First fix pipes before screed

[Sanke]

Hi all
When laying out first fix pipes before the screed is laid how do you guys advise fixing the pipes ?
Ordinary pipe clips secured in concrete blocks between floor beams ? Or is there a recommended method ?
Thanks

 

[Mike Jackson]

Pipes shouldn't be laid in screed unless they are ducted or plastic pipe in pipe system. Pipe in pipe system nail clips. Copper standard clips.

 

[Sanke]

Builder wants to just use felt lagging as that is what he has always done ! Pies will be laid for heating as well as hot/cold

 

[SimonJohns]

walk away!

far far away

 

[Mike Jackson]

Doesn't comply with the water regulations regardless of what he's always done. Be wary as any comeback could be laid at your door.

 

[ADM360]

should be layed in sleves, or ducted!!

 

[TGor]

Never use felt lagging in concrete or screed with copper pipes .. it gives off ammonia when wet which is fatal to copper might last a year if your lucky. Don't walk RUN!!!

 

[AWheating]

copper will need to be covered in insulation tape minimium. Pipe in pipe would be a better option, especially for the hot and cold.

 

[stevetheplumber]

we use a bit of strapping to keep them down the galvanise strip with holes in sometimes called pattent band last few jobs theve plasted first and we had the rads to fix pipework to

 

[mylesy]

if its only having water it the pipes, then use hep 20 or another brand of plastic barriered pipe as it doesnt react to the chemicals in the screed. also insulate them first with lagging then clip them down. laggin not only insultes the pipes but gives it room for slight expantion when covered in the screed and prevents cracking.

 

[mylesy]

iv also made clips out of flattened copper pipe before to suit the width, which you can drill a hole at the sides for the screws. just shape it around the pipe. btw foam tube lagging is what i i use

 

[mylesy]

also avoid joints under the floor with plastic pipes

 

[PlumbBobBob]

also avoid joints under the floor with plastic pipes

joints in any pipe should be avoided when buried in screed not just plastic imho

 

[mylesy]

goes without saying i suppose, but you cant solder plastic lol

 

[dancinplumba]

if its only having water it the pipes, then use hep 20 or another brand of plastic barriered pipe as it doesnt react to the chemicals in the screed. also insulate them first with lagging then clip them down. laggin not only insultes the pipes but gives it room for slight expantion when covered in the screed and prevents cracking.

dont insult the pipe, wots it done to you ?? sorry mylesy couldnt help myself. no offence lol

 

[mylesy]

hahaha im rubbish at spelling, and worse when i have to type lol good call though haha

 

[wiggers]

Ive just laid pipework for my extension using john guest ive got to admit im not a lover of plastic pipe but it has it uses.
Laid 25m in 15mm speedfit in 22mm sleeve and my only joints are my radiator tails which i have made access boxes to replace fittings in the future and covered in 6mm plywood then laid floor on top, like others have said avoid copper try hep or john guest when using screeding

 

[Destroyer2813]

Seems somewhat ironic saying all plastic should be pipe in pipe systems when you then go and lay polyplumb under floor and then screed straight over it, when was it changed to stop using hairfelt just finished first fix with a mate covered all pipes with hairfelt going under screed. Oh poo

 

[Mike Jackson]

The water regulations came into effect in 1999.

 

[mylesy]

i dont think there is a problem with hair felt lagging?? i may be wrong, i just prefer tubular. and yeah your right with underfloor, still there are no joints in underfloor and at the edges of the room there should be a foam gap to allow for expansion of the screed. usually it all comes with the spec anyway.

 

[TGor]

Sorry but there is a problem with hair felt lagging on copper pipes .. the hairfelt when damp can generate ammonia which will cause copper pipe to corrode in rapid time. you might find this link useful.

[DLMURL]http://www.kembla.com/assets/Uploads/general-PDFs/The-Plumbers-Handbook.pdf[/DLMURL]

 

[mylesy]

hate to point out that link is austrailian lol interesting though, i didnt know that.

