tanneja

@Red Kite that remark on the suckers is a little alarming, we have just had our internorm install and they are fairly prominent. You have focused me on getting them clean before the scaffolding is down. Maybe car windshield polish?

@SimonD do you think I would be any better off with the felt back 18mm TG ply that I can see online? Unsure if it would be of any assistance to squeaks. http://www.provincialfloors.co.uk/hushply28.html Part of me isn't convinced by TG for squeaks in these large sheet material applications, where some minute deflection is easy to imagine. I am guessing not having TG, instead a 2mm gap between sheets, and mechanically fixing would be insufficient rigidity from the lack of interlocking. Just feels like then I could remove any TG noise.

Ok understood thanks, I guess we would have access to see if there is some inherent bend at the timber top surface if we remove, I can't tell while all together, as while any camber should be evident from below if the timber is of uniform thickness, it sounds like there could be any number of imperfections from the materials used, to the installation, causing the creaking, so direct inspection is the best chance to identify. The joist installation is on hangars on a wall plate, I can try do pictures at some point, they are nailed into the metal hangars. I am a layman, so if I am told 22mm chipboard will outperform 22mm ply, that is valuable information. I could go for a thicker material up to around 30mm if that further helps our cause. I just have relatively little faith in chipboard. Asking friends with renovated houses with 18mm chipboard, all by different builders, all say their 1st floors squeak and so they avoid stepping in places, that drives my scepticism of any chipboard, it seems to me it is cheap rather than having advantageous properties relative to other sheet material.

Thanks @SimonD I am struggling with your second passage unfortunately. Should I be taking from your comment that 18mm chipboard (as in place now) is more suited / recommended relative to the properties the layman in me presumes we would get from 22mm ply?

@PeterW it is a small room, so one stud runs parallel on a triple joist, the perpendicular wall sits on the joists too, not on the chipboard. The other two walls are external masonary. I feel like I would be surprised if it were the studs given where I identify the sound coming from. The chipboard is well clear of the perimeter of the door opening and walls (10mm),

@markc the squeaks are mainly centre of room, but so also happen a little further away too, for one room it happens immediately as you enter the room. The noise is coming from the area very close to the footstep (when listened to from underneath), not from the hangar location. Of course that doesn't mean they the aren't perhaps responsible for the noise in some way, maybe we can inspect everything critically when the chipboard comes up.

I can see how that is a logical conclusion, however I feel the screws we have are overkill. Maybe the gluing of the joists to the board (where locally in some places it may have more glue thickness than others) has meant for an inconsistent level with the boards, and so walking on them creates flex in areas, which manifests as noise on the board joins, this despite screwing them all down within an inch of thier life. I don't think we can try anything else at this point, seems more cost effective to get them up and see if 22mm ply solves things. Wondering whether to glue them to the joists/noggins or not. Maybe just the multi-thread screws first and see if they alone do the job.

The joists should be as however specified, they appear to be 170x50mm joists with 400 centres. I expect the existing 18mm TG chipboard used came with glue but perhaps it was separate. screws have been done every 200mmish around boards. I have instructed the builder to have a think about how we could instead do the floor in 22mm ply. I like the idea of its rigidity, with everything else in the house being the highest standard we can afford, these creaking floors would be a disappointment. I dont see any deflection in the joists myself, I feel it has to be some failure of the TG product or installation.

If there is any doubt about some miniscule joist deflection existing (seems unlikely and cannot detect), would we be better going with 22mm ply rather than 22mm chip board? For what you lose with the interlocking, perhaps you end up with a firmer floor? Material cost not a concern given the small surface area, it is just wanting a silent room experience.

I have use a support just now, applying pressure from underneath and it can have some localised reduction at that spot when stepping on the floor above, but it is very localised, rest of the floor has the same creakiness. I have got up a ladder and pushed and pulled on the joists and the chipboard from underneath, even being a few centimetres away I can't discern if it is the joist to noggin interaction, the joist/noggin to chipboard interaction, the crew to timber / chipboard interaction, or the chipboard to chipboard interlocking interaction, I can't see how anyone can tell that as they are all basically next to each other. It feels like I have no option but to strongly consider getting this chipboard up. I'll take out some screws first to eliminate them as the issue, but as before, I would hope multi thread screws would avoid any movement allowing a tight fit. Maybe where i put them back into the previous holes from the first set of screws could be problematic. I don't think there is anything more than tiny deflection (if any) with the joists, my inexperienced gut says that the 18mm board is deflecting due to its lack of rigidity, and so the interlocking mechanism rubbing. If grinding out some joins removed the creak, I would have my answer, but as stated above, will lose some floor rigidity. Maybe I can claim some of that back with a 12mm ply overlay, rather than switching the whole thing out for 22 or 25mm. If we did want to really go the whole hog, what is the most rigid, best quality flooring we could go with? I don't think I would feel confident with standard 22mm chipboard given this headache. It isn't a big area, so cost should be manageable, will be labour more than materials I would think. Presumably cement board is too heavy. Unsure if the foam backed board I have seen advertised is helpful if you plan to glue to the joists.

Was looking at wood slat ceiling or walls for aesthetics, however this range claims some acoustic benefit, which is interesting given the hard flooring we plan in our open plan area. https://www.acupanel.com/gallery For any sound gurus, if I were to attach to the ceiling (after checking fire regs, likely would need a Class 0 coating of the veneered wood), it seems we have two options: - attach directly to joists, filling between joists with rockwool, it would give us maximum height in the room, but won't represent much mass in the ceiling. - single or double high density plasterboard the ceiling to add mass, then fix these panels to that, however the thickness of that will make it that I can touch the ceiling when on tip toes, and there is the consideration that Acupanel says get much better acoustic performance if it mounted on batons... batons as well and the ceiling really would be getting too low for my liking, every 10mm starts making a difference. I know sound is a dark art, but which approach will likely give us the all round best result in: isolating upstairs generated noise getting down stairs, likewise downstairs noise getting upstairs, and perhaps reducing echo in the hard landscaped open plan area downstairs? Thanks in advance for any guidance

Should I cut through the 18mm chipboard joins, to see if that works, or just overply?

