ROCKWOOL external wall insulation is crucial for developing energy-efficient walls and meeting modern code requirements. It provides continuous insulation for residential spaces, such as flats and apartment buildings. Kraft-faced fiberglass insulation helps control temperature and humidity within the structure. Adding external wall insulation (EWI) to your house is an effective way to save energy by reducing the amount needed to heat your home, saving money on energy bills, and lowering carbon emissions.
There are two main types of insulation: internal dry lining (Dry-lining) and external wall insulation. Dried-lining involves fixing insulation to the inner surfaces of your external walls, usually by attaching an insulation board to the wall. External wall insulation can act as a vapour barrier, especially if it is a closed cell foam type. For urethane foam, it likely has the most insulation value for thickness. To seal the inner lining of the building, use foil-backed board with taped joints.
External wall insulation can last for decades due to its weatherproof rendering, making it an economical and environmentally friendly option. Planning permission is not required for external wall insulation installation. In summary, ROCKWOOL external wall insulation plays a vital role in improving energy efficiency and meeting modern code requirements.
📹 Exterior Insulation – What NOT to do! (And the Correct Way)
Today’s video is sponsored by my friends at ROCKWOOL and we will be talking about how to use their Insulation on the outside of …
Does it matter if insulation is faced?
Facing acts as a moisture barrier, preventing moisture from escaping through insulation folds. Excess moisture can cause mold and mildew, damaging the framing lumber of a home over time. Whether made of paper or plastic, facing the warmest space in winter ensures moisture doesn’t travel. Unfinished or uninsulated attics require facing to prevent hot or cold air from migrating to the rest of the home. The facing is installed against the top of the ceiling drywall or plaster, providing moisture protection between the living space below and insulation materials above.
Can you leave insulation outside?
The sun is the greatest enemy of PIR insulation, as UV radiation can degrade its surface, leading to discoloration, embrittlement, and decreased thermal performance over time. Direct exposure to the sun can change the color of edges and affect the core structure of PIR foam. It is not recommended to leave PIR boards outside, especially in hot climates, but they can be left outside with a protective layer like Corex or general OSB board. The edges of PIR boards are the most vulnerable areas and should be adequately shielded from sunlight.
Water is the ultimate enemy of PIR insulation, as even the best insulation can be destroyed by water. Leaving PIR foam insulation exposed to water for prolonged periods can cause permanent damage, affecting its thermal properties. Insulation must be warm and dry to function properly. Foam insulation sheets, made from materials like PIR (polyisocyanurate) or XPS (extruded polystyrene), exhibit varying degrees of water resistance, but possess certain qualities that make them highly resistant to water penetration.
What are the downsides of external wall insulation?
External wall insulation is a crucial component in creating comfortable living spaces and enhancing home energy efficiency. However, it is important to note that not all insulation types are created equal. Traditional methods, such as using insulative boards like fibre cement and polystyrene, can enhance thermal performance. A render is applied over these boards to protect them and create an aesthetically pleasing finish. Rockwool, a type of mineral wool insulation, is also popular in the UK.
8 disadvantages of external wall insulation types include impermeability, size, cost, insulation issues, irritation to the skin and respiratory system, weight, limited insulation value, and environmental impact. While these types can be effective, they come with several disadvantages, such as impermeability, size, cost, insulation issues, irritation to the skin and respiratory system, weight, limited insulation value, and environmental impact.
Is external insulation worth it?
External wall insulation can prevent damp by raising the internal walls’ temperature, reducing condensation risk, and providing a waterproof barrier against penetrating damp. It also improves the U-value of a home, as walls closer to zero have less heat loss. Current building regulations require walls to have a U-value of 0. 30 W/m2K, but solid walls, especially in older properties, tend to have higher U-values. External wall insulation can significantly improve the U-value of a home.
Can you put external insulation on cavity walls?
External wall insulation (EWI) is a layer of insulation installed on the outside face of an existing wall, typically used to thermally upgrade solid masonry walls or improve cavity walls. It can be finished with render or clad with alternate facing material to protect it from weather. EWI can help reduce carbon emissions by preventing condensation build-up, which can lead to damp and mold. Heating homes contributes to 14 of annual national emissions, with older properties being the worst polluters. Understanding the main considerations for EWI can help plan your project effectively.
Does exterior wall insulation need to be faced?
Fiberglass and mineral wool batts come in faced and unfaced versions, with unfaced products suitable for interior walls. Faced insulation should be installed on exterior walls, attics, and crawlspaces, with the facing always pointing towards the interior, heated, or air-conditioned space. The facing should touch drywall on exterior walls, down towards the ceiling in attics, and up towards the subfloor above floors.
