Hello, we are renovating a house from the 1940s. The house has 400mm of sawdust under the wooden floor. I am wondering if we can place the water pipes directly on the current floor, or if we need something between the pipes and the floor? The old wooden floor is very strong and stable.
We plan to use the gypsum method, where we fill up between the pipes with gypsum boards and then fill where the pipes are with gypsum paste or some type of mortar.
The house is located in southern Finland, if that makes any difference.
Johan
We plan to use the gypsum method, where we fill up between the pipes with gypsum boards and then fill where the pipes are with gypsum paste or some type of mortar.
The house is located in southern Finland, if that makes any difference.
Johan
Hello! Concern with the wooden floor. It's the temperature sensitivity that would worry me. Particle board, which is usually used, is a "deader" material and can handle much higher temperatures. So you probably won't be able to run water as hot as you can with particle board. It's usually said a maximum of 27 degrees for wooden floors. Then the heat must rise through the rest. So with such a low forward temperature as 27 degrees, the floors probably won't be so warm.
I would say that there are no problems at all with running the underfloor heating on the old wooden floor. When talking about underfloor heating and wooden floors, people think of parquet placed on top. If the floor gets too warm, the parquet can gap in the seams and become unsightly. However, this is not a problem with the subfloor, so don't worry about it.
From what I understand, the gypsum method is something that basically only exists in Finland. It probably works well, but it will be difficult to get much feedback on it from anyone other than Finns.
I converted my house to underfloor heating a few years ago and I partly chose to lay EPS in most of the rooms, but in the kitchen, it was routed floor chipboard directly on the old subfloor. If I were to redo the project, I would probably choose to lay floor chipboard everywhere since it builds slightly less in height and gives a slightly sturdier construction. The downside is that it is more work to lay floor chipboard and that it is a bit more expensive.
From what I understand, the gypsum method is something that basically only exists in Finland. It probably works well, but it will be difficult to get much feedback on it from anyone other than Finns.
I converted my house to underfloor heating a few years ago and I partly chose to lay EPS in most of the rooms, but in the kitchen, it was routed floor chipboard directly on the old subfloor. If I were to redo the project, I would probably choose to lay floor chipboard everywhere since it builds slightly less in height and gives a slightly sturdier construction. The downside is that it is more work to lay floor chipboard and that it is a bit more expensive.
Thank you for your response Janus82.
Yes, I've received a lot of feedback about the plaster method here in Finland, and most consider it a good method. And by good method, I mean affordable and something you can easily fix yourself.
If I had more $$, I would probably choose one of your tips
There are a few mixed opinions about whether I need to place an additional layer of drywall over the tubes or not. Some say you can place the laminate floor directly on the tubes, while others say you need to have a board in between. Do you have any opinions on this?
At least it seems okay to lay the tubes directly on the existing wooden floor.
Johan
Yes, I've received a lot of feedback about the plaster method here in Finland, and most consider it a good method. And by good method, I mean affordable and something you can easily fix yourself.
If I had more $$, I would probably choose one of your tips
There are a few mixed opinions about whether I need to place an additional layer of drywall over the tubes or not. Some say you can place the laminate floor directly on the tubes, while others say you need to have a board in between. Do you have any opinions on this?
At least it seems okay to lay the tubes directly on the existing wooden floor.
Johan
Is it really that much cheaper with plasterboard compared to routed boards? When I fixed up my house, I got a quote for the plasterboard method from a Finnish company that wanted to establish itself in Sweden, and it was more or less the same cost for the material.
As I said, I don't know anything about the plasterboard method and how you should build up over it before laying the floor. But when embedding pipes, it's always important to get a sufficient overpour so the heat is even and doesn't come in hot streaks. The downside of too large an overpour is that it insulates so that you have to have a higher forward temperature, and then you lose one of the big advantages of underfloor heating (low forward temperature gives better COP on the heat pump).
Just because I'm curious, how much does the plasterboard method add to the height? With routed chipboards, there's no problem laying parquet or laminate (at least 14mm) directly on the boards. This means that only a floor height increase of 22mm over the old subfloor is needed.
As I said, I don't know anything about the plasterboard method and how you should build up over it before laying the floor. But when embedding pipes, it's always important to get a sufficient overpour so the heat is even and doesn't come in hot streaks. The downside of too large an overpour is that it insulates so that you have to have a higher forward temperature, and then you lose one of the big advantages of underfloor heating (low forward temperature gives better COP on the heat pump).
