Sikaflex...or?

[VanKitten]

I have followed these threads and thought I figured sikaflex was the answer.   But...now I think about the price and the size of the project and I am not so sure.

As I have begun to remove the insulation and gotten down to the rot...I find I will be rebuilding the walls completely.    The luan/outer wall sandwich is mostly rot on the inside (The outer wall is not just ot fiberglass...it's aluminum on top, vinyl composition bottom).    

So, I expect to remove nearly all of the old luan and replace.   This means I will have a completely new wall.  Sandwich.   Sikaflex is sort of expensive to do the entire thing....19 feet long 7 ft tall.  Both side, roof, and background...approx 65 foot by 7 ft.    Big area.

What can I use that is effective?    Seal and bond.   

I will post the pictures as I get deep into it starting next weekend.    Want I have the materials on hand before I start.   I plan to do half of one side first....then the remainder on the same side.   

What do recommend for such a large amount of area?

 

[abnorm]

HiYa Kat....from your previous posts.........I understand you're rebuilding the interior of an older RV........

Sika 221 is a Polyurethane Adhesive and Sealant........it's a fantastic Glue and Caulk 

Another Polyurethane ADHESIVE (but not sealant/caulk) is Original Gorilla Glue.......Like all Polyurethane glues it cures with moisture.......(you don't need the caulk properties on the interior laminations) ........It is an EXPANDING  polyurethane foam adhesive........you can use a small amount and get big strength........you can use it on all standard wood metal fiberglass as well as FOAM insulation.........It's a (thick) liquid so you aren't restricted to buying it in cartridge tube sizes........The LARGE bottle is 36 oz.......that's a lot of glue.......generally about a $1 an oz

To use for instance:

Adding a stud to the wall.........with the stud cut to size and the "skin" clean and ready for lamination...............apply a thin bead of Gorilla down the entire length of the stud..........SPRAY the skin with a fine mist of water from a squirt bottle.......press the stud into place and immediately brace the stud with a couple "spring poles" made from 1x lumber that span the space wall-to-wall........important because the glue expands and needs to be restrained to effectively bond ........Tight=good bond.........1-2 hrs and you can remove the clamps (24 hrs for full cure).....Of course you can still add "toe-screws" from stud-to-plates to tie the structure together

Next when you add the (foam) insulation you only need some blobs to anchor the panel .....wet........and of course brace until set............

Adding the Luan or interior skin............apply the Gorilla to the studs and wet the sheet goods with the sprayer..........Clamp or brace or staple into place

Gorilla makes a number of adhesives these days ......You want the ORIGINAL Gorilla Glue.......I suggest you buy a small bottle and due a test:

(I'm a big believer in personal product testing......."Read Understand and Follow all the Instructions"..........In my case I "glued" and clamped an 8' 2x4 horizontally to ONLY four vertical studs at the garage door.........leaving 4' of wood hanging in mid-air........After curing for a full 24 hrs I was able to hang all 300 lbs of Doug from the end of the stud without failure)   

You also want to wear some disposable gloves............ just like the Sika it's a b*tch to remove from skin

good luck.....doug

 

[highdesertranger]

also if you try to relaminate Luan to the outer fiberglass I like Titebound III. in fact I use that as a general wood glue if I am screwing the wood together. then if I need a adhesive/caulk I like the Sikaflex or 3m 5200.

here's a link where we repaired water damage on a trailer, it was not as extensive a yours but will give you an idea, https://vanlivingforum.com/Thread-repairing-water-damage . highdesertranger

 

[BradKW]

I would probably steer away from Gorrilla Glue for a couple reasons. I use it often, it's a great product, and Abnorm provided good advice for usage. However I really find it hard to picture it being a friendly process with a refit of a wall laminate due to 1) vertical application 2) work time and 3) adhesion where surface (or prep) might be considered "marginal". If I was building a wall on the ground, sure...if I'm fitting pieces that will probably require some bullying, cussing and a few smacks to get positioned before I can even start tacking or clamping...probably not.

Titebond 3 would probably work better due to a longer work time, but again, you'd need to have well prepared and solidly mated surfaces to be able to get away with a liquid glue instead of a caulk-grade adhesive.

Which brings up other cheaper alternatives like liquid nails, PL, etc...avoid these, they are not meant for mobile use and I've demonstrated their failure points with my own build.

The Sikaflex 221 is great, and a bit pricey at $12/tube, but I trust it to exceed expectations and perform even in spots where maybe I missed something or got lazy. There's another Sikaflex product which I've seen talked about, but not used...it's Sikaflex 1A, One Part Polyurethane Caulk. At under $6/tube it's very reasonable...in fact, as a generic rule of thumb, anything under $5 a tube probably isn't worthwhile. But I'd try the 1A if cost was a make-or-break factor: good company and I'm going to guess the real difference between 1A and 221 comes down to multisurface adhesion and elongation...neither of which would be a concern for interior RV builds.

