Hello everyone!
As the title suggests, I'm considering how to insulate a garden shed and a summer cabin that will be unheated when not in use throughout the year. They will temporarily be heated the few times we are there during autumn/winter/spring.
The reason for the question is that I heard from a friend over the weekend that you should consider whether you have stone/mineral wool insulation or some form of wood fiber wool. Additionally, you should or shouldn't have vapor barrier plastic; I recall that you shouldn't have it in my case. The problems that could arise are if moisture gets trapped in the insulation somehow, if I understood correctly.
Does anyone have full insight into what I should use? The garden shed is a Jabo Smara, meaning wooden facade on wooden studs. It is currently completely uninsulated apart from the floor, no interior paneling installed, only wind barrier between outer walls and frame structure. The floor was insulated during assembly with, from top to bottom - floorboards, vapor barrier plastic, insulation (some sort of mineral wool, I believe), fiberboard. The roof consists of - concrete tiles, battens, tar paper, sheathing of tongue-and-groove boards. The shed stands on pillars with 2-5 decimeters of air under the floor. How should I proceed?
The cabin currently consists of exterior walls, frame structure, and a metal roof, some form of sheathing paper/tar paper, sheathing of tongue-and-groove boards, trusses. There is currently no floor at all. It will stand on pillars with about half a meter of air under the floor. What should I do here?
For both buildings, I want to insulate adequately to be able to heat it up for a few days/nights during winter. Heating costs are a lower priority than actually being able to heat with, for example, one or two electric radiators in the shed and a stove/radiator in the house. The house may have some form of underfloor heating, probably a thin mat with electrical wires. This will be solely for comfort heating and not for heating the house.
As mentioned, does anyone know how I should think? Tips, links, or other suggestions are welcome!
Best regards,
ToRy
As the title suggests, I'm considering how to insulate a garden shed and a summer cabin that will be unheated when not in use throughout the year. They will temporarily be heated the few times we are there during autumn/winter/spring.
The reason for the question is that I heard from a friend over the weekend that you should consider whether you have stone/mineral wool insulation or some form of wood fiber wool. Additionally, you should or shouldn't have vapor barrier plastic; I recall that you shouldn't have it in my case. The problems that could arise are if moisture gets trapped in the insulation somehow, if I understood correctly.
Does anyone have full insight into what I should use? The garden shed is a Jabo Smara, meaning wooden facade on wooden studs. It is currently completely uninsulated apart from the floor, no interior paneling installed, only wind barrier between outer walls and frame structure. The floor was insulated during assembly with, from top to bottom - floorboards, vapor barrier plastic, insulation (some sort of mineral wool, I believe), fiberboard. The roof consists of - concrete tiles, battens, tar paper, sheathing of tongue-and-groove boards. The shed stands on pillars with 2-5 decimeters of air under the floor. How should I proceed?
The cabin currently consists of exterior walls, frame structure, and a metal roof, some form of sheathing paper/tar paper, sheathing of tongue-and-groove boards, trusses. There is currently no floor at all. It will stand on pillars with about half a meter of air under the floor. What should I do here?
For both buildings, I want to insulate adequately to be able to heat it up for a few days/nights during winter. Heating costs are a lower priority than actually being able to heat with, for example, one or two electric radiators in the shed and a stove/radiator in the house. The house may have some form of underfloor heating, probably a thin mat with electrical wires. This will be solely for comfort heating and not for heating the house.
As mentioned, does anyone know how I should think? Tips, links, or other suggestions are welcome!
Best regards,
ToRy
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Okay, yesterday I discovered that under this box where you write new posts, there is a box that suggests some similar threads. Very convenient! Why haven't I noticed it before? Anyway, I read through these and came to the following conclusion:
If you're going to mothball a building like the one I am asking about above, you should not have plastic inside the insulation, but the house should be able to breathe. Both of these houses will have vents for natural ventilation and no mechanical ventilation whatsoever. Will it be okay if I have, from the inside; plasterboard, OSB, insulation, building paper, and cladding? No one in the other threads has mentioned other insulation materials apart from mineral wool so I assume this has a very marginal significance and maybe is just someone's unsupported idea?
The garden shed I bought - a Jabo Smara - already has the building paper installed between the wall studs and outer cladding but there's no air gap. Will I have problems if I put the insulation directly against the building paper?
Another thing is that the floor was insulated when the garden shed was assembled. Now, from the inside, there is; tongue and groove wood, plastic, insulation, and fiberboard. Is it a bad idea to leave the plastic, or is it enough if the walls can breathe along with the vents?
