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Concrete floor - best type of insulation?


 
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The Riviera Kid

from United Kingdom

Joined: 22 Jan 2008
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Location: Tyne and Wear,
United Kingdom

PostPosted: Mon May 31, 2010 1:43 pm Reply with quote

Reading through some other unlrelated posts, I've noticed freddy has added a comment "polystyrene is cheap because it's crap" lol. icon_lol.gif

This got me thinking. Currently our ground floor consists of a concrete base, polystyrene blocks, a sheet of DMP, and the chipboard tongue and groove floor panels sitting directly on top. There is no joists or other support for the floor.

The ground floor is very uneven. I've been tempted to pull the whole lot up down to concrete so I can chip away the high spots, screed the low spots and maybe put down a self levelling compound to take care of any other smaller areas.

If I ever go as far as this (quite possible as it irritates the life out of me), I'm wondering what the options are as far as insulation goes. Should I replace the polystyrene blocks or upgrade to something else. Any recommendations? Also there are air bricks at the same level as the polystyrene - just to mention.
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mointainwalker

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PostPosted: Mon May 31, 2010 8:32 pm Reply with quote

I don't know why FMT posted that. Expanded PS has the same insluation value as Glass-wool etc.

Extruded PS is approx 30% better for 300% ( ? don-t live in UK _ so not sure ) the cost

PIR is 60% better for 500% of the cost.

PS is an open-cell insulant. PIR is closed-cell and relies upon the enclosed gas to maintain the high U value.

There is now some initial research that says that these insulating gases leach out over the first 7 years which reduces the U values of these very expensive materials down to that of fibre-wool.
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freddymercurystwin

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PostPosted: Mon May 31, 2010 9:28 pm Reply with quote

Aye its a conspiracy to keep Celotex and Kingspan in business! icon_rolleyes.gif
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The Riviera Kid

from United Kingdom

Joined: 22 Jan 2008
Posts: 96
Location: Tyne and Wear,
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PostPosted: Tue Jun 01, 2010 10:39 am Reply with quote

So getting back to my original question icon_razz.gif ....

Are either of the above named products any good for use in a floating floor? Or if not would it be a good idea to construct some sort of wooden framework on top of the DMP to support the floor with these things slotted in between?

Just a thought.
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mointainwalker

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PostPosted: Tue Jun 01, 2010 11:02 am Reply with quote

What is going to be your replacement floor ?
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The Riviera Kid

from United Kingdom

Joined: 22 Jan 2008
Posts: 96
Location: Tyne and Wear,
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PostPosted: Wed Jun 02, 2010 5:06 pm Reply with quote

mointainwalker wrote:
What is going to be your replacement floor ?


Not too sure to be honest. I'm happy to listen to suggestions. All I want is an even floor which isn't too cold.

Floor covering would likely be laminate again (looks okayish and is kid friendly), as for the construction of the floor underneath - open minded at the moment.
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The Riviera Kid

from United Kingdom

Joined: 22 Jan 2008
Posts: 96
Location: Tyne and Wear,
United Kingdom

PostPosted: Wed Jun 02, 2010 5:18 pm Reply with quote

I probably need to hit the 'net a bit more and get learning....

As stated above the construction is concrete, polystyrene blocks, DMP and chipboard. At the same level as the polystyrene (ie under the level of the DMP) we have airbricks around the house - which I gather is to assist air flow so that moisture from the concrete curing (which takes more than 20 years I hear) doesn't cause excess moisture under the DMP.

Could a DMP be laid directly above the concrete (be it plastic sheet or some sort of liquid DMP), the air bricks replaced with standard bricks, allowing for a thinner (and better?) insulation (some sort of large sheet product) to be installed?

Or will this (even after 20 years, the house is a 1990 build) just result in some sort of moisture related problem?

I really do need to read up more lol.
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Deluks

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PostPosted: Wed Jun 02, 2010 11:39 pm Reply with quote

Is there an actual problem you are trying to fix?
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The Riviera Kid

from United Kingdom

Joined: 22 Jan 2008
Posts: 96
Location: Tyne and Wear,
United Kingdom

PostPosted: Thu Jun 03, 2010 10:47 am Reply with quote

Yeah, as per my original post the floor in the house is very uneven with high and low spots. So much so that the living room door only opens 75% of the way before it catches on the floor, despite there being a massive 1" gap on the far side before you open it.

I can probably pull the whole lot up, level the concrete, then replace like for like. But if there's a better product out there that polystyrene, I'd like to use it.
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mointainwalker

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PostPosted: Thu Jun 03, 2010 1:01 pm Reply with quote

Depends what you mean by better.

Both extruded-polystyrene and PIR boards insulate better than expanded polystyrene ( white and brittle) but will cost two to three times more for 30%-50% better insulating properties.

In my opinion definitely not worth it under the floor as the temp is generally low at floor level.

Expanded polystyrene is also softer than the other two materials, so it will conform to a small extent to unevenness (ridges etc) whereas the others will tend not to do so.
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