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moisture
Moisture
Q: Is a plastic sheet always required on the inside of a wall structure?
A: Yes, but primarily as an air barrier; not a moisture barrier. Without plastic sheets a structure with light stone wool would be all too permeable, with draughts indoors and leaks as a consequence. Ventilation is used for ensuring indoor air quality.
The basement walls are an exception. No air barrier is required, and a plastic sheet can cause the structure to become moist on the outside; so moist that it can cause problems. No plastic sheets are to be used in the basement.
Q: Should all basement walls be provided with a moisture barrier on the outside?
A: No. Moisture barriers are only required when there is high water pressure on the wall. If the wall is to be insulated on the outside, PAROC GRS 30 will provide adequate protection both as thermal insulation and as a moisture barrier.
Q: Can PAROC GRS be used for insulating piping or other structures in the ground?
A: No! PAROC GRS 30 will only work when one side is warm, i.e. when placed on a basemen wall or a a slab on the ground.
Q: How does wet stone wool work?
A: This is one of stone wool's many unique characteristics! Stone wool can retain moisture, it can dry and return to "business as usual". When no more moisture enters stone wool, and the conditions are right, stone wool will dry fairly quickly and then return to its original state.
Roof insulation that has become wet time and time again can lose some of its mechanical strength. Once dry the material will, however, insulate heat normally.
Ventilated insulation is recommended to be used in flat roofs when there is a big risk that the roof structure might get wet during the construction. We also recommend ventilated insulation in cases when the moisture content of indoor climate is very high.
> More about moisture and stone wool
Q: Are slabs or timber required on the ground for floor construction?
A: The foundation is "traditionally" the most damage-prone part of a building. Many instances o damage to structures due to timber and concrete etc. The fact is that both a slab on the ground and a suspended foundation will work. Provided they are built correctly.
Slab on the ground: The best alternative is insulation – primarily stone wool – on the slab's underside. Timber should never be in contact with concrete. A thin floating floor on the topside is good choice for comfort.
Suspended ground floor: Over a century old, the principle is based on the fact that heat radiates into the crawl space through the floor and from the fire place foundation extending to the ground. In other words, the modern foundation should be ventilated with indoor air in order to be comparable with the methods used in the "good old days".
Well insulated floor joists and insufficient ventilation during summer can cause mould in a crawl space ventilated with outdoor air.
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fire
Fire
Q: How do various insulating materials work with regards to fire safety?
A: A material has to be inorganic to be classified as incombustible. Materials made of plastic or cellulose material are organic and thus combustible. Combustibility, or actually flammability, can be reduced with the reduced with additivies.
Once these materials burn, the fire can become even more intense.
Only inorganic materials can contribute to the fire protection of a structure.
Stone wool is inorganic and hence non-flammable.
> More about fire and stone wool
Q: What affects the level of fire protection and therefore the choice of materials in various structures?
A: Building authorities in each country have regulations regarding the fire protection for various types of buildings.
Insurance companies affect the fire protection and choice of material indirectly with their fire insurance premius. There are no official standardised rules applied by all insurance companies. It is a good idea to contact your own insurance company when a new building is being planned.
Q: What critical aspects are there with regards to practical fire protection?
A: A chain is only as strong as its weakest link! The classified structures are ideal cases. In practice wiring, ventilation ducts etc. penetrate the structure. It is of utmost importance to make these lead-throughs and to make them as fire proof as possible.
Q: Does only the choice of classified structures – walls, roofs etc. – affect the level of fire protection?
A: Classified structures prevent fire from spreading from one part of a building to another. You should, however, also choose classified coatings for escape routes. Fire protection is a matter of saving lives, i.e. occupants should be able to escape if and when a fire breaks out.
Q: I am in the process of building a boiler room with brick walls. The building inspector demands that the ceiling must conform to a 60 min fireproof requirement. I have got wooden beams on my ceiling. I cannot use concrete or bricks. Is there anything I can do?
