osprey

Interesting. Any idea why it didn't work out?

By the way: are we just talking about traditional UFH (buried in thick screed)? Retrofit overlay UFH suppliers claim they are more 'radiator-like' in that they respond quicker, and can handle higher temperatures (high 20c's?) depending on floor covering.

@Johnmo Doubling the size of the rads would be problematic: they would start to dominate the room! They were probably sized for the house with no insulation, and CWI has allowed me to keep warm with flow temperature of 50-55c this winter (and we had a few cold days) but 40c would be pushing it.. 15mm pipe feeds to all (off larger distribution pipes).

@Johnmo Interesting. I know the more the better with insulation, but I understood 100mm pir was enough for retrofit. The new block and beam floor will have whatever insulation is required for Part L, I guess: would it still be worse? Yes, gas boiler, that will be replaced anyway. Thanks for constructive comments.

I am driving myself crazy going around in circles with this, so am appealing for opinions. I can't settle on a heating scheme for my house/extension. I want to future proof it if possible, but do not want a cold house, obviously. Current house is 1926 build, 50mm cavity, outside rendered, two story detached. Suspended wooden floors. Floor plan is 'L' shaped, 10m on long sides. I am planning a 5m × 5m extension, to make the footprint square, which will create a 10m x 5m kitchen/utility/dining area. The 5 x 5m extension will be 150mm cavity eps beads, floor block&beam. The house has had its 50mm cavities filled with blown eps beads, and the old kitchen area will have 50mm IWI added during extension build. It is possible, in the future, to add 50-100mm EWI to the house side walls. The front has bay windows, making EWI impracticable. I have added 100mm pri under one existing room, and plan to do the second. Hall will be done when extension is built. So, question: UFH to extension+kitchen? Whole ground floor? Stick with radiators? Rooms have 2.8m ceilings, so can take 20mm or so build height of retrofit UFH, but have heard various stories (positive and negative) of effectiveness in old houses. Current Lounge has carpet, which I would like to keep. Thanks.

I DIY'ed it. I had house cavities done just before, but guys injecting the beads said they 'were not allowed to' inject flues, even if capped off, 'in case somebody wanted to use them in the future'. I was about to have the roof replaced, so I bought a few bags of eps beads (sadly not grey, but an individual cannot buy them for some reason) off ebay, climbed the builders scaffolding, and poured them in. They flowed easily, and it was quite enjoyable!

My chimneys had the stacks removed to loft level, and I filled the flues with eps beads. I did not want warm room air being vented into the loft space. The chimney breasts are external (I.e. stick out of the outside wall) and I was surprised at the size of the void that was either side of the flues. I needed more eps beads to fill those.

Interesting. I have just had EXACTLY the same problem. The membrane? Roofshield.

Thanks, intereting they work, but I am not sure how. The e.g. Spax screws have two different threads. I assume the lower, coarse one bites into the joist first. The screw then goes into the joist until the fine thread reaches the chipboard. The next couple of turns of the coarse thread would be sufficient to pull the board in tight, but the fine thread would be 'travelling' more slowly (taking maybe four turns to travel the same distance). Would it not just rip its way through the chipboard?

I have seen that type of screw advertised, but I have not heard if they work. I have seen the theory that a screw with a smooth section above the thread helps in pulling the sheet to the joist firmly. I am not sure how the top thread in that screw works.

Hmm, might try that.

Thanks.

Just looked at that site, very useful. Just a thought, If screws cause the squeak, and you glue t&g sheets together, do you actually NEED screws? Just have a floating floor?

Thanks all for replies. When people are saying 'glue' with chipboard, is that for just the t&g? I have read of people gluing the sheets to the joists as well... Those using OSB: I can only find 18mm t&g. Did you use t&g? I would have to add 4mm to the joists I guess. Any DISadbpvantage to using OSB? Chipboard seems to be the 'standard' even for (cheaper) newbuilds. What screws do people use? There are special ones for flooring chipboard, with a smooth part at the top, 'to make boards be pulled to the joists firmly'. Other people say fully threaded. Other suggestions: I don't have access from below. Interesting idea about punching nails down. Will think about it.

I want to insulate under a suspended wooden floor of a 1920s house. No alternative but to lift floorboards, which will destroy them. The question I have is: what is the best replacement? Current original floorboards are 22mm thick. Skirting boards are large, and will not be removed. I have done one smaller room and used 22mm chipboard from Wickes, but since have seen lots of reports of squeaking using this board. I have it slightly in one place so far, but dread it in a larger, more frequently used room. So for a robust squeak- free floor, what do I use: OSB, ply, chipboard, new softwood boards, other? Cost needs to reasonable. Room is about 5 x 4m. Floor currently carpeted, and will remain so. Thanks.