# underfloor heating problems



## griffandco (22 Nov 2006)

Our builder dropped the level of three of our rooms by 2 to 3 inches thinking we were going to put battons to secure our timber floors. Concrete is now poured over our underfloor heating so no going back.Question is can we pour another layer of concrete to have our floors level or will this affect the effeciency of our heating?


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## qwerty? (23 Nov 2006)

griffandco said:


> Our builder dropped the level of three of our rooms by 2 to 3 inches thinking we were going to put battons to secure our timber floors. Concrete is now poured over our underfloor heating so no going back.Question is can we pour another layer of concrete to have our floors level or will this affect the effeciency of our heating?


 
So how many inches will be covering your UFH pipes? 6" i'm guessing, which to me sounds why too much, 3-4" would be maximum imo. I

 assume by concrete you mean screed? in which case I think you should consider lifting it and adding extra insulation to make up the difference and redo the pipeworth in the 3 rooms.


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## extopia (23 Nov 2006)

Sounds like a right screw up by your builder and/or your architect. I'd try to get him to fix this at his own expense. You're going to have to take up the lot.


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## yop (23 Nov 2006)

that is some balls, under no circumstance would I go about the 4" of screed, it bring up your responses times way to much


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## xt40 (23 Nov 2006)

i recently put in ufh and was worried about this as i have about 6 inches of cement over it.  my worries were totlly unfounded.  response times  are a little slower than rads but from cold, you can feel the room getting warmer within an hour or 2, way before the tiles start to feel hot. last week we ran out of oil on a sunday morning  and there was still noticeable heat in the floor at lunchtime the next day when the oil man came. this has got to be due to the thick screed. ufh really is light years ahead of rads.
if you are bringing your levels up, i would roughen the existing surface up before pouring and bring the ufh on very slowly initially.


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## LiamC (23 Nov 2006)

Hi xt40 - apologies this is off-topic ..

You are using oil to run your UFH - how do you find this cost wise?
I'm getting ready for a self-build, want UFH but still have to decide how to run it - thx


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## yop (23 Nov 2006)

xt40 - When you say "hot" I presume you mean warm? What temp is your UFH running at?


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## xt40 (23 Nov 2006)

not sure yet about the costs as its only been up and running for a couple of weeks and there was some oil in the tank from last year. il run the tank dry and that will give me some idea. whatever it costs, it is worth it.
regarding the floor temp. we vary it to speed up the response time but probably use 30-35 most of the time (range is 25-50) even at 25, the difference underfoot between the kitchen/dining area (ufh) and the utility(rad) is huge


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## yop (23 Nov 2006)

I presume that is the flow temperature & not your room temperature!!!


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## xt40 (23 Nov 2006)

yes flow. room temp 18-20


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## yop (23 Nov 2006)

You must have very tight loops to get it down to 30 degrees, most installations run about 40 degree, otherwise you would not achieve the 20c in the room temperature.


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## Carpenter (23 Nov 2006)

On a technical point, even if you were to pour an additional screed over the exist slab this may pose a problem from the point of view of cracking or curling of the topping.  Thin screeds (less than 4") can crack, delaminate from the substrate (too thin and too light) and in extreme cases- curl at the edges.  Such screeds wear poorly and give trouble.  You won't be able to achieve a great bond with the existing base if it is already too well cured.  To avoid all this you will need to incorporate a light mesh or fibre into your screed topping.  I'd imagine the UFH would exacerbate the effects noted above if some precautions were not taken.  These defects are most likely on large floor screeds.


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## xt40 (23 Nov 2006)

yop said:


> You must have very tight loops to get it down to 30 degrees, most installations run about 40 degree, otherwise you would not achieve the 20c in the room temperature.





yes the loops are fairly tight  and i also used high quality foil backed insulation. at 30 it rarely goes over 17-18. when set to 40 it can go a good bit higher. im still at the experimenting  stage


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## yop (24 Nov 2006)

xt40 said:


> yes the loops are fairly tight  and i also used high quality foil backed insulation. at 30 it rarely goes over 17-18. when set to 40 it can go a good bit higher. im still at the experimenting  stage




Aye, we did the same as yourselve, have loops from 25mm, means we are running at 28 deg c for the flow rate, it keeps the running costs down big time!!

