Open Cell Spray Foam - crawl space and interior walls
 

Hi WinniPeople!

This forum is a great resource and I'm happy to be able to participate here. Thx!

We are looking at getting a small cottage above a lake. It is a pier and beam construction (floor beams on poured cement piers) with wooden slats protecting the crawl space from entry by larger critters, but not affording much other protection.

We're thinking to winterize the thing, which is moderately insane, I know.

It appears the floor joists are closed in above the dirt below the cottage with some sort of particle board, and they seem to be holding up pretty well (the particle boards). Reportedly, there is no insulation between the joists. Obviously, I'll confirm that. I'm thinking about drilling from the cottage floor and filling the joist cavities with open cell foam, then vapor sealing from the floor above (will put in new new flooring) to keep the warm moist air from traveling to into the foam below and then condensing on the cold particle board at the bottom. I might also cover the dirt floor w/ 6 or 10 mil poly to reduce summer moisture.

I hope someone might be able to point me in the direction of large quantities of open cell spray foam components, either spray or poured liquid. Any leads would be greatly appreciated.
Chris

Locally, Kamco Supply Corp sells spray foam insulation for what you want to do.

You can also buy the 2 component spray foam online from Dynamic fastener.

Just Google either name for contact info....

Dan

Thank you.

Has anyone done anything similar?

Closed cell foam
 

I have always been told in the past to use closed cell foam for these insulation projects. Mike Holmes on the tv show "Make it right" also used closed cell foam.

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I am a retired workaholic and continuing aquaholic.

This is why I posted the specifics, to discuss. Here is my reasoning: I understand that open cell will allow moisture to penetrate. This is not good for a ceiling as moisture from showers, etc will travel through the open cells to the cold roof deck unless a vapor barrier is created between the living space and the foam. Closed foam provides its own vapor barrier if applied @ 1.5" or more. Conversely, moisture from the house traveling "downwards" towards the crawl space, should, in theory, hit the "warmed floor" vapor barrier and not condense as the insulation is on the other side, allowing the floor (and vapor barrier) to stay above the dew point.In the summer, moisture should travel towards the cooler (air conditioned?) interior. However, this doesn't seem to be an issue presently - the currently visible parts of the fibre(?) sheathing below the joists aren't falling down, so I don't yet see how insulation might change that. Air can "blow" under the cottage, lowering odds of condensation on anything unless it is really colder than the ambient temp.

I have two reasons to 'buck' the conventional approach. One - it could be VERY difficult to get under the narrow crawl space, remove the ?fibre board?which closes in the bottom of the floor joists, spray LOTS of closed cell foam upwards. Clearances look to be about 16" at some parts of the crawl space from the photos I've seen. If I tried to cut holes and spray the foam downwards, as is my thought for open cell foam, and not completely fill the space with closed (or open) cell foam, it would be ideal critter country for mice to establish their own home owners association.. My hope is that the more expanding open cell foam might completely fill the void.

The other thing - open cell foam is cheaper per cubic foot I believe. If I'm going to fill hundreds of cubic feet (ouch), it is a little less ouchy with cheaper foam.

However - this is all theory on my part, save for some reports from Louisianna where some LSU folk chose open cell for the floor joists of homes built up on pilings.

Would love to hear how others are dealing w/ winterizing a camp/cottage!!!

What does "cottage above a lake" mean.

Thank you

Spraying foam upward calls for a certain amount of clearance below the floor for the applicator to crawl under and work. While closed cell foam provides more "R" value per inch, roughly 6 to 6.5, it must be applied in "lifts" of no more than about 2" at a time, due to the need for the heat released in curing to be dissipated by conduction. Open cell foam provides typically 3.6 to 4.0/inch of R value, which is similar to what you would get with a blown cellulose or fiberglass insulation, but it can be applied in thicker lifts. I'd certainly advise waiting until warmer weather, for best results. Also, with either open or closed cell foam or any other insulation, you won't get the same overall R value as you will between joists, due to thermal bridging of the framing. The R value of framing wood is roughly 1.2/inch, only a third that of porous insulation or just a fifth or less of what closed cell gives.

Considering the difficulty of application in a tight space, you might consider having a contractor do a dense-pack of borate-treated cellulose through holes cut in the sheet goods underneath the joists, much as is done when insulating a wall from the outside through holes cut in the sheathing. As a side benefit, the borate treatment of the cellulose provides a deterrent to rodents and insects.

After installing insulation between the joists, consider also installing a vapor-permeable insulation layer below the joists, such as Roxul board (https://www.homedepot.com/p/Roxul-Co...1224/206789748). This will provide an additional amount of insulation below the whole floor assembly, eliminating a lot of the thermal bridging effect of the framing.

Finally, another option is to change the skirt material to something that will keep out the weather and insulate those walls, especially if you have any utilities down there. For sure, apply that 6 or 10-mil vapor barrier over the ground. If you do go the route of building a weather-proof and insulated skirt, and the ground is flat or nearly so, consider also laying down at least 2" of closed cell insulation board, then the vapor barrier, and finally some course material like crushed stone over that for protection of the insulation and vapor barrier. With the skirt and ground insulated, there would be no need to insulate between the floor joists.

I had a cottage with a concrete block foundation and a dirt floor crawl space with clearance ranging from 2 to 3 ft from dirt to floor joists. It was damp and smelly and you could see the batt insulation in the joists was absorbing the dampness and beginning to drop. After much research I did whats called an encapsulation. Had a company come in and lay heavy plastic on the floor and up the walls. They then sprayed the walls and rim joists with closed cell foam. No venting at all, totally closed up. I left the batt in the floor joists but I think I could have removed it as well. Crawl space is now dry and no more smell or dampness. I do have an insulated door to enter and I run a small dehumidifier during summer months that drains to the outside. Overall I am very happy with the results. I also have my hvac, water heater.... in the crawl space. I had the block walls but I think you could apply concrete board inside your slat walls, spray foam to that and achieve the same effect.

