Filling crawl space with foam glass / cellular glass / hasopor?
Yes, then it is out of the question as it becomes about twice as expensive, excluding the labor. Yes, I'll do it myself.
As far as I know, there is no organic material except for the soil itself, which is certainly partly topsoil. I haven't dug all the way down to the moraine.
As far as I know, there is no organic material except for the soil itself, which is certainly partly topsoil. I haven't dug all the way down to the moraine.
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The question is also which of the basic types is most moisture-risky, or whatever you want to say.
Sealing the ventilation and filling up with Hasopor should significantly reduce the moisture load from the outside and also make the entire foundation more insulated and therefore warmer = less humid.
The underfloor feels like a riskier construction in my eyes, but at the same time easier to monitor because I can crawl down and see and measure the moisture later, which I won't be able to do in the Hasopor foundation.
Sealing the ventilation and filling up with Hasopor should significantly reduce the moisture load from the outside and also make the entire foundation more insulated and therefore warmer = less humid.
The underfloor feels like a riskier construction in my eyes, but at the same time easier to monitor because I can crawl down and see and measure the moisture later, which I won't be able to do in the Hasopor foundation.
I think one should assume that moisture always enters all constructions, no matter how tight.
The moisture sources one reads about are ground moisture and moisture from ventilation, i.e., outdoor air that comes in.
What is the difference between a crawl space with building plastic on the ground and sealed walls versus a foundation filled with air-permeable material like gravel, leca, or hasopor that is sealed in the same way?
The advantage of filling the space must be the insulation, which makes the subfloor (or whatever one has) warmer and thereby has lower RH. The ground, however, should become colder and have higher RH, but perhaps that doesn't matter much?
If one completely seals the foundation wall, what happens if moisture still comes in (which it does! building plastic is not 100% waterproof against water vapor).
The moisture sources one reads about are ground moisture and moisture from ventilation, i.e., outdoor air that comes in.
What is the difference between a crawl space with building plastic on the ground and sealed walls versus a foundation filled with air-permeable material like gravel, leca, or hasopor that is sealed in the same way?
The advantage of filling the space must be the insulation, which makes the subfloor (or whatever one has) warmer and thereby has lower RH. The ground, however, should become colder and have higher RH, but perhaps that doesn't matter much?
If one completely seals the foundation wall, what happens if moisture still comes in (which it does! building plastic is not 100% waterproof against water vapor).
Building conservationist
· 3 467 posts
I am planning a similar project and got the tip in another thread about sealing the foundation from the inside with clay plastering. It seals against drafts and mice. At the same time, by having the foundation stones covered with clay that can absorb and release moisture, problems with condensation on the foundation stones are prevented when warm air meets cold stone in the winter.
In the instructions for Hasopor, sealing with a membrane against the foundation is recommended (absent in your sketch), but I find this clay method an interesting alternative since it both seals, insulates, and is hygroscopic.
Regarding whether to keep the load-bearing beams or not, I wonder why you think they might need to be removed. You place the Hasopor in the compartments.
In the instructions for Hasopor, sealing with a membrane against the foundation is recommended (absent in your sketch), but I find this clay method an interesting alternative since it both seals, insulates, and is hygroscopic.
Regarding whether to keep the load-bearing beams or not, I wonder why you think they might need to be removed. You place the Hasopor in the compartments.
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Sealing with fabric against the foundation is probably most relevant in new constructions and serves the function of preventing the material from mixing with the soil underneath. The geotextile fabric still lets through all the moisture anyway.
The idea with the Hasopor solution is that ground moisture can travel straight up into the house, while the warm indoor air can help maintain a certain warmth in the upper layer of Hasopor, which decreases the RH. The question is whether the RH stays below 75% in the top 20 cm so that the sill and joists are protected.
I plan to only remove the beams in the bathroom where I will fill the entire foundation with Hasopor and then level it with clay and unglazed tiles. The other floors will keep the beams so that I have something to nail the floorboards into.
