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happiinesshunter 05-15-2017 04:39 PM

Flooring insulation and Subfloor
 
Hi again everyone! :)

I am still making slow progress on my conversion!

I have successfully removed all the seats/heater and wheelchair ramp, removed the floor, painted and patched the holes. I am now ready to install my floor insulation and sub-floor.

My question is what is the best method to adhere the insulation and sub-floor. I've ready a lot of contradictory methods. Some say to just lay the foam down, others say to use liquid nails.

I am also interested in how to adhere the plywood. I am using 3/8" plywood (to save on height space) and again I've read a lot of contradictory methods here. I've heard to try a "floating method" and others say use self-tapping or decking screws.

My current plan was going to be to use liquid nails to attach the insulation and tape the seams with aluminum tape. For the sub-floor I was going to use liquid nails to attach plywood to the insulation and then use decking screws on the seams.

Thanks again for the help and advice! :))

Robin97396 05-15-2017 05:23 PM

It's a personal choice, just like most of the build decisions. It all accomplishes the same thing. If you think your insulation and subfloor are going to move around, you can sure glue to your heart's content. The floating floor generally has walls or partitions installed over the top of the floating floor, so it is fastened down quite well anyway. By time you put a cabinet here and there, the floor is fastened down pretty firmly with or without glue.

Zombiepatrol 05-20-2017 11:37 AM

We are leaning toward using a spray adhesive on our subfloor because of the ease of application. We have also heard some people say it is a great noise reducer while traveling. The only concern for the future would be if it ever needed to be ripped up for any reason to reinstall something. At this point I think we are counting on not doing that for at least several years.

Robin97396 05-20-2017 12:21 PM

I'm not understanding the purpose of using a spray adhesive. Agreed it would be easy to apply, but for what purpose? The adhesive won't reduce noise levels, but insulation will absorb a lot of the vibration and noise. The adhesive would break down over time and may not have any stickiness left after a few years, depending on many things like humidity levels.

I'm suggesting you read a number of other build threads to see how they put their floors together. I've never heard of anyone using adhesive spray. Most people simply build an insulated floating floor, depending on the cabinets and partitions to actually anchor the floor in place. The floor really won't tend to move very easily anyway. Some people use furring strips to allow for thicker insulation, but taking up that much height usually involves raising the roof of the bus to make up for interior height lost from thicker insulation installs. There are frequent discussions on how much is to much insulation. You'll notice that some bus walls have so much insulation that the windows are actually boxed in. Affectionately referred to as meat lockers on wheels.

Zombiepatrol 05-20-2017 07:07 PM

Have you heard the noise rigid foam makes? The metal floor on the bus bends and pops loudly as you walk over it as well, so that is a lot of movement while stationary, let alone for traveling. Adding layers of material is not going to take that away. I have watched several videos on youtube where people have used this technique after not liking the noise of their friends' buses. Maybe they are learning from someone else's mistakes. To each his own, one of the reasons we chose to go with a bus.

I think we have also decided to just go with the liquid nails already on hand rather than getting a spray version. Maybe I am misunderstanding what you are asking, are you saying spray is not as good as liquid nails? It seemed like it would cover a better area and be much quicker and easier to use.

New2Skool 05-20-2017 07:55 PM

I would avoid spray adhesives, they dont hold up well or long in my experience.

A heavy set glue, large tubes work best. One very important note, make sure the glue doesnt damage the insulation.

I have had a few friends doing random vehicle jobs that have used liquid nails or silicone to attach rigid insulation and the combo dissolved the insulation where it contacted the adhesive.

Read the labels on the back and make sure it is poly safe and all that crap.

In my bus, I used liquid nails, put down the first 1" layer foil face down, taped the seams, put the 2" rigid pink down and taped the edges. Applied more adhesive and then put 5/8" plywood down.

Off cut the seams and ran a bead of glue into the seams just to be extra firm or tight. Once it was all in and freshly glued, I ran 4 inch self taping construction screws down through everything. It pulled the plywood down pretty well and sandwiched everything together before the glue cured.

All of it only took about 7 hours, I started with pre-cut insulation and plywood, ran the glue and tape, screwed glued and done. It all went together very quickly but, it is easy to say that when you are working with four foot wide building blocks haha.

I was never a fan of the wood framework on the floors, way too much cutting and trimming to fit each piece. Then you end up with delta temp differences everywhere. My entire plan was to remove all thermal bridging and gaps.

Plus, northern minnesota so, insulation is critical if I dont want to wake up blue in the morning haha.