If you're going to mothball a building like the one I am asking about above, you should not have plastic inside the insulation, but the house should be able to breathe. Both of these houses will have vents for natural ventilation and no mechanical ventilation whatsoever. Will it be okay if I have, from the inside; plasterboard, OSB, insulation, building paper, and cladding? No one in the other threads has mentioned other insulation materials apart from mineral wool so I assume this has a very marginal significance and maybe is just someone's unsupported idea?
The garden shed I bought - a Jabo Smara - already has the building paper installed between the wall studs and outer cladding but there's no air gap. Will I have problems if I put the insulation directly against the building paper?
Another thing is that the floor was insulated when the garden shed was assembled. Now, from the inside, there is; tongue and groove wood, plastic, insulation, and fiberboard. Is it a bad idea to leave the plastic, or is it enough if the walls can breathe along with the vents?
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Hello! I will be facing a similar situation with the construction of a storage room that should be heated to frost-free but not more. I think like this (I'm not fully sure about this, so someone else can confirm or refute it):
You shouldn't use diffusion-tight plastic because under certain weather conditions, condensation may form. For example, when the outside temperature goes from -20 to +5. Then it will be many degrees below zero inside when it's +5 outside. The outside air contains much more water vapor (higher absolute humidity). When that air cools against the plastic inside the wall (since it’s still several degrees below zero inside), it condenses and you get moisture in the wall. Therefore, you must always have it warmer inside than outside if you have plastic in the walls.
I don't think rock wool or cellulose insulation makes a big difference. Cellulose can bind some moisture, but probably doesn't help with the basic problem.
I believe that ventilation is necessary to create equilibrium in temperature and humidity inside/outside relatively quickly. Otherwise, there's a certain risk of condensation somewhere in the wall even without plastic.
Reducing air movement in wall insulation with, for example, wind barriers (diffopen) outside the insulation is probably good for retaining heat when it is heated. It shouldn't affect moisture issues. I’m not sure if it might be smart to also place a wind barrier on the inside instead of plastic?
A small solar air heater that provides ventilation and some warmth fits perfectly in a cabin like yours.
You shouldn't use diffusion-tight plastic because under certain weather conditions, condensation may form. For example, when the outside temperature goes from -20 to +5. Then it will be many degrees below zero inside when it's +5 outside. The outside air contains much more water vapor (higher absolute humidity). When that air cools against the plastic inside the wall (since it’s still several degrees below zero inside), it condenses and you get moisture in the wall. Therefore, you must always have it warmer inside than outside if you have plastic in the walls.
I don't think rock wool or cellulose insulation makes a big difference. Cellulose can bind some moisture, but probably doesn't help with the basic problem.
I believe that ventilation is necessary to create equilibrium in temperature and humidity inside/outside relatively quickly. Otherwise, there's a certain risk of condensation somewhere in the wall even without plastic.
Reducing air movement in wall insulation with, for example, wind barriers (diffopen) outside the insulation is probably good for retaining heat when it is heated. It shouldn't affect moisture issues. I’m not sure if it might be smart to also place a wind barrier on the inside instead of plastic?
A small solar air heater that provides ventilation and some warmth fits perfectly in a cabin like yours.
The reason I choose cellulose insulation is that it provides better protection against moisture than mineral wool. Mineral wool allows air to travel, which introduces moisture into the mineral wool. Cellulose can be packed better, reduces air flow, and thus moisture. In places that are not well-tempered, mineral wool is inferior. Solving the problems of mineral wool with "perfect" wind protection is tedious, and more of a countermeasure than a good solution.ToRy said:
--- Mats ---
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If you're only going to heat the houses on a single day each year, it's worth considering whether you need to insulate them at all. The risk is that the insulation might cause more problems than it improves comfort.
If you have warmth on one side and cold on the other, air will at times flow from the warm side to the cold one. This results in condensation in the insulation. The least that can happen is a reduction in insulation capability (if not complete loss), more condensation occurs, and it might freeze into a large ice block inside the wall. If you're lucky, nothing else happens; the moisture will dry up when it gets warm. If you're unlucky, it begins to mold.
One method to reduce the airflow into the insulation is to maintain a permanent underpressure inside the house. The downside is that you constantly have an influx of cold outdoor air. In a larger house, this is solved with an FTX unit, but that's not reasonable in a small cabin.
