Sir Percy Posted June 27, 2020 Author Report Share Posted June 27, 2020 44 minutes ago, blackrose said: The only thing is that my subfloor is quite uneven so what's the best way to level it? I can't easily get the floorboards up so is a plane and belt sander the way to go? If you laid a sheet of hardboard over the subfloor, would that work? Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 53 minutes ago, Sir Percy said: If you laid a sheet of hardboard over the subfloor, would that work? Well I was going to lay 12mm celotex over the subfloor as insulation and then 6mm ply, but I don't think that will level it out as it will just follow the unevenness below. Won't I have to level the subfloor first? Edited June 27, 2020 by blackrose Link to comment Share on other sites More sharing options...
Sir Percy Posted June 27, 2020 Author Report Share Posted June 27, 2020 8 minutes ago, blackrose said: Well I was going to lay 12mm celotex over the subfloor as insulation and then 6mm ply, but I don't think that will level it out. Won't I have to level the subfloor first? Oh, I see. I don't know, but I'm not sure that laying anything directly on top of celotex would be advisable. Have you got advice on this from somewhere? Link to comment Share on other sites More sharing options...
LadyG Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) On 21/06/2020 at 20:18, blackrose said: I'm thinking replacing my carpet tiles with those woodgrain vinyl planks you can get from B&Q as my subfloor is uneven and I think they'd cope with that better than real wood. Also they wouldn't be as cold underfoot as I'd lay them over 12mm celotex and 6mm ply. But they can't be laid floating, they have to be stuck down. I have a few inspection hatches on one side of the boat so I suppose in those areas the celotex and ply could float and the vinyl planks could be stuck onto that. Don't try vinyl planks f floor not stable,.I laid mine tight, meticulously. and they are chipping/moving. Where they were just stuck down quickly with expanson on the outside edges, they seem OK, but you will not get a perfect result; dirt gets i n to gaps, vinyl lino might be better. Celotex is not the right material underfloor Edited June 27, 2020 by LadyG Link to comment Share on other sites More sharing options...
pearley Posted June 27, 2020 Report Share Posted June 27, 2020 37 minutes ago, blackrose said: Well I was going to lay 12mm celotex over the subfloor as insulation and then 6mm ply, but I don't think that will level it out as it will just follow the unevenness below. Won't I have to level the subfloor first? When our Karndean in the kitchen was laid professionally they screwed 12mm water resistant MDF in 2ft squares down then filled the joint lines on top of the original 18mm ply flooring. Our bathroom originally had ceramic tiles so a proper screed was laid. Not without problems if you see earlier post. Link to comment Share on other sites More sharing options...
ditchcrawler Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) What do you consider would be wrong with laying Celotex under a floor like that as a sandwich Edited June 27, 2020 by ditchcrawler Link to comment Share on other sites More sharing options...
TheBiscuits Posted June 27, 2020 Report Share Posted June 27, 2020 Just now, ditchcrawler said: What do you consider would be wrong with laying it under a floor like that as a sandwich Nothing if it's the load bearing one for walking on, lots if it's the standard celotex insulation. Celotex reckon you should lay 22mm chipboard on top of it though, so 12mm ply might be a bit springy. Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 50 minutes ago, Sir Percy said: Oh, I see. I don't know, but I'm not sure that laying anything directly on top of celotex would be advisable. Have you got advice on this from somewhere? The karndean wouldn't be laid directly on top of the celotex. I'd be laying 6mm ply between. https://www.insulationsuperstore.co.uk/product/celotex-12mm-tb4012-2400mm-x-1200mm-33-sheets.html 48 minutes ago, LadyG said: Don't try vinyl planks f floor not stable,.I laid mine tight, meticulously. and they are chipping/moving. Where they were just stuck down quickly with expanson on the outside edges, they seem OK, but you will not get a perfect result; dirt gets i n to gaps, vinyl lino might be better. Celotex is not the right material underfloor What brand did you use? Vinyl flooring planks are used extensively on floors in loads of different situations without a problem. Contrary to what you say the specs for the 12mm cellotex above says it is suitable for flooring applications. What makes you say it isn't? Edited June 27, 2020 by blackrose Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 16 minutes ago, TheBiscuits said: Nothing if it's the load bearing one for walking on, lots if it's the standard celotex insulation. Celotex reckon you should lay 22mm chipboard on top of it though, so 12mm ply might be a bit springy. Can you provide a link please? I thought you'd just need thin ply to spread the weight. This is all I can find. https://www.celotex.co.uk/assets/tb4000_product-datasheet_nov18.pdf I could lay the Karndean directly on a (levelled out) subfloor. But I know it would be cold. Edited June 27, 2020 by blackrose Link to comment Share on other sites More sharing options...