Just because I'm curious, how much does the plasterboard method add to the height? With routed chipboards, there's no problem laying parquet or laminate (at least 14mm) directly on the boards. This means that only a floor height increase of 22mm over the old subfloor is needed.
I found only one website that listed prices for grooved chipboard, and they were priced at 30€/m2 (hohho). Gypsum boards intended for flooring go for 8€/m2. However, it takes two layers of these (13mm+13mm). We are planning to use 20mm pipes. If using grooved chipboard, you also need heat distribution plates, which cost about 10€/m2. With the gypsum method, you don't use these. So the price difference should be quite significant.
If I place the water loops directly on the floor and put two gypsum boards next to them and another layer of gypsum board over everything, the floor will rise by 13mm+13mm+13mm + laminate/parquet. With grooved boards, the floor would rise by 22mm for the chipboard + laminate/parquet. We have no problem with the floor rising a bit.
Another advantage of the gypsum method is that you can better choose where the loops should be placed, for example, closer together near windows and exterior walls.
Johan
If I place the water loops directly on the floor and put two gypsum boards next to them and another layer of gypsum board over everything, the floor will rise by 13mm+13mm+13mm + laminate/parquet. With grooved boards, the floor would rise by 22mm for the chipboard + laminate/parquet. We have no problem with the floor rising a bit.
Another advantage of the gypsum method is that you can better choose where the loops should be placed, for example, closer together near windows and exterior walls.
Johan
Now, I'm not going to nag you to change the system, but if you're going to have 3 layers of plasterboard, that'll be a total of 24 EUR per m[SUP]2[/SUP] just for the plasterboards, then there's also the plaster you need around the pipes, what's the cost for that?
In Sweden, you can buy chipboard for 20 EUR per m[SUP]2[/SUP] or alternatively, grooved EPS for 10 EUR per m[SUP]2[/SUP]. For both of these solutions, you would also need heat distribution plates for about 13 EUR per m[SUP]2[/SUP]. The total would then be somewhere around 23-33 EUR per m[SUP]2[/SUP] excluding the tube. Surely you should be able to get roughly the same prices in Finland? Otherwise, there are ferries from your side too.
Regardless of which installation method you choose, you shouldn't worry about placing the loops more densely near windows and exterior walls. My house has only 80mm insulation in the walls, and about half of the windows are classic 2-glass from 1962. I haven't noticed any cold drafts or similar issues at home, even though during winter, it can get down to -20 degrees.
In Sweden, you can buy chipboard for 20 EUR per m[SUP]2[/SUP] or alternatively, grooved EPS for 10 EUR per m[SUP]2[/SUP]. For both of these solutions, you would also need heat distribution plates for about 13 EUR per m[SUP]2[/SUP]. The total would then be somewhere around 23-33 EUR per m[SUP]2[/SUP] excluding the tube. Surely you should be able to get roughly the same prices in Finland? Otherwise, there are ferries from your side too.
Regardless of which installation method you choose, you shouldn't worry about placing the loops more densely near windows and exterior walls. My house has only 80mm insulation in the walls, and about half of the windows are classic 2-glass from 1962. I haven't noticed any cold drafts or similar issues at home, even though during winter, it can get down to -20 degrees.
M
Marcussjogren
Member
· Västra Götaland
· 3 081 posts
Marcussjogren
Member
- Västra Götaland
- 3,081 posts
I believe that tracked chipboards with reflective sheets are the best option to avoid heating the crawl space too much.
It is the surface temperature of the floor that should be max 27C, not the supply temperature. The supply is probably between 45-50C when the floor reaches 27C.
I would also recommend starting the underfloor heating at a low temperature as soon as possible so that the floors do not get shocked if you immediately pump in 40C water. That's what we did, and it created many large movements with some cracks and issues with moldings.
Also, wait to install moldings until after winter as it will look nicest
It is the surface temperature of the floor that should be max 27C, not the supply temperature. The supply is probably between 45-50C when the floor reaches 27C.
I would also recommend starting the underfloor heating at a low temperature as soon as possible so that the floors do not get shocked if you immediately pump in 40C water. That's what we did, and it created many large movements with some cracks and issues with moldings.
Also, wait to install moldings until after winter as it will look nicest
But plasterboard retains heat better than chipboard, which is advantageous if, for example, you want to heat the house at night with cheap electricity. Just a comment from the side in the debate...