Robin97396 05-20-2017 08:34 PM

I'm questioning why you need to glue the floor insulation and subfloor down. They don't tend to move. I'll admit, I put about six screws into each plywood sheet on the (ahem) floating floor. Beyond that the cabinets or furniture tend to hold the floor down.
I'm just saying I don't put any more solvent based materials in my bus than I absolutely have to. We close these things up tight during the winters, which is bad enough by itself. No solvents if I can help it.

DreamWeaverBus 05-20-2017 08:36 PM

Quote:

Originally Posted by Zombiepatrol (Post 204876)
Have you heard the noise rigid foam makes? The metal floor on the bus bends and pops loudly as you walk over it as well, so that is a lot of movement while stationary, let alone for traveling. Adding layers of material is not going to take that away.

I never thought of that before, somehow... So, is there no solution? You say adding layers doesn't help. So if you have a skoolie you're gonna have the groaning and popping and squeaking of metal and styrofoam? No matter what?

New2Skool Cool! Minnesota is my eventual destination! How does your insulation in your bus work for you in the Minnesota winters? Did you really just use rigid foam?

Robin97396 05-20-2017 09:40 PM

My bus is like riding in a pickup truck concerning noise levels now. It's also lined with styrofoam between the spray foam and plywood. Guess what, no squeeks. All the bus noise is gone because of the spray foam.

People in warmer climates just put plywood back down on the floor, then install laminate flooring or whatever they like. Obviously you'd have to have some lavers if you're going to insulate the floor.

Clean up your steel floor, treat the rust, paint it as much as you like and then start laying down a floor. Use insulation before you put down the plywood subfloor if you wish. It's done commonly, but you should read the insulation portion of several builds to better understand.

You'll get a lot of free advice here. Read the build threads and make up your own mind.

superdave 05-21-2017 06:41 AM

Quote:

Originally Posted by happiinesshunter (Post 203731)
Hi again everyone! :)

I am still making slow progress on my conversion!

I have successfully removed all the seats/heater and wheelchair ramp, removed the floor, painted and patched the holes. I am now ready to install my floor insulation and sub-floor.

My question is what is the best method to adhere the insulation and sub-floor. I've ready a lot of contradictory methods. Some say to just lay the foam down, others say to use liquid nails.

I am also interested in how to adhere the plywood. I am using 3/8" plywood (to save on height space) and again I've read a lot of contradictory methods here. I've heard to try a "floating method" and others say use self-tapping or decking screws.

My current plan was going to be to use liquid nails to attach the insulation and tape the seams with aluminum tape. For the sub-floor I was going to use liquid nails to attach plywood to the insulation and then use decking screws on the seams.

Thanks again for the help and advice! :))

you should use a t&g flooring product and glue the t&g together. insulation is a must, use fan fold at least. I got some self drilling screws from ebay to screw down the ply. just a few screws will do, mainly in the center where you walk to keep it from flexing.

Robin97396 05-21-2017 09:39 AM

You're going to want to use plywood heavier than 3/8ths for flooring. You won't find 3/8ths with a tung and groove anyway.

You think about this. Insulation isn't made for strength. If you glue down the relatively soft insulation and then glue the plywood to the top of the insulation, where exactly are you getting enough strength from to hold it all in place?

If it was a vertical, wall instead of a floor, you'd never consider gluing plywood over the top of insulation that's glued to the wall. You'd screw it to the wall.

You're over thinking this. There are many methods for accomplishing the same goal. Use your basic building skills to decide your best method of attaching the floor.

jazty 05-21-2017 10:11 AM

I put down 2" of ship-lap XPS foam and 5/8" tongue-and-groove plywood several years back and it has held up amazingly. Not a squeak, not a shift. Rock solid.

Here's what I did:
First clean, prep and paint the floor. Let the paint completely cure. If you're using Rustoleum then give it several days beyond what they recommend on the tin. That stuff is slooooowwwww to dry.

Start at the rear of the bus. Cut your first piece of rigid XPS foam (not EPS. PolyIso is ok) to fit the floor, but leave a gap at the walls. Put a zig-zag bead of original (slow dry) PL Premium adhesive on the downward side of the foam and fit it in place.
There is also a PL foam adhesive, but it's a weird, thick consistency and doesn't hold nearly as well. I tested PL Premium on XPS foam and it cured flawlessly without burning through and held much better. I've used both Liquid Nails products and PL products and PL Premium has always come out on top.

Put a light bead on the ship-lap edge and fit another. That should give enough of a foam surface to put down a piece of plywood. Doing it this way gives you two firm surfaces to stand on. Just like the foam, cut the plywood so there's a wall gap. Note that you want the plywood edges to be centered on the foam board. You don't want a foam edge and a plywood edge meeting up.

