Supporting pipes under floorboards + insulation

[kasser]

Hi,
How do I support with clips pipes run under a floating timber ground floor? The joists are too small to notch or drill into and in any case, there's plenty of space underneath. Where do you place the pipe clips if running perpendicular to the joists?
And if plastic pipes, this means lots of clips, every 300 mm for Speedfit! Lots of floorboards going up?
I've never had to do this yet.
Now I've got a job fitting central heating in a bungalow. Pipes could go under the wooden ground floor or over in the loft. Which route would you take? What insulation would you use? Finally, how do you fit the insulation snugly around with plastic pipe clips in the way?

 

[Brambles]

Attic and down for me, but I can see the benefits of going under the floor too. Being old, if I was going under the floor, I would pipe in copper - safer from a leaking perspective, longer lasting, less clipping and fewer floorboards to lift.

For the attic route, pipe in plastic, possibly with copper droppers

 

[Best]

Copper also for me. It will require very little support.
You could still use push fit fittings to the copper pipes if you wished so to avoid difficult soldering and fire risk.

 

[Burger]

You can get spacers for talon clips, that would give space to allow for insulation. Insulation doesn’t stop freezing, just which type depends on how long before it could freeze. Also I’d say up and over, if they ever fit a difficult floor (glued laminate) then if there’s an issue it’s harder to repair.

 

[kasser]

Do you fit the pipe clips on the bottom face of the joist facing the ground, when running pipes perpendicular? I've done it before for a gas pipe, not easy and it was just a couple of clips. I can't imagine having to do that every 300mm.
I would prefer to run it up and over but it does mean using more copper where the pipes are exposed, and more pipes generally.

 

[Burger]

Do you fit the pipe clips on the bottom face of the joist facing the ground, when running pipes perpendicular? I've done it before for a gas pipe, not easy and it was just a couple of clips. I can't imagine having to do that every 300mm.
I would prefer to run it up and over but it does mean using more copper where the pipes are exposed, and more pipes generally.

I can’t visualise what you mean, however you could use insulation around the pipe and use nail in clips, a bit harder to do, but achievable.

 

[kasser]

I can’t visualise what you mean, however you could use insulation around the pipe and use nail in clips, a bit harder to do, but achievable.

If the pipe runs across the joists, so underneath them, where do you fit the pipe clip? It'll have to be under the joists? So hanging off them in a way...

 

[Burger]

Ah I see what you mean now, I did try and envisage that, but was struggling. Depends on how much hammer room you have, use nail in ones, but I’d go with using copper so less spacing as opposed to every 300mm.

 

[kasser]

You can't wrap insulation around if you use the nail clips?
Copper more expensive 🙁
As the pipe won't be seen, plastic would have been ideal.

 

[Burger]

You can't wrap insulation around if you use the nail clips?
Copper more expensive 🙁
As the pipe won't be seen, plastic would have been ideal.

Do it before nailing and nail afterwards if possible?

 

[kasser]

I doubt the nail clip with fit over and around the insulation that's over the pipe.

 

[Burger]

I doubt the nail clip with fit over and around the insulation that's over the pipe.

It depends, I have managed to insulate plastic in a loft and carefully clip 15mm nail in clip. Just push hard until the clip sinks into insulation, then hammer home. 🙂

 

[Millsy 82]

Lag the pipe with thick climaflex then strap band to the joists.

 

[kasser]

Sounds good. Something like this:
Galvanised Perforated Banding

What minimum thickness do you recommend for climaflex?

 

[Millsy 82]

Sounds good. Something like this:
Galvanised Perforated Banding

What minimum thickness do you recommend for climaflex?

That's the stuff and I use 19mm wall under the floors. It's a pain to work with but it is quite firm so will protect the pipe from the banding.

 

[Jerry]

Is there a crawl space under the floor?

 

[kasser]

Yes, but I don't fancy crawling there!

 

[Jerry]

Yes, but I don't fancy crawling there!

Its character building

 

[Millsy 82]

Is there a crawl space under the floor?

I hate doing that.

 

[kasser]

I hate doing that.

Do you have to?

 

[Millsy 82]

Every now and then if there is enough room. Sometimes it's just easier to do that then lift all the boards.

 

[Last Plumber]

My advice:-
Crawl under the floor, use Copper and clip every 3 foot (roughly). Solder the joints, watch your face and eyes for molten solder and your ear holes and nasal passages for the odd spider who might be a tad nosy......... some will stare at you like this

and some will have no fear and ask who you are and what you want.