Do you need plastic sheeting over insulation?
Vapor barriers are essential for protecting exposed ceiling insulation, especially in mixed climates or hot, humid climates. They are typically made of polyethylene plastic and start at a minimum of 6 mils thick. Insulation blankets, made of fiberglass, polyester, wool, polyurethane, or cotton batting, are typically thicker than vapor barriers. The best insulation vapor barriers are made of polyethylene plastic and reinforced to stand up against wear and tear.
For extra protection, choose an insulation cover with mold and fire protection. Americover is a one-stop shop for contractors and builders looking for specialty plastic sheeting products like vapor barriers. They can help find the product for your application, whether it’s covering insulation in ceiling, walls, attic, or crawl space. Consult with a building or safety expert to determine where a vapor barrier may be required.
How do I protect my exterior insulation?
Insulation placed on the exterior surface of a concrete or masonry basement wall offers several advantages over interior placement. It provides continuous insulation without thermal bridges, protects and maintains the waterproofing and structural wall at moderate temperatures, minimizes moisture condensation problems, and does not reduce interior basement floor area. If the insulation extends up to cover the rim, it can be left open for inspection from the interior for termites and decay.
However, if not treated adequately, it can provide a path for termites and prevent inspection from the exterior. Insulation exposed above grade must be protected with a coating to prevent physical damage and degradation.
Exterior wall insulation must be approved for below-grade use, typically using extruded polystyrene, expanded polystyrene, and rigid mineral fiber panels. Extruded polystyrene is a common choice, while expanded polystyrene is less expensive but has a lower insulating value. Below-grade foams can be at risk for moisture accumulation, which can reduce the effective R-value as much as 35-44. Research conducted at Oak Ridge National Laboratories showed that moisture may continue to accumulate and degrade thermal performance beyond the fifteen-year time frame of the study. This potential reduction should be considered when selecting the amount and type of insulation to be used.
Does insulation need a moisture barrier?
In regions with cooler climates, the heating of domestic properties from the inside is a significant source of humidity. It is therefore essential to install a barrier between the drywall and the insulation to prevent the accumulation of moisture within the home.
Is it OK to leave insulation uncovered?
Exposed fiberglass insulation in occupied areas of a home can be harmful to health due to its potential to enter the air and end up in the eyes, lungs, and skin. Fiberglass, made of spun glass fibers, can cause irritation and health problems. Covering the insulation with drywall is not the only solution, as it can also be a potential health risk. Therefore, it is essential to cover the insulation to prevent its spread in occupied areas.
What are the downsides of an external wall insulation?
External wall insulation boards can improve a building’s energy efficiency, but they have several disadvantages. The biggest is impermeability, which can cause damp without proper planning. The size of these boards is another disadvantage, and they can be expensive. Insulative boards, which are commonly used to insulate a wall from the outside, are available in various materials like fiber cement and polystyrene.
They usually require a layer of render on top for added protection and a decorative finish. Cavity wall insulation is not an option for solid walls. It is essential to understand these disadvantages to make the right decision for your property.
📹 How to Choose and Use Insulation | This Old House
This Old House general contractor Tom Silva explains the wide world of insulation. (See below for a shopping list and tools.)
In my denver 1.5 story home, i could not get the upstairs below 78 on hot days with the AC cranking full time. (My system was working properly but flow upstairs was weak). My cellulose insulation was only about 15 inches. I had a contractor add “caps” to the 15 can-lights and seal them, top off the insulation to 36 inches, and foam a few spots like where my two-story living room wall abutted the attic over the garage. The difference was amazing. If the AC is on, the upstairs is about a degree warmer than the 73 degree main floor, and the AC will now cycle. But even on hot days, if i run the house fan at night, the house is cool enough to where i wont need the ac until the afternoon, if at all.
I just had my attic air sealed before I added new cellulose insulation. The process was: All the old insulation was removed. Then an electrical contractor rewired the entire house; all knob and tube wiring was removed, not just deactivated. After the electrical inspection by the city, the insulation guys came back and air sealed the attic. They used foam board and various foams for cracks, etc. I saw pictures of what they did and the amount of work that was done was amazing. They also air sealed my basement in the same manner. Then new insulation was blown into the attic and more insulation was blown into the outer walls of the house. All the insulation work was done by a BPI certified contractor. Then an inspector came with a heat device and checked the heat loss. A few spots in the walls needed to be ‘topped off’ and that was done. The difference in my house is amazing; no more cold spots! I have a 1927 Craftsman Bungalow so I still have, and intend to keep, all the original windows, so heat loss happens there. I have caulked all the windows. I am working on getting interior storm windows but in the meantime, I put up plastic coverings. Even with the old windows, the house is significantly warmer. What a difference.
