UFH spacing from wall.

[ianR1]

Hello, 1st post so please be gentle !

 

I have carried out searches in which almost all of my questions have been answered other than a couple.

 

I am near enough ready to run in all of my pipe for my full downstairs UFH system and I was curious to why the pipe has to be 100mm from the wall ?

 

The reason I am asking is that my external walls have a step out brick in which my insulation board is butted, do I measure a 100mm from that or from the wall in which the screed will go up to ?

 

Picture attached to show what I have.

[markc]

Not related to your question but the step out brick … is that the stepped footing? Have you lowered the floor below footing level to get the insulation down? Or has it been underpinned?

[PeterW]

You need to insulate and isolate around that brick so the screed doesn’t bond to it and provide a crack plane. 100mm out from the wall is where I would have the pipes usually but I would also make sure you’re not creating issues with that step first. 

[ProDave]

The general rule is no closer than 100mm to the wall. There is no harm if it is further, mine are no closer than 200mm to any wall.

[ianR1]

20 minutes ago, markc said:

Not related to your question but the step out brick … is that the stepped footing? Have you lowered the floor below footing level to get the insulation down? Or has it been underpinned?

Yes it is a stepped footing. When we moved in the floors where found to be damp as it is an old house the was no membrane just concrete painted in bitumen which had broke down as the floor boards where nailed directly through it. We have dug out the floors for the floor to finish as it was originally.

 

23 minutes ago, PeterW said:

You need to insulate and isolate around that brick so the screed doesn’t bond to it and provide a crack plane. 100mm out from the wall is where I would have the pipes usually but I would also make sure you’re not creating issues with that step first. 

The new DPM that was installed when the slab went in will be covering and the perimeter foam edging (its going to be pain to do). What is a crack plane ?

 

25 minutes ago, ProDave said:

The general rule is no closer than 100mm to the wall. There is no harm if it is further, mine are no closer than 200mm to any wall.

So would you go 100mm form the stepped brick or the actual wall - it is only like this on the external walls of the house ?

 

 

Thanks for all the replies so quickly !

[markc]

@ianR1 

Yes it is a stepped footing. When we moved in the floors where found to be damp as it is an old house the was no membrane just concrete painted in bitumen which had broke down as the floor boards where nailed directly through it. We have dug out the floors for the floor to finish as it was originally.

I guessing you dug out to below the footing, so now only insulation to stop the footing sliding/moving sideways off its bearing/support. Screed will help to stabilise but I would keep an eye on the floor for movement. Rare but it does happen when the ground outside swells and pushes on the founds, if there is nothing solid on the inside to resist the walls can move.

[ianR1]

Hi Mark,

 

Thanks for the reply

 

Not below the footing, including the row you can see in the pic there is another below this and then it steps out again for another two deep and then that is on top of concrete which I can't confirm how deep it is but deeper than 6", although the house needs a lot of work where it has been neglected for so long it does seem very well built - was early 1900.

[RHayes]

To answer your original question I would measure 100mm out from the wall, or finish wall if possible to gauge where that will be.  As another mentioned 200mm is quite satisfactory too, or anywhere inbetween.  The reason for this is so that you avoid coving the pipe with the final buidup of the wall, or hit the pipe with carpet griper (I'd still glue these anyway) or anything else that is up against the wall, e.g. skirting.  In otherwords it is to give you the perimeter around the edge to avoid pipes conflicting with structure and any fixings and heat isn't needed any closer than that, especially on a screeded floor as the screed spreads the heat out the best.