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HomeExclusiveHow To Insulate A Roof From The Inside

How To Insulate A Roof From The Inside

Cold Roof A Very Bad Idea

How to Insulate your Roof | Fuel Poverty

Although cold roof systems were used extensively in the past, they are now considered out of date and are highly inadvisable. In fact, insulation from the inside will inevitably lead to the formation of condensation caused by the humidity present inside the building. As a consequence:

  • the insulation will quickly become saturated with water and cease to be effective.
  • the supports will rot if they are made of wood, or rust if they are of reinforced concrete.
  • frost will accelerate the damage.
  • this situation will lead to destruction of the roof in just a few years.

Is there an efficient method to prevent the accumulation of humidity? Installing a vapour barrier membrane over the insulation is not enough to stop the migration of vapour. The air gap intended to ventilate the insulation isnt efficient either. In fact, it can actually aggravate the problem as the weatherproofing supports are often colder than the outside air, condensation forms there as well, and adds still more to the humidity.

Size Up Your Existing Insulation

Grab a tape measure and a flashlight to see what kind of insulation you already have in the attic and how deep it is. Then use the numbers in the chart at right to estimate its R-value. Pull up and dispose of any material that’s compressed, water stained, or moldyit’s useless.

Owners of houses built before 1990 take note: If what you see is lightweight, grainy, loose-looking insulation with shiny flecks, it could be vermiculite from a mine with asbestos deposits. Get it tested, and if necessary, call in a pro to remove and haul it away safely.

Cons Of Batt Insulation

Low energy efficiency – Producing batt insulation requires a lot of energy, contributing to more air pollution than other processes. Due to its low R-value, batt insulation does not perform well in colder temperatures and may require several layers of insulation.

Safety – Glass fibers from these insulation rolls can irritate the skin and eyes as well as cause potential lung damage. Make sure you wear protective clothing before you perform the installation.

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Insulate Roof From Inside Rooms Not Inside The Attic

Hi. Were undertaking a fairly majoy refurb. Will be doing an extension, re-wiring. Also looking to make the house more snug, so looking at improving the overall insulation.

External wall insulation is not an option as its a listed external structure, so were going to slab internally.

The ceilings in our upstairs rooms are slanted at the wall, we have pretty high ceilings, about 10 ft. What this means is that in order to insulate the slanted part of the ceiling, wed need to do it from within the bedroooms. Ive drawn a pathetic representation of this, where the red indicates this section of insulation. The black lines are the walls, roof, and ceiling. We have some rock wool insulation in the attic at the moment, but I dont know how well it works, the wind whistles through the attic old house, no membrane below the 1920s roof tiles.

Now I know the standard approach to insulation would be to insulate the attic properly/better, represented by the yellow colour in the attached image. But given the draightiness of the attic, I dont know if this can be done effectively without putting in rigid insulation, or some sort of membrane over the rock wool. Im presuming that rock wool is not performing well because of the excessive draught.

Really just want to understand why this approach might be a bad idea, or why sorting the attic insulation might definitively be a better approach.

Dealing With Restricted Attic Space

Is it more important to insulate walls or attic?

Many attics, including those under low-sloped roofs, do not have enough space for adequate insulation at the edge of the attic floor. If soffit insulation requires a baffle to keep a ventilation opening against the sheathing, there may only be about 100 mm of space left for insulation. This restricted insulation level will allow the snow to melt just above the overhang and promote ice damming.

Try to put the best insulation possible at that edge to reduce heat loss. Spray foam is ideal as it air seals as well as insulates. Cut pieces of extruded polystyrene will help as well. Install a piece of extruded polystyrene 25 mm from the sheathing to maintain the ventilation air space and then fill between this foam board and the attic floor with insulation .

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Getting A Roof Replacement Now Is The Time To Update Your Insulation

Roof replacements are optimal times to update your attic insulation. If your roof was leaking, your insulation might have been impacted. Your insulation is especially likely to be water-damaged if your roof decking has developed wood rot, as this means moisture has been present in the roof for some time and has likely intruded on the insulation. Although, some types of insulation, such as closed-cell insulation, are not affected by moisture. You should replace other types of insulation when they get wet as they will not function properly.

Also, during a reroofing job, your roofer may need to add new ventilation to your roof to ensure you get the best life span from your shingles. If thats the case, they may need to remove some of your insulation anyway. Although, if the floor of the attic is insulated, a new vent opening can be easily cut into the roof deck without removing or disturbing the insulation.

Its highly beneficial to consider if you could benefit from better insulation before you get a flat roof installed. Once you have a flat roof installed, you may need to remove it to add new insulation.

Ready to reap the many benefits of proper attic insulation? Reach out to a roofer to discuss your attic insulation options through IKOs Contractor Locator.

