Brand New Extension; Very Cold Floor!! Due to No compacted Hardcore??

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Hi all,
Just had a new 2 room extension on ground floor only (end terrace). This runs the whole length on the side of the house. It is 30 sq metre. It has a pitch roof. As the build went along I felt the builder was trying to save pennies. Having just had the carpet fitted now, I see how cold the room is and it is quite obvious that the cold is due to the cold flooring. As you sit you can feel the cold travel up your feet/leg and its just not habitable (lounge/bedroom). After half an hour you cannot leave your feet on the ground. My son went back to his boxroom bedroom. The builder used the Ballytherm 90mm and for the perimeter he has used what I gather now might be called Expanded Polystyrene Foam which I found a piece of and it measures 22mm(by 4inch height). After the visit from the Building Inspector he removed the Hardcore and said there was already hardcore in the ground and that he would use it in his other project where he was working simultaneously.(I wonder if Hardcore was there in the first place only for the Inspector to see it visually sitting on the driveway only to be taken away later??) I didn't think much of it at the time and thought this can't have too much of an affect on the building. However the things I saw him put down only because I was not at work on the day was Ballytherm/Blue sheet of membrane and perimeter foam (the type you would find in toy packaging).Cant say I saw the blinding sand go in either but it may well have. Its only now online when I see what the required procedure is (doh) The temperature first thing in the morning in the old lounge at floor level is 22deg C and in the new lounge is 17deg C!!! The rad is correct size and there is nothing that can be done to improve the temp. as temp setting in the old lounge has already moved from a max of 5 to 4 on the TRV. What are the solutions for this disaster?? I am thinking digging up and putting it down as it should have been done in the first place. Is this possible and what might the consequences be on the walls/building/structure?? Ideally some kind of insulation without digging up but I'm just not prepared to add more inches to the flooring either. How much might this cost dare I ask?? Should my first port of call be to invite the Inspector and see what he says?? Could this cold be due to no compacted hardcore?? Windows and Patio dooors are Triple Glazed and carpet underlay is 10mm and carpet is fairly thick also. All suggestions will be very much appreciated.
Thanking you all in advance,
Jon.
 
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If it's new build, it might be still drying out? It won't be anything to do with the thickness of hardcore.
 
Thanks dazlight, unfortunately I don't know the answer to screed thickness. Carpet went in last week. Screed was done end October so about 10 weeks after. Still 5 deg C difference is a fair bit I would have thought. Thanks, Jon.
 
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Thakns tony1851, I hadn't thought of that. I very much hope its the case. If so how long before temperature in the extension matches the old house (built 23 yrs ago).
Cheers, Jon.
 
So 10 weeks from screed done to carpet fitted. That's 70 days.

The drying time of screed is 1mm per day for 1st 50mm then about 1mm per 2 days if thicker.
The average slab is 100 to 150mm thick.

So your looking at 6months to a year to fully dry out so what should have happened before carpet was fitted was a moisture suppressant should of been used like stopgap F78 / Ardex MVS95

So you could have moisture raising through the carpet mate. That would make the room colder.
 
How long after the screed was done was the carpet fitted? Also how thick is the screed?

So 10 weeks from screed done to carpet fitted. That's 70 days.

The drying time of screed is 1mm per day for 1st 50mm then about 1mm per 2 days if thicker.
The average slab is 100 to 150mm thick.

So your looking at 6months to a year to fully dry out so what should have happened before carpet was fitted was a moisture suppressant should of been used like stopgap F78 / Ardex MVS95

So you could have moisture raising through the carpet mate. That would make the room colder.
So, lack of Hardcore wouldnt be the reason for the cold floor then?? And is a 5deg C difference to be expected until the floor fully dries out??
Cheers, Jon.
 
I did use a dehumidifier for 3 wks which did collect about 5 pints of water overnight to start with and then by the end of 3rd week only about half a pint overnight.
 
Most of water will be at bottom and raises slowly. It might not be that. The carpet fitters should of taken a moisture test but most don't.
I'd get a local flooring company out to take a look. They should do that for free.
 
How sure are you that the Ballytherm is actually there? Did you see the concrete being poured? If I was a penny pinching builder, then that's what I'd get back in the van at £40 a sheet, rather than a £35 bag of hard core!
 
How sure are you that the Ballytherm is actually there? Did you see the concrete being poured? If I was a penny pinching builder, then that's what I'd get back in the van at £40 a sheet, rather than a £35 bag of hard core!
garyo thanks for your reply; yes I did see all the Ballytherm go in also the concrete being poured (although this was done manually rather than straight off the back of the lorry).
Cheers,
Jon.
 
Is there any way of finding out the root cause of this problem through a surveyor or structural engineer?? I am just wondering if I might be on the wrong track here and it might that the cold room is due to something else.
Thanks.
 
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This isn't an ideal time of year to be moving into a new-build extension. It will only be drying out slowly, and the excess water is not just in the floor but some will be in the walls as well. It seems you have a reasonable thickness of insulation under the slab - is there sufficient insulation in the walls? And in the roof? And assume the rads are adequate?
Perhaps just be patient - let it dry out thoroughly during the summer, and see how it is this time next year.
 
This isn't an ideal time of year to be moving into a new-build extension. It will only be drying out slowly, and the excess water is not just in the floor but some will be in the walls as well. It seems you have a reasonable thickness of insulation under the slab - is there sufficient insulation in the walls? And in the roof? And assume the rads are adequate?
Perhaps just be patient - let it dry out thoroughly during the summer, and see how it is this time next year.
Thanks tony1851, yes I did see insulation going in the 95mm cavity (brown sheets of insulation) and the roof has 300mm. The rad in the bigger room is 6900btu (18ft x 10ft); the smaller room its 4000btu (13 x 10ft). However there may be a balancing issue and my only measure is that they get hotter then the rad in my older lounge simply bcos this is turned down to 3.5/5. I may need to get someone to do a proper balance as the builders gas-safe engineer didn't seem to want to hang around after the rads went up. Hopefully as you say it may dry out, until then
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Cheers,
Jon.
 
Interesting thread - sorry to hear your problems OP.

On a similar note, we are having an extension floor built with the insulation going on top of the concrete floor - presumably this will mean we won't necessarily have the cold issues associated with the drying concrete mentioned above? or will we?

What is the advantage of the insulation underneath concrete rather than vice versa?
 

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