Asphalt shingle installation FAQs.

This article series discusses best roofing practices for the installation of asphalt roof shingles, including installation temperature, shingle sealing methods, shingle course offsets, asphalt shingle nailing location and specifications, low slope and steep slope limits for asphalt shingles, and roof flashing at building eaves and around skylights.

Asphalt Shingle Roof Installation Procedure FAQs

These asphalt shingle roof installation method or procedure questions and answers were posted originally at ASPHALT SHINGLE INSTALLATION best practices, so be sure to review the advice given there.

On 2018-11-03 by (mod) - Lowes is repairing the roof after they inspected the work.

Excellent going, Gary and thank you for reporting back to us. Your experience will help other readers.

It would also be helpful to know the country and city where your home is located.

On 2018-11-03 by Gary

Lowes is repairing the roof after they inspected the work. It is nice to have a company stand behind the owner. Glad I used a respectable company to back me up with a satisfaction guarantee. YEA

On 2018-10-31 by Gary

I am sorry I do not know how to post pictures. Thank you for your help

On 2018-10-28 by (mod) -

Gary

It would be helpful to see some before and after photos of the roof - you can attach one per comment using the Add Image button.

A 2 1/2" dip in shingle installation sounds to me like rather poor workmanship.

If the shingle nailing is improper - which might also accompany poor workmanship - then the shingles would not have been installed in keeping with the manufacturer's instructions, voiding the shingle warranty and possibly giving a reduced roof life.

So you might want a closer inspection to distinguish between a cosmetic issue and a more substantive one.

Also, in the ARTICLE INDEX you'll find an article on resolving roofing contractor disputes.

On 2018-10-28 by Gary - Some shingle rows sag from 1/2" in the middle up to 2 1/2"

I just paid Lowes to install a roof and I was concerned about the sagging roof rows. I took a picture of the old roof just before the new roof was installed and all of the rows were straight along with the roof caps.
My new roof has GAF 30 year asphalt 3 tab shingles and one side of the roof size is about 24ft X18ft If I stretch a chalk line on the rows from edge of the roof to the far edge of the roofing tiles.

Some rows sag from 1/2" in the middle up to 2 1/2"

The lines of tiles on roof caps vary a gap up to 3 1/2 difference on the exposure of the tiles is this normal for a new installation? The roof looks bad like this. Can I complain and ask for them to be fixed?
Thank you
Gary

On 2017-07-26 by (mod) - nails missed boards?

Valerie:

I'm not sure what you mean by boards were missed.

The nailing schedule requires a specific number of nails per shingle, varying by shingle type; the nails must be driven into sound roof sheathing. Indeed if there is a roof shingle warranty claim

AND if the manufacturer sends an inspector to your home

AND if the inspector is looking out for his/her employer, s/he will perhaps void the warranty if s/he is able to see any roofing practice that violates the manufacturer's instructions.

You can send photos using the page bottom or top CONTACT link.

On 2017-07-26 y Valerie

During the roofing process, several boards were missed while nailing and also, several boards were broken when being nailed into. Is leaving this okay? Is it considered Standard Roofing Practice? Or will this void my warranty?
I can send photos if it helps. Thank you!

On 2017-01-24 by Emilio

To understand and comply with the requirements for a composite sloped asphalt shingle roof in terms of roof material values or U factors in relation with title 24 energy requirements? where can I find this information?.

On 2015-11-17 02:38:15.350726 by (mod) -

Jack:

Try lifting up the shingle tab carefully so as not to break it; put a dab of roof cement on the top of each exposed nail - enough to seal it but not so much that it oozes out and makes your roof look like you or I were the ones working on it. That ought to be sufficient.

When looking for a leak point, look at all of the roof area that is above the point where inside in the attic you first see water. Concentrate your sealing efforts there.

On 2015-11-16 04:06:12.350134 by Jack

Hi. My north Florida home has a 10+ year old three-tab shingle roof and one mystery leak.

Two roofers have been unable to find a specific spot for leak. One roofer showed pictures of the nails being too close to the seam. Both recommend manually sealing that section with wet-or-dry roofing cement (nails & seams only) .

For financial reasons, I will being doing the sealing myself. Here are my questions:
1. Should I also seal the corners of each shingle (per Figure 2-7) or only seal the nails & seams?