Which Material To Choose For Interior Insulation

There are 5 types of insulation for your roof. To choose the most suitable method for your project, we offer an overview of the benefits of each process.

  • Cellulose wadding

In addition to its longevity, it has excellent thermal inertia and good sound insulation for the roof.

  • Glass wool

A natural insulating material, glass wool traps the air and offers efficient thermal and sound insulation. Itis not flammable.

  • Expanded polystyrene

Made from crude oil, expanded polystyrene is a lightweight material with good insulation and impermeability properties.

  • Polyurethane

Polyurethane offers good thermal and acoustic insulation for the roof, as well as high mechanical strength.

  • Stone wool

Stonewool is obtained after a melting process. It is a material that benefits from good thermal insulation. Its sound insulation is superior to that provided by glass wool.

Do you have an insulation project? Contact an authorized Onduline professional near you, and benefit from customized advice.

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Understanding Flat Roof Insulation

Before anything else, it is important for you to know the basics of flat roof insulation in order for you to understand the following helpful techniques. Flat roof insulation is basically done to increase energy efficiency and energy use in your home. Its main purpose is to minimize heat loss inside your home, which will result to energy-saving benefits. In general, there are two types of flat roof insulation, which will depend upon the climatic condition in your area, its location, and the local building regulations. These two types are highly related to how to insulate a flat roof from the outside and how to insulate it from the inside.

Insulation Of A Metal Roof Without Attic

Insulation Works – Insulating a roof from the outside in

Metal roof insulation approaches two significant purposes preserving the interior temperature and blocking the substance from accumulating under the roofing. Providing a sheet of insulation under a metal roof is necessary as the metal is generally a better heat transmitter than wood.

Quality insulation assists in retaining heat in the wintertime and keeps warm when the temperature drops. The best options to insulate your metal roof include:

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Two Major Types Of Flat Roof Insulation

As mentioned previously, there are two major types of flat roof insulation. The first one is the cold roof insulation. This is when you insulate your flat roof from the inside. On the other hand, the second major type of flat roof is warm roof insulation, which is the exact opposite of cold roof insulation because, in this case, you will insulate your flat roof from the outside. At this point, we will now go to the specifics and the helpful techniques on how to insulate a flat roof from the outside and from the inside.

Cold roof insulation is more commonly used by many homeowners since it is much less expensive as compared to warm roof insulation. In this type, the insulation is snugly placed underneath the roofs surface and in-between the joists. To be more specific, you will have to put the insulation between each of the supporting joists and leave a gap in each for about fifty to sixty millimeters. On the other hand, if you are going to replace the insulation in your current flat roof house, one recommended piece of advice is for you to take down your ceiling too to ensure proper installation. Also, in the case of a shallow joist above your ceiling, the best way is for you to use spray foam as your insulation.

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Five Ways To Insulate An Unvented Low

Of the various methods to insulate a shallow roof, applying insulation to the exterior is easier than working in a space with limited access. Whatever method is used, the amounts of insulation must achieve R-values mandated by local codes.

1. Exterior rigid foam

Install a thick layer of rigid-foam insulation above the roof sheathing.

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Concentrate On Air Sealing

It is a good idea to paint the room side of the ceiling with two coats of oil-based paint or apply a single coat of latex vapour barrier paint to inhibit vapour movement. Ordinary latex paint is not a suitable vapour barrier.

See Section 4, âComprehensive air leakage control,â for detailed information on sealing all air leaks into the attic.

Install polyethylene over top of the joists

If the attic is relatively unobstructed with chimneys, plumbing stacks or structural members, consider installing polyethylene directly over the ceiling joists. This method involves the least number of seams and requires less caulking and stapling than other methods. It also leaves existing insulation in place. However, seal all obvious air leakage paths before laying down the polyethylene.

To avoid trapping moisture between the plastic and the ceiling, which might lead to possible wood rot or other moisture-related problems, install a minimum of twice the insulating value over top of the air vapour barrier . For example, if the joist height is 89 mm and contains RSI 2.1 , install at least RSI 4.2 over top of the polyethylene.

Install polyethylene between the joists

Where obstructions, such as a truss roof, make the previous method too difficult, install a polyethylene air barrier or low-permeable foam insulation board between the joists. However, note that this is a lengthy and painstaking process.

Spray foam between the joists

Spray foam under the roof

Important Points To Keep In Mind:

Best Insulation For Attic Remodel  Attic Ideas

When insulating your attic space, make sure that soffit vents remain open. Inadvertently covering or clogging soffit vents will disrupt the air intake and thus harm the air circulation and the overall ventilation dynamics within your attic space. This is a fairly common and very costly DIY error.

Did you know? Hot, poorly-ventilated attic spaces can cause asphalt shingle cracking and melting, thus shortening the lifespan of the roof.

If you have any heating equipment in your attic space, it needs to be properly insulated so that no worm air can escape into the attic. The goal is to keep your attic space dry, cool, and well-vented.

