22mm T&G first floor install advice required

[ruggers]

I'm about to install the first floor on my self build using Krono span P5 fast shield t&g 22mm boards and D4 glue.

 

These are a similar product to caberdeck and egger protect for those unfamiliar with the brand.

 

My question is, can they be installed with D4 glue only after the first row is mechanically fixed using screws or ring shank nails, or, does every board need fixed and glued?

 

My builder who's installing them on this occasion, has said just glue after the first row because nail holes or screws will let water in. Is this ok, or cutting corners?

 

I thought tape or filling the holes covered this issue.

 

In the past i've always screwed as well but i do like to do things properly or belt and braces at times. I called krono for advice but the person i got didnt seem overly confident in their advice saying glue only should be enough.

 

 

[ToughButterCup]

1 hour ago, ruggers said:

..., or, does every board need fixed and glued?

 

My builder who's installing them on this occasion, has said just glue after the first row because nail holes or screws will let water in. Is this ok, or cutting corners?

...

Yes.

and

Bollocks

[Bonner]

Needs to be screwed to pull the boards down flat onto the joist.

[crispy_wafer]

I’d say that he’s right to concerned that screw/nail holes can be affected by rain/moisture, no different to the board joints really, so put a small dob of d4 over the nail/screw will help.  A floor scraper when watertight to lift the foam.

Edited Monday at 19:40 by crispy_wafer

[LaChab]

The Egger instructions seem to say either is ok......

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjI0OOZp7iPAxXjbEEAHX5LOO4QFnoECBwQAQ&url=https%3A%2F%2Fwww.egger.com%2Fget_download%2Fc19090af-796c-4d84-86bf-33909a20f6bf%2FFlyer_Advanced_Structural_Flooring_System_Fitting_guide_UK_05_2024.pdf%3Fcountry%3DGB&usg=AOvVaw1t1ze_7xhNmM1ygxieNHff&opi=89978449

[ruggers]

1 hour ago, Bonner said:

Needs to be screwed to pull the boards down flat onto the joist.

This is what i thought. I dont like a glue only idea. Tempted to fit them all myself. 

 

Do they need pulled tight with ring shanks or screws as the glue is setting or could i let him install them then follow on after he's gone same day or another day?

[Bonner]

3 minutes ago, ruggers said:

Do they need pulled tight with ring shanks or screws as the glue is setting or could i let him install them then follow on after he's gone same day or another day?

Must be fixed down before the glue sets 

[ruggers]

49 minutes ago, crispy_wafer said:

 no different to the board joints really, so put a small dob of d4 over the nail/screw will help.  A floor scraper when watertight to lift the foam.

Yes to this, also the perimeter edges are all exposed so would need sealed too with d4 glue or an alternative?

 

Ive never used d3 or d4 glue, only pva and screws 15 years ago which was weather tight. No issues.

21 minutes ago, Bonner said:

Must be fixed down before the glue sets 

Does a nail gun give the same pull down or would screwed be better, pilot drill and impact driver i could be following on behind as he lays them.

 

Can't believe the krono tech advice and the linked above egger guidance says that glue only can be an option. Wind uplight could loosen them.

[Nickfromwales]

Glued and screwed every damn time!

 

100% defo need to be screwed down before the glue cures or the board won't ever pull back down, the glue will win that fight.

 

I use 5.0 x 50mm screws which are partially threaded, to prevent 'jacking' that a fully threaded screw promotes. No need for a pilot, as the impact will send these through and out the other side with complete ease, plus you want the meat left intact to maximise on the purchase of the screw.

 

If you're at all worried about weathering, then just fill each screw hole with a scraper and some cheap clear silicone, seriously unnecessary imho though unless this is going to be open to the elements all winter?

[Gone West]

Our 22mm Caberdek flooring was glued and ring shanked nailed and only the T&G joins were taped. It was open to the elements for a couple of weeks and had puddles on it at times but when the covering was peeled off it was fine.

 

 

 

[ruggers]

On 01/09/2025 at 21:42, Nickfromwales said:

I use 5.0 x 50mm screws which are partially threaded, to prevent 'jacking' that a fully threaded screw promotes. No need for a pilot, as the impact will send these through and out the other side with complete ease, plus you want the meat left intact to maximise on the purchase of the screw.

Can you elaborate on the partially threaded screw so i can look for some.

Not quite understanding why it would jack up?

 

I thought 22mm boards would require a small pilot to get the screw started easier as they're quite hard but ive never used my impact gun on them.

 

Nothing worse than cursing screws that wont start and end up with the driver head slipping into the fingers 😂

 

I had been looking at 4.0 x 60mm.

 

Ill be laying them next week if its dry then exposed for 4 to 6 weeks. They are 60 day boards, no peel off, anti slip and protected both sides.

 

@LaChab

After you posted the Egger fitting guide, i looked for a krono fastshield one and it also tells you to fix the board on all 4 corners and 2 in the middle so I've no idea why their tech support said to just glue only. 

 

@Gone West what tape did you use, any old duct tape?

 

 

kb-fast-shield-fitting-guide-final.pdf

[LaChab]

I used https://www.toolstation.com/floor-tite-tri-lock-pozi-screw/p65750

[Mr Punter]

I have used https://www.screwfix.com/p/spax-tx-countersunk-self-drilling-flooring-screws-4-5mm-x-60mm-300-pack/88716.

 

Glue and lay the boards a few rows at a time, then chuck in a few screws.

[ruggers]

How many srews did you put in a 2400 x 600 board? My guide shows 3 per sheet i thought it was 6.

 

Ive 90 boards to lay.

[Nickfromwales]

56 minutes ago, ruggers said:

How many srews did you put in a 2400 x 600 board? My guide shows 3 per sheet i thought it was 6.

 

Ive 90 boards to lay.

I do 5 of 5.0 x 50mm. One each end, about 50mm in, one in the middle, then one in each gap in between.

Fully threaded screws can leave the deck boards and the joists separated, but still allow you to countersink the screw head in, thinking they’ve pulled together.

 

If you look at the tip of the screw you’ll see a self cutting slot in the threads, which acts like a pilot cutter. A bit of weight behind the impact and these will shoot in with ease. 
 

I defo wouldn’t use 4.0 screws as they’re very skinny and can snap easily.

[ruggers]

1 hour ago, Nickfromwales said:

I do 5 of 5.0 x 50mm. One each end, about 50mm in, one in the middle, then one in each gap in between.

So thats one on every joists

0, 600, 1200, 1800, 2400.

 

Assuming the 1200 and 1800 fixings, your fitting them on the opposite side to the 0 and 2400 ones but only after the 2nd row t&g are fitted to make it easier to pair them up and not be over clamped

[Gone West]

13 hours ago, ruggers said:

@Gone West what tape did you use, any old duct tape?

The installers used what looked like standard duct tape. It did the job for a couple of weeks.