2. Is there any value in manually sealing the shingles on the entire roof? Will this extend my roof life or just be a waste of time & effort? I have more time than money right now. lol

Please advise.
Regards, Jack

On 2015-09-30 22:50:15.665763 by Anonymous

Rubber roofing base 1or 2sheets then asphalt shingles acceptably
.

Question: roof shingles installed upside down on low slope roof

(Oct 21, 2014) MaryS said:

My neighbor is having a new roof installed and not by an established company, more like friends of a friend. Because the pitch is a low slope roof, the installer is installing the 3-tab shingles in reverse of the normal way, leaving the black solid part of the shingle exposed, instead of the 3 tabs (which are being covered by the above shingle.

This does not seem right at all. He said he is a roofer and because of the low slope roof, this is the way he installs shingles. Opinions wanted, thank you.

Reply:

Mary S

The roof installation you describe3 is fundamentally incorrect and will give a short life and a leaky roof.

1. The upper portion of roof shingles are not intended to be exposed to the weather.

2. When installing shingles on a low slope roof, other methods are required to avoid a leaky short-lived roof.

See this article:

LOW SLOPE ROOFING

where we quote

As noted at ASPHALT SHINGLE INSTALLATION and in the printed text Best Practices Guide to Residential Construction:

Asphalt shingles can be installed on roof slopes of 2:12 to 4:12 if special procedures are followed for underlayment (see “ ROOFING UNDERLAYMENT BEST PRACTICES” or see page 54 in the printed text Best Practices Guide).

Eaves flashing to a point at least 24 inches inside the interior wall is recommended if there is any possibility of ice dams or water backup from leaves or pine needles.

A conservative approach is to run self-adhering bituminous membrane over the entire lowslope area. Once the underlayment is complete, shingles are installed in the standard fashion.

In cold weather, manual sealing may be required as wind uplift will be greater on shallow roofs (see “WIND DAMAGE to ROOFS).

Question: rows of shingles too far apart?

7 Sept 2014 Pam said:

Is anyone familiar with this type of roofing installation? We could be wrong, but it seems as if the rows are too far apart? We would be very grateful for any information or insights. Thanks in advance!

Reply:

Pam I took a look at your photo and will also post it here for others to comment. It looks as if there was a deliberate effort to expose a black shadow-line between courses. I can't know if this is a shingle appearance feature or if the roofer separated the courses by more space than the usual 4-5" of asphalt shingle exposure. Make some measurements and tell us the shingle exposure amount: that is, the distance from the lower edge of a course of shingle tabs down to the lower edge of the successive course below.

If you know the shingle brand and model number that would also be useful.

Pam said:

Thank you so much for your prompt reply! We are considering purchasing the home, and the seller was gracious enough to allow our contractor friend take a look around this weekend before the home inspection this coming week.

He's in excavation and said he knows nothing about roofing, but he seemed to think the courses were spaced a little bit further apart than they should be. I could see if the seller could provide more information on them.

The only thing stated in the disclosure is that it was approximately 3 years old. Here are the only other pictures our friend took on the roof. Again, thanks so much for your time assistance!

We are very grateful. Any information you would be willing to provide would be very much appreciated. That way we can compare notes with the inspector we hire, too! Here are links to the other pictures:

We are considering purchasing the home, and the seller was gracious enough to allow our contractor friend take a look around this weekend before the home inspection this coming week.

He's in excavation and said he knows nothing about roofing, but he seemed to think the courses were spaced a little bit further apart than they should be. I could see if the seller could provide more information on them.

The only thing stated in the disclosure is that it was approximately 3 years old.

Here are the only other pictures our friend took on the roof. Again, thanks so much for your time assistance! We are very grateful. Any information you would be willing to provide would be very much appreciated.

That way we can compare notes with the inspector we hire, too! Here are links to the other pictures: [...]

Reply:

Pam

Your photos show that the shingles are NOT properly installed in my opinion because at least where you show the plumbing vent, I can see a shingle cutout that extends over and above the top edge of the plumbing vent flashing - so this will certainly be a roof leak.

Measure the distances of shingle tab exposure and compare them with the data we give in our article

SHINGLE EXPOSURE AMOUNT where we will also post your photos.

