Buckled torn vinyl siding due to building movement (C) Daniel Friedman Causes of Vinyl Siding Buckled, Rippled, Bent, Loose

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Causes of vinyl siding damage: buckled, rippled, bent, deformed, loose, or un-clipped: why does some vinyl siding take on an ugly look with ripples, bends, bulges, or even loose ends?

Here we discuss all of the know causes of this defect. Watch out: rippled or loose vinyl siding may be more than just a cosmetic worry, and may indicate structural defects, building movement, leaks, or even heat or fire hazards. Our page top photo shows wrinkled vinyl siding - often caused by heat exposure but in this case the extent, location, pattern and size of the damage made us suspect that there was another cause, as we explain below..

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Causes & Cures for Damaged Vinyl Siding: Bent, Buckled, Rippled or Sagging Vinyl Siding

Rippled buckled vinyl siding (C) InspectApedia JBArticle Contents

How do we Sort Out the Causes of Rippled, Bent, Buckled Vinyl Siding: Product Defects, Sunlight, Heat, Installation Errors, other Causes?


Reader Question: what is the probable cause of the buckled, rippled, loose vinyl siding in these photos?

First of all I would like to commend you on an excellent web site. I have considered it a valuable resource in my field of investigative engineering.

[Photos courtesy J.B. Click any image to see an enlarged, detailed version]

I was recently on your website viewing your information about vinyl siding damage and defects. I had an investigation just yesterday where I saw warped or rippled siding at a north side wall. This is a non-weathered side in Tacoma, Washington.

There is about 5’ of space between the wall and the property line fence and no utilities, etc. at that wall. There is a main floor living room and an upper floor master bedroom and that is all.

I have included some pictures for you that you may want to share on your web site and possibly comment on. There was no visible physical damage and no evidence of any water intrusion. At the worst areas the vinyl siding was pulled away from the wall and there was no staining or streaking over the building paper nor was there any bubbling of the paper or damage to the OSB sheathing found.

Trapped moisture between the siding and building paper due to late fall-early spring damp weather and low temperatures is the only thing that seems reasonable at this time, except for the possibility of material defect, but I am not aware of any such defects matching the conditions seen. The residence was built in 2005. Thanks, - J.B. P.E., Auburn WA

Reply: probably defective vinyl siding product; list of other siding buckling rippling bending diagnostic questions

Rippled damaged vinyl siding (C) InspectAPedia JBWithout a confident diagnosis of the cause of these vinyl siding anomalies I'm reluctant to rule out anything yet, but moisture as a root cause of rippling/buckling would surprise me; I think that plastics buckle and bend more in response to heat and physical stress, or sunlight and photo oxidation than to moisture exposure.

If I had to make a guess before we know more, I'd guess a defective product, thin and poorly formulated;

We might see product defects showing up inconsistently on different building walls for several reasons: exposure differences, installation differences, even different boxes or batches of product at the jobsite.

Since it would be odd for a quantity of defective siding to precisely match the square feet of a single building side or wall, I'd expect to find either some un-damaged siding (different product) on the mostly-damaged building wall, or some damaged siding (defective product) in some areas on other walls.

According to our siding contractor Eric Galow and somewhat supported by my own field inspections, some vinyl siding may be both buckled horizontally and rippled across the vertical width of segments because of what seems to be an inferior product formulation.

Twenty or more years ago there were (and there might be today) some lots of thin, poorly-formulated vinyl siding that warped and bent when exposed to intense sunlight or other heat sources, deforming worse than some of the more special cases we have already documented in our article series at VINYL SIDING INSPECTION & REPAIR

Vinyl siding defective product ? (C) InspectApedia JBThe siding in your photos seems to me to suffer multiple problems:

  • it is rippled across the width of the "board" segments (a heat and formulation problem most likely), and
  • ends have come loose and curled
  • the clip-on bottom edge of the siding segments failed to remain clipped in position.

Although you have not yet seen water damage, leaks can be a bit subtle and even hidden unless the siding is removed entirely.

