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
How Much Insulation Does My Metal Building Need
The amount of insulation needed will depend on:
- Type of heating/cooling system
- Area of the building that is being insulated
The more insulation that is installed will increase the R-value, which also increases the effectiveness of the insulation.
There are minimum R-value requirements for non-residential buildings. These requirements vary based on location. Be sure to consult your local building code to verify the minimum R-value needed for your state.
The Guide On How To Insulate Under Metal Roof Panels
Talking about metal roof insulation, this thing is one of the most challenging things people work in this field is facing. It demands and requires excellent skill and expertise which you may only get from a reputable roofing contractor.
In this article, we are going to explore both financial and technical aspects when it comes to looking for the best method to insulate the metal roofing.
You May Like: How Big Is One Roofing Square
Choose Your Insulation Type And Material
For DIY attic insulation, you’ve got two choices: loose fill or batt . Both can be added to uninsulated attics or layered over existing material. Once you’ve decided which type is best for you, examine the material options and prices to home in on the right product. Always check labels for specifics on whatever you buy.
Is It Recommended To Insulate Under Metal Roofs
Insulation under metal roofs is a highly recommended choice. Even more than the control of heat transfer, it serves as soundproof.
Metal roofs are naturally noisy. But with the right type of insulation, you can beat the noise down to quiet levels.
At first, people may turn to fiberglass batts to insulate the underside of metal roofs. That is because it is a cheap option and is popular among homeowners.
But you do not want to go for insulation with poor quality. Always put quality first. But, do not go to the extreme to make that happen.
If your budget can only get fiberglass batts insulation, you can install it with a vapor barrier. Fiberglass batt is a low-class vapor retarder. But adding a vapor barrier to the fiberglass batt gives it more function.
Spray foam insulation with open-cell spray foam comes highly recommended for metal roofs. It is a high-class vapor retarder.
Spray polyurethane foam works as air-impermeable insulation, so it has proper moisture control. Unfortunately, air-permeable insulation leads to moisture control issues.
That is not ideal for metal roofs because moisture leads to many roofing problems.
Also Check: What Is The Best Color For Roof
What Is A Roof With No Attic Called
A roof with no attic is called a slate roof or vaulted roof. This type of roof is made of several layers of slate that are tightly attached to each other.
The roof is designed to keep the sun and rain off of your home and is a great choice for areas that receive a lot of snow. A roof with no attic is also a popular choice for new homes.
If you decide to go with a slate roof, be sure to have a contractor inspect the roof and certify that it is structurally sound.
Place Between Purlins If Using Them
One of the more popular methods of placing metal roofing on a home is to lay down purlins across the existing shingles. In this case, simply lay the insulation between the purlins. Make sure that the insulation you are using is the same thickness so that the metal roof will fit better.
When you purchase through links on our site, we may earn commissions at no cost to you.
Don’t Miss: How To Install Cedar Roof Shingles
Topping Up Your Attic
If your attic just needs a top up, you can apply a second layer of batting perpendicular to your current one. Just lay the new batting right on top of your current, between-joist batting.
When insulating, check to make sure that your insulation fits snug to the boards and joists for optimal energy efficiency.
Follow the same rules as if you were doing it from scratch and ensure that all spaces are covered and that there arent any gaps.
Can I Apply Spray Foam Insulation Directly To The Underside Of A Metal Roof
Question
Can I apply spray foam insulation directly to the underside of a metal roof?
The 3-foot roof panels will be anchored to purlins that run diagonal to the rafters. I would like to avoid installing sheathing if possible , but I don’t want to compromise the R-value of the spray foam or to have the foam ooze out between the metal panels as it expands. I live in Virginia, and I’m planning to apply open-celled spray foam because it is vapor permeable & ndash a good thing in this mixed-humid climate.
Answers
The system of installing metal roofing over the trusses or over purlins is typical. It gets more complicated when you look at adding the foam into the equation. You’ve got the metal, the foam, and the interaction between them to consider.
- With the complexity, I’ve enlisted the help of my designer partner, Jeff Frost, who also contacted Mike Uniake, a foam insulation expert at Advanced Insulation, and MBCI, one of the largest metal roofing manufacturers whose products Jeff frequently uses.
- Our assumptions are that you are doing this to the roof of a home and that your metal roofing assembly is of an architectural grade that will not cause safety issues if it is not supported by sheathing.
Also Check: How Do Solar Panels Attach To Roof
Fibreglass Batts & Rigid Foam Existing Structure
Inspect the Underside
When inspecting the underside of your existing structure, you should see existing plywood horizontal beams and larger angled beams called joists.
To begin insulating the existing structure, start by placing fibreglass batts into the gaps between the horizontal beams and the roof decking. Dont fit the fibreglass too compacted as this could hinder the performance of the material. Fitting as loosely as possible into the gaps will be more effective.
Next, use rigid foam insulation to provide a wider span of coverage for the roof decking between the joists. You can cut the sheets to size using a utility knife and then simply secure into place using staples or an appropriate adhesive.
It is advised that you dont use nails/screws as these types of fixings may penetrate through the metal roof sheets and cause leakages.
Cold Roof A Very Bad Idea
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.