Question: shingles are blowing off the roof

(Nov 28, 2012) Stan Hackett said:

When is it acceptable, if ever, to install new shingles on top of old shigles without removing them?

(Apr 27, 2014) dale carpenter said:

a part time contractor installed 100 square of GAF, best 40 year shingle over new 1/2 cdx ext plywood on our barn 5 months ago,

he removed only the bottom plastic strip on the shingle, not the middle one or the top one, six times now, since installation the shingles are blowing off from high winds 50-60 mph,

he says they need the summer heat to seat, he never applied additional tar, cement and or any other adhesive to secure them for our location,my install warranty is up by time summer comes around, please help,what do I do ? Dale

Reply:

Dale,

5 Months ago means you were installing roof shingles in December. You don't say where you are, but indeed in cold winter weather the self adhesive tabs may wait until warm weather to heat up enough in sunlight to seal.

It is not necessary, nor recommnded by the manufacturer to remove the "plastic strip" if you refer to the strip that keeps shingles from sticking together while in the bundle. When on the roof the plastic strip is not in the way of the bonding process.

See inspectapedia.com/roof/Shingle_Cellophane.php for details.

Nevertheless, if shingles have blown off, unless your roofer's workmanship warranty excludes all wind damage, it's reasonable to ask that the roof be repaired.

I don't like roofing in very cold weather because of problems like this one. I think if I were the roofer (and also if I were an English major who was good communicator) I'd warn my client that if s/he wanted me to do so

I'd install the shingles in cold weather but have to warn that they won't seal readily and unless we do something extra - beyond the standard installation process and thus maybe at more labor cost - there is risk of wind damage.

It'd be a hell of a lot of additional work to add roof mastic under every single shingle tab on a roof as an extra step. And in cold weather I'm not sure even how well it'd work.

Question: removed vent, cut holes for new vent - structural damage?

(July 22, 2014) Anonymous said:

We had our roof re shingled and had an electric vent removed and 2 new holes were cut to install 2 of the larger max vents. What is the correct procedure for repairing the hole in the roof where the old electric vent was removed. Also is there any chance of structural damage to the roof if approximately one inch x the length of the vent was cut off of the roof truss where the new vents were installed?

Reply:

Anon I can't say I've got a clear idea of the situation, but generally if we are removing something that leaves a hole in roof sheathing, before re-roofing we patch the hole, typically by a filler inside the sheathing opening (plywood?), supported by additional plywood screwed to the sheathing underside from below.

Roof Trusses: manufacturer's instructions, many texts, and in this InspectApedia article

inspectapedia.com/structure/Floor_or_Roof_Trusses.php

you're warned not to chop, hack, shorten or modify trusses as the truss strength is compromised. From what I *think* you are describing, if repair is needed it's probably minor.

Question: rows of shingles too far apart?

7 Sept 2014 Pam said:

Is anyone familiar with this type of roofing installation? We could be wrong, but it seems as if the rows are too far apart? We would be very grateful for any information or insights. Thanks in advance!

Reply:

Pam I took a look at your photo and will also post it here for others to comment. It looks as if there was a deliberate effort to expose a black shadow-line between courses. I can't know if this is a shingle appearance feature or if the roofer separated the courses by more space than the usual 4-5" of asphalt shingle exposure.

Make some measurements and tell us the shingle exposure amount: that is, the distance from the lower edge of a course of shingle tabs down to the lower edge of the successive course below.

If you know the shingle brand and model number that would also be useful.

Pam said:

Thank you so much for your prompt reply! We are considering purchasing the home, and the seller was gracious enough to allow our contractor friend take a look around this weekend before the home inspection this coming week.

He's in excavation and said he knows nothing about roofing, but he seemed to think the courses were spaced a little bit further apart than they should be. I could see if the seller could provide more information on them.

The only thing stated in the disclosure is that it was approximately 3 years old. Here are the only other pictures our friend took on the roof. Again, thanks so much for your time assistance! We are very grateful. Any information you would be willing to provide would be very much appreciated. That way we can compare notes with the inspector we hire, too! Here are links to the other pictures:

We are considering purchasing the home, and the seller was gracious enough to allow our contractor friend take a look around this weekend before the home inspection this coming week. He's in excavation and said he knows nothing about roofing, but he seemed to think the courses were spaced a little bit further apart than they should be. I could see if the seller could provide more information on them.

