Idiot's guide to laying LVT?

[Mander]

I'm in the process of ordering everything for a bathroom renovation and was planning to buy Karndean Knight LVT to install myself. The room is about 2.75m2. The current floor is made of hardboard nailed to the floorboards, with peel and stick tiles from Poundland that I put down many years ago (aided with some regular floor adhesive). It has held up very well despite the cheap flooring so I was feeling quite confident in my ability until it came time to actually place the order!

I just want to check that I have all the stuff I need before I pull the trigger and buy the flooring. I'm assuming I need new hardboard (and condition it with water), adhesive, measuring tools and a good knife, patience, and knee pads. It's such a small area that I imagine that an ordinary household rolling pin will be sufficient for going over the planks once they are glued down. Am I being wildly over-optimistic here? Should I buy an offcut of lino instead??

 

[dazlight]

Buy decent 6mm / 9mm plywood 1st.

 

[Deleted member 174758]

And find some patience - the plywood should be nailed with something like 19mm ring clouts at 100mm centres (that's 325 nails per sheet)

 

[Mander]

And find some patience - the plywood should be nailed with something like 19mm ring clouts at 100mm centres (that's 325 nails per sheet)

That seems like a lot of nails for an area less than 3 square meters. The current floor is nothing like that. Why are so many suggested?

 

[Deleted member 174758]

It is the industry standard, certainly for 5.5mm plywood going down beneath LVT such as Karndean. On my current project it has been specified for all areas where LVT or roll vinyl is to be fitted subsequently. We install the ply as part of the sub-floor prep and the floorers put down primer followed by SLC before the finished floor goes on

Bear in mind these are only 2mm nails, and that you need to ensure that the plywood has minimal voids beneath it where the original boards meet, repair sections, etc are and that the ply cannot flex, which you really don't want. This way leaves you with a relatively flat and very stable floor almost regardless of what lies beneath it.

 

[drives]

Board with 6mm marine ply as suggested above. I used 20mm screws at 150mm centres

Use Karndean skimcoat or similar, and spread evenly with a decent plasterers trowel (quite easy to use):

https://www.amazon.co.uk/Karndean-Skimcoat-5kg-Hardening-Levelling/dp/B0196MLQ28

Check for any ripples etc you might have left and sand them down.

Install flooring. I use F45. Get a proper LVT roller

https://www.amazon.co.uk/Amtico-kar...289520&sprefix=karndean+roller,aps,172&sr=8-4

I install in smaller sections, rolling each in turn. Obviously where you lay the first tile in the most critical so dry lay it all out first

Done a few floors now with the above method without any issues.

 

[dazlight]

The joints of the plywood every 4” ( 100mm )

 

[Deleted member 174758]

The joints of the plywood every 4” ( 100mm )

Or 164 screws per sheet if you screw them down. OP - make sure you flush the heads of the screws properly because otherwise they can telegraph through later on

 

[Mander]

Thanks all, this is helpful. Seems like I might have just been lucky with the existing floor because I don't think it had anywhere near as much prep! The difficulty is that I will need to do the floor after the installers have put in the new bath & toilet etc. so I'm not sure how to deal with that if I'm putting in new plywood, other than cutting it around the toilet. Maybe I should ask if they can put the plywood down before they put the toilet in, at least.

 

[Deleted member 174758]

It's certainly a lot easier to install plywood with the basin pedestal and toilet pan out of the way (BTW the same goes for installing the finished flooring). I've not long plied our bathroom floor - it being an existing bathroom the bath stayed in place, as did the sink pedestal but the toilet pan and close coupled cistern came out (about 10 to 15 minutes work). Cutting round the bath (panels removed) was a doddle - cutting round the sink in 5.5mm ply took a bit (lot) longer and TBH the only reason I didn't take the pedestal out was that I was being lazy. When I (eventually) redo the room I'll lift all the ply and lay a whole new (cement board) floor in one go before I install the new bath suite.

 

[Mander]

Ok so I have sorted the timing with the installer. Now the issue is buying all the supplies. Can I get the levelling compound or similar in smaller quantities? I really don't think I will need a 5kg tub for this small foor area. Or is there another product I can use?

I'm thinking I might change my mind on the Karndean brand stuff and look for something less heartbreaking if I screw it up.

 

[Deleted member 174758]

Can I get the levelling compound or similar in smaller quantities? I really don't think I will need a 5kg tub for this small foor area. Or is there another product I can use?

5kg? The jobs I work on the floor layers often turn up with 20 or 25kg bags. TBH you may struggle, but if your LVT supplier has their own fitters you may be able to cadge up a part bag left over from a job. Not saying it's a definite, but possibly worth trying. Also enquire about whether/what type of primer you'll need for the job

Whatever else, if you are installing an expensive flooring material, good prep work is essential. And against the price of Karndean the price of your levelling compound isn't really that much.

And if you want a laugh about prep: I spent more than two days repairing, patching (plywood), levelling then ply cladding a corridor on the current project ready for a Karndean floor (that was 6mm plywood nailed on 100mm centres, or around 3.5k nails). The client, in their infinite wisdom, changed their mind and decided that it would be "nice" to have the original floor boards on display, despite at least 1/4 them having been replaced at various times by plywood and the rest being frankly almost beyond repair (they are more than 150 years old, and every electrician and plumber on the planet seems to have dug around under the floor over the years - and we all know how neatly they reinstate floors). Anyways, it took two labourers and a joiner three days to lift the all ply and denail the floor (BTW screws often won't come up that easily because the recesses get damaged very easily), as it came up in small pieces, each about the size of a Post-It note. Now the client has decided that the sub-floor isn't worth keeping, so they'd like the Karndean/plywood/SLC again, please. So I now have to schedule the time to reply the floor...

...b.good job I have a coil flooring nailer

Be thankful you have only 1-1/2 sheets to do. On another part of this project I was wrong footed badly, so me and my mate had to hand nail 18 odd sheets of plywood because my compressor and gun were on another job. If they did that to me again, I think I'd go sick for the week

Sorry, long post

 

[drives]

Ok so I have sorted the timing with the installer. Now the issue is buying all the supplies. Can I get the levelling compound or similar in smaller quantities? I really don't think I will need a 5kg tub for this small foor area. Or is there another product I can use?

I'm thinking I might change my mind on the Karndean brand stuff and look for something less heartbreaking if I screw it up.

The 5kg tub did me that room, and a small toilet room I think. It doesn’t go that far.

only a keen diy er myself but have done most types of flooring. I find karndean the easiest to be honest- it’s just vinyl tiles at the end of the day which are easily cut with a Stanley knife and metal ruler. For the radiator pipes I think I just sandwiched it between some ply and used a hole saw. The trickiest part is probably doing the levelling compound but you only need a thin layer of a couple of mm. I use a large flexible plasterers trowel.

 

[robinbanks]

Board with 6mm marine ply as suggested above. I used 20mm screws at 150mm centres

Think I might have relaxed the "bang on 150mm" grid a little, to avoid sending entire lines of screws down the very edge of substrate planks, there..

 

[drives]

Think I might have relaxed the "bang on 150mm" grid a little, to avoid sending entire lines of screws down the very edge of substrate planks, there..
View attachment 307455

Good spot! I was a bit ocd with my grid. I was still securing into solid wood below, with around 10mm to spare I think.