@PeterW Fairly sure they are 400mm spacing. Yes overlaying 12mm is possible, again that makes where the stairs emerge to teh 1st floor an interesting detail. Also the door kits are in, so guessing that means taking off some of the door height to fit with a slightly raised floor (doors not purchased yet). It certainly sounds like a better plan than taking up anything that is there already. I was thinking of using some splice plates to go into the joists and floor above around mid span just to hold them relative to each other a little better, in case the glue and screws are allowing a bit of movement if the beams are suffering any deflection.

Thanks @Onoff I will look into it and make revisions if needed

The floor viewed from underneath. I should say, I am as sure as I can be from when I get up close, that all noise is from the centre of the floor, not the hanger ends.

@Onoff no they ate 10mm shy, filled now with a flexible acoustic sealant. They were squeaking before that sealant went in.

Brining this post back from the brink as we have not managed to solve the issue. We have nogginned everywhere. Used the multi thread (with part clear thread) screws everywhere. There is still loud creaking, and some subtle floor bouncing. I have attempted the person being upstairs as I have my ear right underneath, I can't tell if the noise is from the (glued) chipboard joins, or where the chipboard is glued to the joists, or the screws. The chipboard is just 18m standard stuff. I can't see any gaps between the chipboard and floor above to shim, but i guess it could be a mm in places and I wouldn't know. Pipework going through the joists doesn't seem to be rubbing. I guess it would be considerable work to take it all out and replace with 22 or 25 mm flooring. Plastered stud walls have already been built over it, and since the staircase is in, makes the transition of FFL upstairs a complicated detail. The downstairs ceiling still not boarded so have full access from underneath. Was thinking of grinding out the board joins, seeing if that is the issue. If that solved the creak, could then noggin underneath all joins and mechanically fix the boards to those, and fill the 3mm gaps with a silicone, then perhaps overboard with maybe 6mm board of some kind if we had any concerns that the underlay and carpet doesn't do enough to eliminate the gaps. It would reduce whatever rigidity we get from the interlocking. I don't want bounce in the floor, I don't have limitless budget either. Upstairs rooms that have been boarded are only around 25m2 so not a huge area. Any help greatly appreciated

I have wondered whether I should spec internal or external blinds for our flat roof lights, it would need to be internal now, I wonder if there is a manual version that can feed into a pocket like a door would. I should give that more thought.

Feels like a similar issue if one wanted to have a cinema room with a sound insulated door with minimal air gaps, thanks for posting

This is very informative @MikeGrahamT21, certainly worth considering paying more it seems.

The prices of those are quite different, around an extra £40 per roll as of now (£140 vs £180 that I can see). Was there a similar price differential when you bought? And if so, what inspired paying the extra for Zehnder? Good to know it is easier to pull, I'm sure that is worth a bit extra. Maybe the ribs are less pronounced, or the pipe is relatively stiffer / less stiff which made pulling simpler.

Would anyone have any concerns for using this ducting? It seems new to BPC and would be a very decent cost saving on 6 rolls vs anything else that is anti bacterial. It doesn't specifically mention whether it is anti-static, perhaps that is where the cost reduction comes from?

Our install of EWI is due first week of March with a voucher for £5k from the scheme, the installer hasn't raised any concerns with me about any of this, from my perspective hopefully it still goes ahead.

Speaking with Zehnder customer support, where my required trickle rate for building regs is around 200m3/hr, they said the Q350 would be fine for me, where it's maximum airflow is said to be 350m3/hr, so close to your % capacity of the unit you were looking at. They explained that the unit has more capacity than stated, so could shift more air if asked when in boost function, probably at detriment to the heat recovered (that last part is my assumption). I was considering upscaling to the Q450, however they confirmed that a harder working Q350 would be quieter based on their data. I plan to double check all this with them again, but this conversation, along with personal accounts throughout the site of users electing for a lower ventilation rate relative to building regs, it feels like I would be fine with the smaller unit. I also asked about using F7 filters with the unit, thinking that would demand a high capacity from the unit, but they still felt that would be ok, all this in consideration of the MVHR unit being in a hallway cupboard, rather than tucked away in a loft where noise is less of an issue. Interestingly when speaking with PAUL heat recovery about buying a Q350, they offered to look at my calcs and confirmed my 200m3/hr based on part F regs. However they said they usually recommend passive house level ventilation levels which would bring my trickle up to around 250m3/hr. Given I am a refurb project unlikely to have a stellar ACH despite my best efforts, spec'ing for that level of ventilation would mean a bigger unit, more runs, and just a more complex task overall asking more of the living spaces to be claimed by MVHR infrastructure. My instinct is to keep things as part F regs level and hope that will be comfortable in the house, further hopeful of being happy to reduce the flows to result in the unit and vents being as quiet as possible. Any thoughts are welcomed of course.

Those silencers look quite short. I am space constrained and so effective short flexible silencers have been on my wish list. Probably subjective, but do you think they do a good job for you, and if so, what are they please? Are they the perforated on the inside as other attenuators would be? I'm not sure how you would really ever know whether cross contamination was happening, perhaps only with some CO2 monitoring? Speaking with PAUL today, they said the exhaust air speed is forced at least 1m away from the unit before it would slow enough to be capable to coming back to the intake for any kind of contamination, so in effect there is zero cross contamination.