You can forget the idea that the house should "breathe." It’s a buzzword without any technical basis. If you choose to insulate, I would recommend placing diffusion-tight plastic on the inside. Otherwise, you'll certainly get condensation in the insulation when you heat the house. With the plastic, you only have the specific case when it quickly becomes warm outside but still cold inside to worry about. But then it's warm outside, so there's a chance it will dry up.
Also, read the threads on air solar heaters. It could be a way to get it warm and ventilated inside at a low cost. There are ready-made ones available for purchase if you don't want to deal with it yourself. Like this one: http://www.byggmax.com/se-sv/byggva...ppvarmning/solpaneler/64120005/luftsolfangare
If you have warmth on one side and cold on the other, air will at times flow from the warm side to the cold one. This results in condensation in the insulation. The least that can happen is a reduction in insulation capability (if not complete loss), more condensation occurs, and it might freeze into a large ice block inside the wall. If you're lucky, nothing else happens; the moisture will dry up when it gets warm. If you're unlucky, it begins to mold.
One method to reduce the airflow into the insulation is to maintain a permanent underpressure inside the house. The downside is that you constantly have an influx of cold outdoor air. In a larger house, this is solved with an FTX unit, but that's not reasonable in a small cabin.
You can forget the idea that the house should "breathe." It’s a buzzword without any technical basis. If you choose to insulate, I would recommend placing diffusion-tight plastic on the inside. Otherwise, you'll certainly get condensation in the insulation when you heat the house. With the plastic, you only have the specific case when it quickly becomes warm outside but still cold inside to worry about. But then it's warm outside, so there's a chance it will dry up.
Also, read the threads on air solar heaters. It could be a way to get it warm and ventilated inside at a low cost. There are ready-made ones available for purchase if you don't want to deal with it yourself. Like this one: http://www.byggmax.com/se-sv/byggva...ppvarmning/solpaneler/64120005/luftsolfangare
Wow, why even ask? 
Building/renovating a house seems to be quite the science. You get diametrically different answers no matter what you ask. :x However, THANK YOU for the answers!
Okay, first of all; the "big" house will certainly get a solar air heater of some kind when it's finished, not sure about the "friggebod," but maybe we should consider it there too?
Both buildings will have vents for natural ventilation, so the problem with a large temperature difference between outside and inside should be quite sporadic?
Anyway, it doesn't seem like I need to worry too much about the type of insulation, so we'll go with mineral.
I still want to insulate them. Today, we sometimes heat the "friggebod" because we use it as a kitchen and dining room during the renovation, and we have two heaters of 2000W, one of which runs almost continuously when it drops below zero outside.
Plastic or no plastic, opinions really seem to differ a lot there. Maybe it's one of those things that's hard to generalize about? One thing I'm wondering; those who advocate NOT using plastic argue that warm moisture from outside can condense on the cold plastic. If you don't use plastic, won't it just condense on the cold OSB/gypsum instead?
I don't quite understand this about air flowing through the insulation when there is a temperature difference. Isn't the idea of insulation precisely that the air should be contained and NOT conduct heat/cold further? I understand there will be some movement, but exterior paneling, wind barrier, and interior paneling should effectively stop air from moving more than marginally, right? Or is it just a way to express it? If you have open vents, wouldn't any pressure difference due to temperature changes even out through these primarily?
Well, there is plenty of time left before it needs to be insulated anyway. I'll just have to mull over this for a while longer. THANK YOU once again for the answers so far! Feel free to share more!
Best regards,
ToRy
Building/renovating a house seems to be quite the science. You get diametrically different answers no matter what you ask. :x However, THANK YOU for the answers! Okay, first of all; the "big" house will certainly get a solar air heater of some kind when it's finished, not sure about the "friggebod," but maybe we should consider it there too?
Both buildings will have vents for natural ventilation, so the problem with a large temperature difference between outside and inside should be quite sporadic?
Anyway, it doesn't seem like I need to worry too much about the type of insulation, so we'll go with mineral.
I still want to insulate them. Today, we sometimes heat the "friggebod" because we use it as a kitchen and dining room during the renovation, and we have two heaters of 2000W, one of which runs almost continuously when it drops below zero outside.
Plastic or no plastic, opinions really seem to differ a lot there. Maybe it's one of those things that's hard to generalize about? One thing I'm wondering; those who advocate NOT using plastic argue that warm moisture from outside can condense on the cold plastic. If you don't use plastic, won't it just condense on the cold OSB/gypsum instead?
I don't quite understand this about air flowing through the insulation when there is a temperature difference. Isn't the idea of insulation precisely that the air should be contained and NOT conduct heat/cold further? I understand there will be some movement, but exterior paneling, wind barrier, and interior paneling should effectively stop air from moving more than marginally, right? Or is it just a way to express it? If you have open vents, wouldn't any pressure difference due to temperature changes even out through these primarily?