TheBiscuits Posted June 27, 2020 Report Share Posted June 27, 2020 22 minutes ago, blackrose said: Can you provide a link please? I thought you'd just need thin ply to spread the weight. This is all I can find. https://www.celotex.co.uk/assets/tb4000_product-datasheet_nov18.pdf Click the "Floors" link in that PDF. I chose to treat it as upgrading a concrete slab floor, as I assume you don't want to rip up your entire floor and insulate beneath it! The application datasheet https://www.celotex.co.uk/assets/concrete-slab-floor_application-datasheet_nov18.pdf recommends at least a 65mm sand/cement screed on top of the insulation, but that sheet offers an alternative of a chipboard floor. The chipboard must be minimum 18mm tongued and grooved flooring grade type C4 to BS 5669. Lay the chipboard with staggered joints, glued with a woodworking adhesive. In the Celotex Blog, the article on upgrading a garage floor https://blog.celotex.co.uk/technical/garage-conversions-part-2/ says An alternative to laying 65mm screed is a 22mm tongue and grooved floating chipboard floor. Laid to manufacturer’s instructions this also provides a stable surface but offers a thinner floor build up which is ideal if space is a premium. [...] Any decorative finishes such as carpet or laminated timber boards can then be laid on top of the screed or chipboard floor. Link to comment Share on other sites More sharing options...
Sir Percy Posted June 27, 2020 Author Report Share Posted June 27, 2020 2 hours ago, TheBiscuits said: Lay the chipboard with staggered joints What a pain. Less of a pain on a widebeam, but still. Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 Thanks. Surely the closest floor to a boat subfloor in that datasheet is a suspended timber floor? Anyway, I've got half a sheet of celotex so I'll lay a thin piece of ply on top and stand on it and jump up and down. If it doesn't compress I reckon it'll be fine. There are lots of things we install on boats where we don't follow the manufacturer's advice to the letter. If we did we'd need a 3.5m combined flue and chimney length for a stove like a squirrel for example. Link to comment Share on other sites More sharing options...
LadyG Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 3 hours ago, ditchcrawler said: What do you consider would be wrong with laying Celotex under a floor like that as a sandwich There are floor insulations designed to go under flooring, Celotex will not stand the concussion, I think it will crumble like a digestive biscuit going through a mangle. Edited June 27, 2020 by LadyG Link to comment Share on other sites More sharing options...
Sir Percy Posted June 27, 2020 Author Report Share Posted June 27, 2020 2 minutes ago, blackrose said: I'll lay a thin piece of ply on top and stand on it and jump up and down. If it doesn't compress I reckon it'll be fine. Think it's where boards join where you might need to be concerned - which is why Celotex recommend staggered joins. Try jumping up and down on the edge. Link to comment Share on other sites More sharing options...
TheBiscuits Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 12 minutes ago, blackrose said: Thanks. Surely the closest floor to a boat subfloor in that datasheet is a suspended timber floor? Yes, but you would need to lift your subfloor and insulate underneath it then replace it, getting it all down straight and applying bridging compound to the joins. Your new Karndean then goes above it - and Karndean specifically recommend against laying their vinyl flooring on wood and it invalidates the warranty. Where they say you can do this using 6mm high quality ply they are expecting that laid on a solid concrete floor, not on top of Celotex. Existing floor, Celotex, 65mm cement screed then Karndean vinyl would be perfect, but will take about three inches off your headroom and mean you need to refit the galley ... I used commercial grade engineered wooden flooring instead. Edited June 27, 2020 by TheBiscuits spellink Link to comment Share on other sites More sharing options...
