How To Tie In A Flat roof With A Shingle Roof

In the field of residential roofing, flat roofs are fashionable. Flat roofs are a common feature of off-grid compact dwellings built in rural areas and metropolitan cities. Flat roofs are a common choice for house expansions, extra porches, garages, and garden accents like pergolas and gazebos.

The process of roofing is not simple, but certain undertakings, like tying into the roof shingles already in place, are simpler than they appear. If you take safety precautions and construct joists that meet at the eave of your roof, it is a simple project.

Although installing shingles on a flat roof is usually not the best course of action, if you do decide to do so in place of shakes, tile, or metal there are a few helpful guidelines to keep in mind.

The intersection of a flat roof and a pitched roof is more susceptible to damage than other areas of the roof. To avoid leaks in this region and to allow for appropriate water drainage, roofers must take great care when installing the roof. The transition of the shingle to a flat roof needs extra care and one should know how to tie a flat roof and shingle roof properly.

Why is a tie-in needed?

To reduce any potential gaps and chances for leaks, the addition’s roof should be connected to your existing roofing. When a new addition is placed incorrectly, there is a danger that air and moisture can enter, which might cause structural damage, the growth of mildew and mold, and other problems.

You can guarantee that the installation is sealed against water by carefully tying it in. This will avoid all of the previous water damage problems and their potential consequences.

Consequences of if a flat roof is tied with a shingle roof poorly

In essence, the pitch change is the cause of the issue. Sloped surfaces allow water to flow more quickly than level ones. Fast-moving water thus slows down as it flows from the shingle roof onto the flat roof. This increases the likelihood of leaks and ponding water. Ice dams, which can also lead to leaks, are also more likely to form if the flat roof is over an area that is not heated.

Roofers frequently succeed in joining flat and pitched roofs, but they must take care to make the change between the two surfaces seamless. Installing the flat roof components over the shingles is a relatively easy error a roofer might make. To the unaided observer, this would appear watertight, but there is a big issue here.

Water will encounter a gap where the flat roofing starts as it cascades down the shingle roof. Water is held back and moved more slowly by the lip, which might result in leaks. Additionally, if this area doesn’t dry up, the standing water will corrode the roofing components over time, necessitating an early replacement.

Moreover, flat roof replacement is more common than shingle roof replacement. Therefore, over the lifespan of your shingle roof, you will probably need to repair your flat roof a minimum of once. To nest the new flat roof underneath the existing shingle roof, your contractor will need to eliminate a portion of the shingle roof; otherwise, the issues mentioned above are likely to occur. If the flat roof is not properly ventilated or drained, other issues might arise.

Read also: Flat roof vs Shingle roof

How to make the transition from a flat roof to a shingle roof

Additionally, having an understanding of the proper methods for attaching a flat roof and shingle roof can help you ask your contractor the appropriate questions and achieve the greatest outcomes for your roof. Of course, a qualified roofer should be trusted with this task. But as the property owner, you could be interested in how the roofer should connect your two roof planes.

Building the new roof

The trusses or rafters of the addition’s walls must first be installed such that they reach the point of the house’s acute angle. The chalk lines on the roofing should be snapped after the structural support for the recent change has been established. This is to designate the location of the new roofing valley’s center.

It’s convenient because you can either remove the shingles or leave them in place and frame over them later.

Removing some shingles

If your pitched roof is already in place, your contractors will need to remove two or more layers of shingles and reinstall them after the barrier that connects the surfaces has been placed.

Selecting your membrane

Your contractors should install a roofing barrier to fill the space between the two layers. Granulated roof membranes for business flat roofs or ice and water protection membranes are examples of acceptable membranes. The membrane that will be utilized should climb a few feet up the pitched roof from the flat roof.

Tie-in the shingles

The new shingles should now be integrated with the previous roofing system using a cut valley. Snap a line over the current roof shingles once the new addition’s roof has been framed and sheathed. You should be around two inches just above the valley’s actual center.

Cut through the shingles and the base from here. The shingle tabs will then need to be unsealed before you can pull the nails out of the underlying course. Then, start removing two shingles from each side of your new valleys, working your way down to the bottom. Since these will eventually be replaced, be careful to keep them and give them a number.

Installing the waterproof underlayment for shingles

The waterproof shingle rule underlay has to be laid down once the underlayment has been lifted out of the way. After putting it over the valley, you will shingle the roof of the extension. Giving the new shingles enough space to fold onto the old roof deck and into the valley’s center is important; you’ll need around 12 inches.

You could wish to re-lay those shingles which you previously removed and marked for a better outcome. Use a 2-inch ribbon of roofing cement to bed the ends of each shingle.

Choose a roofer with knowledge of both types of roofing when you need work on your flat roof to pitch roof changeover. Excellence construction can help you in this situation and is always there to answer your inquiries.