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Can you please provide any recommendations for face mask when working in very dusty atmospheres e.g. when taking down old plaster or generally working in old houses doing clean ups etc Ideally looking for something which allows for ventilation at the same time e.g. with some sort of respirator. Looking for something that's going to last and doesn't need replacing every few days. Much appreciated https://www.powertoolsdirect.com/dewalt-respiration-p3-half-mask-respirator-large-dxir1hmlp3?_gl=1*146yk5b*_up*MQ..&gclid=EAIaIQobChMIqLvp1-HCjAMVR49QBh0J2iLmEAQYAyABEgKB4fD_BwE Is this any good? Will this be needing filter replacement often?

What is the recommended saw/knife for cutting Knauf dri-therm insulation slabs or Woodfibre/Hemp fibre insulation slabs? And do these require regular sharpening? Thanks

1 other option crossed my mind what if we do 5 layers of 73mm brick with 13 mm mortar giving 86*5= 430mm for outer leaf so for inner leaf 1 lock at 215mm and other block at other 195mm with 2 layers of 10mm mortar giving 215 + 195+ 10 + 10= 430mm Can this be made to work aswell? Thanks

Thank you for this, Mr Punter. Much appreciated Will it compromise the overall build up of the wall or the structural integrity of the wall if the wall ties are not at 450mm centre's vertically? So for context its a rear single storey extension measuring 5.9m by 4.1m outer leaf with 150mm cavity I've already purchased Dri-Therm 32 batts , the spec is 455mm height, 1200 mm length and 150mm thickness.

Also which insulation saw would you recommend for cutting the insulation batts- Dri therm 32. Brickie will be installing the insulation. Are there any special instructions I need to issue? Thanks

Thank you for the input. So essentially with this set up the insulation will be cut into a triangular/slanted shape at the top end after the first installation but then every additional insulation batt piled vertically on the base batt will be cut into a triangular/slanted shape at both top and bottom end to achieve a continuous layer of insulation? Bit like in the diagram shown

This idea is interesting. Can I just that this will satisfy this setup? Mansfield 215 x 100 x 40mm OPC Brick Slip 20N Calcs: 6 course of 73= 438, 5 layers of 13 mm mortar thickness gives 65mm Total outer skin 503mm 2 course of 215 blocks ann 1 course of 40mm brick slip = 470mm, needs 2 layers of mortar which is usually 10mm each so total 490mm leaves shortfall of 13mm Other option is cut the blocks into 53mm heights and use these instead of 40mm brick slips which means outer and inner leafs will equal 503mm 1 other consideration recommendations for wall ties is every 450mm centered vertically but in the above setup they'll be every 503mm centered vertically. Is that going to cause an issue? Thank your guidance

Hi all Can you please advise on the following scenario: Outer leaf of extension will be imperial brick dimension 73mm height * 105mm width * about 225mm length (although the stated length is 228mm). Brick is called classic weathered orange brick, main distributor is Classic Brick Company and retailers such as Jewsons and EH Smith supply it. Inner leaf of extension will be blocks standard height of 215mm. 5 courses of brick with 13 mm mortar joint gives 417mm and 2 course of block with 10mm mortar joint gives 440mm which leaves a difference of 23mm See diagram The reason for doing 13mm joint is to match with old Victorian bricks of 76mm height. Now that means wall ties will be angled down from block to brick and Dritherm 32 cavity blocks (150mm width) will not sit flush with each other when piled up vertically leaving a small gap between adjacent cavity slabs So I'm thinking will this not compromise the insulation effect in parts where there will be small gaps between the 2 slabs piled vertically and cause cold bridging? How do we overcome this scenario? thank you in advance

To provide some compensation for the loss of insulation the architect advised adding 25mm XPS insulation on the outer side of the concrete blockwork under the bifold. The ground level outside is going to be made up with hardcore and a patio to be level with the bifold track, so the XPS insulation will be underground when complete. I am in the UK at about the same latitude as London. My questions are: 4/ Given the XPS insulation will be to a depth of 300mm (maybe 400mm) and this insulation will complicate the patio construction - will this give me a worthwhile heating benefit or should I just forget the XPS altogether ? Am I reading this correct. XPS upstands will will be added to the external blockwork i.ef those facing garden/patio rather than the internal leaf of blockwork. That is definitiely a new one on my (although I am a novice) just never heard of external insulation especially beneath ground level although there is no reason why it cant be used I suppose. Let wait for the experienced members to respond.

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.