore and sand, I may need to dig a little bit more of the floor if go for 150 mm insulation OR I can sacrifice on sand blinding layer by choosing 30mm sand blinding instead of 50mm sand blinding without needing to dig any more floor.

Please correct me if I'm wrong but what I've read are the upstands for external facing walls OR can they be used for internal walls as well?

What is V-VCL...VCL= vapour control layer but the initial V? Thanks

Interesting setup. Out of curiosity what is th reasoning for using 180mm floor insulation? My understanding is 100mm should satisfy building regs. What U value do you want to aim for on the blocks and is the block below DPC (in which case need to aim for 7N)? Have a look at Thermolite blocks- they do some with good U value.

Hi Canski Following your comments: ''my methods posted on a previous full fill cavity hater thread. Just make sure to keep it dry.'' I have been searching for the thread but cant seem to find it. Can anyone post a link please. Follow on question you mention about keeping the insulation dry, can you please expand on this- is that whilst it is being installed and overnight when it is in the exposed wall cavity ? Thanks

Hi All Having a rear single storey extension built and need to achieve U value of 0.18 for CWI. Build up will be brick, followed by 150mm DriTherm 32 slabs, then blocks and then ideally wet plaster on blocks internal face although architect has specifies dot an dab to the blocks. Have been eyeing the following blocks: Plasmor Fibolite 7.3N (U value 0.28) and Plasmore Fibolite 3.4N (U value 0.24)- both of these are lighweight aggregate blocks. Alternative options include Thermalite Hi strength 7.3N (u value 0.19) which is Hi Strength aircrete and Thermalite Shield 3.6N (U value 0.15) which is Standard aircrete Looking for a block which is sturdy and robust not going to crumble and fail when drilled into as the rear storey extension will house a kitchen with lots of wall fixings. From the above options which blocks would you recommend which would satisfy both achieved combined u value of 0.18 and is robust. Thank you

Don't want to dampen the spirit but a point of observation will the gypsum plasterboard and gypsum plaster finish NOT contradict the breathable element of the make up? In addition have you thought about paint finish- certified breathable paint with low SD low? The research that I've done suggests, in order to maintain the breathable aspect, instead of gypsum plaster board to use rigid fibre board say approx 20mm thickness or wood wool boards fixed to the studwork and finished with Baumit 38 or equivalent product which a standard plasterer should be able to cope with. Also, just checking Ankerr with your setup, will there be a cavity between the plasterboard and the insulation fibre board attached to the wall? What sized CLS timber studs are you thinking of using? Thanks

Mike. This is interesting. How did you manage to fix the hemp flexi batts to the walls? With some sort of glue? Very much like this concept and the following dawned on me. can everyone please critique this: 50mm hemp batts fixed to the wall as shown in Mike's photo's with timber battens above instead of the metal studs shown in Mike's photo's to allow for fixing of either plasterboard with standard gypsum finish or rigidi fibre board with lime finish. Critically will the flexi batts stay in play independant of the studs. Previously was going to fix timber studs to wall and push fit flexi batts between the studs but Mike's strategy is much better as it allows for continous layer of insulation not broke by the studs. In addition electrical socket back boxes can be fitted infront of the flexi insulation batts. Dunno whether this is eureka moment, atleast appears to be so thanks to Mike's suggestion.

Hoping wont need to sell. I should have explained that breathable IWI will be applied to solid wall hence the need for breathable paints. Here's the plan for IWI: a) Construct stud wall attached to lime plastered external walls using 3 by 2 treated stud timbers b) Fill between studs with 50mm flexible wood fibre batts c) Cover these with rigid wood fibre boards of 20mm thickness and d) Lime plaster rigid wood fibre boards with Breathaplasta e) Paint the lime plaster with breathable paints. Critique of the above IWI is welcome.

Any suggestions for breathable paints for walls which are on the reasonably-priced side? Earthborne, Farrow and Ball et al. paints are coming out about £100+ for 5 litre buckets. Wouldn't mind so much if I need to do 1 room but with 6 rooms to cover and the hallway trying to see if a more economical option is available but with similar SD value to the above paints.

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