Will these floorboard cracks be a problem? - Tile Advice

[Mathew2019]

Hi there. Ive just had 18mm floorboards screwed down to joists by my builder . Tomorrow i will be getting the builder to screw down 6mm cement boards ready for tiling. Ive noticed that alot of the floorboards are cracked where the screws gone in. Ive attached photos. Although there's no visible movement or creaking, I'm wondering if this means the boards will eventually start moving and cracking tiles.

Could anyone advise me?

 

[Dan]

I think he's just been a bit too rough with the screwing there. You could screw one more screw in the centre at the end of each split board just to be sure. But drill a hole in it first, then screw. And even counter-sink your screw heads.

Typical builder whacking them in lol

There's a method to screwing boards down and wanging the screws straight in isn't the best for tiling. Not a problem if you were having carpet or something.

Your cement boards will save the day though. Screw those down well using the correct screws (that don't degrade over time) and you'll be fine.

 

[Dan]

There's a good guide here

How to Drill Countersink Holes and Pilot Holes

Countersinking and pilot holes - Find out what a pilot hole is and how it is used when drilling wood and metal and how to countersink screw heads to hide them

www.diydoctor.org.uk

(image from DIYDoctor)

 

[Tony_C]

Run your cement boards staggered in the opposite direction from the floorboards also and try avoid any lengths of joints matching on the floor boards and backer boards too 👍

 

[Dan]

If you could hit the joists with some of the screws going through the cement boards any lateral movement in those floor boards won't cause any issues at all. They're just spreading the load then.

I wouldnt worry. If it were mine I'd stick a screw or two in properly before boarding over just for my own piece of mind and OCD more than anything.

 

[al strachan]

builder has used drywall screws by the looks of it. Not something i would be screwing floorboards down with.

 

[Dumbo]

builder has used drywall screws by the looks of it. Not something i would be screwing floorboards down with.

Good spot,

 

[Mathew2019]

builder has used drywall screws by the looks of it. Not something i would be screwing floorboards down with.

Thanks for your reply. Which screws were the correct ones?

 

[al strachan]

Basically any wood screw would be better. I wouldnt go less than 4 mm diameter. ideally 4.5 or 5mm.

Drywall screws are 3.5mm diameter and not great for corrosion. used in a structual application they are thin and brittle and wont take any sheer load. Over time they will snap as the floor gets used. The countersink heads are also concave rather than a straight bevel, so largely accounts for the splitting also.

I could forgive a "builder" (generic term for someone who has a bash at most trades without actually being able to justify any association or experience in a single trade) for using woodscrews without countersinking, but drywall screw without countersinking - oh my oh my.

 

[Mathew2019]

Basically any wood screw would be better. I wouldnt go less than 4 mm diameter. ideally 4.5 or 5mm.

Drywall screws are 3.5mm diameter and not great for corrosion. used in a structual application they are thin and brittle and wont take any sheer load. Over time they will snap as the floor gets used. The countersink heads are also concave rather than a straight bevel, so largely accounts for the splitting also.

I could forgive a "builder" (generic term for someone who has a bash at most trades without actually being able to justify any association or experience in a single trade) for using woodscrews without countersinking, but drywall screw without countersinking - oh my oh my.

Is it too late to replace these screws? Will the threading be too large now? I do not want to take any chances with cracked tiles as ive had very bad experiences in the past
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The screws he used were drywall 4.2 x 75, shall i have them replaced?

 

[al strachan]

not at all, easy to replace. The old screws are thinner, so all good.

I'd use 5x50 countersunk woodscrews. Screwfix gold are quite good and inexpensive. Get a countersink bit while you are at it.

https://www.NoLinksToThis/p/goldscr...k-multipurpose-screws-5-x-50mm-200-pack/16497

https://www.NoLinksToThis/p/erbauer-countersink-9-5-x-65mm/86156

You dont even have to replace, just add one next to each drywall screw if you like.

Just make sure you know theres no pipes/wires underneath where you are screwing if going for fresh wood.

 

[Mathew2019]

not at all, easy to replace. The old screws are thinner, so all good.

I'd use 5x50 countersunk woodscrews. Screwfix gold are quite good an inexpensive. Get a countetsink bit while you are at it.

https://www.NoLinksToThis/p/goldscr...k-multipurpose-screws-5-x-50mm-200-pack/16497

https://www.NoLinksToThis/p/erbauer-countersink-9-5-x-65mm/86156

You dont even have to replace, just add one next to each drywall screw if you like.

Just make sure you know theres no pipes/wires underneath where you are screwing if going for fresh wood.

Thanks alot for your input i appreciate it. My builder seems to be taking shortcuts which is why I'm seeking third party advice. In regards to the hardiebacker boards, do you have any knowledge in the correct application of them? Ie type of screws, priming etc?

 

[Mathew2019]

not at all, easy to replace. The old screws are thinner, so all good.

I'd use 5x50 countersunk woodscrews. Screwfix gold are quite good and inexpensive. Get a countersink bit while you are at it.

https://www.NoLinksToThis/p/goldscr...k-multipurpose-screws-5-x-50mm-200-pack/16497

https://www.NoLinksToThis/p/erbauer-countersink-9-5-x-65mm/86156

You dont even have to replace, just add one next to each drywall screw if you like.

Just make sure you know theres no pipes/wires underneath where you are screwing if going for fresh wood.

Quick update I've just bought reisser high performance woodscrews cluntersunk 5 x 50, will these be adequate?

 

[al strachan]

Quick update I've just bought reisser high performance woodscrews cluntersunk 5 x 50, will these be adequate?

yup, all good. Definately pilot hole and countersink though
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Thanks alot for your input i appreciate it. My builder seems to be taking shortcuts which is why I'm seeking third party advice. In regards to the hardiebacker boards, do you have any knowledge in the correct application of them? Ie type of screws, priming etc?

over to the tiling Pro's!

 

[Boggs]

See here.

https://www.jameshardie.co.uk/import/Documents/HardieBacker%20Product%20&%20Installation%20Guide.pdf