|
|
07-30-2021, 06:28 PM
|
#1
|
Mini-Skoolie
Join Date: Mar 2021
Location: Northwest Washington
Posts: 16
Year: 2007
Coachwork: Thomas
Chassis: Safetyliner
Engine: Cat c7
|
Silicone or Polyurethane?
I will be attaching my L brackets to my bus roof with 1/2" bolts straight through the hat channel. Question is what is a better roof sealant: poly or silicone? I plan on covering the whole assembly with Dicor. And then painting with Henry's. I just cant decide what to squirt into the holes and under the L brackets. No fiberglass on a bus roof everything is steel.
|
|
|
07-30-2021, 07:23 PM
|
#2
|
Skoolie
Join Date: Jun 2021
Location: Minnesota
Posts: 209
Year: 2003
Coachwork: Bluebird
Chassis: International 3800
Engine: DT466e 215hp Allison 2500
Rated Cap: 77
|
Quote:
Originally Posted by Chrise
I will be attaching my L brackets to my bus roof with 1/2" bolts straight through the hat channel. Question is what is a better roof sealant: poly or silicone? I plan on covering the whole assembly with Dicor. And then painting with Henry's. I just cant decide what to squirt into the holes and under the L brackets. No fiberglass on a bus roof everything is steel.
|
There is always a better choice than silicone except maybe for building aquariums. I give tubes of the stuff to my worst enemies for their birthdays.
|
|
|
07-30-2021, 08:28 PM
|
#3
|
Mini-Skoolie
Join Date: Mar 2021
Location: Northwest Washington
Posts: 16
Year: 2007
Coachwork: Thomas
Chassis: Safetyliner
Engine: Cat c7
|
Wow, thanks for your quick reply. I so enjoy hearing from passionate people about whatever, and it seems you have a passionate hate for silicone. Excellent! But why?And also you would go with Polyurethane, or something else?
|
|
|
07-30-2021, 08:35 PM
|
#4
|
Bus Geek
Join Date: Sep 2018
Posts: 2,831
Year: 2007
Coachwork: Thomas Built
Chassis: Minotour
Engine: Chevy Express 3500 6.6l
|
Sikaflex 295-UV
|
|
|
07-30-2021, 08:50 PM
|
#5
|
Bus Crazy
Join Date: Oct 2020
Location: Florida
Posts: 1,554
Coachwork: Integrated Coach Corp.
Chassis: RE-300 42ft
Engine: 466ci
Rated Cap: 90
|
^^ Danjo, that Sikaflex 295 is good stuff.
For the use described, anything is better than silicone.
Urthane based products are preferable. Some use asphalt or even acrylic. I used Dynatron 550 on each rivet of my roof patches. Same, on the flange bolts, of the rear deck a/c.
Are you using washers or flange bolts outside?Completely though the hat channel with nut/washer inside? What size are the holes in the L bracket?
|
|
|
07-30-2021, 09:30 PM
|
#6
|
Bus Crazy
Join Date: Oct 2020
Location: Near Flagstaff AZ
Posts: 1,951
Year: 1974
Coachwork: Crown
Chassis: "Atomic"
Engine: DD 8V71
|
Both the Sikaflex and the Dynatron referred to above are great and reliable. I'm also really impressed with the 3M 5200, which is also a moisture-cured polyurethane adhesive/sealant.
|
|
|
07-30-2021, 10:40 PM
|
#7
|
Skoolie
Join Date: Jun 2021
Location: Minnesota
Posts: 209
Year: 2003
Coachwork: Bluebird
Chassis: International 3800
Engine: DT466e 215hp Allison 2500
Rated Cap: 77
|
Quote:
Originally Posted by Chrise
Wow, thanks for your quick reply. I so enjoy hearing from passionate people about whatever, and it seems you have a passionate hate for silicone. Excellent! But why?And also you would go with Polyurethane, or something else?
|
I'm glad others have replied with some answers more helpful that my anti-silicone rant.
