Gas pipe in cavity/void.

[GrahamM]

Looking for some feedback on this.

Doing some subby work for good ole SG.
At a standard boiler service today. Gas supply comes from meter at other side house and runs all way under floor to kitchen at other end of house. Runs up behind the plasterboard wall 1.5 m and out directly bellow boiler and onto gas connection.

SG quality engineer agreed was a grey area but argued a plaster board wall does not denote a cavity and I should let it go.

My argument is it is still a cavity(definition: hole, hollow place or space) and in absence of any definitive definition of cavity in this respect, should be treated as such.

 

[Billy Bob Bob]

Looking for some feedback on this.

Doing some subby work for good ole SG.
At a standard boiler service today. Gas supply comes from meter at other side house and runs all way under floor to kitchen at other end of house. Runs up behind the plasterboard wall 1.5 m and out directly bellow boiler and onto gas connection.

SG quality engineer agreed was a grey area but argued a plaster board wall does not denote a cavity and I should let it go.

My argument is it is still a cavity(definition: hole, hollow place or space) and in absence of any definitive definition of cavity in this respect, should be treated as such.

i would agree with you,if run in plasterboard it must be encased in building material dot and dab,carlite bonding etc and protected against corrosion if its not then its ncs,or the void requires ventilation

 

[Simon F]

extract from BS 6891 about ventilation requirements

Where ducts are continuous, ventilation can normally be achieved by the provision of openings sized in
accordance with Table 3 [see Figure 7a)]. Where the duct takes the form of an enclosure at each storey level,
ventilation is normally required at high level only in each storey [see Figure 7b)].
Table 3 — Free area of ventilation openings
Additional information is given in BS 8313.
Ducts having a small cross sectional area and volume (i.e. 0.01 m2 or less with a total volume of less than
0.1 m3) are considered to be adequately ventilated by adventitious means and no additional openings are
required.
Minor gas leakage is that which would remain undetected by normal gas tightness testing techniques (see
Clause 10). The level of ventilation is not intended to clear a major gas escape arising from damage or failure
of a gas pipe.
The normal minimum period of fire resistance of the duct is 30 min for buildings of not more than three
storeys. Further guidance on the fire resistance of buildings is given in the appropriate Building Regulations
[3, 4 and 5].
Cross sectional area of duct
m2
Minimum free area of each opening
m2
Not exceeding 0.01 0
0.01 and not exceeding 0.05 Cross sectional area of duct
0.05 and not exceeding 7.5 0.05
Exceeding 7.5 1/150 of the cross sectional area of duct

 

[AWheating]

it very hard to tell once its been boarded over if its been installed correctly. One way is to tap on board ontop of the pipe, it shoud sound solid due to being dabbed/sealed in.maybe note on paperwork that pipework is not visable for inspection.

 

[GrahamM]

it very hard to tell once its been boarded over if its been installed correctly. One way is to tap on board ontop of the pipe, it shoud sound solid due to being dabbed/sealed in.maybe note on paperwork that pipework is not visable for inspection.

In this particular instance the hole cut for gas pipe under boiler was just large enough to see that it did not appear to be enclosed in a channel as per BS6891 so could be potentially classified as AR, but without better sight of it I could not say 100%.
Good point about noting on paperwork.

 

[Leo21]

On my last acs I remember being told gas pipes are ok behind plasterboard, dry lining etc. the plasteres are supposed to use plaster to surround the pipe. Most of what I get taught gets forgotten, but I rember that bit very clearly.

 

[mountainman]

On my last acs I remember being told gas pipes are ok behind plasterboard, dry lining etc. the plasteres are supposed to use plaster to surround the pipe. Most of what I get taught gets forgotten, but I rember that bit very clearly.

I think that you are mistaken, it is the GSR's responsibility to duct the pipe correctly.

 

[tamz]

That is true but in reality never happens. It would mean you had to sit and watch the dry liner doing his job.

 

[AWheating]

i agree with tamz, most new build will workout that the engineer will rely on the boarder to dab the length of the pipe. This is not ideal but i dont know anybody who would pay you to watch somebody boarding a wall. Some builders like for example Lovell will get you to channel the blockwork cement in the pipe and steel plate it up but of course this is extra costs and can only be done to certain depths/in non hollow blocks.

 

[mountainman]

I would duct and ventilate it in accordance with the regs, how could I rely on a dot 'n dabber to to understand and comply with gas regs?

