Disaster with under-floor heating...

tails_naf

We're 6 months into our self-build, and a mini disaster has struck!

There is under-floor heating downstairs, all installed and pressure tested.

The weather had really slowed the build and the heating was not up and running before the cold weather struck - and sure enough the -10 temperatures ended up freezing the underfloor pipes.

I pressure tested a few of the loops this weekend, and none of the loops held the pressure, and after a few minutes I could see water seeping up through the floor. I did not check all loops - but I assume if a few are burst, all of them are likely to be. I also assume each loop may have burst in multiple locations - but there's no way to be sure.

I'm now faced with the dilemma - put in rads or rip up the floor and re-lay the underfloor pipe. I'd appreciate it if anyone here knows if it is possible to pull up a concrete floor (about 65 mil thick slab) - or if it is insanity to even consider it?

If anyone knows if the house-build insurance should cover this too? I contacted the insurance company, and even though the insurance was supposed to cover fire/flood/ and storms 'under the course of construction' they said it would not be covered as a storm is 'wind or rain'. I think I may have a case that storm should include all weather damage and maybe they are trying to put me off. Again, if anyone has any info in this area it would be greatly appreciated.

onq

There may indeed be a colloquial interpretation of floods and rain as constituting a storm, as opposed to a cold spell. See if there's any way this can be broadened out to include unusually inclement weather. Get someone with a legal background to check your contract wording.

In relation to the slab, and the UF installation it sounds like you'll have to replace it competely. Yes you can dig up a screed, lots of work with a kango or if the upper floor is still off you might work with a JCB through the opes. Failing this you could hire a mini digger and work within.

This assumes a 150mm min reinforced concrete slab under the UF installation + the screed you describe. Its likely that the insulation layer under the pipes will need to come up too and you will need to protect all routes the mini digger uses to get in and out to avoid damaging anything.

Precautionary stuff like keeping UF heating systems from freezing would normally be the resposibility of the main contractor. The same kind of issue arise if roofs aren't weather sealed or the windows are late arriving. Ih his stead the responsibilities for all these "extras" fall to you, the self-builder.

FWIW

ONQ.

tails_naf

no chance of getting a mini digger in - the second floor and roof is on.
Looks like a kango is the way to go. I really hope the insulation will survive, as it was quite expensive.

No main contractor to blame but myself - the house is timber frame, and all jobs were direct labour. I installed the under floor heating myself (not that difficult actually), but wish I had the foresight to protect the pipes during the cold!

Might try to take up a small section to see if it's worth pursuing.

ronboy

My heart goes out to you mate sorry to hear about it. The joys of building a house huh. I've had a few problems myself on my own build so I know where your coming from.
Whats the height of your ceilings??
I,m wondering could you relay pipes on top of your floor,cut away your existing pipes and join back into your existing manifold then pour about 40mm of concrete. Just my tuppence worth. Hope you get it sorted anyway

Poor Uncle Tom

Did your pipework have to be charged with water before pressure testing, could this not have been done with air? Anyway what's done is done.

You are building a new house anything short of removing and replacing the defective element will result in a makeshift solution and you will have to make compromises, not ideal in a new build, imo.

imitation

I would be considering rads in your shoes, unless the insurance came through, redoing it sounds like a very messy and expensive job. Sounds like a horrible situation to be in, best of luck with it

gizmo555

tails_naf wrote: »

If anyone knows if the house-build insurance should cover this too? I contacted the insurance company, and even though the insurance was supposed to cover fire/flood/ and storms 'under the course of construction' they said it would not be covered as a storm is 'wind or rain'. I think I may have a case that storm should include all weather damage and maybe they are trying to put me off. Again, if anyone has any info in this area it would be greatly appreciated.

Don't forget if you aren't happy with the insurance company's response, you have the right to take a complaint to the Financial Services Ombudsman. That process might take a few months though.

dunlopwellies

Maybe if the heating is on, there is hot water in the pipes you would be able to use a thermal imaging camera to identify and isolate the leaks on the individual loops. Not sure if this is an option for you but may be worth some consideration before ripping up whole floor.

