When Installing a Roof

roof installationInstalling a roof can be a complicated process, which is why it is best left up to the professionals. Before any work begins, there are many factors to be considered and the average homeowner has many decisions to make.  As a homeowner, it is best to get a general idea of the roofing process so you can know what to expect when it comes time to install the roof.  An informed homeowner will be able to ask the right questions and make informed decisions.


The first order of business is to obtain accurate measurements of the roof. Generally, contractors will draw up a blue print, or equivalent, of the roof dimensions. This document will help the contractor lay out the order of the roof materials before any construction takes place. Planning how and where the roof materials will be laid in advance can cut costs for roof materials and prevents mistakes during installation.

The contractor will also be required t to obtain permits for the new roof before any work takes place. This must be done by applying for a permit with the city you live in and having the permit approved by the local zoning and construction board. It is important that these documents are obtained before any work begins on the roof. If the city finds a violation, it is the homeowner that receives the fine and is responsible for paying the fee.

Removal Of The Old Roof

Your roof contractor will remove all of the other roofing materials including shingles/tiles/slats, the lining underneath as well as many pieces of flashing. The roof removal should reveal the base wood underneath all of the old materials before the new roof is installed.

In some cases, a contractor may suggest leaving the old roof on and adding new materials on top. Generally, this process is approved for a roof if (a) the roof is not significantly damaged, (b) has or had a water leak or (c) does not have more than two old layers of material already.

If your roof has been damaged or has/had a leak, do not allow your contractor to place new roof materials over the existing materials. The entire roof should be stripped and replaced from scratch. If your roof already has two layers of roof materials, the roof should be stripped and replaced. Having more than two layers of old roofing materials can cause more damage by holding water, rotting the wood underneath and cause the roof to collapse or cave in. In many cases, having over two layers of roof can lead to fines from the city.

Installing The New Roof

When it is time to install a new roof, the contractor will typically begin by hauling the majority of the materials onto the roof. This allows them to work faster without having to get up and down, gathering more materials.

Many contractors will locate the center of the roof and place a chalk line to ensure they stay level when placing the shingles.

The first row of shingles is started along the roofline, closest to the bottom of the roof near the house. The shingles will be staggered by row, so that the seam lines alternate.

The remaining shingles will be layered on top of the shingles already in place, working their way towards the top.

In some cases, the contractor may custom fit the shingles around vents or chimney lines as they approach them; other contractors lay these shingles in advance. Neither process is superior towards the other as long as there is a good seal between the shingles and the object.


After installation is complete, there will much debris to be cleaned up. Contractors are responsible for cleaning up and hauling away old roofing materials. Do not allow a contractor to place the debris on the curb for the local trash company. Many cities prohibit these materials from being placed on the curb and will not pick them up.