If you have an asphalt roof and you want to switch to a metal roof, you can leave the asphalt shingles in place and put the metal roof over them, or you can remove all of the asphalt shingles and then put on the metal roof. There are pros and cons to both approaches, and before making your final decision, take a look at these facts.
The Advantages of Adding a Metal Roof Over Old Asphalt Shingles
1. Leaving the shingles on is cheaper than removing them.
If you opt to leave your asphalt shingles in place, you don't have to pay anyone to remove them. That ultimately saves you money. If you are reroofing your own roof, leaving the shingles in place saves time and requires less effort.
2. Asphalt shingles absorb sound.
Metal roofs last much longer than asphalt shingles, and they are typically considered to be more environmentally friendly, but they can be noisier. Putting your metal roof over asphalt shingles helps to absorb the noise, making your house quieter.
3. Metal roofs can be installed over asphalt shingles in any condition.
When you are deciding whether or not to add a metal roof to your asphalt shingles, you don't have to worry about the condition of the shingles. If they are flat and in relatively good repair, you can simply add metal right on top of them.
However, if they are curling and bending, that is fine too. Your reroofing contractor can simply add a frame of timber slightly above your roof. Then, the contractor can install the metal roof on that frame. The frame makes the work surface flat, and the small cavity between the shingles and the new metal roof helps with ventilation.
Disadvantages to leaving your asphalt shingles under your new metal roof
1. Leaving the shingles on adds weight to the roof.
When you leave the asphalt shingles in place on your roof, they add weight to the roof. In most cases, the combined weight of shingles and a new metal roof is fine. However, if you ultimately want to add more weight to your roof -- such as in the form of solar panels -- that can become unwieldy for your roof.
Before adding two layers of roof material, think about your future objectives for your roof, how much weight it is going to have on it and whether or not it can handle it. You may need a roofing contractor, like Select Roofing & Guttering Pty Ltd, to look at them beams holding up your roof to determine how much weight it can handle.
2. You cannot use standing seam metal roofs.
Metal roofs come in a few varieties. There are standing seam roofs which feature long flat sheets of metal, and there are also metal shingles which are panels installed in rows much like conventional shingles.
If you leave your asphalt shingles in place, you cannot have a standing seam roof. You have to opt for metal panels. If you prefer standing seam, plan to remove your existing shingles.