Hello!
We are renovating a house that was extended in the seventies with a slab-on-ground foundation. The foundation is made of lecablocks with the slab cast at the top. Previously, the floor consisted of wood spacers placed directly on the concrete with insulation on top. You can imagine how it smells in the house...
We are considering whether to remove the concrete slab, excavate, and create a crawl space or build a new floor with good ventilation underneath.
We have talked to a construction company and described our ideas. They suggested either cutting up the slab, which would cost around 15,000:-. Then there would be the additional cost of building a completely new floor.
Their other suggestion is to install a nivellfloor, about 22,000:- if they do the work.
I have read on their site, and if I understand it correctly, you draw down dry and warm air under the floor, keeping it dry down there. Don't you lose a lot of warm air then? I assume the air that has passed under the floor is sucked right out? How significant is the difference in heating costs compared to a "regular" floor with about 25 cm of insulation?
Has anyone installed this and has any ideas? Spontaneously, it feels like one could come up with their own solution at a fraction of the cost.
Thanks in advance!
We are renovating a house that was extended in the seventies with a slab-on-ground foundation. The foundation is made of lecablocks with the slab cast at the top. Previously, the floor consisted of wood spacers placed directly on the concrete with insulation on top. You can imagine how it smells in the house...
We are considering whether to remove the concrete slab, excavate, and create a crawl space or build a new floor with good ventilation underneath.
We have talked to a construction company and described our ideas. They suggested either cutting up the slab, which would cost around 15,000:-. Then there would be the additional cost of building a completely new floor.
Their other suggestion is to install a nivellfloor, about 22,000:- if they do the work.
I have read on their site, and if I understand it correctly, you draw down dry and warm air under the floor, keeping it dry down there. Don't you lose a lot of warm air then? I assume the air that has passed under the floor is sucked right out? How significant is the difference in heating costs compared to a "regular" floor with about 25 cm of insulation?
Has anyone installed this and has any ideas? Spontaneously, it feels like one could come up with their own solution at a fraction of the cost.
Thanks in advance!
Hello!
I have installed Nivellgolv in my basement, as the floor was constructed the same way as yours, and I got moisture and rot in it. As you say, Nivellgolv is meant to ventilate out the moisture that comes from below. Now, it doesn't exactly draw out large amounts of air. I have the fan on the lowest setting, and my floor is a bit over 40 square meters. What I've rather noticed positively is that the warm air is drawn to the far end of my basement (where the vents down under the floor are) better than before. I have my air-to-air heat pump mounted down there too, on one end. I paid around 28,000 SEK for my floor, complete with insulation, fan package, and floorboards. You can get away cheaper, partly it's obviously dependent on the size, and then on whether you need the fan. But you'll probably regret it if you don't include the fan, given you have the opportunity to put it in. And, yes, you could probably build your own solution cheaper, but then the problem is how to prevent organic material from being against the concrete (Nivellgolv stands on plastic legs). It's also not that difficult to build a Nivellgolv yourself. I'm a computer nerd by nature who never had a house before and I did it all by myself. A solid Hilti (there were a hundred or so holes that needed to be drilled in the floor to attach the legs) and a long spirit level were probably the most advanced tools I needed to install the joists. And according to my calculations, the floor should now withstand a future wood stove without problems.
I have installed Nivellgolv in my basement, as the floor was constructed the same way as yours, and I got moisture and rot in it. As you say, Nivellgolv is meant to ventilate out the moisture that comes from below. Now, it doesn't exactly draw out large amounts of air. I have the fan on the lowest setting, and my floor is a bit over 40 square meters. What I've rather noticed positively is that the warm air is drawn to the far end of my basement (where the vents down under the floor are) better than before. I have my air-to-air heat pump mounted down there too, on one end. I paid around 28,000 SEK for my floor, complete with insulation, fan package, and floorboards. You can get away cheaper, partly it's obviously dependent on the size, and then on whether you need the fan. But you'll probably regret it if you don't include the fan, given you have the opportunity to put it in. And, yes, you could probably build your own solution cheaper, but then the problem is how to prevent organic material from being against the concrete (Nivellgolv stands on plastic legs). It's also not that difficult to build a Nivellgolv yourself. I'm a computer nerd by nature who never had a house before and I did it all by myself. A solid Hilti (there were a hundred or so holes that needed to be drilled in the floor to attach the legs) and a long spirit level were probably the most advanced tools I needed to install the joists. And according to my calculations, the floor should now withstand a future wood stove without problems.
