Adhesive caulk suggestions

I'm installing these beams later this week to the bottom of my aft deck ceiling . I'm using 1/2 sst carriage bolts with backing plates on the roof top . What adhesive caulk would be best ? I could use 5200 it's cheaper than 4200 but that would be permanent . But then again they are permanent beams .

It seems that you have answered your own question.

David

djmarchand said:

It seems that you have answered your own question.

David

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Yeah I know , just bored . Thought maybe somebody had a better idea .

Greetings,
Mr. PM. Since this is a permanent installation, why not forego the bolts and adhesive and epoxy the beams right into position?

I've used Sika products with great results...

Here's a link that might prove useful to you:

Bonding | Sika Corporation U.S.

I agree with RTF. 5200 sans hardware. Cleaner install, less opportunity for water intrusion and just as strong and permanent.

" Since this is a permanent installation, why not forego the bolts and adhesive and epoxy the beams right into position?"

DAMAGE CONTROL , glue, 5200, epoxy all have a very limited range of motion before failure.

With thru bolts something dumb and ugly can happen and the unit may still accept a load.

"Stuff happens".

RTF and Al . Are you talking about thickend epoxy only and no fiberglass tabbing ?

RT has the right idea. If they ever come out of there after that, then there gonna be ready to come out of there anyway. There's a lot of folks around my area that talk 5200 for everything that attaches, but its ability to flex is not as good as its adhesive qualities. It seems that yours would be a great application for it.

The beam that is up there now is just a 2x6 that's straight on the bottom. It's screwed from the top and thru bolted . The deck roof is a fiberglass sandwich with foam in the middle . The new beam that replacing it is about 3-1/2" x 5" that's radiused on the bottom.

I would still use bolts or lag screws regardless of the adhesive. They will act as clamps during the final assembly. Boat parts move while underway and this will help everything together mechanically. You can always hide the heads by counter sinking and using plugs.

5200 and hardware.

Oh boy, you gave me a chance to say it again!
Real Men Use 5200! Glue it and screw it.

Bill11 it's scary how much we think alike.

I would use bolts. With lag screws one needs a smaller hole and the screws exert much outward pressure on the wood. Bolts use a hole that is the same size as the bolt shank so much less wood stress. I'd use more smaller bolts.

Or quite a few smaller wood screws w the heads on top of the roof. Round heads w fender washers would perhaps be more water tight.

For sealant I'd use Sika Flex 991 bedding coumpound or if the bolts or screws had the "holding things together" covered just use Dolfinite. It will seal for many years and comes right apart when needed. Lots of smaller screws and Dolphinite would be my first choice.

I would 5200 or epoxy it. I would also if for nothing else bolt or screw it for clamping pressure...heavy duty with also add mechanical strength though maybe not needed just to hold the top on.

I would also core out where the bolts screws went to a solid plug for water tightness and compressibility...and glass or fill over top of the bolt screw heads so water could NEVER enter. Both heads with fender washers is just asking for trouble as the slightest movement breaks the sealant joints.

HopCar said:

Bill11 it's scary how much we think alike.

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Well, thinking like me should scare you. Trust me.

If you don't use the bolts you lose the backing plates. I think those would be important to have.

https://en.m.wikipedia.org/wiki/Carriage_bolt

I'm confused why you would use a carriage bolt in this application. I would use a method similar to that psneeld suggests.

Re-Bedding Deck Hardware With Bed-It Butyl Tape Photo Gallery by Compass Marine How To at pbase.com

I was planning on the round head of the carriage bolt against the bottom of the beam with a backing plate , heavy washer and nut on the roof top .

Ah, I see. If you use the through bolt method and some epoxy, there should be plenty of strength. Are you not concerned with a smooth roof- line then? Perhaps there is something else you want to mount up there that can be functional as well and incorporate the other side of the bolts?

Marty are the beams to allow you to carry heavier loads on top? How are the beams supported on the ends? How is the top made?

The beam is basically just a stiffener like the old one was . It's not really for strength . The old one was straight on the bottom and I wanted a radius . It attaches at the sides where the roof turns down right at the uprights that hold the roof up . The old one was attached with screws and bolts . The roof is a fiberglass sandwich with foam core . I have a walker bay on top and a 135 watt solar panel . I can walk on it but that's about it .

psneeld said:

I would also core out where the bolts screws went to a solid plug for water tightness and compressibility...
and glass or fill over top of the bolt screw heads so water could NEVER enter. Both heads with fender washers is just asking for trouble as the slightest movement breaks the sealant joints.

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Agree with psneeld re: plug for cored FG -
- that's what I've always seen as recommended best practice... Many reasons - compression, movement, water intrusion.
Counter sinking top of hole (under backing plate or washer) also a best practice

I'd prefer cleaner looking attachment - if bolting why not head on roof top and use a threaded insert in the beam or counter bore from bottom and sink a washer & nut on the bottom - then cover w/ a plug - visible bottom ends up neat & clean and roof top cleaner as well.

I was also going to suggest c boring and pugging the visible bolt head for aesthetics. You might need something like a 7/8 plug so you'd have room for the socket on the bolt head.

Greetings,
Mr. PM. Re: Post #8. Yes, use thickened epoxy to afix the beams to the bottom of the roof and fibreglass tabbing over a fillet of thickened epoxy as well. Since you say the ends of the beams are in line with the roof supports you might also run a couple of SS lags into each end of the beam on both sides. This would eliminate any penetration of the outside horizontal roof surface and potential for any leaks. IF you do wish to add any fasteners I agree with what has been suggested that the outside heads be countersunk and filled. The only downside I can see using this method would be if the roof flexed sufficiently to crack the bond/fillet.
I'm NOT a fan what-so-ever of 5200 in spite of what "real men" use.

Since it is a foam core you cant clamp down on unsupported bolts without compressing the core.

I planning on a wide backing plate on the roof to keep the compression spread out some . I guess the top was put on mostly for shade . I don't think it's part of the original build . It was built as a work boat with large reel in center of deck .

psneeld said:

I would 5200 or epoxy it. I would also if for nothing else bolt or screw it for clamping pressure...heavy duty with also add mechanical strength though maybe not needed just to hold the top on.

I would also core out where the bolts screws went to a solid plug for water tightness and compressibility...and glass or fill over top of the bolt screw heads so water could NEVER enter. Both heads with fender washers is just asking for trouble as the slightest movement breaks the sealant joints.

Click to expand...

I have given up on calk so I west system epoxy all things that are perment or even semi, with 404 additive. Apply epoxy to the surface and bold secure in place. This summer had to replace two ceiling beams on the back deck roof because the 5200 calking failed around the teak trim.

I have used carriage bolts as the heads are large and round so they look half way descent.

I have used carriage bolts as the heads are large and round so they look half way descent.

The bronze bolts used to hold shaft struts in place are smoothest underfoot .

http://www.chatfieldmarine.com/shop/Hardware/Bolts++Screws++Washers/Strut+Bolts.html