 

[AWheating]

you could not duct and vent on most breeze walls due to depths, you will need to fix to blocks and encase or channel in,encase and plate you would just have to do the work yourself to make sure its done correctly, but you will find tho that most new builds its left to the boarder..... why? because of cost.

From my experience you will get £20 to £40 to first fix a gas carcus on most new build contracts when subbying or working direct for a company. You will get the pipe and fittings and thats it. no s+c or dab nevermind steel plates or ducting. Its a common argument on site over who is responsible for this work, its offten left by all trades which is why you get situations like graham has where its not done. Im not agreeing its a good method but its what tends to be the norm sadly.

On Wimpy Home contracts it was offten included into the platering companies agreed work to correcty dab in the gas pipework and if it was missed they would be made to strip the wall and recover correctly for free.

as regards other trades and gas regs i tend to agree in this situation but generally all trades have to understand other trades regs to do there job correctly and in the eyes of the law im betting the plaster would hold some blame? who knows.

 

[mountainman]

Makes me glad I don't do new builds I suppose.
Old and cantankerous nowadays I suppose.

 

[buckley plumb]

always thought it was ok as long as it was encased in with timber but just took refresher and told gas pipes in a stud wall is a no no

ant

 

[GrahamM]

always thought it was ok as long as it was encased in with timber but just took refresher and told gas pipes in a stud wall is a no no

ant

BS6891 does say it can be enclosed in a tight fitting timber stud channel behind the plasterboard or fully encased in building material; but how can you know if this is carried out as per standard if you cannot see it behind the wall?
My bet is most are just running in an open cavity.

 

[tamz]

always thought it was ok as long as it was encased in with timber but just took refresher and told gas pipes in a stud wall is a no no

ant

The guy who gave you the refresher needs to read up on what he preaches.

My bet is most are just running in an open cavity.

Probably are.

 

[peteheat]

A very rough quote from I.S. 813 (Irish gas regs)

"In the case of pipework installed behind dry lining only steel pipe and fittings suitably protected from corrosion may be used for horizontal or vertical runs where the existence of the pipe will not be apparent (such as pipe runs from one floor to another). Pipes behind dry lining do not of themselves require ventilation."

As most if not all of our regs are copied from the UK regs I expect that you will find similar applies to you, one solution I was allowed on a job was to run the copper pipe inside a length of G.B. (sleeved).

Mods please note:

Not sure if I should have been able to post here, is this for Gas Safe only?

 

[tamz]

Believe it or not the gas safe registered plumbers forum is viewable by anyone afaik. How cool is that if you are not gsr !!!

 

[peteheat]

Believe it or not the gas safe registered plumbers forum is viewable by anyone afaik. How cool is that if you are not gsr !!!

I am qualified for gas in Ireland so I can't do any harm here, just wondering if we can see the posts because we use the Arms?

 

[Hybrid]

If I run a gas pipe up a block wall and someone has boarded over it then the plasterer has caused my work to contravene regs, not me.

 

[Leo21]

As said above, there no way of checking for correct installation in most cases. If it tests up sound and you can't physically check it, I personally don't worry about it. It's not practical to check and I'm pretty sure a court of law would agree.

 

[peteheat]

I wouldn't be too sure about anything a court would agree to especially in my case as the installation standard is covered in the regulations, I think I would have to show (prove) that I did everything to ensure the regulations were adhered to.

The dangers they are covering are someone driving a nail into the gas pipe, it could be a carpenter on site or a householder hanging a picture or mirror in 20 years, if they hit a plaster blob they might think they have just found good grounds and before they know it they have gas escaping.

 

[Leo21]

Can't disagree, but reasonable precautions surely wouldn't involve chopping out and wrecking customers decor.

 

[peteheat]

Can't disagree, but reasonable precautions surely wouldn't involve chopping out and wrecking customers decor.

I agree a tough one to find the right answer without leaving yourself exposed.

 

[AWheating]

I agree a tough one to find the right answer without leaving yourself exposed.

carry a fig leaf in the van just in case

 

[johnnyplumb]

As said above, there no way of checking for correct installation in most cases. If it tests up sound and you can't physically check it, I personally don't worry about it. It's not practical to check and I'm pretty sure a court of law would agree.

seen these in aldi a few days ago, might be handy for situations like this.
ALDI - Sunday Special Buys 26th August 2012