Well, there is plenty of time left before it needs to be insulated anyway. I'll just have to mull over this for a while longer. THANK YOU once again for the answers so far! Feel free to share more!
Best regards,
ToRy
This is the case in all areas where there is either ignorance, many different situations, a lot of money at stake, or a difference between theory and practice. Insulation and plastic are two typical examples of this. There are many materials and many methods because there are many situations, various focuses, and different beliefs about what is right. If there were a completely correct hundred percent valid answer, it would have been simpler. Then either fiberglass or cellulose would no longer be used.ToRy said:
Regarding plastic, as with many other things, its advantage is its disadvantage. It seals against condensation as long as the condensation is on the right side. This means it's said that it's not as bad with condensation on the gypsum side as it is with condensation on the mold-prone insulating material. (Anyone who has torn down old houses with fiberglass has seen how mold-prone it is). But if the condensation comes from the wrong direction, the disadvantage of plastic is that it retains the condensation (vapor-open plastic lets through vapor, but not water). If it also happens that the house or the attachment of the plastic is not perfect, there will furthermore be places where the cold air comes inside the plastic regardless of what is the warm side. Same problem again, but on a smaller scale.
You don't even have to stick to the original problem with plastic to see its disadvantages. In the ceiling of a bathroom, you will get more mold inside if there is plastic above the ceiling that prevents steam from the shower/bath from leaving the ceiling. One way to solve this is more ventilation, but again, plastic has been a factor whose disadvantages must be compensated for.
When you look at cellulose insulation, it's important to approach it from the "non-Swedish traditional perspective" if you want to have complete information. An example is that abroad, cellulose insulation is enclosed with insulweb or other types of netting, while here it is often combined with plastic or wind paper (which is also waterproof). The latter decreases the advantage by combining it with another problem area.
If you are interested in finding a less biased version, search for "cellulose insulation" on Google, and you will find a lot about where it is considered better than fiberglass.
--- Mats ---
I have a bit to think about... Checked the prices of cellulose compared to mineral wool. Not a fun read. Found prices at Cremab which were 78.75 per sqm for 45mm insulation. 45mm mineral wool at Byggmax is 18.45 per sqm. For the shed, this would mean about 3100 (plus shipping) versus 730 (plus possible plastic) for the walls. Maybe it's worth it anyway...? In the end, once insulated and furnished, the shed will have cost 40-50 thousand. Then a couple of thousand extra isn't too bad compared to just looking at the insulation cost separately...
A couple of other things to consider:
The walls, as mentioned, came in modules with windproofing already mounted, without an air gap between the outer panel and the windproofing. Should I create a gap when I insulate?
The studs, I believe, are 70 mm. Should I add a 45 across these, partly to reduce the thermal bridging effect of the studs, and partly to build up the insulation a bit? Maybe it's sufficient for what I'll use the shed for?
Best regards,
ToRy
A couple of other things to consider:
The walls, as mentioned, came in modules with windproofing already mounted, without an air gap between the outer panel and the windproofing. Should I create a gap when I insulate?
The studs, I believe, are 70 mm. Should I add a 45 across these, partly to reduce the thermal bridging effect of the studs, and partly to build up the insulation a bit? Maybe it's sufficient for what I'll use the shed for?
Best regards,
ToRy
Right now, they charge a lot extra for cellulose insulation. The market price often makes it expensive when someone has a product that can be sold at a higher price because it is considered to offer something that another product does not. Additionally, there is less availability of related products in Sweden, as many sell cellulose insulation as a service. If I were to insulate a house that isn't always heated, I would use cellulose despite the cost. My alternative would be to skip insulation. Overall, it's not that much more money in total, but it's more hassle.ToRy said:Have a bit to think about... Checked the prices of cellulose compared to mineral wool. Not a fun read. Found prices at Cremab that were 78.75 per sqm for 45mm insulation. 45mm mineral wool at Byggmax is 18.45 per sqm. For the shed, this would mean approximately 3100
Windproof paper typically means diffusion-open plastic. Having it against the outer panel doesn't matter in itself. What can be debated is having plastic in something that isn't always heated and yet insulated (and this is something that will be debated for years). The alternative is to seal all the gaps in the walls without plastic (you want it windproof and rain-protected). It's a lot of work. The least work is to skip insulation, but you want to avoid that.