I had an apprentice with me a while back and I was surprised at how things have changed on the health and safety front (maybe they haven't but now they get drilled with it a lot longer than we did back in 1800 and frozen to death). Anyway, here is a bit of the type of advice he would have given!!

Mains power off, use battery lamps, observe all the panic and fear over confined spaces, fill a risk assessment form in, take a suitable fire extinguisher with you and mobile phone, tie a rope around your ankles and the hatch, make sure there is someone else in the building who knows you are under there etc etc, can't really remember much else he said because I was too busy crawling under the floor to get on with it.

Lagging:-
Foam and stand off clips is best in my opinion.

Who remembers Hair felt? that used to be popular didn't it? For those who do not, it was highly flammable and very dusty/hairy to work with. You could come out looking like Chewbacca after an hour or two under there wrapping pipes with that.

 

[ShaunCorbs]

Screw to the side of the floor joists ?

 

[kasser]

What did you do with the risk assessment form???
I understand how the strap band works with the insulation-wrapped pipe. But how do you clip a pipe with insulation around? You'll have to remove a small piece to allow for the pipe clip?
Someone needs to invent a long flexible support you can slide under the floorboard, screw to the joists at each end and then slide the pipes onto it. Job done. Basically doing the job of the plasterboard ceiling supporting the pipes that you run under the first floor.

 

[kasser]

Screw to the side of the floor joists ?

Only if the pipe runs parallel to it.

 

[ShaunCorbs]

Only if the pipe runs parallel to it.

Screw a piece of 2x2 if it’s perpendicular

 

[ShaunCorbs]

What did you do with the risk assessment form???
I understand how the strap band works with the insulation-wrapped pipe. But how do you clip a pipe with insulation around? You'll have to remove a small piece to allow for the pipe clip?
Someone needs to invent a long flexible support you can slide under the floorboard, screw to the joists at each end and then slide the pipes onto it. Job done. Basically doing the job of the plasterboard ceiling supporting the pipes that you run under the first floor.

You mean like this ?

Britclips® Rapid Sliding Wall Bracket

 

[kasser]

Screw a piece of 2x2 if it’s perpendicular

If it's plastic I'll have to do it every 300 mm. It seems there's no other way round screwing something every 300 mm whatever support method I choose.

 

[Last Plumber]

What did you do with the risk assessment form???

I can only tell you he didn't like it.

You'll manage OK with it, trust me I'm a Plumber.
The foam lagging will fit around the pipe from beneath and kind of envelope the clips, depending of course on the thickness of the foam. If it is too thick then as you already said, you'll need to nip a bit out.

 

[ShaunCorbs]

If it's plastic I'll have to do it every 300 mm. It seems there's no other way round screwing something every 300 mm whatever support method I choose.

Use mlcp then 😀

 

[Last Plumber]

The job is best done from under the floor otherwise you'll be moving furniture as well as lifting floorboards and carpets everywhere. If you go under, you can have it done.

 

[Last Plumber]

If it's plastic I'll have to do it every 300 mm. It seems there's no other way round screwing something every 300 mm whatever support method I choose.

That's one of the reasons Copper is better.

 

[kasser]

More like this:
https://www.NoLinkingToThis/p/talon...VrZPtCh00uwdAEAQYBCABEgKobfD_BwE&gclsrc=aw.ds
but much bigger and wider to accomodate insulated pipes. You screw slide it 3, 5, 10 metres long below the joists, perpendicular to them, screw it in a few places to hold it then slide all your pipes into it.

 

[kasser]

That's one of the reasons Copper is better.

Yes, I may consider copper then despite the price, if I can finish the job sooner.

 

[ShaunCorbs]

More like this:
https://www.NoLinkingToThis/p/talon...VrZPtCh00uwdAEAQYBCABEgKobfD_BwE&gclsrc=aw.ds
but much bigger and wider to accomodate insulated pipes. You screw slide it 3, 5, 10 metres long below the joists, perpendicular to them, screw it in a few places to hold it then slide all your pipes into it.

Use some 100 x 25mm trunking then elec fact should have that

 

[Last Plumber]

Yes, I may consider copper then despite the price, if I can finish the job sooner.

How new to this are you if you don't mind me asking? Is it just the going under that bothers you or the whole thing?

 

[kasser]

Use mlcp then 😀

what's that?

 

[kasser]

Use some 100 x 25mm trunking then elec fact should have that

So expensive. I'd better go under then!