The way you could get away with a thin screed is to put batten down and pour between, at least the weight will be carried on the battens


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## Carpenter (24 Nov 2006)

yop said:


> The way you could get away with a thin screed is to put batten down and pour between, at least the weight will be carried on the battens


 
Don't really understand what this will achieve?  You are effectively introducing even thinner weak spots in the screed if you go this route, and to no effect.  The screed will crack at every batten location and the battens serve no function anyway.


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## xt40 (24 Nov 2006)

as i already said, roughen the surface sufficiently (with a scarifier)  and there shouldnt be any problems


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## yop (24 Nov 2006)

Carpenter said:


> Don't really understand what this will achieve?  You are effectively introducing even thinner weak spots in the screed if you go this route, and to no effect.  The screed will crack at every batten location and the battens serve no function anyway.




The battens would act as your weight bearers, with your screed as a "filler" in between.
Only good though if you are going the timber route on the floors.
We did that upstairs in our shack and it works grand.


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## griffandco (4 Dec 2006)

Still havent decided what to do...he who hestiates etc., but three options seem evident from replies;
a) Leave the floors with a drop 0f 2 to 3 inches (call it a feature!)
b) pour additional screed and glue timber floors (we hope to put solid)
c) Pour screed with battens at intervals to secure timber floors
Is there an option I'm missing?
Also heard various stories re. solid timber and UFH would like to go this route if possible.


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## qwerty? (4 Dec 2006)

griffandco said:


> a) Leave the floors with a drop 0f 2 to 3 inches (call it a feature!)


 
If you decide to go this route don't have a 3"  step just inside a door, it would be a disaster, anyone walking in the door would stumble, have an area inside the door at the hall level before the step.


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## griffandco (6 Dec 2006)

Thanks for all tips re. dropped floors.
Think Yops reply of battens sounds like the answer to our prayers as we are putting down solid timber floors.
Few Q's re. Yop solution..
Was it solid timber & nailed to battens over concrete floor with UFH?
How long ago did you get it done?
Bit worried re. extra screed bonding to existing baseas Carpenter warned.
Any ideas as to what to pour here? 
Builder suggests sand / cement mix.
How does this go with UFH


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## yop (7 Dec 2006)

griffandco said:


> Thanks for all tips re. dropped floors.
> Think Yops reply of battens sounds like the answer to our prayers as we are putting down solid timber floors.
> Few Q's re. Yop solution..
> Was it solid timber & nailed to battens over concrete floor with UFH?
> ...



We used a semi-solid with special underlay for the UFH (110 euro per roll I think)
Time wise, hard to gauge, you mean how long to put down the battens? Maybe 8 hours 2 of us.
We got standard sand cement mix from Roadstone for the whole house.

It works fine tbh, probably more warmth coming off these floors than the ones downstairs, but also the heat rising will aid to this.


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## griffandco (11 Dec 2006)

i was wondering how long the floors were down and if u had any trouble re warping. Did you ever consider solid timber floors?


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## yop (12 Dec 2006)

No problem with warping, the floors by the time I got to the flooring were down over 6 months, so well dried out!!
I was told that solid were not really recommended for UFH!! Don't know how true that is!


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## griffandco (12 Dec 2006)

have researched till blue in the face ...no definitive answers but missus wants solid timber as she doesnt like the "fake" look of any of the semi/manufactured floors we saw so far!!
My fear is that they may look genuinely warped after a while.