My UFH supplier has a repair kit for such an incident, they suggest that the best way to find leaks is to first dry out the floor as much as possible and then turn on the loop and look carefully for the damp patch as it forms - if you're lucky the dampness will be directly over the leak!

tails_naf

Thanks everyone for the replies and commiserations!
The idea of laying it on top of the existing floor is a neat one - I'd have quite a thickness of concrete to heat up though - but it would be the most cost effective for sure - but the front door and patio doors and they are already fitted, and a higher floor would get in the way.

I was looking into the idea of using a heat camera too - but the one thing I don't know is - would the pipes burst once per loop (to relieve the pressure), or could they burst every few feet? If they are gone in loads of places, it would be just throwing more money away as it would be too difficult to repair hundreds of bursts. All I know is at least one loop has gone in more than one place - as I saw the water come up in at least 3 locations over where that loop was laid, over about a 3sq meter area.

For the loops I have tested, I can see the water come up in a matter of minutes. As I said one loop looks to have gone in a few places, but I only saw the water come up in small patches on the other loops.

I'll definitely talk to the insurance company again tomorrow. Talk of the ombudsman might encourage them take a closer look at the claim.

Thanks again for all the ideas. I'll keep you posted on how I get on!

onq

tails_naf wrote: »

no chance of getting a mini digger in - the second floor and roof is on.
Looks like a kango is the way to go. I really hope the insulation will survive, as it was quite expensive.

No main contractor to blame but myself - the house is timber frame, and all jobs were direct labour. I installed the under floor heating myself (not that difficult actually), but wish I had the foresight to protect the pipes during the cold!

Might try to take up a small section to see if it's worth pursuing.

I don't know what mini-digger you were considering, but our next door neighbour had a builder in who drove a mini digger and a mini skip through the house to work in the back garden. I'm sure you could do it too.

I only suggested the digger to make light work of taking up the scree/ufh pipes/ insulation - it's a lot of work for a kango and you'll run through several bits.

Couple of things - consider your internal stud work, particularly the load-bearing studs. If the UFH screed encloses them and they're not treated you'll need to open out the screed to let them dry out to prevent wet rot.

If they are treated you could take a chance, and if they are resting on the top of the damp screed you may also be okay.

Given the risk and grief involved if something like this happens, you'd think someone would develop a system using an anti-freeze mixture like a car to avoid bursts, per haps with some kind of liquid sealant as well to make it "self-healing" if there was a perforation for some other reason. There's no absolute barrier to preventing this being done is there? Is just materials technology.

I'm thinking of a cold spell with a prolonged power outage, where the system could freeze regardless, because people would have to evacuate the house in such a situation. There's a good business idea for someone! Off you go a make a million - only on condition I'll have 1% of the profits as the inventor - ta. :cool:

ONQ.

onq

onq wrote: »

Given the risk and grief involved if something like this happens, you'd think someone would develop a system using an anti-freeze mixture like a car to avoid bursts, per haps with some kind of liquid sealant as well to make it "self-healing" if there was a perforation for some other reason. There's no absolute barrier to preventing this being done is there? Is just materials technology.

I'm thinking of a cold spell with a prolonged power outage, where the system could freeze regardless, because people would have to evacuate the house in such a situation. There's a good business idea for someone! Off you go a make a million - only on condition I'll have 1% of the profits as the inventor - ta. :cool:

ONQ.

Drifting OT a bit, you have a point there - what if the house was unoccupied for an extended period and during a very severe winter, most UFH systems are almost impossible to drain as the manifolds are almost always above the floor. Anti freeze would be the only practical solution.

ninjaBob

I fear I might be in the same boat here, will have to wait and see as the heat goes on this week.

tails_naf

I'd imagine anti-freeze could be mixed in seeing as it's a closed loop. I know they put glycol in solar systems for that very purpose. The chances of it happening for a up and running underfloor system is slim, but when it happens, ouch.