 

[ShaunCorbs]

 

[kasser]

I'm fairly new, thus why I've never encountered a fairly common situation like this before. But I usually encounter situations where I get to run pipes within the first floor. This one is full central heating for a bungalow. About 16 rads. I'm just trying to find a way to run, insulate and clip all these pipes under the floor boards quickly. It's a shame that I may end up using copper out of sight when I could run plastic instead.

Pipes run in the loft means a lot of exposed pipework when dropping down, not as neat as pipes coming up through the floor.

 

[kasser]

There's no furniture or flooring anywhere in the house. Full access everywhere.

 

[ShaunCorbs]

How big are the joists depth ?

 

[Last Plumber]

Well if you prefer, why not go under with a battery drill and screw plastic stand off (wrap over) clips to the underside of each joist and use the plastic push fit stuff?
I personally don't like it but I am old fashioned and like you say, no-one will see it.

Apart from the next Plumber of course!

Have you sorted all your pipe sizing for the circuit?

 

[Burger]

Yes, I may consider copper then despite the price, if I can finish the job sooner.

Probably quicker than speedfit with all that 300mm clipping business 😀

 

[Burger]

It's a shame that I may end up using copper out of sight when I could run plastic instead.

It is a shame, but copper was out long before plastic, and see loads in lofts in the properties I work in, it’s all they used. You need to weigh up the difference, I’m sure there’s not much in it and you’ll be fitting copper - welcome to OldSkool 😀😀😀

 

[Aire]

Who remembers Hair felt? that used to be popular didn't it? For those who do not, it was highly flammable and very dusty/hairy to work with. You could come out looking like Chewbacca after an hour or two under there wrapping pipes with that.

I remember that stuff, caught some under a crawl space. Went up like a bonfire, first time I'd had to use an extinguisher on the job. Many spiders died that day 😀

 

[Last Plumber]

I remember that stuff, caught some under a crawl space. Went up like a bonfire, first time I'd had to use an extinguisher on the job. Many spiders died that day 😀

Oh the panic!!! .....It happened to me. Never moved as fast I don't think.

 

[Aire]

Oh the panic!!! ...It happened to me. Never moved as fast I don't think.

Certainly gives the heart a good exercise.

 

[Last Plumber]

Certainly gives the heart a good exercise.

Yes.
This is all bringing back memories. I had a mate who was under a floor and need to take a rest after crawling about so he hunched himself up onto his elbows and put his head up between the joists. As he leaned his head back to rest it on the side of the joist behind and it touched one of the old lead cables which was obviously leaking to earth. It gave him a fair crack and as his head flew forward his forehead hit a brad in the joist in front, lol...... Great days !

 

[kasser]

I'm not one of those who are all copper and no plastic or vice versa. I just choose whatever is best for the job. Usually plastic wins based on price if it's going to be out of sight. Here plastic seemed ideal at first glance, going under the floor, but with all the pipe clipping, going down the copper route may save me time.

I'll have to run a gas pipe from one end of the house to another, so will be using copper under the floor anyway.

I didn't check joist depth as I didn't consider notching or drilling them.

 

[kasser]

I was just wondering - combi boiler will be in the bathroom in one corner of the house and the kitchen in the opposite far, far corner. It will take ages for the hot water to reach the kitchen.

I don't think there's a way around this with a combi? The distance is what it is and there's no cylinder to run a return leg for the hot water.

 

[Aire]

Yes.
This is all bringing back memories. I had a mate who was under a floor and need to take a rest after crawling about so he hunched himself up onto his elbows and put his head up between the joists. As he leaned his head back to rest it on the side of the joist behind and it touched one of the old lead cables which was obviously leaking to earth. It gave him a fair crack and as his head flew forward his forehead hit a brad in the joist in front, lol.... Great days !

I'm laughing just imagining that. It's always funny when your colleagues hurt themsleves, some of my best laughs at work have been at the expense of others 😀

 

[Last Plumber]

I was just wondering - combi boiler will be in the bathroom in one corner of the house and the kitchen in the opposite far, far corner. It will take ages for the hot water to reach the kitchen.

I don't think there's a way around this with a combi? The distance is what it is and there's no cylinder to run a return leg for the hot water.

Use the shortest route possible beneath the floor in 15mm and lagg it well. You probably thought that anyway?
That's all you can do really. Try it, you might be surprised how well it works.

