Sooner or later, every roof covering will need replacing. But too often, homeowners find themselves complaining about “extras” on the roofer’s final bill: additional charges for corrective work that wasn’t mentioned in the estimate. Topping the list: work to repair the plywood sheathing, which tends to be very expensive.

A typical case

The Smiths need to replace their asphalt roof shingles. They get estimates from three roofing contractors, all for the same brand of shingles, and choose the one with the lowest price.

A few hours after the work begins, the Dutoits are told that new plywood sheathing needs to be installed over the entire roof surface, otherwise, the job can’t be warrantied. That unexpected extra is going to double the price of the job! The roof is already partly stripped, and the contractor says they have to make a decision fast. The Smiths feel cornered—and rightly so! Things could—and should—have been handled differently.

Questionable practices at the estimate stage

These kinds of add-ons, after the repair job has begun, are unfortunately commonplace. To be sure of getting the job, some contractors employ the devious practice of submitting an incomplete estimate—and therefore quoting a lower price than their competitors. The customer is then hit with a string of “extras.”

More often than not, these nasty surprises stem from a widespread practice: estimates done “on the fly” by representatives who don’t even climb up onto the roof to assess its true condition. “Most estimates are done from the ground so, yes, it opens the door to extra charges,” acknowledges Michel Couture, Technical Director with the Association des maîtres couvreurs du Québec (AMCQ, the provincial master roofers’ association).

In the case of plywood sheathing, should this part of the work be anticipated and included in the estimate? The answer is... yes. Almost without exception, a conscientious professional can tell, during inspection, whether the sheathing under the shingles will need major repairs.

Get the ladder out!

But does the person preparing the estimate actually need to get up on the roof to check?

Not necessarily—some issues can be noticed from the ground:

  • The sheathing will usually need replacing or reinforcing if the entire surface appears wavy and the roof truss lines are visible beneath the shingles. An experienced roofer can often see this at a glance, simply by studying the roofline.
  • Likewise, a contractor may not have to go up on the roof to establish whether some sections of sheathing on one or more sides need replacing.

Some defects, however, can only be noticed from up on the roof. A contractor walking on the roof might notice cracking or sagging of the sheathing between rafters—clues that would be impossible to detect otherwise.

A question of support: boards vs. plywood

One reason often cited by contractors to justify adding a layer of plywood to an existing roof structure is the presence of old-style board sheathing.

While they don't prohibit installation over board sheathing, asphalt shingle manufacturers do specify that the roof deck underneath must be smooth—and tend to recommend plywood as the best option. They note that use of unsuitable materials can compromise stability of the roof covering; old boards can shift, for example, and in turn deform or damage the shingles—which will void the warranty.

To prevent this, roofers recommend installing ⅜-in. plywood sheathing if boards are present (they will first re-nail the old boards to the roof structure). If the customer refuses, the contractor will probably ask him or her to sign off on that decision on the contract, to defend himself against liability if any problems crop up.

Properly doing one’s homework

Even after the most painstaking estimate, there can still be unknowns. For example, minor repairs around roof openings (e.g., chimney, roof vents, plumbing vents) are almost always to be expected. Many roof repair contracts, however, include a provision for such corrective work over a total area of about 32 sq ft.

Still, homeowners can save themselves a lot of hassle by adopting wise consumer practices, such as:

  • asking for detailed estimates from several qualified companies;
  • insisting that the roofer or estimator climb up onto the roof to inspect it;
  • providing the roofer or estimator with easy access to the attic; e.g., ensuring the trap door is free of obstacles beforehand;
  • taking the time to properly compare the estimates;
  • demanding explanations or clarifications, e.g., regarding the need for (and the eventual cost of) repairs to the sheathing; and
  • seeking advice from CAA-Quebec Residential Advisory Services, if need be.

For further information, read the Tips & Tricks article Renovation contracts: When “extras” hit you where it hurts.

Our thanks to à Yoland Therrien of Toitures Île d’Orléans, CAA-Quebec Approved Suppliers, for their contributions to this instalment of Tips & Tricks. Other source : Les Toitures Robert Boucher.