 

[TGor]

I am aware its Australian .. I wrote the first edition!

 

[mylesy]

well in the UK i tend to look for the tell tail WRAS approved, but thank you anyway for your knowledge. is always nice when information can be passed on in here without the air of arrogance. thanks again.

 

[mylesy]

if the reason you say not to use hair felt because of the cupric-ammonium complex ion being formed because of ammonia being present as a result of decay of organisms in the hair felt then, 5 factors are needed to cause cracking of the pipe. water, oxygen, tensile strength, metal that is susceptable and ammonia. And oxygen is the main 'ingrediant'! this ammonial reaction effect mostly copper alloys, such as brass are most 'suseptable' copper on its own has low to very low reaction to ammonial corrosion. also if the pipes are screeded where is the oxygen to assist in this process? is there ammonia in wras approved felt lagging and if your still in doubt (and still want to use copper instead of plastic) couldnt you pre protect the pipe as im sure most would anyway with duct tape or something. then lagg it. all in all id say its a low chance in these circumsatnces. but thank you for your point, iv found it very interesting researching your oppinion, it does happen, which i didnt know before. thanks again

 

[TGor]

Probably worth a bit of background on this seeing as you are interested enough to reseach it (ain't google great!!) .. It was a practice some years ago in oz to run pipes in the floor slab from point to point, usually (but not always), without joints, it was common also to use a hairfelt lagging to wrap the pipes and some this of was factory applied and had a thin poly overwrap for protection (which didn't last 5 minutes on-site or in the truck). There were many instances of pipes leaking after only 18 months and the cost to owners was, in some buildings astronomical. The presence of ammonia was detected in many of the cases that were dug out and tested & it was determined that the culprit was the hairfelt lagging. So to answer your point about the conditions. There will be water in the screed .. it will soak into the hairfelt however you wrap it there probably enough moisture in it before you wrap it!! .. Oxygen .. yes all around between the fibres. Tensile stress .. if you're research was referring to corrosion fatigue I agree brass alloys particularly 60-40 are more susceptible to ammonia attack the tensile stress can come from movement of the pipe both thermal or pressure expansion/contraction. But it is the practice (and regs) to use brass waste pipes instead of copper for urinals .. go figure!! Tensile stress is inherent in the manufacture of copper tube even if annealed (there is an argument that annealed is more susceptible than HD because the grain size is larger) Anyway the mechanism of failure whether it be corrosion fatigue or pitting corrosion is greatly accelerated by the presence of ammonia .. There is a risk that hair felt lagging can generate ammonia.. thus imho the 2 things do not go together.
(which was the original question by sanke)

 

[mylesy]

very interesting!! funny point about urinals haha (ammonia paradise lol) after hearing and learning about this from you i will pass it on. i personnally use the tubular foam (i dont get itchy of it more than anything lol) i would always also, duct tape any pipe (well copper anyway) if it was going anywhere near chemicals, like screed. this is me personnally. most people i talk to do the same, however you never know. but i will pass your knowledge more over though, when it comes to lagging (with hair felt) in an attic. i feel from what iv read that this would be very vunerable to the conditions causing ammonial corrosion. it has dampness (maybe, but more than screed) supply of oxygen, and a lot of pipes are lagged with hairfelt in loft mainly i would say for ease of installation, as pipes are in funny positions ect. would you agree with that?? i maybe miss understanding it.

 

[mylesy]

by the way im on about conventional systems with cisterns and such in the attic.

 

[TGor]

I don't think there is any significant history of failures in the locations you mention with hairfelt lagging it's been used for years .. I believe this may be due to the fact that conditions in a loft will change significantly with the weather whereas in a screed or in concrete it will be more constant and not really have a chance to dry out.

 

[SafeGasInstall]

is it not densol tape any good

 

[mylesy]

denso is good, plus looking at tgor's chart for chemicals on copper, it says gasoline is A which is the same class as potable water. think denso is petrolium based, is that the same as gasoline? think it is anyway.