Shed Dormers Roofing: How to Choose and What to Do With It

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The ability to expand the space of your home is invaluable. For many families, the problem of increasing usable living space is particularly acute. If you have children, you need a separate office for remote work, or you want to create a recreation area in your home, you should think about how to increase the functional part of ​​​​your house. One of the most effective solutions is a shed dormer with a flat roof.

Shed Dormers Roofing
Shed Dormers Roofing

This term refers to an extension located on the house’s upper floors. Moreover, the design of the shed dormer and the roofing options for it can be very different.

Roofing is one of the most challenging tasks in designing and constructing shed dormers. The integrity, reliability of the roof, the choice of materials, and the quality of the roofing installation largely determine how energy efficient and comfortable the dormer will be for living. At ID Flat Roof, we know the answers to the most exciting questions about a shed dormer roof. Let’s talk about them in more detail.

What Is Shed Dormer and What Options of that Construction Are the Most Effective for Living Space Expansion

There are two basic living space expansion methods on the upper floor of a house.

  • The extension of the wall below allows the creation of a full-fledged room. Imagine extending the wall underneath and getting a terrace. Then, you must build the walls and get proper dormer roofing.
  • Another kind of shed dormer can be bumped up from a roof plane. In that case, you get a mezzanine or an attic attached to the roof plane. It looks more stylish yet requires more attention to the choice of materials than a flat roof dormer.

Which one to choose? That depends on the initial plan of the construction and, foremost, on the height of the shed dormer’s window related to the eave height of the house. In any case, developing a shed dormer with a flat roof is easier.

Benefits of a Shed Dormer With a Flat Roof

Shed dormer not only allows you to equip a cozy and functional room under the roof. Due to its flat roof, this option has several critical advantages:

  • Proportional ceiling height and room area. Often, attics aren’t comfortable for life due to the roof’s slope. A shed dormer with a flat roof is entirely devoid of this drawback.
  • Skylights are one of the most costly construction items. You must admit that installing a roof window on a pitched roof will cost you much more, and there will be more requirements for such a window than for a shed dormer with flat roofing.
  • Roof options for a flat dormer are much more diverse. To begin with, you can use the most inexpensive types of roofing, from rolled asphalt or bitumen, and then everything is just up to your imagination. It can be decorative tiles, corrugated boards, and polycarbonate sheets. At ID Flat Roof, we strongly recommend using a PVC membrane as roofing for dormers with flat roof construction. It will be a good solution in terms of price and quality of the roof.

Why You Shouldn’t Use Shed Dormer Rigid Roofing Materials

Clay tiles or metal roofing look more attractive. It’s in fashion. Yet it is still a bad idea regarding a flat roof on a shed dormer. Why so? It is worth paying attention to the roofing material for an attic or shed dormer. Tops should be good-looking, practical, and functional, so they should be energy-efficient, durable, warm, and without water leakages. For example, we don’t recommend using rigid metal roofing materials, such as metal tiles, corrugated boards, seam roofing, etc. Why?

There are several reasons for this:

  • Thermal conductivity quality. Metal has poor thermal insulation qualities and transmits heat. And this means that you will need to apply a thick layer of insulation, which is more expensive. Otherwise, the attic will be cold in winter and hot in summer. That’s the opposite of comfort.
  • High noise level. Everyone has heard the sound that metal makes when rain falls on it. The noise is loud and obnoxious. No one will be pleased to live in an attic when the rain drums are on the roof and do not give rest.

So it turns out that for an attic, it is better to use a soft roof, bituminous roofing, or the best choice – a PVC membrane.

Merits of a PVC Membrane Roofing

A shed with a flat roof should withstand several factors to provide the homeowner with maximum comfort. These factors are:

  • Absence of extraneous noise. High sound absorption is a must for a shed dormer because this room is often used as a bedroom.
  • Protection against heating. Nothing is worse than an overheated roof that radiates heat into the interior. Since the shed dormer is the highest room in the house, it heats up the fastest. Low thermal conductivity is vital for this room’s roofing.
  • Good insulation. It applies to waterproofing and thermal insulation. A shed dormer roof should not allow heat from the inside to escape and not give access to moisture.
  • High strength. Wind resistance is crucial for shed dormer roofing in regions with high hurricane and tornado activities. A flat roof often suffers from the accumulation of debris on it, the sticking of snowdrifts, and icing.