So it may remain possible that this condition is more than a cosmetic defect; loose siding risks leaks into the wall structure, inviting rot, insect damage, possibly even mold contamination; and the risk of wind blow-off of siding areas is of course much increased.

Siding Damage Diagnostic Questions?

Loose buckled vinyl siding diagnosis (C) InspectAPedia JBAs a technical aside, and certainly not having to do with the root cause of this badly rippled, loose, buckling vinyl siding, in the photo at left (click to enlarge) I see what looks like "more clean" vertical sections of wall siding in the upper right quadrant of the picture. There may be an insulation void or other interesting building condition going on there.

It would be diagnostic in confirming that the root cause of this siding damage is defective product if we could rule out other factors; Can you tell me

  • The age of the building (2005 in this case, or about 8 years old). Eric Galow notes that following Hurricane Katrina (also 2005) not only were many common building products in short supply, but the price of building products using petroleum products increased significantly. We also SPECULATE that around the same time there may have been batches of hastily-produced and defective building products including siding and roofing materials.
  • The estimated age of the siding (2005 in this case) - and can we assume that this is the original siding? Probably.
  • Where the siding was purchased and thus tracing back through that supplier, who made it.
  • Siding thickness and chemical properties: siding age, manufacture, brand name, model, any markings on reverse side, and actual siding thickness can explain product failures. We have noticed particular generations or batches of vinyl siding prone to cracking, breakage, color fading, and surface chalking as the vinyl siding weathered;
  • The geographic location & climate where the building is located

Other useful diagnostics for this siding buckling, rippling, and loose ends all found in one place would include:

  • Is the siding equally damaged on all sides of the building or is the problem worse only on one particular side - the North side per your original note? You indicate that damage is just on one side, the North face - confirmed by your photos and emphasized by the presence of some algae on the siding surfaces. Since North is not the sunny side for buildings in North America, what other site conditions are different for this building side?

    Examples might be different product installed, reflected heat from another nearby building wall or glazing, chemical exposure, prevailing wind, even simply different installation practices by an individual worker or team from those installing siding on other building walls.
Figure 1-23: Vinyl siding nailing guidelines (C) Wiley and Sons, S Bliss
  • Is the siding nailed too tightly (it should be hung, not nailed tightly, and we should be able to slide segments horizontally 1/2" or more)
    (See Thermal Movement in Vinyl-Sided Walls and

    see Nailing Guidelines for Vinyl Siding - Mistakes mean Blow-Off or Buckling Siding )
  • What is the thickness and condition of the building sheathing to which siding is nailed? Did nails simply pull out? This would not explain siding buckling, or rippling but can contribute to loose flapping siding or siding ends at butt joints.
  • Was the siding placed properly when it was nailed in the first place? If the siding was pushed upwards too tightly, clamping very tight on the connecting lip of each siding segment below it might have encouraged stretching then warping and loosening due to subsequent heating;

    This is a bit speculative, but there is no question that structural stresses can deform vinyl siding - as we illustrate
    at Buckled, Torn Vinyl Siding Due to Building Movement.
  • Housewrap: Regarding "nor was there any bubbling of the paper" - was conventional housewrap installed behind the siding or some other building paper or nothing? Housewrap won't explain rippled buckled siding but relates to moisture control and building leaks.
  • Was this siding ever removed and re-installed on the structure? (look for old nail holes, nailing flange damage, etc)
  • Siding performance compared with other siding installations in the same area, of similar age, same contractor: Are there other buildings constructed in the same area, at the same time, or by the same contractor whose siding shows similar damage? This can point to a more extensive use of defective product, or in some cases the same siding installation crew making the same installation errors on multiple buildings.

Reader Follow-Up:

Thanks! My opinion is that it may likely be indirect heat reflecting from an upper floor window of their neighbor’s house which faces the damaged siding.  The siding damage is between the upper floor and stops about 5’ above ground so it is at a specific location.  The somewhat widespread uniform warping would seem to indicate it is not a material defect.

