A bonnet roof looks like a roof with two halves. The upper half has four steeply sloping sides that come together at a point. This sloping half sits on top of four sides with very little slope that connect with the bottoms of the steeply sloping sides. One of the softer sloping sides extend down past the top of the house and form the roof for a porch.
If you are in need of a bonnet roof replacement, you should discuss the best materials for the job with your roofing contractor. There are a few considerations you should think about going into the meeting.
The upper half of the bonnet roof is great at whisking away water due to the steep sloping sides. But those steep sides end abruptly at the bottom, less sloping half of the roof. The areas where these halves meet can lead to a buildup of water or snow if precautions aren't taken.
Metal roofing can help keep this meeting area free of water and leaking. Sections of metal roofing snap together to form alternating vertical seams with gullies between. The water can thus use the gulleys as another escape route from the roof to the ground or into the gutters.
The potential for heavy buildups of snow on the lower roof means you shouldn't use an already heavy roofing material such as slate or clay tile unless your roof has the additional support structures in place to carry the weight. You don't want your roof to cave in the first time you experience a heavy snowstorm.
Surface Area and Visibility
The surface area of a bonnet roof can be quite large due to the differing sections and the relatively flat lower roof. The shape of the roof can thus drive roofing material costs up quickly. If budget is a primary concern for your roofing project, consider using a cheaper material like asphalt shingles.
Asphalt shingles can be made to look like wood or slate shingles and a fraction of the price. The shingles are also durable and weather resistant. Asphalt shingles aren't as good at keeping water off the roof, however, so you might want to combine asphalt and metal for your roof for better drainage.
The asphalt and metal combination will only look visually interesting if your roof is high enough that the lower roof with the metal shingles is mostly unseen from the ground. If the lower roof isn't visible at all and you have a higher budget, consider using a cheap material at the bottom and a more expensive stone or wood shingles on the top half of the roof. For more information, visit Ringer Roofing & Skylight Inc.