The idea with the Hasopor solution is that ground moisture can travel straight up into the house, while the warm indoor air can help maintain a certain warmth in the upper layer of Hasopor, which decreases the RH. The question is whether the RH stays below 75% in the top 20 cm so that the sill and joists are protected.
I plan to only remove the beams in the bathroom where I will fill the entire foundation with Hasopor and then level it with clay and unglazed tiles. The other floors will keep the beams so that I have something to nail the floorboards into.
I don't think you should have clay from the bottom up on the foundation stones because the clay absorbs ground moisture and risks becoming too damp? I believe instead in sealing between the foundation stones with lime mortar so it becomes completely draft-proof. Clay is absolutely good to use as draft sealing between the sill and foundation stone, for example, or as draft sealing if one chooses a blind floor.Sommartorparn said:
Building conservationist
· 3 467 posts
I don't think we're talking about the same kind of fabric. I mean windproof fabric that is placed along the foundation and up a little on the timber. Its purpose is to stop floor drafts. From what I've read about renovating old foundations, you can save on insulation if you succeed in draft-sealing against the foundation and sill. The clay lining can, however, do the same job. When I'm at the computer, I can post links that explain better.pelrik said:
Have no technical advice to give, just wanted to say that your ideas with foam glass, clay, and wooden floors are extremely appealing and very exciting that someone else has such nature-oriented and moisture-working materials in the building plans. Thumbs up, hope it turns out well!
Hello,
Very interesting solution, but perhaps not the best for older foundations.
First, a warning. Insulating a foundation wall/space on the inside will unfortunately make the entire foundation wall colder, especially in winter, and therefore condensation may occur which can damage the bottom sills. The recommendation is therefore that in such cases, the exterior of the foundation wall should be additionally insulated to prevent moisture damage to the sills. Additionally, in some cases, to avoid frost heaving, it may be necessary to lay out ground insulation boards around the house.
As for foundation sills and floor joists, these should, of course, be inspected to repair, strengthen, or replace as needed. If the sills and floor joists are in good condition, likely, nothing more needs to be done.
In this context, however, it may be an idea to take the opportunity to possibly reinforce the floor structure where needed if you plan to build a bathroom with floor tiles, or to install a stove, or a heavy water heater/accumulator tank etc.
I don't think it's a good solution to fill a foundation space with HASopor or any other material.
Firstly, it's not a tried and approved method for older foundations. In theory, with the proposed solution, one would avoid outdoor air entering the foundation that wet organic material, while the insulating effect of HASopor would contribute to warmer floors and lower energy consumption.
However, the problem is that the house is built according to older methods and the foundation construction is therefore as it is. Filling the foundation may lead to future problems with both moisture and rising unpleasant odors, which is bad enough and difficult to remedy without having to empty the foundation of about 36 cubic meters of HASopor and then still having to arrange some form of ventilation and dehumidification.
Crawl spaces built correctly are very good in many ways. A water damage, for example, is usually only local and can be fixed in a few weeks. If you want to move a bathroom or kitchen, new pipes can be laid quickly, etc.
In this case, I would instead focus on first "ground moisture and radon securing" the foundation space and then installing a sorption dehumidifier that also ventilates the foundation somewhat.
If you seal off the vents in a traditional foundation or crawl space to run a simpler type of dehumidifier more efficiently, you will probably end up with quite high radon levels in the foundation over time and likely an unpleasant smell, even if you have covered the ground properly with plastic sheeting. During the winter months, when it is warmer indoors than outdoors, thermal suction occurs in the house that risks drawing up both radon gas and odor if leaks exist, and they often do.
There are many reliable radon membranes on the market, which together with other system details provide very good protection against radon if everything is done correctly, but it's pricey. As I see it, substantial radon membranes are mostly used in new constructions when concrete slabs are to be poured for house constructions.