If I get permission to check the manufacturer I will let you know.   Thanks for your input and I agree that we all learn from each other’s collective experience, etc. - J.B.


Very interesting; I must have missed that option in our correspondence. There is no doubt that reflected heat from sunllight can cause rippled damaged vinyl siding - as I show at the page top photo
at VINYL SIDING INSPECTION & REPAIR and in discussion in this article (below

at VINYL SIDING DEFORMATION) (which you may have already seen) It would be useful to

  • photodocument the site, the relationship of the building wall and opposing windows, and
  • to measure the distance between the surfaces and to
  • project the pattern of reflected heat from opposing windows on an adjacent building to see if the siding buckling or rippling maps those areas
  • If you've got an IR or other thermal scanner you could also make some interesting measurements in and out of the reflected heat areas on the receiving building wall. In the case of window-reflected heat I've already documented, the distances were short, there was some protection from wind and air movement, and ultimately we could practically "see" the pattern of damaged vinyl siding matching exactly the parallelogram of a distorted window shape effected by the angles involved.

Nice going.

Buckled Vinyl Siding due to Thermal Expansion & Improper Nailing

Vinyl Siding buckling & loose (C) Daniel FriedmanVinyl siding will buckle due to thermal expansion if it is not properly installed. Properly installed here means proper placement of siding nails, not over-nailing too tightly, and allowing proper end clearance at single-piece siding runs to allow for thermal expansion.

Experienced vinyl siding installers who want to avoid siding blow-off (see VINYL SIDING INSPECTION & REPAIR) refer to "hanging vinyl siding" on the building wall rather than "nailing vinyl siding to the building wall" precisely to remind workers not to nail siding so tightly that it buckles when heated.

On a wall section long enough to have spliced sections of vinyl wall siding in a given siding course, if we see vinyl wall siding that is buckled, we also check to see if the siding moves freely left and right on the wall.

It's easy to either use the butt of your hand to try to slide a siding panel left or right - it should move about 1/2" or so. If the siding feels tight we may check further by grasping the end or edge of a siding section to see if we can pull or push it.

When locking the vinyl siding panels into position, do not force them up or pull them down to adjust the alignment. Too tight panels can tear and too-loose panels can unlock and come loose. One exception is at the band joint between the first and second floor where panels may come unlocked due to shrinkage of the framing. To compensate for this, some contractors pull the panels a little tight over the band joist area.

Detailed specifications for hanging vinyl siding to avoid buckling and blow-offs are found in our article VINYL SIDING INSTALLATION - see:

Vinyl siding that buckles due to improper nailing (photo shown above) is is not normally extremely wrinkled, and will be more wavy across longer horizontal runs of surface. And of course, more severe buckling vinyl siding will be found on a building sides more exposed to sunlight.

Buckled or Sagged or Rippled Vinyl Siding due to Heat Damage - Barbecue Grille or or Nearby Fire

Heat damaged vinyl siding (C) Daniel Friedman

As we mention also at VINYL SIDING INSTALLATION, heat damaged siding (shown in our photos below) is not a vinyl siding product defect and needs to be distinguished from siding that has buckled from heat from the sun combined with improper nailing.

Heat damaged siding looks like the examples we show in our photographs below.

BBQ heat damaged vinyl siding (C) Daniel Friedman
Vinyl Siding Deformation Caused by Local Heat Source - Barbecue Grill

Watch out: we sometimes find badly buckled or even burned vinyl building siding where someone placed a barbecue grill too close to the exterior wall (photo above left). And on rare occasions we've found siding that was buckled as if by this problem, but in a location where we couldn't imagine a barbecue taking place (photos below ascribed to unknown conditions, possibly heat leaks).

Vinyl Siding Deformation Caused by Other Hazards: heat leaks, chemical spills, reflected sunlight & heat from nearby surfaces, or unknown

Originally we thought the product at right was defective, or that it may have been damaged by a solvent. But it is difficult to imagine that defective siding would have been cut and installed with the rippled effects in such a regular pattern.

