What is causing my siding to melt?

21 Replies

We are considering a new house to live-in flip. The brand new siding (installed June/July 2019) is melting above the front door. Located in Colorado, and it's been hot the last few weeks.

There is no window next to the siding, just a roof. I'm wondering if there is inadequate ventilation in that roof? 

Seller has a warranty, so they're having it repaired, but I'm concerned about next year.

@Jim K. I know you're a DIY guy. 

@Mindy Jensen , my initial guess is you are getting solar radiation off another surface.  Beside the above the door, is it only limited to where the shingles are? They appear dark. And concrete around the door may do the same thing, as a reflective surface. 

If your theory about ventilation is correct, and it may likely be, heat would build up and try to escape around the sides of the plywood sheathing. With the sheathing terminating at the wall, it could be that the siding laps that edge. Heat would go right behind it. You could investigate that detail while they are replacing the siding. If there is no ridge vent, that is the first place I would start.

Hope that helps. Good Luck.

@Mindy Jensen Look at the home that is facing that side of the house, it is most likely reflective sunlight from low E or high reflective windows in a building facing the home (or maybe your own home it is hard to see the layout.)  This is VERY common as more houses get high efficiency windows.  

Absolutely also possible that the corner there near the roof gets very hot and they are touching the roof shingles.  I am not an expert, but transition to the roof looks a bit odd, is there a step flashing behind the siding there?  

First off, I’m a floor pro, not a general contractor. My eyes see a darker colored vinyl siding that is next to a dark roof. Basically an oven when the direct sunlight is hitting it. Vinyl, both in flooring and siding  must have enough expansion space to move freely when exposed to big temp swings. It appears that your siding isn’t melting so much as it is warping from inadequate expansion space.

@Mindy Jensen 99% of the time it is reflection from a neighboring structure, either window or skylight. It will keep happening again and again if that is the case. The only way to solve it is to replace the vinyl with something that doesn't melt [wood or hardie (that is installed properly, it rarely is)] and then have it painted to match the vinyl

I don't think it's melted. I think it was incorrectly installed. (as mentioned above, not enough expansion space)

@Mindy Jensen

Loose/ falling off top runs look like they were poorly installed, likely not enough expansion room left combined with nailed too tight in a few spots. Bottom along the roof looks melted, I’d blame both insanely hot shingles radiating heat and likely the same installation issue. If they get hot enough and can’t expand they’ll warp and hold that shape.

I’d be tempted to try and design an attractive feature on that exterior portion. Something not vinyl but also installed correctly.

Originally posted by @Mindy Jensen :

We are considering a new house to live-in flip. The brand new siding (installed June/July 2019) is melting above the front door. Located in Colorado, and it's been hot the last few weeks.

There is no window next to the siding, just a roof. I'm wondering if there is inadequate ventilation in that roof? 

Seller has a warranty, so they're having it repaired, but I'm concerned about next year.

@Jim K. I know you're a DIY guy. 

 No clue, Mindy. I suck at vinyl siding. BUT..I don't see a single soffit vent there. Is there a ridge vent? Very often, when you see something like that, it's because a window is reflecting on to that area over and over again during the summer.

This video may help explain. Not the Hardie shill, but the pattern of the melting.

Hardie siding and melted vinyl

The wrong kind of paint will do that as well. It has to be paint specifically for vinyl siding. we've had that happen with the wrong paint.

ive seen this happen before when someone installs the siding too tight. Alot of the time they didn't put the nails in the center of the hole where it mounts and it gives it no expansion space. 

I can not see from the picture how it is installed. The darker colored vinyl is designed to take the heat more as it attracts more sun. That's why it costs twice as much as the lighter stuff. My guess and this is only a guess because I can only see what is in the picture, that it was not installed properly. Vinyl siding needs to be able to expand and contract. So it has to be nailed on (hung) properly to allow that. Nails should be right in the center of the slot it gives you. The nail should also not be in super tight against the siding to restrict movement, (it is hung not fastened) If it doesn't have room to expand it will buckle and warp in the heat and once it does it will never go back to normal. Also if the piece is installed to tight and has no room to expand it will also buckle. It's not complicate to install but you still need to know what you are doing.

Not enough expansion room on the top and too much heat off the roof shingles on the bottom. Does not look like the pattern you typically see from a low e window. Replacing it with vinyl is a waste of money; as the owner I would pay the difference and upgrade to LP smart siding.

That siding is definitely melted, not just buckled. The upper portion looks like it was not locked to the next siding properly (installed too loose), the J channel area where it meets the other roof not enough expansion space + excessive heat, likely from reflective heat. I agree with someone above, the step flashing looks really funky on that roof. It would be unlikely that you could get an attic space hot enough from lack of ventilation to melt outdoor siding, because that would be a ridiculous inner surface temperature that might ignite anything combustible in the attic. 

@Rich Kniss makes an excellent point about heat build up escape, however - there will likely be an OSB/plywood seam where the side of that house meets that lower roof. If the insulation is substandard/missing, no house wrap, etc, there could be a heat conduit escape route along that seam. But I suspect it's just reflection from the dark roof on siding that was nailed too tight and/or no expansion space. Vinyl siding doesn't nail to a house so much as hang from the nails, and there is a lot of contraction on vinyl. 

We see warping & some shape disfiguration up here with light gauge cheap Chinese vinyl siding especially if it butts up to metal facia or there is metal flashing under the vinyl. But we don't have the intense UV you have down there.

@Mindy Jensen . If that front door has a glass "storm door" and gets significant sun I've experienced doors delaminating and trim around smaller view windows within the door warping. Temps can get very hot in the space between doors. I can't see much of the picture... Is it possible the heat is rising so to speak?

If you think it might be the case there are companies that can apply reflective film to minimize the penetration of the sun/heat

That is really hot there. Have a look at the drip edge along the shingles. Your heat is coming from the shingles and has no where to dissipate because it's boxed in by the overhanging eave. 

A ton of heat comes off those shingles. Have you ever been on the roof in summer? 

I don't know if there's a better vinyl siding you can get but if I was in your shoes I would replace the vinyl stuff with hardieplank like this stuff: https://www.homedepot.com/p/James-Hardie-HardiePlank-HZ5-5-16-in-x-8-25-in-x-144-in-Fiber-Cement-Primed-Cedarmill-Lap-Siding-615572/202035444

Get the seller to use that. Even if just on that side of the house. It looks great and is an upgrade to that vinyl garbage. Plus, it will outlive you, your kids, and their kids.

If they just replace it with more vinyl, this will happen every year. That's the worst I've ever seen (not that I go around looking at vinyl siding to check for melting). Good luck!

As a home inspector, I'm curious about the flashing exposed under the siding at the roof connection. It doesn't appear to be roof shingles lifting, and if it were a metal flashing it could be a source of heat reflection also. Also looks like a poor installation of the lower trim piece. Another observation is the higher siding pieces that have completely separated don't look "warped" from heat but not correctly interlocked with the adjacent next row of siding. This looks more like a combination poor install, flashing (if it is step flashing) definitely not overlapping enough to prevent water intrusion, and heat. 

Like others here said, it may be that the siding it nailed tight and installed too tight end to end not allowing for expansion and contraction. If you pull a piece off and the buckling flattens out, it's not melting. It's too tight.