What is a gambrel roof?
Gambrel roofs are also called as Dutch colonial roofs and became a popular roofing type in barn houses in North America starting in the 1600s. This type of roof is identifiable for its symmetrical yet sloped look. It has two symmetrical sides with steep slopes hanging in opposite directions. Its bottom sides are steeper in slope than its two top sides.
In present day architecture, gambrel roofs are categorized as multi-pitched roofs because of its multiple peaks intersecting at different angles. It comes in three sub-types: gable gambrel, dormer gambrel and the new style valley gambrel. It is also often confused with the mansard roof but this one is sloped in two directions. Here is what a gambrel roof looks like.
What is the purpose of a gambrel roof?
At the most basic end, gambrel roofing is geared towards a more aesthetic punch. But beyond that, the steeper sides increase the storage space beneath it. It also offers more living space on the upper levels of the building by maximizing the headroom. This is the reason why this roof style is used in barns, sheds, and garages.
Related: 25+ Parts Of A Roof And Their Functions (Explained and Pictures)
Gambrel roof advantages
To understand the rave about gambrel roofs, here are the advantages of opting for this type of roofing designs.
- It gives a unique architectural vibe. Because of its colonial style, it gives the home the romanticism of Dutch or Georgian aesthetic. It is posher than the usual flat style roof and other modern roof designs.
- Includes fewer materials for construction. Since it includes fewer beams or columns in the installation process, it is more cost-efficient in terms of labor and materials. Overall, it only requires two roof beams and fewer sets of gusset joints. As such, you can also add ‘easy to build’ as one of its advantages.
- Offers better drainage. The steep slopes of the gambrel roof offer better drainage since rainwater can easily run off to the sides without puddling on the joints connected to the gutter’s pipe. This also means that you would also spend less money on possible water and moisture problems down the stretch.
- It lasts longer. When the right materials are used, gambrel roofs last longer than other types. As a matter of fact, some even last for over a decade before requiring refurbishment. This alone makes it a good investment.
- Adds more space. As have been mentioned, gambrel roofs add more headspace to multi-storey homes. This added space can be used for an attic room or for an attic storage. Once you shingle the edges, you are making it more waterproof. You can even add windows to your gambrel roof design to get natural light.
- It can be constructed using a variety of materials. Some of the materials used for gambrel roofs would be wood, asphalt or slates. Thus, you can use the most appropriate material for your geographical location. You can also use various materials to pair it with.
Gambrel roof disadvantages
It is also not a perfect roofing system like all else. Here are the disadvantages of gambrel roofs that you should be aware of.
- Exhibits poor resistance to snow puddling. The flatter side of the gambrel roof is not made for snow puddling, and it shows. When this is not mitigated early, snow buildup can cause damages and even possible building collapse.
- Prone to uneven wear. Since various material combinations can be used for gambrel roof, it becomes more prone to uneven wearing. This is the reason why regular maintenance checks are needed for it to last a long time.
- It is not retrofitting friendly. The bad news about this type of roofing is that you cannot upgrade it anytime or when the wearing is too obvious to even patch up. Contractors who are not familiar with the design may also damage it entirely.
- It is more vulnerable to wind gusts. In some locations where winds are stronger than usual, year-round, gambrel roofs can easily be damaged. It has something to do with the principles of aerodynamics since there is an uneven air flow over the steep slopes compared to the lower slopes.
- It requires waterproofing. To reinforce it with snow damages down the stretch, you must ensure that there are waterproofing shingles around the ridges. This means additional costs to your gambrel roofing plan.
- Some designs have ventilation issues. Although it provides more headspace, insulation could be a problem. Because of this, all the moist, hot air rises. But then, that is another problem in the making because the precipitation from the hot air could lessen structural integrity over time.
Related: Types Of Roof Vents
Where are gambrel roofs more common?
For one, gambrel is the preferred roofing type for barn and farmhouses. They can also be installed in log cabins as well as in Dutch colonial homes and Georgian style homes. As they are incorporated in modern or mid-century homes, its headspace has proven its utility especially in adding extra living spaces like an attic room or a loft.
Are there types of gambrel roof?
Yes. There are three types of gambrel roof, and they are the following.
- Gambrel combination: For a unique and modern look, you can combine a gambrel roof with another roof design. The most common options to combine gambrel with would be gable and hipped roof styles.
- Dormer gambrel: You need dormers to accommodate more natural light inside the home. This sounds essential for extra living spaces provided by the gambrel. It can be one big dormer or sets of smaller ones scattered around the roof.
- Gambrel with a wide overhang: An overhang does more than just aesthetics. It is also a protective layer for the sides and to cast shade for the patio or porch.
- Gambrel combo: And just as you think that you should be conservative with gambrel, you must think again. This is because you can incorporate the three styles mentioned here in one gambrel roof plan.
Gambrel roof house ideas
Here are examples of houses featuring a gambrel roof that you can refer to if you are ever thinking of having one.
Newport style home with classic gambrel roofing
This one makes use of a classic gambrel roofing. It stands on 3,481sq.ft., housing 7 bedrooms and 5 baths. It also gives space to 2 garages and features two attic rooms and one attic storage.
Gambrel gable roofing for a colonial style home
This gable and gambrel roof plan for this home is specially designed to provide the indoor spaces with as much natural light. It features 4 beds, 2.5 baths and a 3-car garage. The roof’s primary pitch is 8 on 12 and its roof frame is made of trusses.