Regarding potential moisture in the foundation, you should always lay out an age-resistant diffusion-tight (vapor-tight) plastic sheet against the ground in the foundation, which closes as tightly as possible (any soil and organic material must of course be removed first and if you have a base of gravel you can lay out a drainage mat before the plastic to protect it).
The plastic sheet is fastened a bit up on the foundation wall with special tape and adhesive if you're very thorough.
(The plastic sheet, however, will not be able to stop the penetration of radon gas, it is treated and managed by a sorption dehumidifier as mentioned below.)
You then add insulation to the bottom beams in the usual way.
(Note that it is the vapor content of the air, not the relative humidity, that determines the direction of moisture movement. In winter, with, for example, 7 degrees and RH 60% in the foundation and 22 degrees and RH 40% indoors, we have a vapor content of about 3.7 g/cubic meter in the foundation and about 6.5 g/cubic meter indoors. If we were to allow free diffusion/equalization, i.e., not have a diffusion barrier in the subfloor, the relative humidity in the foundation could theoretically become about 105%, meaning the air would precipitate free water in the foundation and when that process starts you've got a "self-playing piano" playing mold and rot boogie.)
Finally, install an effective sorption dehumidifier type ACETEC, which requires sealed vents in the foundation, but which also ventilates the foundation with a slight vacuum. Thus, you gain control over both moisture and radon in the foundation and the house. Just the fact that this type of dehumidifier also circulates about 350 cubic meters of air per hour via 3 outlet pipes means that a significant proportion of any radon daughters will automatically stick to the ground, foundation walls, dust particles, and subfloor because radon daughters (which cause ionizing alpha radiation) are positively charged metal particles that are attracted to "negative surfaces". Such a particle that has stuck is said to be "detached". Most of the remaining radon daughters and radon gas are vented out by the machine.
The dehumidifier comes with a control panel, where you can constantly read the current climate in the foundation.
With such a solution, you can sleep well at night and it will not be particularly expensive either. The installation of the dehumidifier can be done relatively easily by a handy person. However, an electrician should probably pull the necessary power including the circuit breaker to the machine. Once the environment in the foundation has dried, or is dry, the dehumidifier will not need to regenerate the silica gel crystals as often, and thereby not consume much energy either.
Good luck!
Very interesting solution, but perhaps not the best for older foundations.
First, a warning. Insulating a foundation wall/space on the inside will unfortunately make the entire foundation wall colder, especially in winter, and therefore condensation may occur which can damage the bottom sills. The recommendation is therefore that in such cases, the exterior of the foundation wall should be additionally insulated to prevent moisture damage to the sills. Additionally, in some cases, to avoid frost heaving, it may be necessary to lay out ground insulation boards around the house.
As for foundation sills and floor joists, these should, of course, be inspected to repair, strengthen, or replace as needed. If the sills and floor joists are in good condition, likely, nothing more needs to be done.
In this context, however, it may be an idea to take the opportunity to possibly reinforce the floor structure where needed if you plan to build a bathroom with floor tiles, or to install a stove, or a heavy water heater/accumulator tank etc.
I don't think it's a good solution to fill a foundation space with HASopor or any other material.
Firstly, it's not a tried and approved method for older foundations. In theory, with the proposed solution, one would avoid outdoor air entering the foundation that wet organic material, while the insulating effect of HASopor would contribute to warmer floors and lower energy consumption.
However, the problem is that the house is built according to older methods and the foundation construction is therefore as it is. Filling the foundation may lead to future problems with both moisture and rising unpleasant odors, which is bad enough and difficult to remedy without having to empty the foundation of about 36 cubic meters of HASopor and then still having to arrange some form of ventilation and dehumidification.
Crawl spaces built correctly are very good in many ways. A water damage, for example, is usually only local and can be fixed in a few weeks. If you want to move a bathroom or kitchen, new pipes can be laid quickly, etc.
In this case, I would instead focus on first "ground moisture and radon securing" the foundation space and then installing a sorption dehumidifier that also ventilates the foundation somewhat.