A: Not to worry. The problem is easily solved. Fire resistance class REI 60 that the building inspector means, can be obtained for a normal wooden ceiling by using stone wool structures. A steel wire is attached to the bottom surface of the roof supports horizontally in relation to the supports, e.g. a 1-2 mm wire nailed to the bottom of k 300 mm supports. The purpose of the wire is to keep the insulation in place even if the lower structure is destroyed by fire. After that you can proceed as normal; a vapour barrier or an air block, supporting rails 45x45 k 400 and on the inside double Gyproc GN 13. Finally, use a 300 mm PAROC UNS 37 as thermal insulation on the top side.
Q: I am building an extension to an industrial building in Finland and I have now come across the problem of obtaining a fire resistance time of 60 mins in the wall between the old building and the new building. The wall is made of wood, with a 150 mm frame structure, Gyproc on the inside and bitulite wind-proofing. There is presumably glass wool inside the wall. Is it possible to use the old wall or will I have to build a completely new one?
A: In the case of a non-structural wall with a maximum height of 3.3 m, the procedure is as follows: remove the bitulite and the glass wool. Use PAROC UNS 37 as insulation and replace the bitulite with Gyproc. That will give you an EI 60 wall. In the case of a structural wall, the procedure goes like this: disassemble as above. Replace the glass wool with PAROC UNS 37 slabs. Replace the bitulite with double Gyproc and add an extra Gyproc slab on the other side. This process creates a REI 60 wall.
Q: What wool do I need to obtain a fire resistance class of 90 mins for a steel block?
A: The product is called PAROC FPS 14. For defining the thickness of the wool more information about the insulation target is required. We would need to know the type of the block, the cross-sectional measurements and the design temperature. The installation is the most critical factor and there are instruction relating to it in the type approval.
> Fire protection of steel structures
Q: A fire inspector stumbled across the loft of our terraced house and found inadequacies. Apparently there are holes big enough for a Kozak hat to go through (and should not be able to) in the fire stop between the flats of the loft and inside the brick ceiling. He recommended putting fire wool in the gaps. What is fire wool and are there any other good ways?
A: The so-called fire wool is PAROC FPS 14, which is a hard wool slab. It is easy to cut into carefully measured pieces even up in a cramped loft and the pieces are then placed tightly into the aforementioned gaps. This is definitely the easiest way to improve the fire stop. All types of stone wool are fire-resistant so you can also fill the gaps with soft stone wool. In this case the wool must be packed in so tightly that it will stay in place if the building catches fire and remains sufficiently compact to stop the hot fire gases from penetrating. If this is not done and the house next door catches fire, the fire is guaranteed to spread to your house as well. In cases like these the fire will spread with relative speed throughout the whole terrace of houses.
Q: How can I improve the fire resistance properties of the bottom side of a hollow slab when the requirement is a fire resistance class of 120 mins? This is in connection with a requirement resulting from the changing of the purpose of the building.
A: The requirement can be met by using the 50 mm PAROC FPS 14 fire stop slab. A minimum of 8 mechanical attachments are required per slab. The installation instructions can be found on our website. By using a thicker slab it is possible to reach a fire resistance class of 240 mins. The idea of the fire stop is to prevent the heating of the steel cords situated at the bottom of the hollow slab, which would make them lose their strength properties before the required period of time is up.
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roofs
Roofs
Q: How large can a gap in a trapeze-profiled steel sheet be so as to avoid the stone wool breaking?
A: Paroc have a table which lists the maximum distances for various insulation material thicknesses.
Q: Should a low-sloping roof be insulated with one or two layers?
A: Both alternatives are possible. Paroc recommends the use of two layers, as there are no continous seams, and the entire roof will be flatter. There is less risk for damages or defects when using two layers.
Q: Are air barriers / vapour barriers required in all roofs?
A: Technically seen they are not necessary, but Paroc recommends a plastic sheet or a sealing layer in the lower part on the roof structure. This gives extra security, and the building can, in the future, be used for purposes which increase the moisture load.
Q: Why choose a ventilated roof?
A: In order to remove any moisture coming from the building and "to take care of" moisture that penetrates the structure during the life span of the building!
> More information of ventilated structure
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environment
Environment
Q: How stone wool waste should be disposed?
A: If you have some waste material from cutting of stone wool in the construction site, you can use the pieces for instance in the attic insulation.