Sorry for confusion. It means on the ground, upland a few hundred feet. Bad choice of words on my part.

Hi Dick & Winterh,

Thanks for a careful and informed responses! It sounds as if Dick is suggesting some sort of air "tight" skirting, with 2" foam on the "dirt floor" and "walls", covering the lot w/ 10mil poly and gravel on the floor, over the poly and foam board.

Winter H seems to be along the same lines - basically encapsulating the crawl space area.

Do I have that right?

You'd mentioned the borate treated cellulose sprayed up option. Since the floors will be redone - could I just spray that down? I guess the joists will still be cold 'bridges' in that case. https://www.homeadvisor.com/cost/ins...in-insulation/

Chris

I keep re-reading the comments above... and closing in the crawl space seems to be the consensus approach?

Do you mean like hardie backer?? https://www.homeadvisor.com/r/hardie-board-siding/

what it looks like
 

This runs to ground/grade at the back upper corner.
https://www.winnipesaukee.com/forums...1&d=1515329692

I was thinking of something I believe they call duo rock board. It is about 3/4 inch thick concrete with mesh in it to hold it together. It is often used under tile applications but I was thinking it may be a good choice. I would do more research into what is best product but if you decide to encapsulate you want something that looks ok on the exterior and that will allow you to spray and hold the foam on the inside. If these were put inside of the slats I think you could keep the current look on the outside. I will be heading up mid week and will take some pics and post them or PM me and you are welcome to come by and take a look. It was not cheap but it was worth it. About $5000 for a 1600 sq ft footprint if i remember right.

Hi Winterh - i'd be interested in learning more about your company and how much foam they applied, etc. Sounds like the right approach, if they can get under the farthest reaches. Right now, I'm in FLA and prolly won't be up until the snow is gone (April)?

Thanks for the help in this, and the kind offer to visit!

The cement board product referred to by Winterh is Durock (eg. https://www.homedepot.com/p/DUROCK-N...2965/202263276). If you use that on the inside of the skirt, then you might consider cut/glue application of foam board (2-4") over the Durock for insulating, with beads of can foam at the edges and joints to seal them.

Some good reading on building an unvented crawl space can be found here: http://www.greenbuildingadvisor.com/...ed-crawl-space. In addition to the info in that blog, there is a long "Related Articles" list of links to more info on the general subject.

When I mentioned the use of borate-treated cellulose, what I had in mind was dense-pack blowing of the cellulose into the joist cavities, using a sufficiently powerful blower, like the contractors would have. Sometimes the blowers available at the big box stores are ok for a loose blow into an attic, but not powerful enough for dense packing to upwards of 3 lb/cuft density, needed to counter settling of loose-blown cellulose, as in an attic. If you are redoing the floors inside anyway, then you have more options for insulating. If you have sufficient ceiling height to lose a couple of inches, you could lay down rigid board over the present floor, then a layer of T&G plywood, and finished flooring. But if you see this structure as being regularly occupied year round, then overall comfort might be better with an enclosed and heavily insulated crawl space, with no floor insulation at all, since the floor and crawl space would be reasonably close to interior temperature.

Looking at those pics, if that were mine I would probably lean towards insulating the perimeter walls with rigid and laying a poly vapor barrier on the ground.

Thank you, each/all!

Wow, what a great thread! Thanks to those who contributed, it was very informative!

The end result is what a lot of the 4 season campers do with hay bales between the floor and the ground come winter, I guess.

Two things to think about.

Particle board is nasty stuff, if it gets wet is swells and if it stays wet attracts and holds mold. I'd get rid of that stuff. I'd also be real curious what it looks like under that particle board, what could be hidden out of sight?

Spray foam attracts ants so I'd avoid using it in mass quantity especially in a seasonal application. Plenty of info on the web about it. While some claim that there are variants that are supposedly treated I don't buy that for a minute. Once they get into that stuff it's very difficult to eradicate them.

Whatever you decide to do make sure any area that is insulated is sealed up good and tight or the critters will get into it.

Of course another alternative is to obtain a price quote for lifting the house and pouring a slab or a full foundation.

Yes, it is far more costly but may be better in the long run (especially if you have ever thought about making it livable year 'round).



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Chris or Winter H
 

I have been trying to find someone to give me a quote on something similar or blown in insulation. I've asked a few people and they have given me the name for Quality Insulation truteam.com. Well I have called and emailed several times and have never heard back from any of it. I saw that it looks like you received a quote from WinterH but I can't seem to find out what company he is from. Did you find a name of a company who does this? Any info would be great! Thank you!

Try these guys... http://www.buildersinstalledproducts.net/

I have used them in the past with no issues.

Dan

I used DF Richard for the spray foam. They are an oil/propane company but have a division called Dr energy savers that does the foam. I think thats a franchise and they have this area. Anyway I was quite happy with the job they did.

https://www.dfrichard.com/images/dr-...r-seacoast.png

One more thing. I got a few prices and there can be quite a variance so shop around but in the end you want someone to do it right because the wrong mix of chemicals or a bad application can cause problems

Closed Cell foam WARNING
 

Closed Cell Foam if not applied correctly can self combust due to an exothermic reaction during the curing phase. It can ONLY be applied in specific amounts (thickness) and allowed to cool before applying additional thickness'.

If you go the closed cell foam route, make sure the application company has experience with this stuff.

I am speaking from first hand knowledge and am lucky I still have a house. The rebuilding/repairs took over 6 months to complete while I lived in a rented condo.

Choose Wisely,
Egoody