Heat damaged vinyl siding (C) Daniel Friedman Heat damaged vinyl siding (C) Daniel Friedman
  • Notice that at the left side of the chimney chase there is a straight, small vertical ripple extending through the siding sections
  • Notice that that vertical ripple begins about five siding segments below the fireplace insert air intake vent (one reader mistook that air intake for a clothes dryer vent - it is not)
  • Notice that at the right side of the chimney chase where siding segments are quite rippled in a regular pattern, the deformation begins at the very first siding course and extends upwards at least five siding segments above the fireplace vent
  • Notice that both of these siding deformation patterns vary monotonically in degree of deformation, from slight at the bottom onset, through most severe, and then again back to slight at the highest location of deformation.
  • These deformation patterns and the location of them should suggest possible causes such as a spill or more likely a heat leak from the fireplace enclosed by this chimney chase

Further Investigation of Rippled or Deformed Vinyl Siding Points to Reflected Heat vs Actual Fire Damage

Siding at ground (C) Carson Dunlop AssociatesAs a contrasting example to vinyl siding damaged by reflected or transmitted heat alone, our photograph at left illustrates vinyl siding that was damaged in a Poughkeepsie NY house fire.

Watch out: for heating equipment installers who may run a metal vent through a vinyl-clad wall such as the installation shown at left Vent materials that get hot may risk a fire, or at least risk damaging the siding. (Photo courtesy Carson Dunlop Associates.)

To understand with confidence why the siding at above right shows that rippled, bending effect, we recommended investigation

  • into the condition of the fireplace insert installed in the building, from beneath, from the building interior,
  • and ultimately by removing siding and sheathing to investigate the chimney chase cavity around the fireplace and chimney, looking for safety hazards, heat leaks, or fire risks as well as for evidence of other leaks or spills that might have caused this siding pattern
  • Watch out: heat leaks around a fireplace insert could be a serious building fire or gas hazard
  • Readers, especially Mike in Michigan, offered the best explanation for this particular case of rippled vinyl siding: damage caused by a combination of heat (from sunlight) reflected onto the siding from an adjacent window, and dead air space in the insider corner formed by the building wall and fireplace chase.

    Details are below at Question: diagnosing why there is rippled odd looking vinyl siding - traced to reflected sun-heat
  • Contact Us with your own photos of deformed vinyl siding or windows or similar building products along with any diagnostic information or suggestions.

See How to Repair Loose Vinyl Siding or Remove and Reinstall Part of a Vinyl-Clad Wall for suggestions and special vinyl siding tools that are used to remove and replace vinyl siding in the middle of a wall.

Fire-Damaged Vinyl Siding Photos

Fire damaged vinyl siding (C) Daniel Friedman Fire damaged vinyl siding (C) Daniel Friedman

The photographs above illustrate the more extreme vinyl siding damage observed as characteristic of a building fire.

Vinyl Siding Buckled, Torn Due to Building Movement

Buckled Vinyl siding at ground - termite damage (C) Daniel Friedman Buckled torn vinyl siding due to building movement (C) Daniel Friedman

Damaged vinyl siding (C) Daniel FriedmanAt above left we illustrate a sure clue of hidden rot or insect damage: crushing buckled vinyl siding at or close to ground level. Further investigation in this New York home disclosed a wood floor built actually on and below grade level and very extensive termite damage to the building's wood sills and floor structure.

Though there was no access below the floor without demolition, this visual clue launched an appropriate investigation and avoided a costly surprise.

At above right this building in Northern Main has settled and sagged enough to actually bend and tear the vinyl siding.

Finally, in our photo at left you can see deformed vinyl siding that has pulled away from the building due to collapse of the lower roofed structure to which siding was attached by glued-on (and improper) roof-wall flashing.

The leak into this wall was a contributor to insect damage in the building and is discussed further at Loose Vinyl Siding: Blow-Offs, Fall-Offs & Nailing Defects.



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VINYL SIDING BUCKLED WARPED at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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