Read Also: How To Install Solar Panels On Shingle Roof
Whats The Best Metal Roof Insulation
Now that youve read about the three most common options for metal roofs, youre probably asking which one is best. The answer isnt obvious. It depends on your project specifics and how much you want to spend.
Looking to go for a low upfront cost? Choose fiberglass batts.
Installing a new metal roof, and want to make sure its very well insulated? Go for rigid boards.
Want great insulation for a renovation? Choose spray foam.
No matter which option you choose, remember to ensure that moisture wont infiltrate your insulation and you will have a metal roof that will last a lifetime.
Thank you to the Team at Transcona Roofing for providing this content.
Insulation Of A Metal Roof Without Attic
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 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:
Recommended Reading: How Often Should You Repair Your Roof
Install By Using Staples
Using staples will allow you to install the insulation easily and quickly. You can easily install several sheets of the insulation in only a few minutes without worrying about the security.
Staples will also allow you to get a strong attachment without leaving a big hole yet easy to remove them when a repair is needed.
Frequently Asked Questions About Attic Insulation
What is the best type of insulation for an attic?
Fiberglass batts or blown-in, loose fill insulation are good insulation choices for attics. The type of attic insulation you choose depends on the specifics of your home, such as:
- How easy it is to walk around in your attic space
If youre not sure about the type of insulation to choose, ask a professional roofing contractor or certified energy professional to help.
How much does it cost to insulate an attic?
The cost to insulate an attic varies primarily on the material you choose. You can investigate prices at your local home improvement center to give you a better idea of the total cost.
Pro Tip: Calculate the square footage of your attic to estimate how much insulation youll need for the attic floor.
What insulation R-value do I need for my attic?
The U.S. Department of Energy provides a list of recommended R-values by U.S. Zones and parts of the house. However, youll also have to consider local building codes and your contractors recommendations.
Is adding fiberglass insulation to my attic worth it?
Absolutely. Proper attic insulation helps to prevent heat from escaping in the winter, and it can help moderate indoor temperatures in the summer, too. In addition to insulating the attic rafters, you should also consider adding insulation to the attic floor if theres room.
You May Like: What Gauge Of Metal Roofing Should I Use
Important Points To Keep In Mind:
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.
Also Check: Metal Roof Extension
How Much Does It Cost To Insulate An Attic
According to Home Advisor.com, the total cost of attic insulation can range from $1,500 to $3,500, which equals $1 to $7 per square foot on average, depending on the choice of material.
The cheapest insulation option is the blown-in type, while the most expensive includes structural insulation panels. Although costly, this ensures the highest energy efficiency and is recommended for new construction installment.
If your attic has already been insulated and you are considering replacing your insulation, this will cost between $2 and $8.50 per square foot, on average. Removing your old insulation may cost around $1 to $1.50 per square foot. Of course, the exact amount depends on the type of insulation you choose.
If you want to keep your existing insulation, check the condition it needs to be absolutely dry to ensure there is no mold, mildew, bugs or rodents present.
If your existing insulation is in good condition, you can use blown-in insulation, spray foam or reflective insulation on top of the old layers.
If you hire a professional insulation company to do the work and have not cleaned and prepared the attic, you may be charged an additional $100 to $300 for cleaning costs.
Recommended Reading: What Types Of Roof Shingles Are There
Metal Building Insulation: The 5 Best Options
Metal Roof Installation | Metal Siding
Insulation is an essential accessory to a metal building to help keep energy costs lower. Proper insulation will keep a structure warmer in the winter and cooler in the summer so that less cooling and heating system usage is necessary. Insulation is also essential to keep your structure up to building code, as the necessary R-value for the insulation needed is always specified.
Insulation comes in many different forms and is certainly not a one size fits all product. At Western States Metal Roofing, weve worked with thousands of contractors that have trusted us to supply the materials for their metal roofing and siding projects. We understand the importance of quality materials and choosing which products are best for each individual project. We want to make sure you understand your insulation options so you can choose which one is best for you.
In this article, we go over the top 5 insulations to consider for a metal roof or metal siding and their respective R-values.
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.
Also Check: How Long Should A 30 Year Roof Last
Combining Foam And Metal Roofing
The challenge comes when you combine systems, spraying foam onto the metal roofing itself. Metal roofing manufacturers typically extend a 25-year warranty. The concern of manufacturer MBCI is over who is going to verify that the foam will not cause corrosive damage over time to the roofing.
- Most foam companies are not willing to provide written guarantees that their product will not cause problems and that they will stand behind any damage that may happen.
- Most roofing companies will void or waive their warranty under these circumstances.
Because of this issue, be cautious of any local roofing contractor who says that they will warranty this type of application. As contractors are able to come and go faster than manufacturers, make sure the manufacturer backs up any contractor representations in writing.
The Number One Prep Step: Seal Air Leaks
Gaps in the attic or between the lower floors and the attic will let heated air escape to the great, unconditioned outdoors, making any insulation you add essentially useless. Here’s a quick primer on fixing draft-prone spots.
Don’t Miss: How Can I Get My Roof Fixed For Free
Rigid Foam Insulation Boards
As the name implies, this setup combines foam on boards. These insulation boards usually have three variants EPS, polyiso XPS.
Or expanded polystyrene, polyisocyanurate, and extruded polystyrene foam. The board type depends on the foam. Polyiso has the highest R-value of the three and is the costliest.