Something no one talks about and most people don’t realize is that the rigid spray foam insulation offers no sound proofing. My neighbor spent a fortune insulating his entire house with it and now he can hear someone’s conversation on the sidewalk as if they were in the same room. Personally, I would spend the money on ICF instead.
I watch this show on You Tube and the the TV……. it’s just too bad we don’t have these type of craftsmen in the Houston area…… where things are very often built the “Houston way”………. aka, build it so it “lasts” a year, after which, the warranty is up and it is the homeowners problem. See these poor workmanship issues all over town. Especially on the west and northwest side. Pretty sad.
If you’re here in 2020, it’s been determined that water vapor amounts for about a quarter of a pint over the period of a year. Compare that to almost 12 quarts of water with just a 1 inch hole in your wall. Air movement > water vapor, every time. Also, a latex primer over your drywall is more than enough of a water vapor barrier.
That’s why these guys work on old homes… so they can stick wiring down cavities where there is little insulation in the way. Most of these methods “blow” your chance of touching that cavity again. Of course if people cared more about external insulation as they should, then the stud bays wouldn’t be such a big deal.
Very nice! Especially for people who is just thinking about insulation! What exactly you would recommend for a plain 20+ years old (not commercial) single level residential house insulation? Brick veneer outside, than timber frame and plasterboard inside (with empty voids of course) 🙂 I can see a soft maths at retail which are very similar to one of your samples. However nobody from experts can advise me about a vapour barier. How to do this? What kind of material I have to use? Is it something special or … any plastic film can be used? A very interesting subject- what do we have to do with … massonry “weep-holes” underneath? Should we cover them or leave them open? And, btw…. while insulating empty walls we are creating a nice environment for “crawlers”. It will be convenient and warm for them to grow their colonies. How to prevent this “side effect”, please? Thank you
I was thinking about putting 2 in. XPS and 4 in. roxul on top of it in my 2×6 exterior walls. Something like a combination between those two types of insulation in search of better performance for less price. But Im not sure. Im afraid of possible moisture collection inside the wall because of this XPS. I live in climate zone 5 (upper part, actually almost zone 6). Do I have to worry and do I have to use vapour barrier/retarder in this case?
No mention on the danger of improperly applied closed cell foam. Poorly trained, lazy contractors tend to spray it too thick in the hard to reach corners, believing thicker is better. In reality it does not off gas’s and cure properly when applied too thick because of heat build up and can render the home in-livable. Formaldehyde gasses build in the house. If going with closed cell insist on a contract that puts the cost responsibility on the installer or the GC if the product is installed improperly and a third party tester confirms the presence of gasses that are a byproduct of improper curing.
There is so much more about INSULATION – thermal barriers and air sealing and perm ratings, testing the air tightness using a blowerdoor. and then there is the off-gassing of foam, and then there is the carbon emissions of creating the product. what product is natural ? Healthy ? Affordable ? DENSE PACK CELLULOSE
Fiberglass? Decades ago we stopped using that in Denmark; 1: Its not fireproof as rockwool is, 2: The glass fibers tear apart lungs and the internals of those who have to work with it. And good luck getting a wire or a pibe behind or into that sprayed insulation, and if you cut a groove then you have to reinsulate that groove
DO NOT USE FOAM! In theory, it is great. In practice, it is horrible. It MUST be mixed in the proper ratios as it goes in. They design the installation machines to be idiot-proof. Except, they have made a higher level of idiot to operate these machines. By letting one or the other chemical get low in the machine, the ratios get screwed up. So, the idiot just keeps going, and blows toxic chemicals into your house that virtually cannot be removed. Ask me how I know.
Tom Silva speaks with confidence but many facts are ignored. For example, how much R-value is lost by the closed-cell foam as it ages in your wall? Tom shows a full depth of closed-cell foam. Common practice is to only fill partially (an inch, or so) to reduce cost. Then the homeowner must pay for fiberglass to fill the remaining inches. Closed-cell foam can separate from the material it’s sprayed on. That’s not cost effective. Sprayed on too-thick, closed-cell does not cure correctly and off-gasses. The fumes will make the homeowner sickly ruining their lives and home. Open-cell foam is not durable over time. Tom seems to confuse open-cell foam with pump foam which is even more problem-laden. It shrinks in wall cavities and turns to dust as it ages. A smart homeowner will INSIST on a Material Safety Data Sheet (MSDS) before wasting their money on over-priced, problematic, foam. All foams are a horrific assault on our ecology. It’s telling fiberglass batting (and loose blown) needs a vapor barrier added to stop air infiltration. For that reason, they are not practical for retrofitting walls. Cellulose is available with an R-3.8 per inch value. Why settle for less? It will never settle like blown fiberglass. Or leak like fiberglass batting. Or shrink like pump foam, or crumble like open cell spray foam. Or need additional fiberglass added like closed-cell foam to shave cost. Cellulose won’t off-gas like foams or lose it’s R-value like foams. Unlike the others, it’s a genuine friend to our economy.