I contacted the UFH supplier this morning - they had said they never heard it happening before, but I explained the testing I'd done and they were satisfied that it's goosed and would have to come up. They recommended against trying to repair - as the pipe would have expanded everywhere (but maybe only burst in a few locations) - but overall it would be weakened.

I hope it goes well for you ninjaBob - but might be no harm in getting the plumber to re-pressure test, as just having the heat on at low operating pressure might now show up the problem right away - and lull you into a false sense that it's ok.

My intention is to use a con-saw to cut about 2 inches away from the exisiting walls - and take up the floor in-between. This will leave the studs untouched and there are no pipes laid that close to the walls anyway. Will also give a good 'guide' for the new finished floor level when it is re-poured

Just called the insurance company - this time they said they would send out a claims assessor - definitely a more positive result.

onq

Deleted User wrote: »

Drifting OT a bit, you have a point there - what if the house was unoccupied for an extended period and during a very severe winter, most UFH systems are almost impossible to drain as the manifolds are almost always above the floor. Anti freeze would be the only practical solution.

"Disaster with under-floor heating" and we're talking about foreseeable problem scenarios and possible remedies - I fail to see where that's OT.



ONQ.

onq

tails_naf wrote: »

My intention is to use a con-saw to cut about 2 inches away from the exisiting walls - and take up the floor in-between.

You may be left with a dodgy joint and leaving the edge will tend to prevent the stops from drying out properly if they're affected. Unless the studs are resting on the UFH screed, I'd say you should break the lot out.

Assuming the studs are off the Floor Slab proper and the installation was done correctly, you should be seeing insulation turned up all around the edges of each room floor plate - it'll all come away.

ONQ.

tails_naf

Sorry for my ignorance - but what do you mean about the stops not drying out properly?

The studs are not sitting on the screed - thankfully all the internal walls have blocks supporting them in the foundation.

Each room was insulated around the edges too with the perimeter strips - so it would be possible to break the screed right up to to each wall - I just thought it was unnecessary to break away parts that have no pipes in them - but if you think it would make a poor job I'll take out all the screed, right up to the walls.

Just Bob

Really sorry to hear about this.

Just a variation of an idea that doesn't seem to be mentioned above, if you have the height in the ceilings could you use use a liquid screed on top of the existing floor and put the underfloor heating in this. I stand to be corrected but you need a must less of depth (think 50mm will suit) and this will be easy poured even though you have the rest of the house built.

tails_naf

I heard of another idea from a buider - kind of a hybrid of the ideas given here and I wanted to pitch it to you to see what you folks think -
- hire a chasing saw to cut 1 inch grooves in the existing slab where I will lay the new under-floor pipe
- lay new piping in these grooves (leave old piping where it is deeper in the slab)
- pour 1 inch completely over the top - maybe use the screedflow material. Will thicken the total slab from 65mm to 90mm.

The only thing that could catch me would be the front door, but I think we have the height. Any opinions on if this is a good idea?

The studs would then be encased in this screedflow material - but should dry out.

onq

tails_naf wrote: »

Sorry for my ignorance - but what do you mean about the stops not drying out properly?

Sorry tails_naf, for "stops" read "studs"

The studs are not sitting on the screed - thankfully all the internal walls have blocks supporting them in the foundation.

I was trying to visualise whether or not the they were on the screed or if UFH screed covered the sides of the studs, but this may be a moot point.
If the UFH screed is laid on insulation and this is turned up at the sides and has kept the water away from the studs then they should be okay.
I'd need to see the detail to comment.

Each room was insulated around the edges too with the perimeter strips - so it would be possible to break the screed right up to to each wall - I just thought it was unnecessary to break away parts that have no pipes in them - but if you think it would make a poor job I'll take out all the screed, right up to the walls.

If the insulation has prevented water getting at the studs and affecting the plasterboard you could be okay. Otherwise you'll have to remove the affected areas of plasterboard and let the studs dry out. Similarly for the UFH insulation if that's been affected, but pulling up the screed may damage it anyway.

