When you get a new asphalt shingle roof, the roofer usually replaces the shingles and the underlayment. As long as the plywood deck is still in good shape, it's not replaced. However, the key is to make sure the deck doesn't have water damage. Here are four ways a roofer looks for water damage on a plywood deck to see if it has to be repaired or replaced when you have a roof replacement.
1. The Deck Looks Or Feels Saggy
If the deck has a lot of water damage, it may have a sagging appearance when you look at it from the ground. This is an obvious sign the deck has to be replaced. This is also a dangerous situation since the roof could collapse if it sags too far.
If sagging isn't obvious by sight, your roofer may notice it when they walk on the roof to inspect it and notice a difference in the way the roof feels underfoot. By catching a bad deck before they give you an estimate for your roof replacement, the cost of the deck replacement will be included and your estimate will be more accurate.
2. There Is Mold, Moss, Or Algae Covering The Roof
Moss tends to hold moisture on the roof, and algae and mold thrive in damp conditions, so the presence of these growths could indicate your roof has a moisture problem. Since there is underlayment between the shingles and the deck, it's possible the moisture is on top of the underlayment. However, if your roof is old, there's a good chance the underlayment has deteriorated, and this increases the odds of water damage to the deck.
3. A Thermal Camera Detects Moisture
Your roofer might use a moisture meter or thermal camera when they inspect your roof so they can tell what's going on under the shingles. A thermal camera detects hidden moisture since a wet roof holds temperature differently than a dry one.
The roofer can tell if your deck has widespread water damage or is just wet in spots. This gives them an idea of how much of the deck will need to be replaced once the old shingles are off.
4. A Visual Inspection Finds Water Damage
When your roofer tears off the old shingles and underlayment during the roof replacement process, your entire deck is exposed. This allows the roofer to walk over it to find even small areas that have water damage so they can be cut out and replaced.
This ensures the entire deck is dry and solid before new shingles are put on. This is one reason your roofer may prefer that you tear off your old shingles rather than put a new layer of shingles on top of them.
For more information about roof replacement services, contact a local company.