Image by Malcolmj, used under the CC BY-SA 2.0 license.
How to tell if your roof needs reshingling
To check whether your roof might need to be reshingled, it's important to carefully examine it. First, the roof should be inspected from the inside. Does it look like it’s sagging? Can you see leakage or any damage from water? Are there dark spots? Can you see daylight? If the answer to any of these questions is yes, chances are you will need to replace at least some shingles.
If things seem good from the inside, inspect the outside. Look for damaged and missing shingles. Check your gutters for decomposed shingles. If your shingles are wooden, they may also need to be checked for termite damage. Shingles need to be replaced if they are decayed or broken. Ignoring damaged shingles will lead to more serious (and more expensive) repair work in the future. Minor damage can be patched with roofing cement or similar products, however this is only a short term fix. A qualified installer should be able to give you a full assessment of the state of your shingled roof.
What’s involved in reshingling a roof?
Support structure
First, the installer will check over your roof’s internal support structure to make sure it remains sturdy and solid. Weathering and rot can weaken wooden beams and trusses. If this is the case with your roof’s support, you will need to have the wood replaced. Your shingling job just got a whole lot bigger! If however, your support structure is still intact, the installer can move onto the inspection and removal of old and damaged shingles.
Remove decayed and damaged shingles
At this point, the installer will most likely remove the decayed or damaged shingles. Although shingles shouldn't be installed over the top of more than one layer of old shingles, it is possible to nail your shingles directly on top of those that need replacing. In most cases, it really is better to start afresh and remove the old shingles though, as adding extra shingles can also add to the weight of your roof.
Check the roof felt
Once the damaged shingles have been removed, a layer of roof felt will be exposed. This is a thick black paper, usually impregnated with asphalt, which helps to repel moisture. It can also be made of other materials. If there are holes in the felt, it will need to be replaced. Alternatively, a new layer of felting material can be nailed over the top of the old one.
Attach shingles
Once the roof felt is ready, the rows of shingles can be installed. Normally rows of shingles are installed from the bottom, working up to the top of the roof. Normally, work also starts in the middle of each row working outwards - a half shingle at the edge of the roof will be less noticeable than one in the centre.
How much is reshingling likely to cost?
The cost of reshingling will depend entirely on the size of your roof and your choice of shingling materials. Asphalt is the cheapest type of shingle, and slate is normally the most expensive of the common types of shingles. There's a significant amount of labour involved, so don't be too surpised if that also accounts for a considerable amount of the quote.
Who should reshingle the roof?
Climbing up on roofs is incredibly dangerous - one slip could lead to a fall, which in turn could easily result in paralysis or death. You should always hire a trained professional to do reshingling work on your roof.
How long will it take?
Again, this depends on how much of your roof needs reshingling. If your entire roof needs to be reshingled, you can expect it to take a roofing professional at least a few days, depending on how big your roof is.
