Should the roof cladding have gaps

Should I be worried about this roof gushing?

This "bubbling" (we call it bubbling) is due to a lack of ventilation.

This is evidenced by 1) blistering in a straight line, 2) blistering around the roof lifter on the 3-inch roof vent, 3) random blistering all over the roof.

1) Bubbling in a straight line is an indication that heat is trying to escape and has found a gap between the roof cladding.

2) Obviously, one of the easiest places for heat to escape is through the vent pipe holes in the roof. The roof cladding AND underlay (moisture barrier) is cut so that the pipe extends through the roof. This allows heat to escape and affect the shingles. (Note that the shingles around the pipe are affected.)

3) If there are random bubbles in the roof it is an indication that the nailing of the shingles in this area is insufficient / correct. Heat escapes through the roof but causes blisters in those places due to missing nails, incorrect nail patterns, etc.

I see a ridge vent, but it's probably not installed properly. I would check the attic and see if you can see a CONTINUOUS streak of daylight on the crest. Often roofers let the moisture barrier (construction paper) jump over the opening (gap) in the roof cladding ... making the ridge ventilation unusable.

The good news is that the roof membrane doesn't expand so much that it rises. This means that the roof cladding was installed with sufficient gaps (distance between the metal sheets) so that they do not bulge upwards when heated and expanded.

By the way, you lost your guarantee from the roof manufacturer because they saw the lack of ventilation.

You can check the lack of ventilation by looking around the house and adding up the area of ​​the vents.

The code requires 1/150 sf loft vents versus sf loft vents, unless you have 40% - 50% of the vents no more than 3 'from the ridge then it is 1/300 of the sf of the house (loft).

For example, suppose your house is 1600 sf and you have ridge vents so they are in the top of your roof. That means you need about 1600/300 = 5.3 sf of vent. (I can't see your gable ends so you may have even more ventilation.)

The ridge vents are usually about 1 inch wide and run the length of the ridge ... let's say 36 '. Therefore, your ridge vent is equal to 3 sf (which is within the range of 40% - 50%.)

Now you need to look for reveal and / or roof vents. Add them up to see if you have enough ventilation. I guess you don't.

In addition, ventilation slots are covered by insulation. Get up in the attic and see if you can see daylight in all of those soffit openings around the house or in one of those roof openings. If not, you need to find out if you can unlock the air vents.

BTW, one reason you think the roof looks better now is because this picture was taken at just the right time to show all of the shadows. When the sun shines directly on the roof, it "burns out" the shadows and looks great. I would go back when the sun is lower in the sky.


Thanks for the detailed answer! It's interesting because the rest of the roof (e.g. along the side of the house) looked good in these 2012 pictures too. But you are making a good point about the angles of illumination. I'll see if the sellers want to let us know what they did with the roof, if anything. But we will definitely endeavor to have the roof inspected as part of our conditional offer. Thanks again for the help!