Roof Seal premature cracking

[Mderou]

Hi all,

I sealed the roof perimeter with Proflex approximately 1 month ago. I've sealed campers before with success, but have never really been completely impressed with proflex. I understand that there is shrinkage during cure. I loaded the camper yesterday for the first time and just the articulation of loading it proved to create 6-7 cracks.

Has anyone found better success with Sikaflex? I am strongly considering this on re-application, and does anyone know if sika will adhere properly to proflex since I don't plan on removing fresh sealant. I will be hitting some rough roads next week so naturally will do it upon return with the presumable new cracks.

Finally, this has sat under a pine tree and there are reddish/brown spots (not sap, although that too) all over the roof. Thus far, soap, WD-40, mineral spirits have not worked to remove it. Kind of unfortunate since I painted this roof a month ago. I envy all of you with barns .
TIA

 

[ckent323]

Mderou, et, al,.

I am not familiar with Proflex. I tend to use Marine Grade sealants on my camper because I have experience with them on my boat and I know the marine conditions are harsher than anything my camper is likely to experience. I have used 3M 4200 & 5200 as well as Sikaflex-271 and Sikkaflex-295 along with other residential grade sealants such as Loctite.

Sikaflex makes a sealant for RV metal roofs, Sikaflex 715 Semi Self Leveling RV Roof Sealant, but I have no experience with it.

https://usa.sika.com/en/industry/transportation/rv/adhesives-sealants/roof-sealing/sikaflex-715.html​

Another Sikaflex product that might be appropriate (again I have no experience with it) is Sikaflex®-1A

https://usa.sika.com/sarnafil/en/pvc-roofing/sealants/sikaflex-1a.html​

General comment:

Sikkaflex, similar to many sealant brands, comes in many different formulations. Each formulation is for a particular application (or perhaps range of applications). Sealants work best when the application a particular formulation is designed for matches the application you are attempting to use it on so it is best to check the manufacturer information to make sure you choose the appropriate sealant for your application.

Some references

https://www.pbo.co.uk/gear/which-adhesive-sealant-is-best-20877​

https://www.ridetheducksofseattle.com/best-marine-sealants/​

https://www.practical-sailor.com/boat-maintenance/marine-sealant-adhesion-tests​

​

​

https://retail.usa.sika.com/en/products/sealants/non-sag/sikaflexr-construction-sealant-0​

https://usa.sika.com/dms/getdocument.get/24062b07-1274-3b32-9f68-0e0b314ddebc/Joint%20Sealants.pdf​

P.S. Always clean the surfaces to be bonded in accordance with manufacturer recommendations and make sure you use fresh and uncontaminated solvents (e.g. alcohol, acetone, etc) to achieve the best adhesion.


I hope this is helpful,

Craig

 

[PaulT]

This is an older thread regarding roof sealants. perhaps some ideas there.

https://www.wanderthewest.com/forum/topic/13484-roof-sealants/


Paul

 

[Beach]

Don't know what the other spots look like but in that picture it looks to me like the sealant did not bond properly to the surface and separated. Could be due to dirt,moisture or chemical contamination. Pull it back and see if there is any sealant stuck on the surface. I'm with Ckent on the use of premium marine grade sealants/adhesives,

 

[Mderou]

Mderou, et, al,.

I am not familiar with Proflex. I tend to use Marine Grade sealants on my camper because I have experience with them on my boat and I know the marine conditions are harsher than anything my camper is likely to experience. I have used 3M 4200 & 5200 as well as Sikaflex-271 and Sikkaflex-295 along with other residential grade sealants such as Loctite.

Sikaflex makes a sealant for RV metal roofs, Sikaflex 715 Semi Self Leveling RV Roof Sealant, but I have no experience with it.

https://usa.sika.com/en/industry/transportation/rv/adhesives-sealants/roof-sealing/sikaflex-715.html​

Another Sikaflex product that might be appropriate (again I have no experience with it) is Sikaflex®-1A

https://usa.sika.com/sarnafil/en/pvc-roofing/sealants/sikaflex-1a.html​

General comment:

Sikkaflex, similar to many sealant brands, comes in many different formulations. Each formulation is for a particular application (or perhaps range of applications). Sealants work best when the application a particular formulation is designed for matches the application you are attempting to use it on so it is best to check the manufacturer information to make sure you choose the appropriate sealant for your application.

Some references

https://www.pbo.co.uk/gear/which-adhesive-sealant-is-best-20877​

https://www.ridetheducksofseattle.com/best-marine-sealants/​

https://www.practical-sailor.com/boat-maintenance/marine-sealant-adhesion-tests​

​

​

https://retail.usa.sika.com/en/products/sealants/non-sag/sikaflexr-construction-sealant-0​

https://usa.sika.com/dms/getdocument.get/24062b07-1274-3b32-9f68-0e0b314ddebc/Joint%20Sealants.pdf​

P.S. Always clean the surfaces to be bonded in accordance with manufacturer recommendations and make sure you use fresh and uncontaminated solvents (e.g. alcohol, acetone, etc) to achieve the best adhesion.


I hope this is helpful,

Craig

Thanks Craig, Lots of good info here. I removed existing, cleaned and prepped with Mineral Spirits and denatured alcohol. I think in some areas I just have to add more Proflex. I'm starting to wonder if my roof latches may be too tight due to the proximity of this crack. I will reapply more liberally.

 

[Mderou]

Don't know what the other spots look like but in that picture it looks to me like the sealant did not bond properly to the surface and separated. Could be due to dirt,moisture or chemical contamination. Pull it back and see if there is any sealant stuck on the surface. I'm with Ckent on the use of premium marine grade sealants/adhesives,

I cleaned it with mineral spirits and denatured alcohol after removing old sealant and let it dry baking in the sun before application in the evening shade.

 

[ckent323]

Mderou, et. al.,

You didn't say how long after you cleaned the surfaces until you applied the adhesive. Hopefully you followed the manufacturer's instructions for cleaning and prepping the surface.

Typically it is best to paint or bond to a freshly cleaned surface within an hour or so after cleaning before it develops new oxidation or dust or other contaminants settles back on it. That written my experience is conditioned from preparing surfaces for use on spacecraft and aircraft where you want to maximize adhesion and lifetime. (but I have noted that most of the commercial paints and sealants I have used on my boat, camper and house have similar prep instructions.) ;-)

In all events, it is always best to read and follow the manufacturer's instructions closely to get the best results.

Hopefully you will have a good long lasting repair.

Craig

 

[craig333]

I agree. Prep is everything. When I put in the effort to prep I get good results. It is work. You can't just sorta clean it. Many years ago I coated the bed of my Jeep, Prepped it according to instructions (not something to do in a garage, you need good air flow) and it worked well. I had some material leftover and kept going on unprepped portions. The prepped portion still adheres well many years later while the unprepped portion has largely peeled off.

I coated my shower. Spent four hours cleaning and getting it ready and coated as soon as the final solvent wipe had dried. Very happy with the results.

Same with my camper. I need to recoat a piece but only because a tree branch tore some off.