What size drill bits for plastic pipe through joists

[Fallout]

Hi, what size drill bits are needed for drilling joists to run 15-22mm pipe through?

 

[Fallout]

Is there certain places were you can and can't drill the joists?

 

[Jackrae]

For 22mm, 25mm assuming you drill true, otherwise around 28mm would be my choice.

For 15mm, 18mm or 20mm

 

[Madrab]

Is there certain places were you can and can't drill the joists?

Yes, you can only drill through the centre of joists, holes cant exceed specific sizes, depending on joist size.

http://www2.redbridge.gov.uk/cms/pl...36630f-bed9-426b-8b5b-647c4bea187b&version=-1

 

[Fallout]

Thanks what about were abouts on the span of the joist?

 

[Jackrae]

Theoretically the neutral axis (centre line of a rectangular joist) is neither in compression or tension so you should be able to drill anywhere over its length providing the hole is small enough. As the hole size increases you need to get closer to a point of support.
This offers some guidance http://www.mybuildingpermit.com/Constuction Tip Sheets/TipSheet06_11.pdf

 

[JimCrow]

Thanks what about were abouts on the span of the joist?

between 1/4 and 2/5ths of the span.

 

[Fallout]

Thanks so if drilling a 28mm hole for the heating flow how close can the next 28mm hole be for the heating return?

 

[Terry lambert]

https://www.broxbourne.gov.uk/resid...building-control/notching-and-drilling-joists

 

[Fallout]

Thanks so a 28mm hole will need to be 56mm from the (28mm) hole need to it?

 

[Madrab]

Just read the doc, and it says twice but the diagram says 3D - It should be 3 times the hole diameter centre to centre = 84mm

 

[Terry lambert]

Yeah, that wasn't the clearest, sorry

 

[Fallout]

Thanks for your help. How do you work out what is between 0.25 and 0.4 of the span on say a 5 meter joist?

 

[muggles]

0.25 x 5 = 1.25m
0.4 x 5 = 2.00m

 

[Fallout]

Thanks so on a 5 meter joist holes can be drilled in the area between 1.25m and 2m of the joist span