In addition to insulation some air sealing may be necessary to ensure that no air can escape from the house into the attic space.

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Polyurethane Spray Foam Metal Roof Insulation

In order to add moisture barrier under metal roof, you can spray the undersides of the roof by using a thick layer of polyurethane spray foam. It will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer.

Since this thing is something that can be sprayed, the foam will get and penetrate into the gaps and crevices to make a complete seal. As a result, any thermal leakage can be prevented since day one.

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The spray can be basically applied on top or bottom of the metal roofing surfaces. Compared to the fiberglass batts, this insulation is much better. Financially speaking, this spray is a great option especially when you need to renovate your roof after the application. The insulation capacity of a 10cm thickness of batts is as same as 10cm of polyurethane foam.

For Energy Efficiency Reasons

  • the thickness of insulation can be at the maximum, not limited by the thickness available between the rafters as is the case in the interior technique.
  • the existing roof trusses and purlins are now entirely included in the protected volume and therefore protected from strong variations in temperature and humidity.
  • thermal bridges at the rafters are non-existent, contrary to the case of insulation from the inside.

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Preparing An Attic For Insulation

Place planks or plywood sheaths across floor joists to improve your mobility in the attic.

Make sure there are no uncovered electrical boxes or exposed wirings. Caulk up any spaces where air can pass between the attic and the rooms below, paying particular attention to areas surrounding light fixtures, electrical wires, pipes, and ducts. Apply weatherstripping around the attic entryway. Check to ensure you have proper venting to eliminate moisture retention.

Figure out how much insulation to buy by following the directions outlined in How to Calculate Your Insulation Needs. If you have preexisting insulation, you may purchase a different type and layer it over your older material.

Options Recognized By Code

Insulation of a pitched roof from inside

Most wood-framed building construction follows the International Residential Code , which provides significant detail on all aspects of wood framing. In particular, Chapter 8 of the IRC specifically addresses Roof-Ceiling construction, while Section R806 is focused on Roof Ventilation. For light commercial or multifamily wood-framed construction, The International Building Code will apply. There, Chapter 12 addresses Roof Ventilation in Section 1202.2 and Table 1202.3. With all of these code references as a basis, we can review the relevant provisions as follows.

Vented Roof Assemblies

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What Is The Cheapest Way To Insulate An Old House

You can simply use a foil for insulation as a cost-effective alternative. By stapling the foil sheets to your attic, the heat reflects down into your living space. Hence, it lowers your heating costs. Attic Insulation Installation Services in Lincolnwood provide satisfactory assistance and properly insulates your home.

Water Spots On The Ceiling

One of the most common signs of a roof leak is water spots on your ceiling. This is a sign of an immediate leak that needs fast action. The longer the water sits and pools, the more damage it will do to your home.

If water is running down the walls, this could be a sign that your roof is leaking near the edge. If you see this happening, its essential to address the problem right away, as this type of leak can seep through all floors of your homedamaging insulation, framing, and drywall.

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Why Bother Insulating Your Homes Roof Or Attic Space

Insulating your roof and attic space will help retain energy in your home, often leading to cooling cost savings and overall home comfort improvement.

Properly insulating in and around your roof attic space can make your home healthier and more durable. It can also help prevent costly long-term damage from moisture build up or ice damming, which often results from poorly insulated/ventilated attics that allow warm air escape through the attic and reach the apex of the roof, thus heating up and melting the snow in winter).

Additionally, roof and attic insulation serve as a way to enhance sound proofing on the uppermost envelop of your house.

New Shingle Roof Average price

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There are five primary types of insulation for roofs, with their own advantages and disadvantages. The key value is always the capacity of insulation to resist heat flow. This is also known as thermal resistance and is often measured in terms of R-value. The higher that value, the better the insulating power.

Can You Insulate A Conservatory Roof Yourself

Attic Insulations

If youve already invested a considerable amount of time and money in rolling out portable heaters through the winter and blasting out industrial-sized fans in the summer, you may well have given up on finding that ideal balanced temperature. But with the right roof insulation, you can finally relax in the comfort of your own home, enjoying your conservatory for what it is. With plenty of options to choose from, theres insulation to suit every conservatory type and every home.

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Should We Insulate The Roof From The Inside Or The Outside

The insulation of your roof can be done from the inside or the outside:

  • Insulating from the outside has several advantages. In addition to avoiding your emptying any rooms in the attic, insulation from the outside does not cause a decrease in your living space and limits the risk of thermal bridges. This is a preferred solution if you are renovating a facade or roof. Among other benefits, this techniques leaves the frame apparent from the attic.
  • Insulation from the inside is an adequate solution, mainly in a new construction. This roof insulation method is ideal if you have not yet fitted out the attic and allows you to keep the roof covering system unscathed.


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