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## qwerty? (12 Dec 2006)

We used a single 120mm oak engineered board, with v groove, and think it's as close looking to solid timber you will find, It's called Delta. And is a click flooring. pm'ing you a link to a photo
[broken link removed]


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## hayabusa (19 Dec 2006)

Yop.
I have just sent in planning for a 3500 sq ft house. Thinking of underfloor + geo. however I have not been in any house where it is. Is the system working ok for you. If so I would like further info etc etc. (will send you more details of the specifice). 
On another note you used your own scaffolding for your build.
My plan was to buy my own use it and sell on. 
However just found outthe it has to be erected and certified as ok to use. 
Did you do this. ? will self build insurance cover it if you erect yourself. 
just concerned. I do not want a problem whereby someone gets hurt and no cover etc etc.


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## sparkey (19 Dec 2006)

Scaffolding must be erected and certified by a trained scaffolder.
Self build insurance will not cover self erect system.
Most contractors that you bring on site will not go up on or let their staff up on non certified scaffolding as their own insurance would not cover them on a "DIY" scaffolding.
Scaffolding certification is a 1 day course like a safe pass course .
Your best bet would be to buy the scaffolding and pay a certified scaffolder to erect and certify same for you. You just sell on the scaffolding when the project is complete.


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## hayabusa (20 Dec 2006)

Sparkey,
Thanks for info, however i think it is more than a 1 day course for scaffolding. 
The reason I think that is bacause half the country would be certifing scaffolding if this was the case. 
Can anyone confirm,
The other thing is that a certified scaffolder may charge a fortune for scaffolding certificate.


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## Meathman99 (20 Dec 2006)

The scaffold management course is a 1 day course.  A basic scaffolders course is longer, you are required to have on the job experience prior to the course.  Both www.iosh.co.uk and www.hsa.ie are good resources for construction health and safety.  
If you are buying scaffold and having a scaffolder erect it you may be able to get him to inspect the scaffold occasionally.  Might work out cheaper than taking a day off work and paying for the course.  Some builders may have also completed scaffold management course.


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## Stunning (8 Feb 2007)

Hi All,

Just wondering what type of screed you guys used over UFH pipes?There are so many that my head is melting.

First time caller long time listener


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## qwerty? (8 Feb 2007)

Standard sand/cement screed, 75mm thick on 100mm of xtratherm insulation is what i've used.

btw. welcome to AAM


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## Stunning (28 Feb 2007)

I was doing some homework and have come to a few conclusions..
sand and cement is old school and by all accounts leaves pockets between the pipes where heat can be lost.Also it seems s&c can crack and is just what builders use when they havent looked at the up to date products on the market.The drying time is at least three months...which is mad.
I intend on using the liquid type screed for UH.This can be flowed in on day one at between 40mm to 120mm and hard by day two,Dry in a month,no cracking.
If anyone needs advice on who to get this from let me know cos its taken me forever to get this info.

seeya


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## yop (28 Feb 2007)

Stunning said:


> I was doing some homework and have come to a few conclusions..
> sand and cement is old school and by all accounts leaves pockets between the pipes where heat can be lost.Also it seems s&c can crack and is just what builders use when they havent looked at the up to date products on the market.The drying time is at least three months...which is mad.
> I intend on using the liquid type screed for UH.This can be flowed in on day one at between 40mm to 120mm and hard by day two,Dry in a month,no cracking.
> If anyone needs advice on who to get this from let me know cos its taken me forever to get this info.
> ...



Have heard that the easi flow takes an age to dry throughly though due to the amount of water in it, therefore u have to wait longer to put down ur timber. 
Don't know about this though.


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## Leo (28 Feb 2007)

Hi Stunning, why not just post the information here for everyone's benefit?
Leo


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## Stunning (5 Mar 2007)

Ok Leo,

Company i used was called Screedtech and their numbers are 01 8357236 and mobiles 0868375782 & 0879471452.They are based in meath and kildare but do all over the country.The question on drying time is not true,the liquid type screed they use is a quick dryer and better than anything i have come across.They also do finishing compounds and dry screeds if that helps.

seeya


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