Sounds like you need six sets of gear, a portable genny and invitations sent out to a Self-builders Kango Party.
You know, like people hold Painting Parties after they've moved into their new home.
With the apropriate Health and Safety briefing before you start, natch.
Could start a new dance craze!



ONQ.

Joey the lips

imitation wrote: »

I would be considering rads in your shoes, unless the insurance came through, redoing it sounds like a very messy and expensive job. Sounds like a horrible situation to be in, best of luck with it

agree. Freezing pipes like this has always been my reason for justifying glycol in the pipes to prevent it. But I dont think boiler manufacturs stand over it.

Joey the lips

Joey the lips wrote: »

agree. Freezing pipes like this has always been my reason for justifying glycol in the pipes to prevent it. But I dont think boiler manufacturs stand over it.

Shouldn't be an issue, most UFH systems are fed from a buffer tank.

tails_naf

tails_naf wrote: »

I heard of another idea from a buider - kind of a hybrid of the ideas given here and I wanted to pitch it to you to see what you folks think -
- hire a chasing saw to cut 1 inch grooves in the existing slab where I will lay the new under-floor pipe
- lay new piping in these grooves (leave old piping where it is deeper in the slab)
- pour 1 inch completely over the top - maybe use the screedflow material. Will thicken the total slab from 65mm to 90mm.

The only thing that could catch me would be the front door, but I think we have the height. Any opinions on if this is a good idea?

The studs would then be encased in this screedflow material - but should dry out.

Sounds like a good idea, may be time consuming they arn't exactly the fastest things in the world. You'll need to use a bonding agent otherwise the new screed may flake away from the original.

Rather than doing grooves why not use a scabbler and remove an inch and relay the pipework from there.

tails_naf

Thanks for the clarification onq - there is perimeter insulation all around, so the studs are mostly dry - but over the course of the build some of the studs have gotten a little water - I'm sure once the heating is (eventually) on they will dry out. I have HRV installed too, so once the house is sealed the humidity should be taken out.

I'd never heard of scabbling until now - just looked it up - sounds like a good idea - a machine designed to remove a layer of concrete - except it seems to do it in very shallow amounts - would it be a huge amount of work to remove a 1inch wide 1inch deep trench with one of these machines?

As for bonding agent - I think I'll run this by the screedflow flolks to see if it is needed. There certainly is a lot of excellent advice here on boards - you guys have brought up a number of things I'd never have thought about, and could have bit me down the road!

Niall Keane

UFH can work with a peat based screed with depths of 35mm I believe? This takes longer to dry out from memory. Could something like this work on top of the existing, and overcome the door problems? As the insulation is below the 75mm screed, that section would act as a thermal mass, absorbing heat but then letting it seep back into the house when it's off. So the overall effect might not be as bad as you think. I'm sure there's a green calc that could be carried out by certain universities that would recommend the approach?

sunnysoutheast

Sorry to hear of your problems.

How about cutting channels in the floor screed and just putting new UFH pipes in?

SSE

etcetc

tails_naf wrote: »

The only thing that could catch me would be the front door, but I think we have the height..

how about leaving rectangular square where door is at existing level big enough to allow door to open/close (or hacking out a thin layer to maintain existing height) and treat it as a dirt catch area with suitable matting like you see in commercial buildings/shopping centres etc the perimeter can be edged and sloped up to new height

go down well with the missus

http://www.c-sgroup.co.uk/products/pedisystems/pedisystems.html?gclid=COTpooqc5p8CFaFi4wod3EjOHA

some ideas here obviously yours will be on a smaller scale

http://www.entrance-matting.com/products.htm

ronboy

It's easy to take out your doors and doorframes. You could ring the company you got them off and ask them to cut them down a bit for you. The easy-screed will do a minimum of 35mm but I'll tell you it's expensive. I got a price on 150 sqm and it was costing me 3400 + vat:eek::eek:

tails_naf

Hi All,

Just wanted to update the board on the burst UFH.

