faby Posted June 18, 2022 Share Posted June 18, 2022 Turning to the crew for advice! I am renovating a period property. The plan for the ground floor is low profile wet UFH panels. Wunda have told us this needs a flat structural floor and we have gone for 18mm plywood (8x4 sheets). I am really keen to eliminate squeaks and other sound transmission to the basement bedrooms that will be underneath this floor. The existing timber boards have all been pulled up and we have a mixture of new and old joists. They are variable heights with a difference of up to 40mm in certain areas (total floor area is 140 SQM). We are planning to glue wooden shims onto the joists to level them up. Reading other posts on the forum, I am not sure whether to use D4 polyurethane glue to fix the shims to the joists or ordinary wood glue. I have also bought green glue soundproofing joist tape to put on top of the shims but I am a bit concerned that it barely gets a mention on this forum. Does anyone have a view as to whether the joist tape or the D4 glue would be better to fill the gap between the joists and the plywood as apparently I can't have both? There will be Rockwool under these joists and soundshield plasterboard on the basement ceilings below. Any advice that you can give me about the best way to level this floor and eliminate squeaks/ downward sound transmission would be very very welcome. Link to comment Share on other sites More sharing options...
JohnMo Posted June 18, 2022 Share Posted June 18, 2022 Have you purchased the ply yet? 22mm interlocking waterproof boards may be better, fully glued with D4. Perimeter screwed. Gap around wall for expansion. If ply, fully glue with D4, leave gaps between panels for expansion and around room edges. Glue should expand to fill small gaps instead of shims. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 18, 2022 Share Posted June 18, 2022 Use the right type of screws. Link to comment Share on other sites More sharing options...
bassanclan Posted June 18, 2022 Share Posted June 18, 2022 No way is d4 glue going to make up 40mm 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted June 18, 2022 Share Posted June 18, 2022 You need to plant some timber screwed and glued all along the low joists to make up the height. Just a few shims won't give good results. Link to comment Share on other sites More sharing options...
faby Posted June 18, 2022 Author Share Posted June 18, 2022 3 hours ago, JohnMo said: Have you purchased the ply yet? 22mm interlocking waterproof boards may be better, fully glued with D4. Perimeter screwed. Gap around wall for expansion. If ply, fully glue with D4, leave gaps between panels for expansion and around room edges. Glue should expand to fill small gaps instead of shims. Link to comment Share on other sites More sharing options...
JohnMo Posted June 18, 2022 Share Posted June 18, 2022 22 minutes ago, bassanclan said: No way is d4 glue going to make up 40mm I did say small gaps , not huge ones Link to comment Share on other sites More sharing options...
faby Posted June 18, 2022 Author Share Posted June 18, 2022 I should have posted this a week ago! Unfortunately the ply is now on site! Thanks for your response, sounds like a strong endorsement for glue rather than the joist tape. Regarding an expansion gap, the room edges will be fine but do you have any thoughts on what size of gap should be left between the boards? The joists are mostly 47mm wide so to rest two separate boards and have a gap would be quite tight. Is it acceptable for the end of a board to rest on a fixed noggin rather than a joist? Link to comment Share on other sites More sharing options...
faby Posted June 18, 2022 Author Share Posted June 18, 2022 Sorry for the technical fail, previous message was in response to JohnMo Link to comment Share on other sites More sharing options...
faby Posted June 18, 2022 Author Share Posted June 18, 2022 3 hours ago, SteamyTea said: Use the right type of screws. What are these called please? The ones I have are different because my understanding was that it was best to use partially threaded ones. Oops! So far I have only bought a starter pack of 100 but I will need about 1800 screws in total. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 18, 2022 Share Posted June 18, 2022 33 minutes ago, faby said: What are these called please? https://www.toolstation.com/reisser-torx-diamond-point-flooring-screw/p49364 34 minutes ago, faby said: partially threaded ones. They will be bolts, not screws. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 18, 2022 Share Posted June 18, 2022 21 minutes ago, SteamyTea said: They will be bolts, not screws You are mixing up engineering and woodwork here. You can have partially threaded wood screws. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted June 18, 2022 Share Posted June 18, 2022 Just now, MikeSharp01 said: You are mixing up engineering and woodwork here Yes, bit like Physics and Phycology. If chippys want to be taken seriously, they got to learn the lingo of engineering. Probably save the lads legs as he could pick up the correct fastener first time. Link to comment Share on other sites More sharing options...