Silicone caulk is a pet peeve because it fails always. Removing every trace so a better choice can replace it is usually difficult and sometimes impossible. I've spent summers removing silicone from windows where it failed. Spent hours and hours removing it from floors, bathrooms, woodwork... you name it. Oh how I dislike silicone caulk. Silicone caulk fails any where it's used. But it sells like hot cakes... Comes in sooooo mannnny colors toooo! OH I HATE THAT STUFF!!!!!!!
Oh my, I need to take my relaxer now.....
hehehe just playing and not really mad
John
|
|
|
07-31-2021, 01:14 AM
|
#8
|
Bus Crazy
Join Date: Jan 2020
Location: Fraser Valley British Columbia
Posts: 1,043
Year: 2007
Coachwork: Thomas
Chassis: Freightliner
Engine: C7 Cat
|
Anything that is NOT silicone is the way to go.
As everyone has said sikaflex, 3M products and urathane’s are the way to go.
Please reconsider using any silicone, It is really not a good adhesive and it can not be painted. Bed all your roof vents, hatches and penetrations with something like sikaflex then cover in Dicor is a great plan. Follow that up with yearly inspections on your Dicor and you’re good to go.
Also Henry’s is silicone based.
Good luck
Cheers
|
|
|
07-31-2021, 01:21 AM
|
#9
|
Mini-Skoolie
Join Date: Mar 2021
Location: Northwest Washington
Posts: 16
Year: 2007
Coachwork: Thomas
Chassis: Safetyliner
Engine: Cat c7
|
Excellent help! Thanks!
Wow I love this site for just that reason, so many helpful peeps. I will steer completely clear from silicone and also find another elastomeric roof coating that is not silicone based.
Cheers!
Chris
|
|
|
07-31-2021, 07:07 AM
|
#10
|
Bus Geek
Join Date: Nov 2016
Posts: 2,775
|
3M 5200 is a very (very) strong adhesive but only for **permanent** use cases
much too strong if you ever want to undo a join without destroying the substrate.
4200 is just as good a sealant but easier to remove when needed.
And yes the Henry products are silicone, excellent reputation for that final coating seal
but I don't know how we don't hear about the usual horror stories, it must at least adhere to itself in subsequent applications years later
|
|
|
07-31-2021, 01:49 PM
|
#11
|
Mini-Skoolie
Join Date: Mar 2021
Location: Northwest Washington
Posts: 16
Year: 2007
Coachwork: Thomas
Chassis: Safetyliner
Engine: Cat c7
|
Well my plan is to use 1/2" bolts up through the hat channel and the skin, then through the L bracket which is made to accept a 1/2" bolt (but there is some wiggle room), perhaps a washer if there is clearance for it, then a nylock nut. Any comments or help would be appreciated. BTW this whole rack will be constructed of off the shelf uni strut components.
|
|
|
07-31-2021, 04:07 PM
|
#12
|
Bus Geek
Join Date: Sep 2017
Location: Swansboro,NC
Posts: 2,973
Year: 86
Coachwork: Thomas
Chassis: Ford B700
Engine: 8.2
Rated Cap: 60 bodies
|
if you are looking at unistrut stuff then look into spring nut that fit and lock into the unistrut itself.
then the only thing anchored through the roof is the strut itself.
|
|
|
08-01-2021, 12:25 AM
|
#13
|
Bus Geek
Join Date: Nov 2016
Posts: 2,775
|
Stuff like solar panels, anything with high lifting force at highway speeds,
do not rely on anything but the most robust connecting hardware to hold it down
|
|
|
08-01-2021, 06:53 AM
|
#14
|
Bus Geek
Join Date: Sep 2018
Posts: 2,831
Year: 2007
Coachwork: Thomas Built
Chassis: Minotour
Engine: Chevy Express 3500 6.6l
|
Quote:
Originally Posted by Chrise
Well my plan is to use 1/2" bolts up through the hat channel and the skin, then through the L bracket which is made to accept a 1/2" bolt (but there is some wiggle room), perhaps a washer if there is clearance for it, then a nylock nut. Any comments or help would be appreciated. BTW this whole rack will be constructed of off the shelf uni strut components.
|
Are you using strut or just the other strut parts? Here’s what I did:
I mounted the Z-brackets on the panels. This gave me the center-center measurement for the strut.