 

[karl]

I agree with Brad's thinking with one exception- I have had no failures of PL polyurethane in mobile or other construction involving wood products. It will bridge gaps far better than the liquid glues.
I do agree the other(cheaper) formulas of caulking gun applied adhesives are next to worthless.

Sikaflex is king though- used it for assembly/caulking of manufactured log homes for years. Logs would split before the adhesive gave way.

Titebond 111 is my go to glue for cabinets and well fitting joints in most anything wood, as long as it can be clamped/nailed/screwed immediately so that it doesn't run out of the joint.

Gorilla glue is great if boil out/expansion and the associated mess/cleanup isn't an issue.....I rarely use it for those reasons.

 

[BradKW]

I agree with Brad's thinking with one exception- I have had no failures of PL polyurethane in mobile or other construction involving wood products. It will bridge gaps far better than the liquid glues.

I've used tons of PL Premium in home construction over the years and not had any reason to doubt it. So here is what happened in detail and what I concluded and you can reach your own conclusion:

1) Box truck has interior aluminum "studs" exposed on walls and ceiling braces and I needed to attach 1" x 2" untreated furring strips.
2) I used PL Premium to lay a decent bead on the aluminum and then used 1.5" self-tappers to mechanically fasten every 24"
3) Many weeks later I needed to attach some cross pieces, using 2" self-tappers through furring strip and aluminum.
4) In every instance where new screw was over 6" away from furring fasteners, the thread of new screw would pop the furring strip off of aluminum while it was attempting to self-drill.
5) The dried PL Premium popped off cleanly and was very brittle.
6) subsequent pre-drilling prevented further occurrence.

The poor adhesion to a material listed as recommended, combined with the very brittle cured product, has me believing it is far from an optimal choice for mobile use. When I compare it to how 221 performed in identical circumstance, there's just no comparison.

 

[karl]

Ahh, My bad- assuming porous to porous adhesion.

In that case I would expect anything without significant flexibility to fail due to the different expansion rates and vibration. Dunno what I'd use other than the 221 in that case.

Thanks for the details, I now agree completely with your assessment.

 

[VanKitten]

Thank you...everyone. I figure that pricey or not...sikaflex is the one to go with.

I am thinking that if I apply a bead of sikaflex 221 around the perimeter of a board..cross corner to corner...then clamp to the exterior ...that will work? Or..do I need to figure out how to paint it on the entire surface evenly then clamp to the exterior wall?

I am in the high desert...so I was thinking to simply drive screws through the exterior to "clamp" Lack of humidity will stretch the cure time.... The whole thing will need painting anyway when I am done...so a little sanding to cover the patch I use on the screw holes should not be that much extra work at the end.

It is supposed o be seriously cold this coming week here...so I think the extra time to order the materials will work for me. I see where I can get sikaflex for 24 10.3 oz tube for $200

 

[BradKW]

Some pictures of surfaces would be helpful.

Perimeter + "X" is generally a good bet, but you need to assess low spots and places where laminate might not conform to shell shape perfectly. Sometimes heavy dollops or piles of caulk are preferable. It's not a product you would attempt to apply to entire surface...if that were the situation, you'd look more toward a trowel-grade adhesive such as FRP adhesive or carpet glue.

Before you go making lots of holes trying to clamp it down, spend some time figuring out if cross-bracing could work out. Or, stated a different way, cross bracing would work out better but will require more thought and planning, and possibly more time since braces generally prevent working on some areas until they are removed in 24+ hours.

Cross braces could simply be a bunch of cheap 1x2 furring strips chopped to length. Two pieces hinged on a drywall screw can give you some additional options. Padding or plates on ends can be desirable...

 

[Gary68]

yea,wouldnt make holes in the exterior do something like brad said or use small finish nails or small self tapper screws to hold till the glue is cured

 

[VanKitten]

I ordered a case (24) from Jamestown Distributors today. Works out to less than $10 per. I think I will use it all. If not..I'll have a deal to offer here.

Mom is not doing well. I expect to only be able to get a few hours a week into this. Combined with the really cold weather for this coming week...I do not expect to get over to the RV. It is parked at a friend's farm. This is where I will work on it.

When I get there....I will start with lots of pictures. Even though I already started some of the work..believe me..it's current condition shows much more the damage to be repaired than the original interior (it looked ok when I go it). With aluminum sides with a vinyl composite lower half...the ripple effect you would see on fiberglass was not present. But...you knew the damage was widespread from the condition of the floor and the smell.

