Gem77

Underfloor and screed in before windows

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Hi All

 

Just reaching out for advice on something that has happened our on build.

In short we have had the underfloor heating installed and screed laid before the windows have been installed.

Should we be concerned about this as the winter is now approaching and its not likely that we'll have windows in before Christmas? Will the screed or underfloor be damaged by the cold weather?

 

Thanks!

 

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I take it the window openings are boarded up to keep the rain and worst of the wind out?

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Neither will be damaged by cold, but if you can get an airline in to blow the water out of the pipes it would be good if you can’t seal up the whole building as @ProDave says. 

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8 hours ago, ProDave said:

I take it the window openings are boarded up to keep the rain and worst of the wind out?

@ProDave they have plastic up at them - so I guess that this will do what you say?

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8 hours ago, PeterW said:

Neither will be damaged by cold, but if you can get an airline in to blow the water out of the pipes it would be good if you can’t seal up the whole building as @ProDave says. 

That's great - I don't actually think there is any water in yet - they have run an air test. 

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Even in Arctic conditions, they would be fine as long as the pipes are taped and not capped off with a tightly sealed fitting. They need to allow air in and out for expansion. 
After that just make sure the pipes are fixed so they can’t become kinked at the slab. It’s VERY easy to kink them if they’re pulled / pushed on ( but conversely it’s very hard to damage them otherwise ).

Blow down one and see if you can easily do so, and that will tell you that no water resides in them. 

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Has everyone forgotten the first episode of most recent Grand Designs series. No windows and water left in the UFH pipes, resulted in destruction of the screed as the pipes froze.

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5 minutes ago, epsilonGreedy said:

Has everyone forgotten the first episode of most recent Grand Designs series. No windows and water left in the UFH pipes, resulted in destruction of the screed as the pipes froze.

 

opps! so i presume once the UFH pipes are laid (even before the screed goes down) get the ends capped off and sealed

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20 minutes ago, Moonshine said:

 

opps! so i presume once the UFH pipes are laid (even before the screed goes down) get the ends capped off and sealed

You do that regardless, to stop contaminants entering ( and later blocking ) the pipes, but yes, get them taped off, not capped off, instantly after installation. 

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1 hour ago, Nickfromwales said:

but yes, get them taped off, not capped off, instantly after installation. 

 

What type of tape to use please?

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4 minutes ago, Dreadnaught said:

 

What type of tape to use please?


Any..! Duct tape is ideal as it’s tough, just don’t make it fully airtight on both ends of the same loop. 

  • Thanks 1

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3 hours ago, Moonshine said:

opps! so i presume once the UFH pipes are laid (even before the screed goes down) get the ends capped off and sealed

 

 

I think the problem is what is the default pressure test method by the installer. I discussed the freezing risk with one screed/ufh installer and his reply was "well we could pressure test with air instead of water or maybe put in an antifreeze for the winter". I did not follow up and ask what the antifreeze might do to the pipes.

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2 hours ago, epsilonGreedy said:

 

I think the problem is what is the default pressure test method by the installer. I discussed the freezing risk with one screed/ufh installer and his reply was "well we could pressure test with air instead of water or maybe put in an antifreeze for the winter". I did not follow up and ask what the antifreeze might do to the pipes.

If it's proper central heating inhibitor / antifreeze, none whatsoever.

 

25% will usually prevent freezing down to about -10

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2 minutes ago, ProDave said:

If it's proper central heating inhibitor / antifreeze, none whatsoever.

 

25% will usually prevent freezing down to about -10

 

Good to hear this. My concern was that the solvent type characteristics of the anti freeze might weaken the plastic ufh pipes. 

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