LadyG Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 4 hours ago, blackrose said: What brand did you use? Vinyl flooring planks are used extensively on floors in loads of different situations without a problem. B&Q, it is shrinkage and movement of the floor I think, it will be done again as I have some left, it could be me! I just think Celotex will not be the best available product, I could well be wrong. I understand the idea is to get a level base with a slight "spongy" surface to absorb movement, ie a sandwich. Edited June 27, 2020 by LadyG Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 16 minutes ago, LadyG said: There are floor insulations designed to go under flooring, Celotex will not stand the concussion, I think it will crumble like a digestive biscuit going through a mangle. Concussion? You mean compression? What's the insulation designed to go under floors? I've stood on celotex before and its compression strength is greater than one might think, especially if there's something spreading the load above. Sir Percy's point is a fair one - it's about the edges. Edited June 27, 2020 by blackrose 1 Link to comment Share on other sites More sharing options...
ditchcrawler Posted June 27, 2020 Report Share Posted June 27, 2020 Just now, blackrose said: Concussion? You mean compression? What's the insulation designed to go under floors in boats ? Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 (edited) 13 minutes ago, Sir Percy said: Think it's where boards join where you might need to be concerned - which is why Celotex recommend staggered joins. Try jumping up and down on the edge. I'd be laying ply down over the celotex and then the vinyl planks on top of the ply, so I'll but up two pieces of ply and lay some vinyl over the join and jump up and down on that area. Edited June 27, 2020 by blackrose Link to comment Share on other sites More sharing options...
ditchcrawler Posted June 27, 2020 Report Share Posted June 27, 2020 2 minutes ago, blackrose said: I'd be laying ply down over the celotex and then the vinyl planks on top of the ply, so I'll but up two pieces of ply and lay some vinyl over the join and jump up and down on that area. You could always lay 2 sheets of ply , half the thickness with the joints staggered Link to comment Share on other sites More sharing options...
blackrose Posted June 27, 2020 Report Share Posted June 27, 2020 1 minute ago, ditchcrawler said: You could always lay 2 sheets of ply , half the thickness with the joints staggered Yes, that's not a bad idea. Thanks Link to comment Share on other sites More sharing options...
BWM Posted June 27, 2020 Report Share Posted June 27, 2020 https://floormart.co.uk/rhinofloor/ This is good stuff, we have had it down for years with no deterioration. Has a pleasant warmth and slight softness, and being in the back cabin it is lifted occasionally for access without tearing or cracking. Link to comment Share on other sites More sharing options...
WotEver Posted June 27, 2020 Report Share Posted June 27, 2020 1 hour ago, LadyG said: There are floor insulations designed to go under flooring, Celotex will not stand the concussion, I think it will crumble like a digestive biscuit going through a mangle. Rubbish! I laid a Celotex floor covered with flooring grade chipboard with staggered and glued joints as per the above advice over an area of at least 50m2 6 years ago to cover and insulate an uneven and cracked concrete base. I did this over 6 years ago and it’s as good today as the day I laid it. 1 hour ago, ditchcrawler said: You could always lay 2 sheets of ply , half the thickness with the joints staggered That’s a good idea. Not as good as flooring grade chipboard but at least the joints are less likely to witness through the floor covering. 1 Link to comment Share on other sites More sharing options...
blackrose Posted June 28, 2020 Report Share Posted June 28, 2020 14 hours ago, WotEver said: Rubbish! I laid a Celotex floor covered with flooring grade chipboard with staggered and glued joints as per the above advice over an area of at least 50m2 6 years ago to cover and insulate an uneven and cracked concrete base. I did this over 6 years ago and it’s as good today as the day I laid it. That's good to know, thanks. I just talked to a neighbour who's been a painter and decorator for about 25 years and he told me that he knows a couple of floorers who do lay Karndean directly over thin ply and celotex, so perhaps it's not such a crazy idea after all. 1 Link to comment Share on other sites More sharing options...
WotEver Posted June 28, 2020 Report Share Posted June 28, 2020 5 hours ago, blackrose said: That's good to know, thanks. I just talked to a neighbour who's been a painter and decorator for about 25 years and he told me that he knows a couple of floorers who do lay Karndean directly over thin ply and celotex, so perhaps it's not such a crazy idea after all. I think the joints will witness through. Place a couple of pieces of thin ply over some Celotex and stand on the edge. As you rock back and forth I think you’ll feel the ply edges move against each other. Link to comment Share on other sites More sharing options...
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