Here are the only other pictures our friend took on the roof. Again, thanks so much for your time assistance! We are very grateful. Any information you would be willing to provide would be very much appreciated

That way we can compare notes with the inspector we hire, too! Here are links to the other pictures: [...]

Reply:

Pam

Your photos show that the shingles are NOT properly installed in my opinion because at least where you show the plumbing vent, I can see a shingle cutout that extends over and above the top edge of the plumbing vent flashing - so this will certainly be a roof leak.

Measure the distances of shingle tab exposure and compare them with the data we give in our article

SHINGLE EXPOSURE AMOUNT where we will also post your photos.

Question: roof shingles installed upside down on low slope roof

(Oct 21, 2014) MaryS said:

My neighbor is having a new roof installed and not by an established company, more like friends of a friend. Because the pitch is a low slope roof, the installer is installing the 3-tab shingles in reverse of the normal way, leaving the black solid part of the shingle exposed, instead of the 3 tabs (which are being covered by the above shingle.

This does not seem right at all. He said he is a roofer and because of the low slope roof, this is the way he installs shingles. Opinions wanted, thank you.

Reply:

Mary S

The roof installation you describe3 is fundamentally incorrect and will give a short life and a leaky roof.

1. The upper portion of roof shingles are not intended to be exposed to the weather.

2. When installing shingles on a low slope roof, other methods are required to avoid a leaky short-lived roof.

See this article:

LOW SLOPE ROOFING

where we quote

As noted at ASPHALT SHINGLE INSTALLATION and in the printed text Best Practices Guide to Residential Construction:

Asphalt shingles can be installed on roof slopes of 2:12 to 4:12 if special procedures are followed for underlayment (see “ ROOFING UNDERLAYMENT BEST PRACTICES” or see page 54 in the printed text Best Practices Guide).

Eaves flashing to a point at least 24 inches inside the interior wall is recommended if there is any possibility of ice dams or water backup from leaves or pine needles.

A conservative approach is to run self-adhering bituminous membrane over the entire lowslope area. Once the underlayment is complete, shingles are installed in the standard fashion.

In cold weather, manual sealing may be required as wind uplift will be greater on shallow roofs (see “WIND DAMAGE to ROOFS).

Question: leaks at plumbing vent flashing

29 October 2014 Beverly Gaydos said:

We had High Definition Roofing Timberline installed over 3 tab asphalt roofing.

The flashing &vent piping were not redone & still leak. WE purchased new flashing for vent pipes & chimney & swamp cooler. What would be the best way to install this new flashing over these 2 layers of roofing ?

I was thinking of removing the few appropriate courses of HIGH Definition Roofing install the new flashing then cutting out the new Timberline asphalt shingles appropriately & replacing it with the lower portion of flashing exposed & sandwiching it between old 3 tab & new high definition roofing using adhesive nails etc.

As recommended on a new one layer roof. Can't seem to find info. about this on roof overlayment. What is your recommendation ? Everyone asked seems to have different opinions. The so called roofers aren't worth calling back.

So please give your PRO ADVICE. THANK YOU beverlygaydos13@gmail.com Roof is 3to 12 pitch in windy snowy

Reply:

Beverly,

As the old vent piping flashing installation leaks and there are now three layers of roofing, the best approach is probably to remove enough of the new roofing to give access to cut and remove the old flashing down flush with the original 2 layers of roofing that remain,

the install a new vent flashing boot and shingle over it with proper flashing positioning so that any water entering around the new flashing and boot is delivered atop the shingles down roof. For added protection you can include sealant both beneath and atop the top and sides of the new flashing boot.

...

Continue reading at ASPHALT SHINGLE INSTALLATION or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ASPHALT SHINGLE LIFE / WEAR FACTORS
• SHINGLE EXPOSURE AMOUNT
• ASPHALT ROOF SHINGLES - home
• WARRANTIES for ROOF SHINGLES
• WIND DAMAGE to ROOFS 

Suggested citation for this web page

ASPHALT SHINGLE INSTALLATION FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ROOFING

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