Ok..so, I begin in earnest this coming week. Meanwhile I wait for sikaflex delivery.

 

[Vagabound]

I'll just add one thing about Sikaflex although mine is a different product than the one you ordered.

I needed an excellent external sealant and chose an available Sika product from Home Depot -- Sikaflex+ Construction Sealant.  Polyurethane based. Around $6 per 10 oz tube.   I'm using it now to work on a box truck build-out.

Mine is listed as a sealant, whereas 221 is listed as a sealant / adhesive. How much real difference there is between them, I can't say.  From reading their technical data sheets, I can tell you that they sound very similar.  Regardless, they probably share a characteristic, which is why I'm posting this. 

I could not figure out what would cut or dissolve the Sikaflex sealant in order to clean it up. After finally making contact with Sika Corporation via Home Depot, we were told by their tech support department that nothing dissolves it. Period.  The rep explained by saying,  "Sika is not in the business of making things that come off." Probably the best example of product spin than I've ever heard.

So, if you're applying it in places that will never be seen, this is less of an issue. However, if you're going to use it anywhere on the outside of something which can be seen and you need to limit it to certain borders, the best technique that I have found so far is to treat it like it was a paint.  In other words, mask off the area with masking tape such that you only leave a thin strip for the bead to be applied. You can move it around and work it, and then take the tape off, and very carefully feather the edges if you want. In addition to the masking tape, the best tool I found so far is my index finger inside of a latex glove.  (cough please)

No matter what you're using it for, there is the issue of cleanup. The only thing that works is mechanical means. When it's wet, you can wipe it off to a degree with paper towels. That works somewhat though the product tends to smear on flat surfaces and take quite a while to wipe off. After I got it on my gloved fingers, I would also wipe it off and keep going. Buy lots and lots of paper towels, and a healthy supply of disposable latex or vinyl gloves.

After it dries, the only way to remove it is by cutting and scraping.

In terms of temperature, I have been regularly pushing the limits by applying it at or near 40F degrees, and sometimes slightly below that.   Although I can tell that it flows less well when it's colder, it still comes out of the tube well enough to use it, unlike that damn Geocel 2300 which was completely unusable.

All said, so far the Sikaflex acts like an excellent sealant.

Tom

 

[BradKW]

I always use these gloves from HD...10 pack for $10 is a steal: Nitrile Gloves

Sikaflex and most any poly or urethane based caulking will clean up nicely with acetone, so I keep a quart handy. Wet a rag with acetone and wipe off your gloves while wearing them...try to avoid acetone on the skin.

[img=300x300]http://www.homedepot.com/catalog/pr...35-4d20-4439-b1ca-2b81b9dcdba9_1000.jpg[/img]

 

[Vagabound]

...
Sikaflex and most any poly or urethane based caulking will clean up nicely with acetone, so I keep a quart handy. Wet a rag with acetone and wipe off your gloves while wearing them...try to avoid acetone on the skin.
...

I never tried because the Sika tech rep supposedly said nothing removes it.  Now I'm wondering if the Home Depot guy actually contacted the Sika rep or just made that stuff up.  I questioned the HD rep at the time whether that was a sales answer or tech support answer.  He swore up and down it was tech support.  Hmm.  I'll have to give it a try now.

I also wonder now if it can be removed with paint thinner or mineral spirits?

Tom

 

[highdesertranger]

nothing removes it once it's cured. but acetone should cut it before it's cured, it does on 3M 5200. however I would not use acetone when fiberglass or paint is involved. highdesertranger

 

[VanKitten]

Well.. my intent is to use this to glue/seal new luan to exterior skin (I refuse to call it a wall). Also, to glue/seal studs to that skin.

I have thought that I would proceed with normal (sticks and bricks) construction from there. ( (Joist hangers and the like). I plan to lay a stud on the floor at the wall...using it like a sill..and properly anchor the studs to it. Then, again at the top for the framing for the roof.

It seems weird to me that I am going to have a glued outer "wall". But I guess that is the way it is done.

I am still thinking about how I will create a brace. If I had a solid "wall" on the opposite side to use..I could create a solid enough brace to use instead of a clamp for the time to cure the skin/sikaflex/luan But..I don't. Least...I won't for the first side. I am thinking maybe I should just build a temp wall of studs in the middle of the rv....screw the studs top and bottom and use that for the braces....removing it once the first side is done.

I promise full set of pictures here this weekend.

Thank you...all of you. Always learn so much each time I ask a question!