If this is not possible, stone wool waste can be disposed at a landfill for non-hazardous waste, i.e. on the normal dumping site. However, individual landfill holder can have specific rules for waste types dumped at landfill.
There are also loose wool contractors who can use pure stone wool waste as raw material for loose wool insulation (blowing wool).
In Sweden Paroc has developed a specific system for recycling stone wool, so called Rewool concept.
Stone wool waste from demolition is seldom pure enough to be used as loose wool insulation. In most cases the only alternative is to dispose it at the landfill for non-hazardous waste.
> For more information see waste handling
Q: Does stone wool emit any dangerous substances into the air?
A: No it does not.
Paroc stone wool is tested in accordance to the Finnish building material classification. It fulfils the strict requirements in order to be classified in the best emission class M1. (http://www.rts.fi/emission_classification_of_building_materials.htm)
Q: Does it leach harmful substances from stone wool to water or
to soil?
A: No it does not.
Paroc stone wool is tested in leaching test used for acceptance at landfills. In those tests it is shown that amount of leached substances is extremely low.
Q: How does stone wool behave in high temperatures?
A: Stone wool is made from stone melted in temperatures over 1500 oC. It does not change during a new heating, with the exception in temperatures over 1000 oC, then the wool is deformed.
Stone wool contains organic binder 1 – 4 % of weight. This binder will breakdown in temperatures over 150 oC. The breakdown products have a specific smell. Paroc does not recommend staying in the same room where an insulated application (like oven or fire place) is heated for the first time. When the smell is not detected, the breakdown products have disappeared and you can stay in the room.
Q: Why does mineral wool itch the skin?
A: Mineral wool consists of small needle like particles. The sharp endings of these particles can make miniature cuts on the skin. Because the cuts are so small, they cause itching or prickling.
Precise rinsing helps to get rid of particles on the skin and of itching.
> For more information
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sound
Sound Insulation
Q: We want optimal sound insulation for an internal wall so that we can argue in peace. What wool should we use?
A: Wool alone will not solve your problem. The weight of the structure is the deciding factor. To avoid constructing an internal wall out of stone, the procedure is as follows: two plasterboard liner slabs will be installed on both sides of the frame in order to increase the weight of the structure. Prior to sheeting the other side a soft stone wool slab will be installed inside the frame. The top of the wall must reach the ceiling insulation so that the sound will not circulate through the light structure of the joint. In the case of a supported wooden floor, the base of the wall must reach the concrete slab. The air insulation of the structure also plays a major part in relation to high pitch sounds.
Q: I live in an old tower block and my problem is the sounds coming through the wall from the flat next door. How can I improve the sound insulation of the internal wall?
A: The problem can be alleviated as follows: A new wall is constructed in front of the wall that is to be insulated, the new wall being approx. 10 mm away from the old wall and attached to both the ceiling and the floor. The frame can be approx. 50-70 mm. A flexible stone wool slab PAROC UNS 37 is then installed inside the frame (or it can also be attached to the old surface) with double plasterboard covering on the inside with staggered joints. The joints between the new wall and the old joining walls and the ceiling are sealed with silicone mass.
Q: How can I reduce the sound of footsteps coming from upstairs? Will acoustics help?
A: Acoustic wool will not solve the problem but flexible strongbacks will be attached to the ceiling. A thin stone wool slab will be installed between the strongbacks and plasterboard will be used as covering on the inside.
> For more information see intermediate floors
Q: We are in the process of building a two-floor detached house with a wooden internal floor. What wool should we use in the floor to stop hearing the noises from upstairs while we are downstairs?
A: Normal flexible stone wool PAROC UNS 37 of app. 100-150 mm is sufficient for insulating the floor. Good sound insulation requires a so-called floating floor, i.e. a structure where the surface level of the floor lays on top of a flexible stone wool slab. This is the only solution for avoiding the sound of footsteps, a common problem with a light wooden structure.
Questions Relating to Dampness and the Functioning of Structures
Q: The house was built in the 1950s and the basement floor has been serving as a cold storage area and now we would like to develop it into a warm hobby area. How should we approach the question of thermal insulation? What about dampness insulation?
