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Just when I thought I had a full understanding of requirements :cry: My understanding was 100mm of PIR in-between the joists would be under the required u value of 0.25 - according to the Kingspan u-value calculator 90mm of PIR would be 0.24, and 100mm 0.22. Where I am the required u value is...

Hi All, For a couple of reasons (radiator pipes, ceiling height, avoiding blocking air vents), and to avoid a lot of faffing about with all those things, I'm stuck with 100mm joists in a suspended timber floor. From what I can tell the only insulation that will achieve the u-value I need (0.25)...

Hi All, Trying to address some issues with our dining room floor. I think it was previously two rooms knocked together, with one side of the opened up area sunken down in middle about 40mm. That was the main issue I wanted to address. Not sure why it sunk but seems like it's settled and not for...

Thanks Woody - appreciate there may be some dampness but with adequate ventilation this isn't really an issue. No standing water thankfully even after some thunderstorms a few weeks back that put down an awful lot of water in a short space of time. I think I'll rule out any pipe leaks nearby...

Thanks. Missing/failed DPM crossed my mind - a builder I had out suggested drilling out a sample of the floor to see what's going on but I'm not too convinced on that plan. I had thought it was potentially just poor ventilation, with just one air brick in the corner and the other blocked off by...

Hi All, Doing some work on floors and a particular room is giving me a bit of stress. One room I've lifted the floorboards in and the oversite is dry, dusty to touch. Another room at back of house (pic attached is a different story). It's patchy at best, with some areas apparently dry and you...

Thanks, SDS has been on my list to get for a while, have numerous jobs building up that I need one for. Thanks for all the info!

No hangers, joists sitting on sleeper walls at each end and in middle, assume hangers for the noggings wouldn't be necessary? Will be fun and games trying to get the correct brick on the inside once I've knocked out the outside one! Assume if I can fit a drill in from the outside I should pilot...

ok, thanks. Should I put noggins in at the ends, essentially creating like a closed frame, or is that overkill? I also need to install a couple of new air bricks - should I be worried about removing bricks from the wall or is 1 (2 max - 1 whole and 2 halves) nothing to worry about in terms of...

Thanks - ply makes sense now I think of it. It's ground floor - if I sister to top should I also stick some ply under there to bridge the gap to bottom? Noggings - does it matter where you place them (flush top, bottom or middle)? for the noggings what is the right joining method? is it...

Morning All, Struggling to find any answers to the following questions, and hoping someone out there has them. Situation: replacing rotten 110mm joist (end of the room) and part of the wooden sole plate it rests on (cutting back to where not rotten). Closest matching joist I can find is...

Promise final question on joists - does the clear span in the tables and notching guidance only apply to the full length of the joist regardless if there is a sleeper/multi sleeper walls in-between? for example one end of the room to the other is 3m, but when you put a sleeper wall in the middle...

Apologies if I'm using the incorrect terminology - setup is a suspended timber floor, with joists resting on dwarf walls on inner leaf (with honeycomb walls in-between). The dwarf walls on inner leaf have a bit of timber on top which the joist ends rest on.

Thanks for all the info. Couple of final questions - what fixings are suitable for the joist sitting on the timber wall plate (nailed/screwed down)? Is a mutli-purpose mortar mix that comes bags ok to use to set the new timber wall plate & DPC underneath?

ok, thanks. Therefore, leaving 25mm each side to wall on a 3m room, I can either have 8 joists at ~370mm centres or 7 joists at ~420mm - as long as the spans are ok per the tables? Also, in terms of treated v.s. untreated joists, local builders merchants seem to carry a much larger range of...

Thanks - so is it common practice to space the joists to suit the situation and not stick rigidly to 400, 500 or 600 exactly? In my 3m room, going by the guidelines of leaving 25-75mm from the wall, none of those centre distances would work unless I'm totally confusing myself at this stage which...

Hi Everyone, I'm sure this is relatively straightforward for someone out there. Planning on replacing existing suspended timber floor with deeper joists and insulating. I've looked at joist spans/spacing etc and understand all this but I can't find anywhere about how you practically layout and...

Thanks AiY - options you put forward are nice and clear, just have to make up my mind! Re the rotten joist and board ends butting up against the wall - should if be concerned about wood worm/potential for rot to spread to other timber if keeping existing joists? It looks isolated enough but...

Sorry, hopefully final question on this. Attached pictures are from a joist and floorboards at the side of the room (beside door opening onto old tiled floor). Obviously seen better days - I think this was caused by a chunk of concrete stuck between the wall (below DPC) and the joist and the...

Agree insulation makes sense while floor is up - is it any concern filling insulation flush to the joist bottom at sleeper wall effecitvely blocking the air flow over the sleeper wall?