Roofing over an old roof is acceptable?
Leaving an old roof in Place:
- Two layers are acceptable in some situations, roofing over an old roof is acceptable.
- The main benefits of applying two leaders..
- Roofing cost is greatly reduced.
- The roof gets two layers of protection.
If conditions are right, new shingles laid over old shingles can be just as attractive and durable as shingles laid on bare sheathing.
Installation is easier than for a tear-off job because you can use the existing shingles as guides for laying the new ones. But you must take care to install the shingles correctly so they lie flat. And a good job involves installing new flashings rather than relying on the existing ones.
Reroof jobs are sometimes done without replacing flashings. However MJT Roofing recommends new flashings -- including special drip-edge flashings made for reroofing -- will ensure a tight seal and a long life. Some roofs will need to install a layer of waterproof shingle underlayment on chimney, skylights, as would be done for a roof laid on bare sheathing. This provides added protection against ice dams.
When to install a second layer:
Install two layers if. Your local building codes access the practice. The existing roof has a relatively smooth even surface any curled or broke shingles are either nailed down or removed. Fasteners are of sufficient length to penetrate the wood deck 3/4'' or penetrate through a plywood deck.
Installing three layers:
MJT Roofing does not recommend the installation of three layers of shingles on any roof deck. Nailing through three layers does not fasten shingles properly.
Most building codes do not allow.
For more information call us at 8604656841
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Posted By:
Manny J Tenecota Owner of MJT Roofing