What is the Best Insulation for a Flat Roof? St Louis, Missouri

What is the Best Insulation for a Flat Roof?

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insulate flat roof spray foam St Louis, Missouri
spray foam insulation for flat roofs St Charles, Missouri

What is the Best Insulation for a Flat Roof?

If you have a flat roof, whether for your home or your business, you may wonder if the insulation you have right now is sufficient, or if you should have it replaced. If you’re a builder or contractor constructing a flat roof, you may wonder which insulation would work best in this application.

Flat roofs are notorious for their challenges in construction. They can be difficult to maintain, waterproof and, yes, insulate. Choosing the wrong insulation in St. Louis MO can lead to leaks, energy inefficiency and more. There are a few factors to consider.

Insulation: Ceiling Rafters

To insulate between ceiling rafters, there are two main types that are best: spray foam (closed or open cell) insulation or affordable dense-pack cellulose insulation It’s tough to properly insulate and ventilate flat spaces since air doesn’t always move in a linear fashion. This allows moisture to get into small spaces, which can then become trapped.

Therefore, it is often easier to start with a non-ventilated area and either fill the cavity with cellulose, or seal it up with about five inches or so of spray foam.

You’ll have to consider rafter height, of course. For 2x6 rafters, closed cell spray foam is your only choice due to R-value restrictions. If you have 2x8s, dense pack cellulose or open cell spray foam would work best.

Insulation: Exterior Roof Surface

Commonly used for commercial flat roofs, a strong adhesive can be applied to the foam board, followed by a rubber waterproof membrane as needed to achieve the desired R-value. You’ll need to insulate the rim joists to prevent moisture and air filtration problems.

Insulation: Ceiling

Last but not least, this option is not widely recommended due to the need to drop the ceiling to maintain code requirements. This option also makes it difficult to add lighting or hardware later on.

With so many limited options for insulation, you can see why flat roofs are not a desirable roofing type, especially for residential use.

Knowing which insulation to add for your home or business is critical. For traditional roofs with eaves and dormers, the go-to option by many today is spray foam. That’s because it can easily be applied to the spaces between attic rafters. Not only does this act as a moisture barrier, it can provide a high R-value for optimal energy efficiency.

Fiberglass batt insulation has historically been the go-to choice to add between attic rafters, but it is being overtaken in popularity by modern methods of roof insulation. That’s because fiberglass insulation tends to compress and lose R-value over time, and is quite inefficient at stopping air from getting into and out of your house.

If your home has a flat roof and you’re unsure which insulation to go with, get in touch with your trusted insulation contractors in St. Louis MO.

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To make an appointment with your St Louis & St. Charles MO insulation specialist, contact us at 636-233-7314.

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