How to Bid on Slate Roofing

Use the tape measure to assess the length and width of the roof and multiply those figures to obtain the square footage.

Contact a local roofing supply store. Ask for prices of the slate roof tiles and related materials per square feet. Most roofing supply stores will have a list of the slate roof tiles and other related materials required to build a slate roof to make it easier for contractors to make a bid. If your roofing store does not have such a list, ask them if they can make a list for you.

Multiply the square footage of the roof by the price per square foot of materials. This number will represent the cost of materials.

Calculate the number of days of work and the amount of employees you will need. Count on using at least three employees per day to install about 400 square feet of roofing. If your roofers are inexperienced with slate roof, figure they will install about 300 square feet per day. Divide the total square footage of the roof by the number of square feet installed per day to obtain the amount of days you will need the three employees. For example, a 2,000 square-foot roof divided by 400 square feet installed per day equals five days of three employees.

Multiply the salaries of your three employees by the number of days you will be working on the roof to obtain the cost of labor. If you want to have more than three employees, add them to the cost.

Add the cost of materials and labor to obtain the average cost of the project. Add 10 percent to the average cost to compensate for any additional costs associated with materials or labor you might encounter.

Add your desired profit margin to the total cost. Align your profit margin so your bid will be competitive in comparison with other roofers around your area. Contact other local roofers and ask them the cost to do a slate roof based on the square footage of your project. Subtract your estimated costs to obtain the profit margin most are charging. Aim for at least 20 percent profit margins on slate roofs, as unexpected costs can creep up and make the project unprofitable.

Submit your bid to your client. Include all relevant sales brochures with your bid. Send the client your roofing license information and your insurance information. The license and insurance will make the client more likely to take your bid seriously.