Cons of spray foam insulation?

[jkordzi]

We're filling out our build sheet for a 5.0TA to be picked up in April. We are getting the extra insulation package but I was wondering about the spray foam insulation underneath. The only drawback I can see is potential access to the underside for maintenance. Can anyone tell me if the spray foam covers up anything that may need replacing in the future. I saw Ron in BC's thread on adding foam sheets instead of the spray foam and wonder if that approach would be better for future maintenance? Thanks.

 

[cpaharley2008]

I do not plan on doing an maintenance underneath my water tanks and the warm floor reminds me of that. Other than tank sensors, there is little else down there.

 

[padlin]

I had to replace the black tank dump valve this spring when I found the cracked. To do the job I had to cut away the spray foam, replace the valve, then spray new foam back on. A guess would be it turned a half day job into a full day job. I can't think of any other items that might need maintenance down under, anything buried in the foam is unlikely to get damaged enough to need maintenance.

On the Pro side, I've driven over 3 items in the road that got tossed up into the undercarriage. In all cases I could see where they whacked into the foam and tore off some of the foam, not much, but it saved any damage to the grey tank.

So it's good and bad. Getting the foam was the thing I couldn't decide on when I go the trailer, after 3 years I'm okay with it.

If I had seen Ron's foam job when I was ordering I may have gone that route. Then again, "a man's got to know his limitations".

 

[Jim Bennett]

If you don't plan any modifications, and if you want foam, then I would say go for it. There is only a small risk of needing to do maintenance under the foam, and while it makes it more difficult, it is still doable.

I have already repositioned two gas lines and the fridge pan drain underneath. I am hoping to install my spare tire winch under the front today, and after that have no further plans to do more work under. I will likely use 2" rigid foam, most likely WEDI fibreglass reinforced tile backer in the flatter areas, as though the frame is 3", all the cross members are only 2". I could then do spray in areas against the floor where the rigid foam could not easily be installed.

At this time I am not real concerned with insulated under the tanks, as I don't plan to camp with the trailer in extended cold weather, and would drain them if I did. The foam under the tanks would do little to keep the floors warm where they are located, as you would need to get the liquids warm first.

 

[skyfree-ESC]

It's remarkably easy to scrape off if you need to get to something. I completely removed it from the sewer lines when I installed heat tape. Took about 10 minutes with a putty knife.

 

[jkordzi]

It's remarkably easy to scrape off if you need to get to something. I completely removed it from the sewer lines when I installed heat tape. Took about 10 minutes with a putty knife.

Thanks. So when you do need to repair an area from which you've had to remove the foam, do you just use the spray foam in a can like "Great Stuff?"

 

[padlin]

I used a Froth pack, 2 part foam with hoses and nozzle, about $40 on Amazon.

 

[thoer]

Thanks. So when you do need to repair an area from which you've had to remove the foam, do you just use the spray foam in a can like "Great Stuff?"

I had to cut a bit away on to tighten the outlet hose clamp on the fresh tank. I will just be using Great Stuff to repair that small area.