If you seal off the vents in a traditional foundation or crawl space to run a simpler type of dehumidifier more efficiently, you will probably end up with quite high radon levels in the foundation over time and likely an unpleasant smell, even if you have covered the ground properly with plastic sheeting. During the winter months, when it is warmer indoors than outdoors, thermal suction occurs in the house that risks drawing up both radon gas and odor if leaks exist, and they often do.
There are many reliable radon membranes on the market, which together with other system details provide very good protection against radon if everything is done correctly, but it's pricey. As I see it, substantial radon membranes are mostly used in new constructions when concrete slabs are to be poured for house constructions.
Regarding potential moisture in the foundation, you should always lay out an age-resistant diffusion-tight (vapor-tight) plastic sheet against the ground in the foundation, which closes as tightly as possible (any soil and organic material must of course be removed first and if you have a base of gravel you can lay out a drainage mat before the plastic to protect it).
The plastic sheet is fastened a bit up on the foundation wall with special tape and adhesive if you're very thorough.
(The plastic sheet, however, will not be able to stop the penetration of radon gas, it is treated and managed by a sorption dehumidifier as mentioned below.)
You then add insulation to the bottom beams in the usual way.
(Note that it is the vapor content of the air, not the relative humidity, that determines the direction of moisture movement. In winter, with, for example, 7 degrees and RH 60% in the foundation and 22 degrees and RH 40% indoors, we have a vapor content of about 3.7 g/cubic meter in the foundation and about 6.5 g/cubic meter indoors. If we were to allow free diffusion/equalization, i.e., not have a diffusion barrier in the subfloor, the relative humidity in the foundation could theoretically become about 105%, meaning the air would precipitate free water in the foundation and when that process starts you've got a "self-playing piano" playing mold and rot boogie.)
Finally, install an effective sorption dehumidifier type ACETEC, which requires sealed vents in the foundation, but which also ventilates the foundation with a slight vacuum. Thus, you gain control over both moisture and radon in the foundation and the house. Just the fact that this type of dehumidifier also circulates about 350 cubic meters of air per hour via 3 outlet pipes means that a significant proportion of any radon daughters will automatically stick to the ground, foundation walls, dust particles, and subfloor because radon daughters (which cause ionizing alpha radiation) are positively charged metal particles that are attracted to "negative surfaces". Such a particle that has stuck is said to be "detached". Most of the remaining radon daughters and radon gas are vented out by the machine.
The dehumidifier comes with a control panel, where you can constantly read the current climate in the foundation.
With such a solution, you can sleep well at night and it will not be particularly expensive either. The installation of the dehumidifier can be done relatively easily by a handy person. However, an electrician should probably pull the necessary power including the circuit breaker to the machine. Once the environment in the foundation has dried, or is dry, the dehumidifier will not need to regenerate the silica gel crystals as often, and thereby not consume much energy either.
Good luck!
Interesting points!
I wonder what you mean, that it can cause moisture and odor if you fill up the foundation? In an unventilated torpargrund, it shouldn't make a difference in humidity whether the space between the ground and the floorboards is filled with air or Hasopor.Real North said:
If you don't have a problem with radon, you shouldn't get a concentration of radon either when running a dehumidifier, right? Here you're also talking about a thermal suction force that moves in the opposite direction of the diffusion you mention a little later (the example with humidity differences). Is that correct? I'm a bit confused about which way the movements actually occur. If radon and odor are to be drawn into the house, it presumably happens via air movements, or have I misunderstood this?Real North said:
This can't be right. Houses have been built for hundreds of years without plastic sheeting. What you're saying sounds good, but I'm a bit skeptical when you so confidently advocate plastic and dehumidifiers for houses that have functioned for 100-200 years without them.Real North said:
You don't happen to sell those, do you?Real North said:
Building conservationist
· 3 467 posts
Here is the sketch from Ekologiska byggvaruhusets page showing how to fill a foundation with Hasopor and place a wind barrier along the foundation and a bit up on the sill:
http://www.ekologiskabyggvaruhuset.se/Userfiles/Image/products/801_972_2.jpg
http://www.ekologiskabyggvaruhuset.se/Userfiles/Image/products/801_972_2.jpg
Building conservationist
· 3 467 posts
Here is the thread from this forum where we discuss clay plastering of the foundation.
https://www.byggahus.se/forum/byggnadsvard/216997-isolera-mullbank-forslag-2.html
There are several threads about this which you can find if you search 'hasopor' on the forum.
