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Pipe location


Russell griffiths

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Hi all, is there an optimum location within the floor slab to position the pipe work,

for example in a 150mm floor slab laid on insulation could the pipe work be pinned to the insulation or is it better to be located centrally in the slab fixed to the reinforcement mesh. 

 

I like the the idea of fixing it down low in the slab just for piece of mind of fixing anything to the slab while the build continues it is out of harms way. 

Cheers. 

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You don't really want it on the underside of the slab, but I'd say 50mm up would suffice. A pita to facilitate though, so I'd go for clipped to the mesh and use caution when fixing down. Bearing in mind that with accurate plans you would be laying the pipes away from the stud walls at the very least so this risk can be reduced or mitigated against with reasonable sense / ease. 

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We are just designing at the moment,

we know we can get away with 100mm of concrete as a non structural floor slab,just a few internal non load bearing stud walls. 

But for the extra cost I would rather go 150mm as I'm a bit ott and like things chunky. 

 

I suppose I could use mesh with pipework tied to mesh which would put pipes at 70 mm below slab finish so well out of harms way. 

 

The reason I wanted to do it without mesh is I will be doing 90% of this build myself with just some hired in labour so thinking if I can get a mix delivered that has the same strength as a slab with reo without having to handle all those sheets of reo and holding up on chairs then I can cut out a step making it easier for me to complete on my own. 

I will ask a few questions regarding slab design. 

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Not sure why you would go to 150mm slab tbh. 100mm unreinforced can span 2m under normal loads so 150mm seems overkill for 50% more material cost and the added removal of spoil etc. 

 

I've seen slabs crack very occasionally but that is down to poor design usually. Adding fibres is a better solution as the reinforcing is through the entire slab and not just focused into the mid section. 

 

If you want pipe protection then go with the Polypipe or Wunda trays and then the pipes are at the bottom. You can reinforce by simply placing A146 over the top which also stops your pipes coming up as well but that's serious overkill for a domestic slab. 

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The last place I built had a100mm slab, but had thickening beams criss crossing it for strength and to stop cracking, after all the faff of digging out the beams I thought it would have been so much easier to go for thicker all over. 

 

So we seem to have deviated a bit from the original question which was pipe location. So if I have a

 

100mm slab where would the best place be to have the pipe, bottom, middle

150mm slab where would the best place be to have the pipe, bottom ,middle

 

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Heat rises, so as long as you've got at least 200mm of insulation then go for the trays as said. That'll lift the pipe slightly and make laying the pipe easy. It'll also absorb some of the volume of concrete required due to the castellations.   

At 150mm I'd just add fibres.  

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I think both @TerryE and @JSHarris had a discussion on this about the thermal performance of a slab and the gradients around a pipe. 

 

In all honesty I don't think it makes much difference - the slab will warm through at a specific gradient and it's all about controls as you need to watch for overshooting of room temperature as the slab will keep getting warmer on the surface as the temperature evens out. 

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10 minutes ago, Nickfromwales said:

Heat rises, so as long as you've got at least 200mm of insulation then go for the trays as said. That'll lift the pipe slightly and make laying the pipe easy. It'll also absorb some of the volume of concrete required due to the castellations.   

At 150mm I'd just add fibres.  

 

Trays make life very easy - I laid 85 sqm in less than 2 days on my own. IMG_0730.thumb.JPG.920c2798a0a1361d1f6ee55b3e665e8f.JPG

 

Thats at 200mm spacing - had some fun with the dog bone ends but easy to do. 

 

This was round the kitchen layout - means I know where I can and can't put screws in the floor ..!! 

 

IMG_0731.JPG.576065abc4a3565d74588d9d17a81dbd.JPG

 

 

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1 hour ago, PeterW said:

 

Trays make life very easy - I laid 85 sqm in less than 2 days on my own. IMG_0730.thumb.JPG.920c2798a0a1361d1f6ee55b3e665e8f.JPG

 

Thats at 200mm spacing - had some fun with the dog bone ends but easy to do. 

 

This was round the kitchen layout - means I know where I can and can't put screws in the floor ..!! 

 

IMG_0731.JPG.576065abc4a3565d74588d9d17a81dbd.JPG

 

 

Not too shabby ?

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