 

[Burger]

Yes.
This is all bringing back memories. I had a mate who was under a floor and need to take a rest after crawling about so he hunched himself up onto his elbows and put his head up between the joists. As he leaned his head back to rest it on the side of the joist behind and it touched one of the old lead cables which was obviously leaking to earth. It gave him a fair crack and as his head flew forward his forehead hit a brad in the joist in front, lol.... Great days !

I bet that never made the accident book 😉

 

[Last Plumber]

I bet that never made the accident book 😉

No, it just made two thuds and everyone laugh!

 

[kasser]

Yes, I'll use the shortest route of course, saves me on piping too.
But I was briefly considering running the pipe in 22mm due to the distance. however, the initial pressure and flow rate at the meter is very high, so losses will be acceptable. And a 22mm pipe I realise now will have too much cold water sitting in it. Maybe run it in 8 mm 🙂.

 

[Last Plumber]

Yes, I'll use the shortest route of course, saves me on piping too.
But I was briefly considering running the pipe in 22mm due to the distance. however, the initial pressure and flow rate at the meter is very high, so losses will be acceptable. And a 22mm pipe I realise now will have too much cold water sitting in it. Maybe run it in 8 mm 🙂.

I would stick to 15mm personally.

 

[Burger]

Yes, I'll use the shortest route of course, saves me on piping too.
But I was briefly considering running the pipe in 22mm due to the distance. however, the initial pressure and flow rate at the meter is very high, so losses will be acceptable. And a 22mm pipe I realise now will have too much cold water sitting in it. Maybe run it in 8 mm 🙂.

Most are ran in 15mm, just go with the MI’s.

 

[kasser]

I agree with 15mm. There'll be just one hot water pipe in the kitchen anyway.

 

[Burger]

How big is this bungalow? 16 rads? did you mean 6?

 

[kasser]

4 bedrooms, 2 living rooms, conservatory, office, en-suite, etc. I was surprised at the number of rads too.

 

[Jerry]

No way I am lying on my back soldering pipes above my head. Plastic all the way.

If i am running perpendicular to the joist i will drill. I make up a drilling template from cardboard (for depth of wood and space between pipes) and a laser level to keep everyhting straight.

If i cannot drill when running perpendicular, then i will use Talon pipe clips with spacers and a laser again. I find an impact driver is small and quick in tight spaces. I also make up all the pipe clips before starting.

If i am running parallel, then i use Talan pipe clips on the inside of the joists or if their is not enough room, then a cheeky batternscrewed to the underside of the joists.

People are moaning about the spacing for plastic pipes. I generally add way more, especially at bends. Plastic pipe can be arguementative and needs to be wrestled into place frequesntly and the additional clips help.

As for insulation, i generally go with cheap 9mm wall. Each section is cut in between clips. If its in an area where there could be high heat loss, then i cover the expsoed clips with more insulation. Insualtion on show gets the treatment from my new pipe lagger pro cutter thingy.

 

[kasser]

People are moaning about the spacing for plastic pipes. I generally add way more, especially at bends.

Try adding way more when screwing the clips under the joists! Not easy.

You could use straight 3m of plastic pipes. Easier to work with and not much more expensive, though if you need long runs, you'll need to join them which defeats a little the advantage of using plastic.

Shouldn't your pipes in the pic be spaced further apart? 3 times hole diameter?

 

[ShaunCorbs]

Try adding way more when screwing the clips under the joists! Not easy.

You could use straight 3m of plastic pipes. Easier to work with and not much more expensive, though if you need long runs, you'll need to join them which defeats a little the advantage of using plastic.

Shouldn't your pipes in the pic be spaced further apart? 3 times hole diameter?

Correct

 

[Jerry]

I knew you guys would see that! Well spotted!

Yep, the pipes were not in my first choice location. The client refused to let me space them out. I have no idea why.

Truthfully, I can find it very hard to meet the drilling and notching regs. Especially when you are coming across old joists that have been ravaged by previous trades.

 

[ShaunCorbs]

I knew you guys would see that! Well spotted!

Yep, the pipes were not in my first choice location. The client refused to let me space them out. I have no idea why.

Truthfully, I can find it very hard to meet the drilling and notching regs. Especially when you are coming across old joists that have been ravaged by previous trades.

Especially sparkles

 

[Jerry]

Especially sparkles

Are they like twinkles? but with more glitter and unicorns?

 

[ShaunCorbs]

Are they like twinkles? but with more glitter and unicorns?

😀 sparkies

 

[gmartine]

I've used stainless cable ties and mounts for securing heavily insulated pipe in awkward places before ... rock solid and insulate to your heart's content. A bit overkill and made for cable but it's the business.