Hi in New York, NYSERDA and coned offer company’s to come in with a rebate and insulate attic with loose fill and closed walled with a blown in insulation without removing the pink. It feels like they just want to get in and out. And make a lot of money Can you tell me what I should use in the attic and in the walls …. Should they suck out old stuff
Which is the best retrofit material for a cathedral ceiling through the fascia & soffit to add present bat insulation in Illinois weather. Venting along the soffit was shut due to the moisture condensation inside & vents at top of roof left open cause scaling at top of beam inside. Thermal imaging was done and the corners & a 4 x 5 foot area over the front door was missing insulation. Advise would be greatly appreciated.
I’m not so sure that heat wants to transfer to cold but cold with add force to heat. I’ve noticed this with my insulated over shoe that in the truck I will have the heat on high and not feel the heat in my boots but 30 seconds after I step out side I feel my feet getting really warm and can feel it for awial. Now with houses I’ve noticed ac will run for 15 minutes at a time during the day when it’s 90 outside but as soon as temps out side reach 60 starting at 7pm I notice inside temps go up and the ac is running almost none stop till 2am we keep inside temps at 65 2×6 fiberglass insulation with internal vapor barrier. Also before adding ac inside temps would be ok at 75 during the day till it started getting colder outside then temps would reach 90 inside with all the windows open the best way to solve the issue was to have fans on one side of the house sucking and another blowing it out to force the air otherwise it didn’t seem to really move. I’m thinking a heat shield may work better if you could build a awning around the whole house with a air gap atleast three in from the actual house may help? Since heat Shields work very well for car exhaust. Even better would be to add a three inch vacuum chamber around the whole house but can’t think of any good way of creating that
A-frame house in California. The section I’m thinking about currently has a sheetrock ceiling with insulation blown on top of it in the attic. Temps can get above 100F here. Can I get away with taking out the ceiling (and therefore insulation) and install stuff directly to the inside of the roof as an insulation replacement and reasonably expect the space to not get super hot on a 100-degree day?
Two questions for Tom please? 1- How can a DIY homeowner put any of the retrofit insulation in ourselves without hiring out the job or renting a blower? 2- Why is the foam (or other full compact insulation) so popular to you Tom, when I have seen you trying to run wire or cable down the inside of an existing wall? Or for that matter, repair or run short plumbing vertically? Thanks to the team for all these articles!! I learn something from all of them (wish your team could come to my house and article some needed repairs).
I have a house built in 1935 and it has no insulation on the outside walls. All it has is wood vertically going across the frame of the house then this black paper and finally the original wood siding. Should I use a Vapor Retardant on both sides of my fiberglass insulation? I live in Northeast Ohio so we get weather like New England.
i have an old house 1930 no insulation.. stick built.. it has a cavity to insulate.. but right now its got a lot of wet on the bottom of some of the walls.. about a foot off the floor.. those floors are close to the ground the crawl space, is literally so low you cant crawl under those parts.. there is vinyl siding outside but i do not think there is a vapor barrier at all.. its just the clapboard and walls, i think its plaster but i dunno if someone has put sheetrock over it in an attempt to cover wet walls…. i have to drill in to see if its plaster, but i’m guessing that it is due to its age… how can i insulate these exterior walls.. can i use foam in insulation with a vapor retarder on the inside and put up new drywall.. ripping out all the exterior plaster walls. or will it still sweat and get damp because there is no vapor barrier outside ? i know i cannot strip all the clapboard cladding off the house and add vapor barrier i just don’t have the funds.. can a vapor barrier be put between the vinyl siding and the wood clapboard siding? or will this trap moisture.. another thing i thought about doing was taking down the outside walls, putting an inch of cut to fit styrofoam between the studs leaving a little room between the clapboard siding and foaming all around the styrofoam… to stop air infiltration and then putting the fiberglass batting inside and then drywall… will this work? or is there a way i can blow something in the walls and not cause it to get damp and rot down the walls.
