October 12, 2021
You might start noticing some signs that your roof is in need of some serious attention. You have broken or missing shingles, mold growth and consistent leaks! Patching and minor repairs may no longer be enough to keep your home dry and protected from the elements, it may be time for a whole new roof.
For some people this may mean stripping off the existing roof and replacing all the shingles, but for many others, this may not be necessary. If there is only 1 layer of shingles on the roof currently and the sheathing and shingle structure are for the most part intact, you may be able to apply a new layer of shingles over the ones already on the roof. This can work out a lot cheaper and quicker that other options.
So how many layers of roof shingles are allowed?
In some instances, 3 layers may be allowed, but this is rare. Most areas only allow for a maximum of two layers. This will also be constrained by other factors. The contractor may do a walk on the roof and also inspect from the attic for any rot before installing a second layer of shingles. If there is rotted wood, this would need to be replaced before any further roof repair work is undertaken.
The roof needs to be able to bear the weight of two layers of shingles plus be able to bear the added, weight in winter due to a layer of snow, without the framing being stressed to breaking point. Laying a second layer over the current layer of shingles means that longer fasteners (nails or staples) need to be used to anchor them down. This is also why three layers would generally be impractical.
What are the benefits of more than one layer of shingles?
Depending on the pitch of your roof and the type of shingles currently being used, the number of layers may be restricted. For fiberglass-asphalt and organic shingles and a pitch under 4:12, as long as the roof structure remains sound, you should be able to have two layers of shingles. One of the largest benefits associated with double layering as opposed to stripping and laying a complete new set of shingles is simply saving costs. There is a significant labor cost involved in tearing off the current layer of shingles before replacement.
This can save the homeowner a chunk of cash. There is also the cost involved in disposing of the old shingles and other roofing material. These can actually become quite high as well if there are a variety of material types that need to be disposed of. The underlying wood is exposed while the new shingles are being laid. The time taken in stripping the roof and disposing of the rubble can be significant as well, making the project take longer and adding noise and inconvenience while the project is ongoing. Double layers of shingles can also reduce the likelihood of ice dams.
What are the disadvantages of more than one layer of shingles?
When a second layer of shingles is laid over the first, roofers do not usually apply a water and ice shield before laying the second layer of shingles. This means that if there is damage to the layer underneath, the roof is vulnerable to water and ice getting in under both layers. The second layer of shingles would also need to be heavyweight shingles to hide hollows and higher spots on the roof.
These are more expensive than the single weight shingles. The second layer of shingles will add stress to the structure due to the extra weight. This can result in settling and movement of the house which can cause some foundation and wall cracks to develop. Even if the house has a concrete foundation, premature settling can cause damage.
There is added time and labor costs involved in a prolonged roof inspection if there is damage to the roof in the future. Storm repairs will cost more due to 2 layers of shingles needing to be removed for the repair work. Roofing over asphalt shingles can diminish and even invalidate the manufacturer’s warranty.
Should I re-roof or add a layer?
It is usually best to go along with the guidance of a roofing professional. Roofs that have a high pitch, damaged structures or light-weight frames or already have 2 layers of shingles are most definitely better candidates for a tear off and shingle replacement. The roofing professional can check all the other variables and then advise if your roof would be a good candidate for a second layer of shingles over the old. You can perhaps get a quotation on both options and make an informed decision based on your budget and long-term plans.
When should my home be re-roofed?
Just like any other part of your home, your roof needs inspection and adequate maintenance. Don’t wait for the roof to cave in or to have bucket loads of water leaking into your home before you do something about it. Do a quick inspection once a month and look out for the following:
If you notice any of the above, you may want to get in a professional to repair the damage before it gets worse. Damage to the roof will only escalate over time, costing you more in the long run. If the roof is in a bad state, you may want to look at a complete roof replacement. You can however look at remodeling your roof at any time to improve the curb appeal or simply to improve the look to suit your own preferences.
It is recommended that homeowners do not attempt to do a second layer of roof shingles on their roof unless they are qualified to do so. Attempting repairs such as these without professional experience and qualifications can result in serious damage to the home and even the homeowner. There are specific inspections and techniques required to ensure a home can safely have two layers of shingles and that these are applied correctly.
It is important to look at the positives and the negatives before deciding on adding a second layer of shingles to your roof. The positives of convenience, faster completion and cheaper price may be perfect in the short term, especially if you are buying to repair and resell.
For the long term, the extra layers may trap heat and moisture causing the underlying structure to break down faster and ripping off two layers of shingles at a later stage will more than likely be a lot more costly than replacing the single layer of shingles twice. The extra weight can also cause sagging, causing moisture to be trapped when it rains or snows. This can result in the roof having its lifespan reduced by half.
The second layer of shingles may also not look that great. The layer underneath may have many imperfections and these may show through the new layer on top. A brand-new roof is laid on a flat surface and should not show dips and rises as dramatically as a layer on top of them would, especially if heavy duty shingles are not used for the second layer.
Some property inspectors also note a double layer roof as a negative and some potential buyers may be put off if the roof looks messy even with the new layer of shingles. A double layer of shingles also makes inspections more difficult and potentially more costly. A complete roof strip and re-shingle allows for a full roof inspection, a fresh layer of felt on the roof deck and evenly laid shingles.
If you are looking to do something that is reasonably priced as a short-term fix, then a second layer of shingles would be a good idea, provided your roof can handle it and it is within the local building codes.
This can give you time to arrange your budget to strip and re-roof your house in around five to ten years if you have damage to your roof and cannot afford a complete roof shingle replacement at the time. Just remember to factor in the cost of stripping and disposing of two layers of shingles the next time around.
Some of the more common types of roofing used today include: Metal roofs, tile roofs and even rubber roofs. If you decide to completely re-roof your home, you can look at a variety of options to find one that suits your needs with regards to price, durability and style.
Adding another layer of shingles as opposed to stripping and doing a new roof is usually a lot risky for the homeowner and contractor alike, even though it may be cheaper for the homeowner and less profitable for the roofer. There is less chance of damage to the home, driveway and garden from a dumpster, dropped shingles and nails from the shingle removal entering tires (and even feet).
There is also a lot less risk of damage to the underlying structure as it is not exposed. In the case of a sudden rainstorm, there is no scrabbling around to cover up the work area to prevent water getting into the home. Two layers, as long as they are in good condition offer double protection against the elements.
Ask your roofer to do an evaluation of the suitability of your home for having a second layer of shingles laid as opposed to a complete re-roof if you are looking to save costs in the short term.
Then you can get a comparative quote for a re-roof with the shingles of your choice. The roofer will also be able to advise on any other repairs that may be required, which should be undertaken at the same time.
These repairs need to be done before the shingles are placed/replaced. In many instances, a repair may be needed and if the roof was replaced within a 10 to 15-year time period, it may not need a complete roof shingle replacement.
A qualified professional will be able to make an assessment, break down the work needed and then recommend whether to repair or replace. They will also check for damage to other roofing structures as well as measure the size of the shingles currently on the roof.
New shingles will have to match the current shingles in size for a repair or if new shingles are being laid over the existing layer. Even for a tear off and replace, it would be recommended to use the same size shingle as previous or the re-roofing could be disastrous.
Use a recommended, professional roofer to ensure the job is done well and that you are able to contact them should anything go wrong. Many fly-by-night roofers may offer cheaper prices, but the job may not be done properly and there is no recourse if something goes wrong.
Your roof protects your home from the elements and it is important to keep it clean and in good order to ensure may years of happy living. If you think that you may have any problems with your roof, get a professional to take a look and give you advice on the best route to follow to safeguard your home.