 

[Aire]

I knew you guys would see that! Well spotted!

Yep, the pipes were not in my first choice location. The client refused to let me space them out. I have no idea why.

Truthfully, I can find it very hard to meet the drilling and notching regs. Especially when you are coming across old joists that have been ravaged by previous trades.

I wasn't aware you could go against building regs because the customer says so. I'll remember that next time I'm asked to flue the boiler out the window because they don't want a new hole drilling 😛😀

 

[sailesh]

Hi folks - nice to join this forum and I wish I'd done so earlier. Some urgent advice needed please..

Our plumber has had to repipe the central heating in our Victorian house because the existing system was single pipe. He has done this using plastic pipe and push fittings. The first time we turned the heating on, the ground floor system leaked into the underfloor void at a sagging 90 degree joint that sits in the middle of circa 4 metres of unsupported pipe. I've attached a video which shows exactly what this looks like..

I'm not convinced by his argument that the pipes don't need any support and only the fitting is at fault, so to save me the roundabout discussion could anyone please point me to the relevant guidance that defines how much sag is acceptable and what the support criteria is or isn't for 22mm plastic pipe?

 

[ShaunCorbs]

Needs clips every meter and lagging

 

[gmartine]

Hi folks - nice to join this forum and I wish I'd done so earlier. Some urgent advice needed please..

Our plumber has had to repipe the central heating in our Victorian house because the existing system was single pipe. He has done this using plastic pipe and push fittings. The first time we turned the heating on, the ground floor system leaked into the underfloor void at a sagging 90 degree joint that sits in the middle of circa 4 metres of unsupported pipe. I've attached a video which shows exactly what this looks like..

I'm not convinced by his argument that the pipes d5on't need any support and only the fitting is at fault, so to save me the roundabout discussion could anyone please point me to the relevant guidance that defines how much sag is acceptable and what the support criteria is or isn't for 22mm plastic pipe?

No sag is acceptable the lazy scrot, should be clipped every 0.5m minimum for horizontal run in 22mm.

See page 19.

https://www.johnguest.com/wp-content/uploads/2019/08/RWC-JG-Speedfit-Technical-Specs-Guide.pdf

 

[exedon2]

Polypipe exactly the same 500mm horizontal 15mm every 300mm

 

[gmartine]

...and btw the fitting isn't necessary leaking because it's faulty. It's more likely to be leaking because the pipe isn't properly seated and or the fitting is under stress because of the lack of support.

 

[sailesh]

Needs clips every meter and lagging

agreed about the lagging -

No sag is acceptable the lazy scrot, should be clipped every 0.5m minimum for horizontal run in 22mm.

See page 19.

https://www.johnguest.com/wp-content/uploads/2019/08/RWC-JG-Speedfit-Technical-Specs-Guide.pdf

Perfect, thanks! I’m using a registered gas engineer so never expected this 🙁

Besides the manufacturer‘s spec, what / where are the building or other regs that installers should be following?

also, from a trade perspective, what is a customer’s recourse when work doesn’t meet regs or standard? It strikes me that a lot of work could / should be checked by an independent, or at least recorded as proof of continuing competence.
[automerge]1604740603[/automerge]

...and btw the fitting isn't necessary leaking because it's faulty. It's more likely to be leaking because the pipe isn't properly seated and or the fitting is under stress because of the lack of support.

totally agreed, and also, no idea how my plumber expects to be able to drain the ground floor.

it gets worse really as I removed the floorboards and can see that other (15mm) pipe is only supported by a partition wall and - no kidding - an electric cable.. see attached pic.

 

[exedon2]

No pipe lagging under a floor void big no needs insulating

 

[sailesh]

No pipe lagging under a floor void big no needs insulating

sorry, do you mean it does or does not?

The pipes are feeding three radiators, each 1.5kW, so I can see the case that at max demand the flow is high enough that piping heat loss is relatively low, but at lower flow does insulation make that much difference?

 

[exedon2]

Have a look at building regulations part L insulation is a necessity needed for thermal efficiency and for frost protection

 

[gmartine]

British Standards BS6700:2006
Design, installation, testing and maintenance of services supplying water for domestic use within buildings and their curtilages.

Maximum spacing of fixing for internal piping

PB or PEX pipe

clip spacing = horizontal/vertical

Up to 16mm diameter = 0.3m/0.5m
18 to 25mm diameter = 0.5m/0.8m