Screw sizes for loft boarding project

[Mister Banks]

I will soon be boarding my loft and need a bit of advice re screw sizes. I will be battening the loft with 175mm x 47mm battens and laying 18mm chipboard on top, what size screws would be recommended to screw the battens to the 3xisting ceiling joists and the chipboard to the battens?

Thank you.

 

[blup]

How deep are the current joists?

Blup

 

[Mister Banks]

How deep are the current joists?

Blup

Current joists are 100mm. I have ordered 4 x 40mm for chipboard and 5 x 70mm for battens so can change them if necessary.

 

[blup]

Why are you laying the battens side on, they only need to be at 400mm centres and 50mm or so deep.

blup

 

[freddiemercurystwin]

I would have gone a little longer for the batten screws, one each side skewed in.

Why are you laying the battens side on, they only need to be at 400mm centres and 50mm or so deep.

blup

They need to be as deep as his insulation, presumably 170mm.

 

[Mister Banks]

Yes battens are 175mm because the insulation I have added is 170mm.

 

[Mister Banks]

I would have gone a little longer for the batten screws, one each side skewed in.

They need to be as deep as his insulation, presumably 170mm.

Wickes didn’t have longer screws in stock so I had to go with the 70mm screws, hopefully will be ok.

 

[conny]

Are you screwing the battens alongside, and into, the existing joists or at right angles across them?

Is the flooring simply for storage or are you considering using the loft as a play/study area?

 

[Mister Banks]

Are you screwing the battens alongside, and into, the existing joists or at right angles across them?

Is the flooring simply for storage or are you considering using the loft as a play/study area?

I am placing the new battens on top of the existing joists at a 90 degree angle and screwing down into the existing joist from the side. The finished platform is only for storage.

 

[nitrochicken]

Duplicate post

 

[nitrochicken]

If the timber your are adding is going on top and you are screwing diagonally, I would recommend piloting the holes with a 5mm drill bit first. I'd say 70mm is a little less than ideal for this but you may get away with it. Make sure you alternate the screws on each side.

If I've not understood what you are doing correctly, if you are screwing through the whole width of the 47mm timber, I would recommend getting longer screws. 90mm would be ideal.

You can buy screws specifically for fixing down chipboard flooring, they are normally 45mm I think but the 40mm ones you have bought should be fine for what you are doing.

I'd recommend buying screws from Screwfix or toolstation if you buy any more as you'll find they are a fair bit cheaper

 

[Mister Banks]

I dont think I am explaining this very well! Hopefully the attached pic helps. The diagonal lines are the screws. My thoughts are to screw diagonally into the batten and the joist.

 

[freddiemercurystwin]

I dont think I am explaining this very well! Hopefully the attached pic helps. The diagonal lines are the screws. My thoughts are to screw diagonally into the batten and the joist.

No, you explained it fine, it all made sense to me.

 

[nitrochicken]

I dont think I am explaining this very well! Hopefully the attached pic helps. The diagonal lines are the screws. My thoughts are to screw diagonally into the batten and the joist.

Thanks for clarifying. I think you'd be better using longer screws for the diagonal ones if you can

 

[Mister Banks]

No, you explained it fine, it all made sense to me.

What size screws would you use in this situation?