Thank you for your response!
Another thing I was wondering is if it's foolish to draw air from the kitchen and bathroom (what's currently on the plate) and if you should instead draw fresh air from another room?
Our floor is about 26 sqm, so the cost for the floor itself should be around 10-11,000:- The ones I talked to mentioned a square meter price of about 420:- Is that reasonable?
Approximately how much air per sqm/day should be drawn through?
Another thing I was wondering is if it's foolish to draw air from the kitchen and bathroom (what's currently on the plate) and if you should instead draw fresh air from another room?
Our floor is about 26 sqm, so the cost for the floor itself should be around 10-11,000:- The ones I talked to mentioned a square meter price of about 420:- Is that reasonable?
Approximately how much air per sqm/day should be drawn through?
The simplest way is to extract the air from the room where you have the floor. Or were you thinking of having Nivellgolv in all the rooms? The bathroom is probably not recommended though, as the vents are placed directly in the floor along a wall. But the kitchen should work. It's often warm and cozy there. Check out www.nivellsystem.se. They have good brochures there. I have built entirely according to the instructions available there. And if I remember correctly, the smallest fan package (which I have) is sufficient, and power setting 1 (out of 5) should be enough for floors up to 45 or 50 square meters. However, I don't know the cubic meter amount of air per day, but the fan should run continuously for a steady flow. Check the brochures under "Vent" for more info.
I asked my local supplier and the lowest height version with plastic rails and screws for 30sqm would be around 7000:- including VAT in my case. No tools included, only plastic rails and screws, as well as a box of proppskruv to fasten the bolts to the floor. This was in January 2011.
I had those "däringa" expansion spikes, and then I had to buy two "dorn", one with a hole to push the spike into the hole and one to drive in the actual spike. A 6 mm concrete drill that's a couple of decimeters long is also needed to drill the holes if you're using such spikes. Managed to kill the father-in-law's Hilti when I did this (over 250 holes)... Luckily, he got it when he retired 20 years ago, and it was already old then....
Thank you for your responses! I've been doing some reading and have had some time to think.
Is there any real disadvantage to building the nivell floor yourself? I found brackets and expander bolts at Byggmax that would fit nicely. How close do the bolts in the floor need to be? I'm thinking you could alternate between regular bolts where the head rests against the floor and expanders. Distance between the bolts in the floor?
There's no doubt that it's warm and cozy in the kitchen and bathroom, what makes me wonder is that the air is often quite humid there. Extracting from the bathroom is completely out of the question, right? Extracting from the kitchen also seems doubtful; if the air is humid and cools against the concrete slab, there will be quite a bit of condensation.
Having a dehumidifier running to dry the air before it goes down seems expensive in the long run?
How tight should it be above the insulation? Is it insulation - plastic - chipboard that applies? Can you lay plank flooring? Does nivellgolv only use foam plastic because of better insulation in thin dimensions or moisture resistance?
Is there any real disadvantage to building the nivell floor yourself? I found brackets and expander bolts at Byggmax that would fit nicely. How close do the bolts in the floor need to be? I'm thinking you could alternate between regular bolts where the head rests against the floor and expanders. Distance between the bolts in the floor?
There's no doubt that it's warm and cozy in the kitchen and bathroom, what makes me wonder is that the air is often quite humid there. Extracting from the bathroom is completely out of the question, right? Extracting from the kitchen also seems doubtful; if the air is humid and cools against the concrete slab, there will be quite a bit of condensation.
Having a dehumidifier running to dry the air before it goes down seems expensive in the long run?
How tight should it be above the insulation? Is it insulation - plastic - chipboard that applies? Can you lay plank flooring? Does nivellgolv only use foam plastic because of better insulation in thin dimensions or moisture resistance?