I would choose to try to calculate it. How much do you save per year on insulation? If it's enough, insulate, and insulate thick enough (and how thick you get from a calculation). If it isn't profitable according to your calculation for the warmth you want there during the time you want it, skip insulation. If it turns out you can't have as much heat as you want without insulation, and that's important, insulate despite the cost, and again let the calculation show if it's worth it to insulate extra when you're insulating anyway.
--- Mats ---
The cost of cellulose is, as mentioned, a couple of thousand more than for mineral, and in the big picture, it's not that much, as mentioned. It's better that it's done correctly than cheaply.
The wind barrier is a perforated white layer that feels like paper but could possibly be plastic, hard to say. I can check the product name next time I'm there and google it, of course.
It's not the heating economy itself that makes me want to insulate; I'm more interested in getting a shed that can be heated up relatively quickly and kept warm without having too many radiators and, above all, no fans. It's more from a comfort point of view. The shed is intended as a guesthouse, and it's not so fun to have a fan humming or a radiator that makes it 32 degrees in one end and 15 degrees in the other. Hence the insulation. I'm sure I could heat the shed on many winter nights for the money it costs to insulate, but as I said, it's not about the money...
Thanks for all the input, everyone!
The wind barrier is a perforated white layer that feels like paper but could possibly be plastic, hard to say. I can check the product name next time I'm there and google it, of course.
It's not the heating economy itself that makes me want to insulate; I'm more interested in getting a shed that can be heated up relatively quickly and kept warm without having too many radiators and, above all, no fans. It's more from a comfort point of view. The shed is intended as a guesthouse, and it's not so fun to have a fan humming or a radiator that makes it 32 degrees in one end and 15 degrees in the other. Hence the insulation. I'm sure I could heat the shed on many winter nights for the money it costs to insulate, but as I said, it's not about the money...
Thanks for all the input, everyone!
I have finally made a decision about the "friggebod"! It will be 70mm cellulose inside the existing wind barrier, then OSB, and finally gypsum. That's how it will be unless someone can provide "proof" that it's wrong. I've also started thinking about electric heating in the floor, although I haven't yet looked into the cost. It can't be too outrageously expensive for 15 sqm...? Or actually 12 sqm since the back gable will be an uninsulated storage room....
However, another question arises, but it concerns how the electrical wiring should be done, so I'll move that to the electrical section instead.
Thanks for all the comments!
Best regards,
ToRy
However, another question arises, but it concerns how the electrical wiring should be done, so I'll move that to the electrical section instead.
Thanks for all the comments!
Best regards,
ToRy
Would not have chosen electric underfloor heating under these conditions: "a small shed or summer cottage that will be unheated during the periods they are not in use, year-round. So they will be temporarily heated the few times we are there in autumn/winter/spring."
If you have a regular wooden joist structure with floating floor installation, I would have chosen regular radiators. Clearly the quickest way to get warm on the occasions you visit your cottage. But consider it in the bathroom or hallway, which we do in our vacation home, but then on a concrete slab and tiles in the hallway.
If you have a regular wooden joist structure with floating floor installation, I would have chosen regular radiators. Clearly the quickest way to get warm on the occasions you visit your cottage. But consider it in the bathroom or hallway, which we do in our vacation home
, but then on a concrete slab and tiles in the hallway.The floor heating is primarily for comfort in that case, not for heating. I hate cold floors! I thought that in combination with smaller radiators, it would be an alternative to more/larger radiators. The floor is/will be a wooden joist construction with 120 mm insulation (unfortunately mineral, insulated during construction and before thoughts on whether to keep the space cold), a wooden subfloor, and eventually some click flooring or similar. We have considered vinyl flooring because it should be easy to clean plus no risk of spilled liquid seeping into a floor that then gets cold and doesn't dry, but maybe there's no risk with a properly installed click floor...? How is it with underfloor heating in such a construction; does the heat penetrate just as easily downwards as upwards? Could this be remedied with some foil or similar?
I thought that in combination with smaller radiators, it would be an alternative to more/larger radiators. The floor is/will be a wooden joist construction with 120 mm insulation (unfortunately mineral, insulated during construction and before thoughts on whether to keep the space cold), a wooden subfloor, and eventually some click flooring or similar. We have considered vinyl flooring because it should be easy to clean plus no risk of spilled liquid seeping into a floor that then gets cold and doesn't dry, but maybe there's no risk with a properly installed click floor...? How is it with underfloor heating in such a construction; does the heat penetrate just as easily downwards as upwards? Could this be remedied with some foil or similar?