Hello,
I didn’t find anything in the search. My architect initially planned to use cellular glass gravel under the slab-on-grade (without a basement) on strip foundations. However, he now suggests that, for cost reasons, this could be omitted and instead the insulation installed below the screed, since the clay soil beneath shouldn’t freeze in winter.
This would save me about 5,000 euros (approximately $5,000). From his perspective, this is acceptable, but he asked me if I think it’s okay. I’ve been researching for two days now but haven’t found any useful information.
What do you think?
I didn’t find anything in the search. My architect initially planned to use cellular glass gravel under the slab-on-grade (without a basement) on strip foundations. However, he now suggests that, for cost reasons, this could be omitted and instead the insulation installed below the screed, since the clay soil beneath shouldn’t freeze in winter.
This would save me about 5,000 euros (approximately $5,000). From his perspective, this is acceptable, but he asked me if I think it’s okay. I’ve been researching for two days now but haven’t found any useful information.
What do you think?
E
elVincent31 Mar 2016 09:0714cm (5.5 inches) Styrodur insulation under the slab
Concrete slab
Knauf Katja Sprint
3cm (1.2 inches) EPS 035 DEO multi-purpose insulation board
3cm (1.2 inches) EPS 035 DES impact sound insulation board
6cm (2.4 inches) screed with underfloor heating
1.5-2cm (0.6-0.8 inches) floor covering
> Interior floor structure approx. 14cm (5.5 inches)
> U-value 0.18 W/m²K
Our wastewater pipes run vertically through the slab and are either bent underneath or routed in pre-wall elements. This does not require additional space.
Concrete slab
Knauf Katja Sprint
3cm (1.2 inches) EPS 035 DEO multi-purpose insulation board
3cm (1.2 inches) EPS 035 DES impact sound insulation board
6cm (2.4 inches) screed with underfloor heating
1.5-2cm (0.6-0.8 inches) floor covering
> Interior floor structure approx. 14cm (5.5 inches)
> U-value 0.18 W/m²K
Our wastewater pipes run vertically through the slab and are either bent underneath or routed in pre-wall elements. This does not require additional space.
S
Sebastian7931 Mar 2016 09:10Impact sound insulation in the basement? Good planner... also the penetrations of the concrete slab – we specifically avoided those.
So, now you have the same build-up height as I do (I have 7cm (3 inches) insulation…) – where exactly is your advantage? Oh right, the U-value is 0.06 better.
So, now you have the same build-up height as I do (I have 7cm (3 inches) insulation…) – where exactly is your advantage? Oh right, the U-value is 0.06 better.
E
elVincent31 Mar 2016 09:21We will achieve KfW55, which was the goal. If I exclude the 14cm (5.5 inches) under the floor slab, I get a U-value of 0.49 W/m²K, or 0.43 W/m²K with 7cm (2.75 inches) of insulation. You might want to double-check your 0.06 value.
Impact sound insulation is not only for reducing the sound transmitted downwards (greetings to the moles), but also for structure-borne sound insulation. Additionally, the panels (Rolljet) accommodate the pipes of the underfloor heating system.
What is the objection to penetrations through the floor slab if they are professionally sealed? In our case, these are pipe sleeves that are cast into the floor slab.
Impact sound insulation is not only for reducing the sound transmitted downwards (greetings to the moles), but also for structure-borne sound insulation. Additionally, the panels (Rolljet) accommodate the pipes of the underfloor heating system.
What is the objection to penetrations through the floor slab if they are professionally sealed? In our case, these are pipe sleeves that are cast into the floor slab.
S
Sebastian7931 Mar 2016 09:31Since you claim to know everything, you surely know what I used for insulation (which I already mentioned here).
PUR...
And definitely not structure-borne noise – floating screed. By the way, I can’t hear any difference compared to upstairs – it just feels "very hard" to walk on.
If properly sealed, it’s naturally not a problem – but it’s one more potential point of failure. And in case of issues, it’s practically impossible to access.
PUR...
And definitely not structure-borne noise – floating screed. By the way, I can’t hear any difference compared to upstairs – it just feels "very hard" to walk on.
If properly sealed, it’s naturally not a problem – but it’s one more potential point of failure. And in case of issues, it’s practically impossible to access.
E
elVincent31 Mar 2016 09:57I’m just using the information that’s readily available, and there was no mention of PUR. But if you could also specify the thermal conductivity class, I wouldn’t have to guess as much.
The best one I quickly found offers a thermal conductivity class of 021, which results in a U-value of 0.3 W/m²K at 70mm (2.8 inches) thickness. However, the cost per square meter is also higher than that of our 140mm (5.5 inches) XPS boards.
Isn’t it rather unconventional not to run the wastewater pipes directly outside?
By the way, we’re slowly but surely drifting completely away from the original topic. I’ve already presented my reasons for preferring exterior insulation. No one has convincingly explained why interior insulation would be better—only that it’s cheaper (which I find debatable given the same insulation performance).
The best one I quickly found offers a thermal conductivity class of 021, which results in a U-value of 0.3 W/m²K at 70mm (2.8 inches) thickness. However, the cost per square meter is also higher than that of our 140mm (5.5 inches) XPS boards.
Isn’t it rather unconventional not to run the wastewater pipes directly outside?
By the way, we’re slowly but surely drifting completely away from the original topic. I’ve already presented my reasons for preferring exterior insulation. No one has convincingly explained why interior insulation would be better—only that it’s cheaper (which I find debatable given the same insulation performance).
S
Sebastian7931 Mar 2016 10:05Less prone to errors during construction – I have mentioned this several times now.
And I had written that with PUR at the beginning of the thread...
Doesn’t matter to me anymore either...
And I had written that with PUR at the beginning of the thread...
Doesn’t matter to me anymore either...
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