I heard of the same happening to at least 2 other people, and was encouraged to hear that they both managed to repair/patch theirs by breaking the concrete where it was wet, finding the leak, and putting in a joiner.

So, with this in mind I continued to pursue the insurance company to see if they would cover it, as well as other parts of the build.

However, the insurance company are giving me the run-around, so it looks like I'll have to go ahead and repair it myself, under the assumption its no covered.

So last weekend I tried to repair one loop of the pipe - I took photos for those interested.

I broke down where the concrete was wet, and by leaving a small amount of water flowing, was able to see the direction of the leak, and within a few minutes had uncovered the burst pipe. I cut a section out and put in two joiners. and then the moment of truth - turned on the water pressure.

I quickly saw that the pipe was burst in another location, which seemed to be on the very next run of the same loop. I could also see water flowing from the other side of the hole I'd dug, which to me indicated the pipe was burst in at least 2 other places.

Quick sums - 13 loops of pipe, perhaps 3+ bursts per pipe = lots of pathcing and lots of risk for future leaks.

Long story short, I'm back to either
a) pulling up the whole floor
b) chasing our 1" channels 1.5" deep and laying new pipe in there (leaving the old pipe in place wherever it lays).

I'm leaning towards b) because of the risk of damage to existing insulation, as well as cost of re-instating all the concrete and risk to wheelbarrowing in concrete over the pipes.

So I'd like to ask the board - have you every heard of a road-saw that has 2 blades, like a chasing saw? Or is the only course of action to use a chasing saw, which sounds like a rough job on the hands and knees.
Any ideas are welcome!

RFL09

Sorry for your troubles - whats done is done. Try pricing up replacing the slab etc and also price rads etc - Whichever is the cheapest should be the solution!

tails_naf

The underfloor is finally fixed!

After a lot of procrastinating, we decided to go ahead and fix it.
I have to thanks everyone here on the board for the advice.

For posterity, here are the details of how we fixed it -

We decided to cut channels, instead of take up the whole floor because
1) expensive - taking up the floor and re-pouring was at least 2 grand
2) unknowns - weren't sure if the insulation would also be damaged, which would cost even more.

I looked into getting a double bladed ruad-saw - they don't exist. And a chasing saw would burn out with that amount of work.
Luckily, my father came across an old road saw and picked it up for 150 euro. A little bit of engineering work, and we had a second blade on it - and it worked a charm (see the picture below)

Cutting the channels was a really difficult job. But the job of taking the piece cut out and then smoothening the trench was worse. Very difficult, and about 1-2 sold weeks work, and quite messy. (see pic below of channels after cutting)

We then laid the new pipe, tested it, and finally put a very fine mix of sand/cement back into the channels and smoothened it flush, so we're back to a finished floor. (more pics below)

It was a hell of a job. I can't really believe how much work it was, but it seems to have all worked out. I owe my family and friends a huge debt of gratitude, as there was a bit of slave labour involved from everyone.

(hit the maximum number of images - will post again with the finished article!)

tails_naf

Here are the final photos!

ninjaBob

I really lucked out with my tiny leaks that were easily fixed (relative to the nightmare you had).

Congrats.

soldsold

Good job!

Nice bit of work. How did you dig out the channels in the end once they had been cut?

tails_naf

A wide-faced chisel fit down into one of the cuts nicely and a light tap cracked the bit of concrete and it pops out. Unfortunately it sometimes left a rough bottom in the trench, so that had to be smoothened by hand - long chisel and a lump hammer.

My brother had a week off from college, and between my father, my brother and myself, we got through it. Can't believe how much work they put into it.

If anyone ever has any need for a double bladed road saw, pm me

Congratulations on fixing what must have been an absolute nightmare of a situation.

imitation

Thats awesome, you must have been buckled after all that work

muffler

You deserve a medal after all that

Poor Uncle Tom

Damn, that's a lot of work,
but, very nicely done.