 

[VanKitten]

Adding a stud to the wall.........with the stud cut to size and the "skin" clean and ready for lamination...............apply a thin bead of Gorilla down the entire length of the stud..........SPRAY the skin with a fine mist of water from a squirt bottle.......press the stud into place and immediately brace the stud with a couple "spring poles" made from 1x lumber that span the space wall-to-wall........important because the glue expands and needs to be restrained to effectively bond ........Tight=good bond.........1-2 hrs and you can remove the clamps (24 hrs for full cure).....Of course you can still add "toe-screws" from stud-to-plates to tie the structure together

Next when you add the (foam) insulation you only need some blobs to anchor the panel .....wet........and of course brace until set............


good luck.....doug

Just read back through your post.

I don't get it...sorry.   Brace the inside surface with a pole stud to stud...but..what is bracing the outside?

I thought to just crew right through from the outside as a clamp to hold the sandwich luan/bonding/exterior fiberglass all together while the bonding cures.    I can envision an expanding pole across the interiors space to hold the luan....but what is outside holding the fiberglass?

I have been looking at ways to seal/paint the exterior when all done.   Since it will need paining anyway..doesn't matter much if I have a bunch of holds I had to plug too.

 

[Vagabound]

Just read back through your post.

I don't get it...sorry.   Brace the inside surface with a pole stud to stud...but..what is bracing the outside?
.
....but what is outside holding the fiberglass?

I have been looking at ways to seal/paint the exterior when all done.   Since it will need paining anyway..doesn't matter much if I have a bunch of holds I had to plug too.

You didn't ask me, but I think you're doing what I already did. 

Long story short, I put new wood in the walls on the inside from the inside, but then I had no good way to brace it. Yes, I could have created a brace on the inside and pushed from one wall to the other, but all that would do is push the fiberglass wall out into a bigger buckle.  I was trying to correct the buckling wall already. 

So I didn't use any internal braces whatsoever. I took an old pallet and cut it up into little slats. I took the slats and placed them against the outside wall and screwed through them, through the wall, and into the new wood. It pulled it all together nicely that way. Worked like a charm. 

The only downside was that I ended up with 60 little holes in the side of the truck that needed to be filled with epoxy. But that job wasn't long or hard. It took me less than an hour. However, truth be told, that was the easy part. I still have to sand them all!

A side benefit is that you can drive around for a day or two looking like The Beverly Hillbillies.

Tom

 

[abnorm]

Kat........I gave a number of ideas without actually "seeing" the damage............YMMV

IF the fiberglass skin is too weak or buckled ..........Temporarily MAKE THE EXTERIOR SKIN STRONGER/STRAIGHTER/FLATTER .......just brace ....PUSH.....some "studs" or plywood or tall ladder against the OUTSIDE of the exterior wall and brace it diagonally to the ground or against the house/garage/tree.......... whatever you're parked nearby (if needed move closer)

If you are using a wimpy luan it may have an unacceptable curve/shape to it.........since you're building from inside-out you may need to screw your wall studs to the luan before you glue it to the fiberglass skin......potentially making the panel tougher to get in place

I personally would not penetrate the skin IF it could be avoided........Tom made the best of his situation at the time........(TOM:  I recommended the JBWELD..... but I said to FEATHER it in place while uncured using alcohol as a solvent.......It is too hard of an epoxy to "sand".....you can grind it but then risk damaging the fiberglass)

Kat.......I know you were also unsure of using the interior springpoles/crossbracing......try the same thing inside there......add some temporary support to the INTERIOR opposite wall to brace the springpole against......wall-to-wall 

doug

 

[Vagabound]

...

I personally would not penetrate the skin IF it could be avoided........Tom made the best of his situation at the time........(TOM:  I recommended the JBWELD..... but I said to FEATHER it in place while uncured using alcohol as a solvent.......It is too hard of an epoxy to "sand".....you can grind it but then risk damaging the fiberglass)

...

Doug, I guess I missed that onelittle detail about feathering the J-B Weld before it cured. Oh well. If it turns out that I can't stand or grind it off effectively, I'll end up painting over it, and my truck will just have a permanent case of the chicken pox. ;-) Never destined to be a beauty queen anyway.

Also, in the beginning before I did that repair, in my imagination, not piercing the outside shell was paramount. But as I got working on the project, and I noticed the little dings and cracks and other blemishes in the outside fiberglass shell, in other words, things that needed to be fixed anyway, I decided to drilling some holes in the side is no big deal. It will end up being painted anyway. 

Time will tell if I made the right choice, but there was no other feasible way to get my thing done. That said, people with other resources or other locations might be able to use other options. Just food for thought for the OP.

-----------

On a prior point, I discovered that mineral spirits or paint thinner will also dissolve the Sikaflex construction sealant when it's still wet. I'm still not sure who lied where, whether Home Depot or the Sikaflex rep he talked to, when they said that nothing at all would dissolve it. Maybe it's like the Bermuda Triangle - - a mystery that will never be solved.

Tom