JohnMo Posted June 18, 2022 Share Posted June 18, 2022 Agree no-one seems to know the difference between a screw and bolt, even lots of so called engineers. A wood screw is just a type of fully threaded self tapping screw, but designed for used in wood. By definition a part threaded wood 'screw' is really a self tapping bolt design for use in wood. Link to comment Share on other sites More sharing options...
Russell griffiths Posted June 18, 2022 Share Posted June 18, 2022 Take the plywood back and buy 22mm tongue and groove chipboard, your ply will have give in it over the gaps between joists, unless you noggin all of those. So much grief. Chipboard is actually very stiff, ply is a bit springy. 1 Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 18, 2022 Share Posted June 18, 2022 45 minutes ago, JohnMo said: By definition a part threaded wood 'screw' is really a self tapping bolt design for use in wood. This sort of radical thinking will get you drummed out of the fraternity! Link to comment Share on other sites More sharing options...
SimonD Posted June 18, 2022 Share Posted June 18, 2022 43 minutes ago, JohnMo said: By definition a part threaded wood 'screw' is really a self tapping bolt design for use in wood. Unless you go by the definition that bolts are used to assemble unthreaded assemblies (using a nut) and screws threaded assemblies, including when they're self tapping. 😊😉 Here is doesn't really matter if they're fully threaded or not. So a woodscrew is a screw unless it uses a nut....but then you have machine screws, that can and do use nuts...... I'll get my coat and leave the argument to all those more sensible than me 😁 Link to comment Share on other sites More sharing options...
SteamyTea Posted June 18, 2022 Share Posted June 18, 2022 4 minutes ago, MikeSharp01 said: This sort of radical thinking will get you drummed out of the fraternity! No it won't. 2 minutes ago, SimonD said: Unless you go by the definition that bolts are used to assemble unthreaded assemblies (using a nut) and screws threaded assemblies Well at least you did not mention head types. Link to comment Share on other sites More sharing options...
joe90 Posted June 18, 2022 Share Posted June 18, 2022 Come on guys, don’t confuse @faby, I prefer to drill the board being held down so the thread does not bite into it, same as wood screws with partial thread (like they all were back in the dark ages 🤣). Link to comment Share on other sites More sharing options...
faby Posted June 18, 2022 Author Share Posted June 18, 2022 36 minutes ago, joe90 said: don’t confuse @faby I am totally confused 😂. Most of the discussion has gone totally over my head! Link to comment Share on other sites More sharing options...
faby Posted June 18, 2022 Author Share Posted June 18, 2022 1 hour ago, Russell griffiths said: unless you noggin all of those Yes, there are basically noggins everywhere. Some are fixed to the joists others have just been hammered in. One of the issues I want to resolve is whether it is okay for the edge of a board to end on a noggin rather than a joist. Assuming I stick with the ply, interested in views on appropriate size of expansion gap between boards. I did consider chipboard but there seem to be so many differing viewpoints. One key consideration for me was the need to keep the total floor height as low as possible and that was what appealed about the 18mm boards. But perhaps I need a rethink. Link to comment Share on other sites More sharing options...
joe90 Posted June 18, 2022 Share Posted June 18, 2022 32 minutes ago, faby said: is whether it is okay for the edge of a board to end on a noggin rather than a joist. As long as there is a connection/support between the edges of the sheets of ply, so yes IMO. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 18, 2022 Share Posted June 18, 2022 17 minutes ago, joe90 said: As long as there is a connection/support between the edges of the sheets of ply, so yes IMO. +1 you MUST support all the edges (T&G does this out of the box) for ply you need noggins / joists to do the job. D4 glue is great for this, we did ours, albeit T&G with the caberfix variant of D4 and we don't get any squeaks although there are quite a few 'snots' running down the joists, which too me means I used enough! Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 18, 2022 Share Posted June 18, 2022 For screw / bolt pedants please explain how the term 'set' fits into the debate. 1 hour ago, faby said: I am totally confused 😂. Most of the discussion has gone totally over my head! Sorry we sometimes do this here - we observe that the head of a pin is a relatively small area and then we try to squeeze as many ideas / concepts / comments into our pockets and do a 'jig' while keeping our dancing equipment within the circumference of the pin head. (I will now also get my coat - it is raining here in Kent!) Link to comment Share on other sites More sharing options...
SimonD Posted June 18, 2022 Share Posted June 18, 2022 3 hours ago, SteamyTea said: Well at least you did not mention head types. Yes, best not to go there, eah? 1 hour ago, MikeSharp01 said: For screw / bolt pedants please explain how the term 'set' fits into the debate. As in a set screw type thingies? They don't use nuts and typically go into threaded components so the screw taxonomy gets my vote 😁 Link to comment Share on other sites More sharing options...
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