I am remodelling an old house, I’m doing this for the first time and now I am about to insulated the exterior walls. The problem is that the distance between studs varies from 10 to 19 inches so if I use fiberglass batts it’s going to be a nightmare. I wonder if blowing cellulose wouldn’t be a better idea, but I am also worried about the cost. Can anybody give me a suggestion here? Thank you.
In the first minute of this article I heard Mr. Silva say heat travels to cold. So, in the north put the vapor barrier inside where the heat is. In the south put the vapor barrier on the outside, where the heat is. My question, I am building a four season camper van, Promaster, to be traveled very north and very south. It is going to be insulated. Any suggestions as to where to install a vapor barrier. Thanks.
I can’t believe you didn’t mention the health benefits and drawbacks and the environmental pros and cons of each system. Air quality and off gassing is a huge factor in choosing an insulation. There are sciences and even laws that do not allow the foams to be used in hospitals anymore do to their poor health hazard. In addition some countries who are more advanced in the health and building policies prohibit their use and manufacturing all together. For recommendations about building products that recognized internationally as being the most effective, responsible I like to review the Product Declarations for the Living Building Challenge: living-future.org/declare/
I live in Southern Ohio, we get both hot summers and cold winters here in the midwest. My home was built in the early 1950’s and has very scattered fiberglass insulation on the attic floor. If I wanted to turn the attic into a usable space during the summer and winter, would I have to insulate interior of the roof instead? Currently it is just framing, nothing but wood. Also- would this mean leaving what is on the floor? replacing it? or adding to it? All recommendations welcome!
So are there any issues with first coating with closed cell and then once set, second coating with open cell? Or is there a reason not to do this? I am in the Tampa Bay area, so most of the time we are trying to keep the heat out. Also, what would happen if we used closed cell against the inside of the roof and then over the years we developed a roof leak? Where would that water go and how would you even know it to know it needed repair? Also, what about fire safety? No one ever talks about fire issues.
There is some misinformation. Cellulose will settle even when dense blown, so when it does how is it a barrier for air and moisture. Also when looking into foam make sure you follow the correct guidelines. All exposed SPF must have a flame retarder, do not let anyone tell you otherwise. If you have an unvented attic with SPF you cannot store anything in the area besides mechanicals (pertains more to the south). SPF is not a cure all for homes. More and more building material is becoming more complex so know that using any insulation can come with moisture issues if not installed or designed correctly.
Hi! Really useful article.,. I’d like to ask a question… I live in Mexico, near Mexico City, where temperatures in winter go to 0 or 1 degree Celsius, so it’s super cold but still it’s very cold. My house is specially cold since it’s oriented to North so it’s also very dark in winter. So my question is, is it absolutely indispensable to insulate all the walls of the house or it’d be ok to insulate a couple of walls and see how better it gets and then pick up from there?… Thx so much for the advise. Regards
I hope you guys look at your old article comments.. Topic: insulation ideas. Imagine this, you have a very old place, that is not insulated at all. Each wall interior & exterior are 4inchs and are covered with Rimu timber T & G. Floor & Ceiling is the same .. used to have the old hessian sacking on it when we have removed for insurance purposes. skirting where the floor meets each wall, door & windows surrounds both inner and outer have 7 1/2″ molding on them.. cannot get under house to insulate.. Firstly we would like to insulate the floor .. Our first thought was to bring the whole floor up 4″ or 6″ and fill with solid insulation, then put down 3/4″ board on top, then flooring of some kind. If we do this where would we put the vapor barrier??? would this be some thing your team could recommend ?? Secondly . the outside walls are stucco with the T&G behind it. At this stage we don’t want to get rid of it, so will be insulating from the inside.. if we take the inside T& G off should we put a vapor Barrier in each cavity before putting in insulation or put it on after we insulate each cavity ??? what sort of insulation would you recommend ?? This old house is not in the USA.. Thank you for your comments.
I am reading that insurers aren’t insuring the worst foam and banks are not financing homes with it in homes there. What are you hearing here in the states? It could be time to redo this article. People are so upset because governments in Europe have grants to insulate. Now it is costing people time and causing their major assets to plummet in value.
Surprised by all the attacks spray foam. There are 2 types. Nothing about them is the same. Read up on the difference before you group them together. We built our home 20 yrs ago using Icynene Spray Foam, it’s open cell. We have zero problems with it. WE used ICF “Blue Maxx” on the walls and sprayed the roof deck with Icynene Spray Foam. We heat and cool the attic. Makes the house feel warm. Also there can be a major storm raging outside and we don’t even hear it.