As mentioned, I myself have not yet done this and am still looking for information for my own part.
https://www.byggahus.se/forum/byggnadsvard/216997-isolera-mullbank-forslag-2.html
There are several threads about this which you can find if you search 'hasopor' on the forum.
As mentioned, I myself have not yet done this and am still looking for information for my own part.
Building conservationist
· 3 467 posts
Real North,
You write that filling the foundation with Hasopor is not a tested method for older houses. However, it is precisely in building conservation circles and among eco-builders that this method is recommended. See, for example, Varis Bokalders' article in Gård och Torp:
http://www.gardochtorp.se/hall-kylan-borta-med-ratt-isolering.aspx?article=5861
OK, just Hasopor is a relatively new material, Leca balls have been used longer, but the principle is the same. If there had been problems with this solution, shouldn't they be well known by now?
Can you explain more precisely where the condensation risks forming? Am I correct in my belief that clay plastering the foundation from the inside and a layer of clay between the Hasopor and the wooden floor would prevent any condensation because the clay is both insulating and hygroscopic?
You have a point that one should plan for reinforcement of the foundation if planning to place something heavy. It's reasonable to do this when the foundation is being redone. Doesn't Hasopor handle weight quite well? It's used as a base in road construction. Can't Hasopor be used as a base for a storage tank and others?
Then regarding radon. You write as if it is obvious that all houses must be protected against radon. Can't one start by determining if there is radon in the ground and then adapt the measures accordingly?
Your advice to insulate the foundation from the outside doesn't feel very building conservation friendly.....
You write that filling the foundation with Hasopor is not a tested method for older houses. However, it is precisely in building conservation circles and among eco-builders that this method is recommended. See, for example, Varis Bokalders' article in Gård och Torp:
http://www.gardochtorp.se/hall-kylan-borta-med-ratt-isolering.aspx?article=5861
OK, just Hasopor is a relatively new material, Leca balls have been used longer, but the principle is the same. If there had been problems with this solution, shouldn't they be well known by now?
Can you explain more precisely where the condensation risks forming? Am I correct in my belief that clay plastering the foundation from the inside and a layer of clay between the Hasopor and the wooden floor would prevent any condensation because the clay is both insulating and hygroscopic?
You have a point that one should plan for reinforcement of the foundation if planning to place something heavy. It's reasonable to do this when the foundation is being redone. Doesn't Hasopor handle weight quite well? It's used as a base in road construction. Can't Hasopor be used as a base for a storage tank and others?
Then regarding radon. You write as if it is obvious that all houses must be protected against radon. Can't one start by determining if there is radon in the ground and then adapt the measures accordingly?
Your advice to insulate the foundation from the outside doesn't feel very building conservation friendly.....
Regarding radon, I'm considering laying a drainage pipe in the gravel layer. This can then be led to pipes connected to the chimney, thus utilizing natural draft. This should largely remove both radon and any soil moisture, right? But what happens if the foundation is airtight? Wouldn't air from the house be drawn down through the floor and the Hasopor and then into the drainage pipe? Would it be better to have the openings of the drainage pipes outside to allow airflow, or would that risk drawing air into the foundation instead? I'm thinking of having a drainage pipe for each room that then opens into the same channel in the chimney.
I think a radon barrier would be difficult in my case as I have some unevenness in the foundation, and the chimney foundation resembles a stone pile.
I think a radon barrier would be difficult in my case as I have some unevenness in the foundation, and the chimney foundation resembles a stone pile.