Separately, it is necessary to draw attention to the features of the materials and the arrangement’s specifics. There are a few rules to keep in mind here:

  • All materials for work with the dormer should be light in weight so as not to load the structure.
  • Impregnations and antiseptics necessarily protect wooden elements to avoid rotting.
  • Finishing inside is done with lightweight profiles and drywall.
  • Thermal insulation materials should be high quality and light.
  • It is essential to provide high-quality waterproofing and vapor barrier.

It is worth choosing a PVC membrane for a shed dormer to meet all these conditions. The advantages of this material are diverse:

  • It has high moisture resistance.
  • Good strength indicators.
  • Optimal elasticity and extensibility.
  • Resistance to ultraviolet radiation.
  • Resistance to aggressive environmental influences.
  • Wide operating temperature range from -35 to +80 degrees.
  • A sufficient level of vapor permeability ensures stable diffusion of moisture.
  • It complies with the fire safety regulations.

Combining these features makes PVC membrane a win-win idea for your shed dormer’s flat roof.

Besides, in ID Flat Roof, you can evaluate a case of a shed dormer installation using a PVC membrane we’ve provided to a household in North Attleboro.

PVC Roof Installation on a Shed Dormer, North Attleboro, MA

A shed dormer is a popular way to expand living space without building an addition. Shed dormers have almost flat or very low-pitched roofs, and if covered with traditional roofing materials, like asphalt shingles or rolled asphalt, they tend to leak and allow ice dams to build up. A rolled PVC membrane is an excellent solution to leakages and ice dams. It fits flat and low-sloped roofs, carries a lifetime material warranty, and reflects a lot of sunlight, keeping the space cool.

Flat Roof On Shed - North Attleboro
Flat Roof On a Shed – North Attleboro

We used a 50-mil white PVC membrane for this project, mechanically attached over ½-inch Styrofoam insulation. Initially, there was one layer of asphalt shingles on the roof, but since the roof deck was in great shape, we decided to leave them and go over the top, which essentially cut the cost for the homeowner. We cut back shingles along the edges, removed the old drip edge, and installed a 6-inch wide pressure-treated nailer to allow proper PVC-coated drip edge installation. In this case, we decided to weld the membrane directly to the drip edge (as opposed to the method when the drip edge goes on top of the membrane and then the 6-inch stripes are welded over), and we used extra screws every 6 inches to hold drip edge in place tight.

Flat Roof Dormer - North Attleboro Massachusetts
Flat Roof Dormer – North Attleboro, Massachusetts

Because this roof had a ridge vent on it, we installed a pressure-treated 2×4 stud along the ridge and wrapped it with a pre-welded PVC flashing piece to serve the purpose of a substrate for the new ridge vent and ridge cap installation.

Shed With Flat Roof - North Attleboro
Shed With a Flat Roof – North Attleboro

Another possible problem is snow slides during the winter. Usually, it is OK on flat or almost flat roofs but shed dormers typically have a substantial pitch (somewhere between 2 and 4). In addition, a wet PVC membrane is pretty slippery. These two issues can be causes of snow slide formation. Since our client had a big porch under the roof section, we decided to install plastic snow guards – every foot in a staggered formation. To ensure the proper installation, we mounted another 6-inch pressure-treated nailer piece one foot above the one along the edge. We used special screws with rubber gaskets to hold the snow guards in place and SolarSeal 900 sealant between the snow guard and the roof to cover the screws up. We also installed two 5-inch two-way vets to ensure proper condensate evaporation from under the membrane.

As you can see, developing a shed dormer project is a manageable task when you know what materials to choose. In the case of roofing, it is a PVC membrane that meets the most sophisticated requirements of a homeowner for the comfort and energy efficiency of a shed dormer.

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Main Contractor at ID Flat Roof | + posts

Denis is the driving force behind ID Flat Roof, a leading company in Boston specializing in flat roof repair and installation for over 20 years.
Denis excels in PVC, TPO, EPDM, and rubber roofing. His meticulous approach ensures quality and customer satisfaction.
Denis incorporates cutting-edge solutions like skylights and solar PV roofing.