I used some masons twine to find the center of the roof and used that to space out the strut.
I drilled each end hole and secured that and then did the ones between.
For the attachment points i used
Carriage bolt from the inside. The low profile head is unobtrusive. (I think 1/2” is overkill, but it’s fine)
Sika 295-UV around the hole
Neoprene-backed fender washer went against the roof surface (does the neoprene add anything the sika doesn’t? I don’t know)
The unistrut
A double-thick fender washer
A nylock nut
Here’s a pic of the panel attachment. That’s a strut nut covered by a saddle washer
|
|
|
08-01-2021, 08:19 AM
|
#15
|
Bus Geek
Join Date: Nov 2016
Posts: 2,775
|
looks good
a flex washer might help maintain a gap for the sealant
metal to metal torqued down squeezes it all out
|
|
|
08-04-2021, 03:47 PM
|
#16
|
Mini-Skoolie
Join Date: Jun 2020
Posts: 22
|
We used 3/8 Rivet Nuts. We drilled holes in hockey pucks, sealed those down with a urethane based sealer,, and attached uni-strut with 3/8 bolts thru hockey pucks into riv- nuts inside hat channel. Saw this on Be Adventure Partners. Being a Yankee and a Redwinga fan, I loved it. Had to send away for pucks cuz I now live in the south, but we have been very happy with this configuration. Plus it raises the unisteut an inch which wasperfect for our solar panel mounts. We used 1.5 inch angle iron for everything else up top.
|
|
|
08-04-2021, 06:01 PM
|
#17
|
Mini-Skoolie
Join Date: Mar 2014
Location: Red Deer, Alberta Canada
Posts: 30
Year: 1979
Coachwork: Thomas
Chassis: IHC
Engine: 366
Rated Cap: 48
|
I agree that silicone isnt good for this application. And fyi; cured silicone wont stick to cured silicone, and nothing much else will either.
If you're having problems with silicone sticking then the substrate hasnt been cleaned properly.
|
|
|
08-04-2021, 07:28 PM
|
#18
|
Mini-Skoolie
Join Date: Jul 2020
Location: Rocky Mountains
Posts: 41
Year: 1971
Coachwork: Carpenter
Chassis: Chevy C60
Engine: unknown... really!
Rated Cap: 69
|
This is fascinating! Y'all have some great recommendations for sealing roof holes. Do these same products (3M 5200, 4200, Sika 295-UV...) work well for sealing windows? The silicon I put on them years ago has long failed, as you knew it would, and I was planning on using more of the same. .. but something that lasts longer would be nice.
Thank you!
(I'd be lost without y'all and skoolie.net!)
__________________
katix and her cats
in #TheBarbieDreambus
a 1971 Chevy C60 skoolie
|
|
|
08-04-2021, 07:39 PM
|
#19
|
Bus Crazy
Join Date: Jan 2020
Location: Fraser Valley British Columbia
Posts: 1,043
Year: 2007
Coachwork: Thomas
Chassis: Freightliner
Engine: C7 Cat
|
Urethane for sealing your windows
Just a few bucks a tube at Home Depot
The Sika Flex would be good here also.
Good luck
Cheers
|
|
|
08-04-2021, 09:21 PM
|
#20
|
Bus Crazy
Join Date: Feb 2018
Location: Golden Valley AZ
Posts: 1,036
Year: 1993
Chassis: ThomasBuilt 30'
Engine: need someone to tell me
Rated Cap: me + 1
|
Quote:
Originally Posted by Timeline
There is always a better choice than silicone except maybe for building aquariums. I give tubes of the stuff to my worst enemies for their birthdays.
|
and your still alive
|
|
|
|
|
Thread Tools |
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Threads |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|