Flush-fitting Gas Meter Box

[Luke]

Hi all, Following on from my thread regarding gas boiler sizing, I now have a question about installing a gas meter box.

When I requested a quote for the provision of a new gas supply, I requested a flush-fitting meter box, which is recessed into the wall, so it doesn't protrude 25cm into the driveway. However, it requires a cutout 366mm W * 532mm H * 160mm D. If a flush-fitting box is specified, then this must be installed by the homeowner prior to the pipe being laid.

I am not fussed about the height element, but in hindsight I am concerned about cutting a hole 366mm wide in the brickwork, in case it has any structural ramifications. The wall is a cavity wall, brick construction both sides, with render on the outside.

Will I need to reinforce the hole over its span in any way? Or is this impossible to tell without consulting a structural engineer?

Thanks Luke

[Rick Hughes]

No need to reinforce ... normally they build in using the box to support brickwork until it sets ... in your case it is already set.

I would advise getting a thin TCT blade on an angle grinder and chop out mortar & cut bricks that way .... walloping about with lump hammer & chisel may crack adjoining mortar beds.

A 4" small grinder will be easiest to use .....

I set a date stone into my house this way.

[Tim Watts]

Luke wibbled on Tuesday 20 July 2010 11:44

Don't take my word for it, but I considered this for my electricity meter[1]:

My house is a cavity wall construction, with the roof and floor load onto the inner leaf.

The outer leaf only needs to support itself, not the entire house.

The "triangle principle" means that if you chop a hole in a brick wall, the most that can fall off is a triangular section of brickwork above the hole.

366mm wide isn't very wide in terms of house bricks. I'd have no problems cutting a hole like that in the outer leaf unsupported. However, I would cut the mortar joints 2" into either side of the hole level with the top of the opening and bang in a bit of flat 1/4" steel bar to support the brick or two that is at risk of falling off.

If I wanted to be belt and braces, I'd do the same, but with angle iron fed into the cavity and inserted from behind the top of the opening. Mortar steel in place. But I think flat bar would be more than good enough. It's what I did with my fireplace where the flat-arch was looking a bit dicey. I did put a slight bend in the bar by placing over a couple of bricks and jumping up and down on it - then it was was under load as soon as it went in.

[1] Until I found the shysters at EDF wanted 600-800 quid to move the cable, *if* I did all the digging for them.

Cheers

Tim

[Andrew Gabriel]

About 1 brick, in this case.

The steel will go rusty, and force the brickwork to split as it swells. You don't want it at all.

That's OK, as that wall should be dry.

[Tim Watts]

Andrew Gabriel wibbled on Tuesday 20 July 2010 13:11

Good point...

[Luke]

Thanks, that has put my mind at rest. I have both a 4" and a 9" grinder and was going to use the larger one, but yeah, the smaller one makes more sense.

Luke

[Rick Hughes]

just don't use standard carbide cutting disc, you need a TCT or even better a diamond blade ... only about a £5 for a 4" blade.

[ARWadsworth]

I'll have to look out for them. Does it happen often?

Adam

[js.b1]

Measure your wall thickness & cavity with a drill. Depending on house age if it needs 160mm from the outer leaf front face, you may find you would have to partly core-drill and breakout part of the inner leaf too (easier to use block and cut them thinner). If you do try to stick a lintel in the outer leaf, you would need to use stainless flat bar or angle which is too expensive unless salvaged.

You can get flush floor mounted gas meters, they use a different compact meter type.

[Mike Clarke]

The rear outlet is one of two possible ways of routing the pipe. Our box had a knockout for it with a label saying "Warning, do not remove unless outlet to be made using special spigot".

The alternative way is to drill a vertical hole through the bottom of the box frame outside the house wall and route the pipe down through that then in through a suitably lined hole through the wall. This maintains a gas-tight seal between the box and the cavity. That's the way National Grid did ours last year as shown in these photos:

[fred]

In article , ARWadsworth writes

Not often, I was hoping to post a link to pics of the Clarkston disaster of 1971 where 22 died and 100 were injured when a shopping centre was demolished by a gas explosion but as it was in a small burb of Glasgow it appears not to have made it to the major news sources.

I've got vivid memories of a few single house gas explosions over the years but who knows whether it was just a cavity wall full or a sewer, underfloor etc, etc full of gas. The common thread is residents complaining of strong smells of gas weeks & months before the explosion but leaks mysteriously not being found by BG/SG. One I'm sure involved a massive censure and fine for BG of about 0.00001% of their annual profits so I'm sure they've tightened their act up.

[ARWadsworth]

The gas explosion that I remember from some years ago was a story in the local rag. A semi had been demolished in a gas explosion and the next day BG were looking through the rubble. When a neighbour asked if they were investigating the explosion the reply was "No, I've come to find the meter so we can give a final reading"

No idea if the neighbour or the editor made the story up, but I liked it.

Cheers

Adam