Gambrel roof shed ideas
Gambrel car garage
This is a 12×16 gambrel car garage in a barn type home. It features two modern doors. One rollup door for the car walkway and one side door to access the tool kit and other equipment.
Gambrel tool shed
This one is an 8×8, one-door gambrel tool shed that is specifically made to house bulky equipment and other gardening and machinery used for all types of home maintenance jobs.
Gambrel roof vs mansard roof
These two types of roofing both have European origins. Gambrel is from the Dutch while mansard is from the French. The main difference between these two is that mansard has four sides and each has double slopes while gambrel has two sides with steeper slopes in opposing directions. Compared to gambrel, mansard is harder to install and harder to maintain.
They have similarities too. Both can be shingled for more weatherproofing. They also add more headspace on the top storey of the structure. As for downsides, they share vulnerabilities to snow accumulation and wind damages.
Gambrel roof vs gable roof
Gable roof is the most common roof frame. It is a shed style, with four steep sides or pitches. These are especially made to deter wind, rain, and snow from damaging the roofing. Unlike the downside of gambrel roofs, gables offer more ventilation in the extra headspace it provides.
On the other hand, gambrel is designed for more storage space and because it is taller than gable roofs, it could offer just that. It is also considered as a more flexible roofing compared to gable roofs.
Related: Skillion Roof: Advantages and Disadvantages
How much does a gambrel roof cost?
According to The Nest, gambrel roofs are 10-20% more expensive than gable. As such, you would have to spend at least $11000-12000 on a gambrel compared to the $9000-10000 cost for gable roofs.
How long does a gambrel roof last?
Depending on how it is maintained, gambrel roofs are said to last for more than 40 years. While inspection should be done regularly, it is more low maintenance than roofing types. Regular maintenance includes proofing it from snow, rain, and wind.
How to build a gambrel roof
The first thing to prepare must be the materials needed in building one:
- Wood trusses (2×6 in size)
- 1/2” plywood
- ¾” plywood
- Waterproofing material
- Decide on how tall your gambrel roof will be.
- Calculate the number of trusses needed to cover your home. The trusses should be at least 16-inches apart.
- Calculate how long each truss would be. The rule of thumb is 60 degrees for lower angles and 30 degrees for higher ones.
- Using a pencil/chalk, mark your angles for the lower and upper trusses. Cut them after following the degrees for the angles. Work on all the trusses following the measurement of the first one.
- Next, build the gusset plate out of the ½ plywood. This will hold the trusses together. Have them joined using nails and brackets.
- Now, put the first truss in position. Straighten it and then secure the joists of the lower floor. And then brace the first and second truss in between to ensure that they do not tilt.
- Continue nailing all the trusses in place down the length of the home.
- After this, you are now ready to cover the entire thing with the ¾- inch plywood.
- Weatherproof the plywood and then finish off the surface of the gambrel roof with shingles.
Related: Rafters vs. Trusses: Which one is better for your home?
How to shingle a gambrel roof
Shingling a gambrel is needed for more weatherproofing and here is how you do it.
- The first thing to do is to count the needed shingles. To do this, measure the roof area and convert your figures to square meters. As per rule of thumb, you will need a square of shingles for every 100sq.m. The store would know how many squares of shingles you need.
- Install the shingles during the sun’s peak. The heat helps in making it more flexible and easier to place.
- Start laying the shingles from the lowest angle. Nail each shingle with nails and then cut excess shingles on the sides with a razor blade. After this, overlap the shingles with another set of shingles.
- Continue laying down the shingles on top of each other until you meet the desired thickness. When you reach the peak, cap off the shingles with ridge caps.
In building the gambrel frame or rafters, here is a visual which you can check.
Gambrel roof calculator
If you are looking for a roof calculator, you can try Block Layer. At best, the recommended width of a gambrel roof should be in between 16-24 ft. This is how wide a gambrel roof can be.
What are the angles for a gambrel roof?
Since gambrel roofs follow a recommended width, the lower angles should not exceed 60 degrees and the upper angles should not be more than 30 degrees.
How do you measure a gambrel roof?
Using a gambrel calculator, you must enter the exact measurements of the following and in order.
- Enter the exact length of the building followed by its width.
- Enter the measurement of the eaves’ overhangs.
- Enter the measurement of the gable’s overhangs.
- Enter the upper roof’s pitch followed by the lower roof’s pitch.
- Enter the lower pitch’s length.
How do you support a gambrel roof?
Almost all gambrel roofs need a knee wall for support. This supporting structure braces the joint between slopes of the upper and lower roof.
The knee wall is built and installed first before the roof’s frame or rafters. The good news is that you would not be needing collar ties for a gambrel roof so you can chunk this out of your expenses.
Why do barns have gambrel roofs?
Gambrel roofs are preferred roofing styles for barns because of the extra headspace that it offers. This is functional in creating another storage for farm supplies, produce and more.
It can also be used to keep smaller farming equipment or those that are used seasonally. It is also strategic to avoid moisture buildup that can cause damage to the stored farm products inside.
Why are the gambrel barn roofs in Kentucky painted black?
The answer to this is more practical than aesthetic in nature. They need the heat induced by black barns in raising the temperature which helps in aiding tobacco curing which is a main product in that state. Traditionally, the paint is made of creosote, which is again, functional in repelling termites.