Now, at this point I went ahead with driving screws through the plywood, the foam and into the metal floor. If I were to do the job again I would skip this step and use weight to sandwich the layers (bricks perhaps?) while the adhesive cures. Screws turn out to be unnecessary and moisture condenses on the screw heads in the cold. Not a big loss of heat, but I commonly have little wet spots on the floor in the winter. I determined that the screws were unnecessary when removing a chunk of the flooring+foam to put in a shower. I had to break and scrape the foam out even after removing the screws.

Continue the process until the floor is covered. Once everything is laid and dry go ahead and put some canned spray foam into the wall gap. Use the window and door foam so the floor can expand and contract without cracking the spray foam.

That should do it! It has worked gangbusters for me. Once the foam is sandwiched between steel and plywood it is incredibly solid. That is, as long as the plywood is thick enough. I would say that 3/8" is a bit flimsy. I wouldn't go with anything less than 5/8".

EDIT: Oh, one more note. PL Premium cures in the presence of humidity. The tube recommends spraying a light mist of water onto non-permeable surfaces after laying the bead. XPS foam isn't 100% air tight so the remaining humidity between the surfaces will wick out. Don't be concerned about water being trapped between layers. Again, it all worked out very well for me.

Stu & Filo. T 05-23-2017 05:29 PM

I just did my subfloor, what I did was lay 2in insulation long ways, started with a 4ft wide piece on the left side then trimmed 3ft 6in piece beside it, the next piece I swapped starting on the right side did this full length swapping back & forth then I laid 1 &1/8 in T&G plywood cross ways & glued the T&G I'm also installing screws just at the very back edge & very fwd edge.

Robin97396 05-23-2017 06:08 PM

No cold feet for you.

New2Skool 05-23-2017 07:49 PM

I am thrilled with my rough floor and insulation.
It has been a um ******* ball freezing ******* cold **** summer so far.
We have averaged 55 degrees with rain for a solid month and it sucks.
My three inches of floor insulation on its own has helped wonderfully.
One little electric space heater from 1956 keeps my bus toasty.
I cant wait to get the windows in, run the conduit and prep everything and insulate the hell out of it.

Robin97396 05-23-2017 08:12 PM

Cool setup.

I've also found that with good insulation one small electric heater pretty well does it. What a difference.

CadaSan 05-14-2018 07:58 AM

This thread had some great information.

I do have one question along the same lines of this thread.
I am ready to do my subfloor. I noticed no one mentioned framing the subfloor with 2x4, etc.

What are the pros and cons of framing the subfloor?
I am trying to keep as much head space as possible and if I can forgo framing the sub floor then I would like to just lay down insulation and and plywood then weight it down until it cures and boom, I got a sub floor.

Does this sound doable?


(I need to start my build thread, we removed all the seats, and flooring and rust converted and painted with rustoleum safety red.)

Twigg 05-14-2018 10:50 AM

Quote:

Originally Posted by CadaSan (Post 269193)
This thread had some great information.

I do have one question along the same lines of this thread.
I am ready to do my subfloor. I noticed no one mentioned framing the subfloor with 2x4, etc.

What are the pros and cons of framing the subfloor?
I am trying to keep as much head space as possible and if I can forgo framing the sub floor then I would like to just lay down insulation and and plywood then weight it down until it cures and boom, I got a sub floor.

Does this sound doable?


(I need to start my build thread, we removed all the seats, and flooring and rust converted and painted with rustoleum safety red.)

It sounds fine.

Yukon Cornelius 05-14-2018 01:20 PM

Quote:

Originally Posted by CadaSan (Post 269193)
This thread had some great information.

I do have one question along the same lines of this thread.
I am ready to do my subfloor. I noticed no one mentioned framing the subfloor with 2x4, etc.

What are the pros and cons of framing the subfloor?
I am trying to keep as much head space as possible and if I can forgo framing the sub floor then I would like to just lay down insulation and and plywood then weight it down until it cures and boom, I got a sub floor.

Does this sound doable?


(I need to start my build thread, we removed all the seats, and flooring and rust converted and painted with rustoleum safety red.)

Opinions seem to be pretty varied on that subject.

Here's a thread to showcase some of those opinions
https://www.skoolie.net/forums/f13/fl...d-22348-2.html

CadaSan 05-15-2018 02:09 PM

Thank you for the link to the thread!

I think I will go with 1/2" of Plywood and 1/2" of insulation. Now I just need to figure out which insulation to use.


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