We all too often get calls asking us if we can install metal roofing in Houston (r-panel roofing or standing seam) can be installed over an existing shingle roof. This is a good question and has two different answers which depend on a few different factors. Below is short description of what the existing conditions may be:
Can you install a metal roof over my existing shingle roof……
- if I have an architectural shingle in place right now? ANSWER: NO …Metal roofs must have a smooth surface so that it can be walked on by installers, if it’s not flat it will cause oil canning or dents which will be visibly noticeable.
- if I have more than one layer of roofing shingles on my home? ANSWER: NO …Although this can be taken both ways, it’s not recommended to have more than one layer of roof shingles on your home. Your home or structure is designed to carry a certain amount of weight or load per square foot (PSF) and by increasing this weight you’re placing more stress than it’s designed for. Even the lightest of roofing shingles weight 200 pounds per square layer.
- if I have one layer of 3-tab traditional shingles ANSWER: YES …Yes, you can install a metal stand seam roof or r-panel roof over an existing shingle roof if it’s only one layer of 3-tab shingles because they offer a smooth, flat surface which will not cause denting or oil canning of the metal being installed.
The removal price of an existing roof is minimal and typically completed within a few hours after your roofing crew arrive and although we never recommend installing a roof over an existing roof, it can be done because occasionally the budget to replace your roof will not allow.
If you’re ever concerned about roofing over an existing roof, check into local and state codes or get several opinions from different roofing contractors.