A: First you need to ensure that dampness cannot penetrate the building from outside, which means that you will have to dig out the soil on the outside of the foundations of the building. The old subsurface drains that may have become blocked must be renewed and the water led out. It is worth installing proper water insulation at the base of the foundation wall by using a welded bitumen felt (up to the height of 1 m). As large a part of the thermal insulation as possible is positioned outside so as to make the structure warmer and dryer. As insulation material you can use PAROC GRS 30 stone wool slab, which serves as both thermal insulation and a subsurface drainage layer. The air-permeable insulation also allows for the seating to dry outwards and upwards. Profiled plastic dampness insulation is installed on the external surface of the insulation. If necessary, insulation can also be installed on the inside, in which case soft stone wool is used. The inside should preferably be covered with stone material (brick laid on its side). If using wood, a layer of bitumen felt must be placed between the concrete and the wood.
> For more information see cellar walls
Q: The heavy blizzard of the previous winter blew snow from underneath the eaves into the loft and on top of the wools. I ploughed most of it away but there is still some left. What should I do; do I have to change everything or is it enough just to change the top layers of the wool?
A: Momentary wetting, such as the snow that you have described and it melting, does not cause problems. Stone wool does not absorb water and if water penetrates inside the wool the insulation will dry extremely quickly due to the difference between the inside temperature and the outside temperature. The wool in your loft probably already dried in a couple of weeks during the winter. Wood and organic materials go mouldy first and if the dampness continues the micro-organisms can also spread to mineral wools and other inorganic materials. Mould does, however, need to be subjected to dampness for a longer period of time as well as a plus-temperature to generate. Therefore, it is not worth changing the wools for no reason. Explaining that to the master of the house next door is a different story altogether.
Q: I remember reading somewhere that stone wool can also be used to insulate against frost and as a replacement for polystyrene in ground slab flooring. Does stone wool not get wet and how can it function as insulation when it is wet?
A: There is dozens of years of experience in using stone wool to insulate against frost and in ground slab floorings. The insulation functions without any difficulties, as the wool does not absorb water. Quite the opposite, in fact, as it functions as a capillary break and stops the moisture rising from the earth to the higher structures. The reason why stone wool is used relatively little in these applications is that it is slightly more expensive than polystyrene. A study conducted by the University of Technology and partially funded by TEKES (Finnish National Technology Agency) concluded that stone wool could be recommended as thermal insulation material for ground slab flooring primarily for the reason that the emissions resulting from it being subjected to dampness were considerably smaller than those of polystyrene.
Q: I have juts bought an old house and am now beginning to get familiar with my purchase. I have dismantled the old Ross floor, and found that the sawdust, straws etc. that had been used as insulation had compacted. There is approximately 50 sm of space reserved for insulation. Can I fill this space with blowing wool? This would be easier than using slab insulation. Will blowing wool compact over time?
A: Although the compacting level of blowing stone wool is the smallest of all blowing wools we would not recommend any type of loose insulation for your floor. Even the slightest compacting will recreate the problem that you are currently trying to solve – in other words, a draughty cold floor. Fill the insulation space with steady stone wool slabs PAROC UNS 37, preferably 10-20 mm over the insulation space. The slabs will be compressed underneath the floor and are guaranteed to fill the total insulation height for the duration of the house's lifetime. The slabs can be considerably (50-100 mm) more narrow than the installation space. The gaps will then be filled with stone wool dust. This will speed up the installation work considerably.
Q: I live in a 1950s house. We have now decided to start improving the thermal insulation of the house in order to cut heating costs. We are going to begin from the easier end, which is the loft. We have approximately 25-30 cm of sawdust there at the moment. By how much should we increase the insulation? Can we blow stone wool on top of the sawdust?
A: Upgrading" your insulation does seem like a sensible thing to do. The thickness of your sawdust corresponds to about 125-150 mm of stone wool insulation. Nowadays the new one-family houses have an insulation layer of 300-400 mm. The experts in the energy industry recommend an insulation thickness of 400-500 mm. Therefore, I would recommend adding at least another 200 mm. Make sure, however, not to block the airing gaps underneath the eaves.
You can add any insulation on top of sawdust as the lower insulation will always warm up and dry. Stone wool has already been used in such applications for around 50 years. Combustible old insulation will thus also receive a fireproof insulation coating to protect it.
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