I have searched the forum and read over Todd's site.  I can't seem to find the answer spelled out for me.  I am insulating my trailer and want to know which side the foil should face - towards the outside (like Todd's pictures seem to suggest, but that assumes that he has foil on the sheets of insulation) or should it be facing the inside like in a house?  I have seen it done both ways.  Double foil-faced is not available at my local big box stores - and I don't think it is necessary.

I am even more thrilled with my 18 yr old trailer - after removing all the paneling/insulation/cabinets, it looks brand new inside!  The aluminum walls are super shiny and clean.  I have decided to remove the blue indoor/outdoor carpeting as well - any tips?  I want to insulate the floor and wall where the carpet is - plus, the blue looks dated even though it is in excellent shape.

Thanks

I always read that the foil should be facing in, however I'm interested in knowing as well. I am getting ready to put my ceiling in and it would be nice to know which way it goes.

The foil goes on the side you want to reflect the heat. If your main concern is heating the interior, the metallic facing would be inward. If you live in especially hot, sunny climates, it would face outward to reflect the sunlight.

If you were to ask a salesperson at the big box stores, double foil faced, rigid insulation, if not in stock can be ordered. It offers the best alternative, reflecting the heat you don't want, whilst maintaining the heat you need.

The shiny foil reflects radiant heat.  That means it needs an air space to insulate.  If you don't leave an air space, the foil conducts heat very well.  (You just wasted your money on the foil)

If you are using a bubble type insulation, the bubbles provide the air space.

The air gap was one of my concerns when putting up the insulation in my trailer and we probably didn't do as effective of a job of it as we could have.

http://www.woodsmithfarm.com/Photos/Stuff/Horse-Trailer-Upgrades/

Do you think it would be better to use a 1/2" foam board (R2.0) w/the reflective side up and have a larger air gap vs the 1" (R4.0) that doesn't allow for much of an air gap?

I still need to insulate the nose after we put the AC supports in and while I feel the back is definitely cooler, I was hoping for a bit more in the nose is possible.

Thanks

If you use a single, foil faced rigid polyisocyanurate insulation, the interior facing can be directly covered by most materials. A homeowner is required by code, to cover it with a minimum of 1/2 drywall for fire protection. If it is two sided, the thickness of the insulation board separating the two foil layers, gives the material its "R" value. The exterior foil can also be directly covered by any sheathing method.

It is important when installing the rigid foam, to close all the seams and cracks. Large areas can be filled with spray foam, and then sealed with metallic tapes. Sealing the surface creates a moisture barrier, and prevents moisture from entering the insulated cavity.

This thread left me with more questions. 

My trailer is dark in color (roof and sides) and the roof is mostly steele.  Now, I like that except for the obvious problem.  I live in a "colder" climate, but it gets hot in summer too, as well as the probability of traveling in hotter climates.

So, do I use double sided insulation and creat air pockets between the steel and the insulation? How is the best way to create the air pocket ?  I'm thinking by placing think strips of lumber?  or are you suggesting that there be some bubble type material between the insulation?

I apprecaite the thread and the information, but would appreciate someone being very specific with me?  I would like to have this well insulated, and may end up insulating the ceiling of the horse part  - or perhaps I really should just paint the roof white, which is something I will consider.

Thanks.

Today I spent the day insulating my trailer.  I used the single-sided foil and faced it inside.  I thought about how I use the trailer and I am never in the trailer during the day for more than a couple of minutes.  However, at night I have no choice.  As I have nearly frozen sleeping inside an uninsulated steel trailer I decided it was more important for me to trap the heat inside at night than it was to reflect the heat during the day.  Having said that, I am going to paint the roof white.  I hope the combination of the two will give me what I need.

Gard  - I was able to get the carpet up with no heat at all - it took all of about 5 minutes.  I guess 18 yr old glue just isn't that strong!! 

I'm still confused on the foil side/air gap concept.

Should my 1" single foil sided rigid poly? foam be tight against the aluminum roof of the trailer, or should I install 1/2" single foil sided and leave a 1/2" air gap for maximum radiant heat reflection? Once I get this worked out then I will follow up with sealing the gaps and taping with aluminum and then surfacing with the PolyMax.

Hope that makes sense.

Thanks!

I'm a relative newby when it comes to trailer fix-er-upers. We did our out weekend package this winter, that's my only qualifications, so don't take my thoughts as gospel, I'm just thinking outloud.

I understand how the shiney side probably matters if you don't cover the insulation with anything. For example, if you were to bake a potato, and the heat/light is shining directly on the potato, then it might possibly matter which way you put the foil. But if you tuck the potato inside something else, does it really matter which way the foil points then? My point is, since you are putting this type of insulation between two layers - the outside wall of the trailer, and the inside paneling, does it truly make any difference which way it faces? If so, why? Light cannot touch the insulation when its between layers, so does it just work as a vapour barrier? If that's so, then does it really matter which way its put, as long as it's there?

I live in Alberta, Canada, and use my trailer form May until September. We simply put the rigid foam insulation between our aluminum beams, taped it well, then put one-side good plywood over everything. I crackfilled, then wallpapered everything. We've used our trailer several nights now, and the insulation has made a HUGE difference. The APHA show that I was at in May had tempetures right around freezing at night, and the show got several inches of rain so it was very humid. Our trailer stayed nice and warm, we used a ceramic heater with a thermastat and it ran on and off night and day when we were in the trailer. We got condensation on the windows, but nothing anywhere else. And believe me, it was humid. Our holiday trailer gets just as much window condensation as our horse trailer did. Our insulation had no foil at all, and it seemed to work fine. Now, it might have been a different story if we were showering non-stop in the trailer, or boiling water alot, etc, but since we don't spend too much time inside in the day this wasn't an issue.

Have you ever read the facts about baking a potato, by the way? Some people say that you must apply the tinfoil with the shiniest side facing outwards for it to work. But studies have proven that if you take two potatos of the equal size, and put them in the oven at the same time with the shiny side facing different ways, they'll still cook at the identical speed. Test it yourself, and you'll see. So I really don't get the explaination of insulation!

Heat is transfered in three ways.  Conduction, radiation, and convection.

When two surfaces are in contact, heat is transfered by conduction.  Think soup pot on a hot element

When two surfaces are separated by space or a vacuum, heat is transfered by radiation.  The heat radiates from one surface to the other.  Think heat lamp

When two surfaces are separated by a medium (air, water, etc) the medium is heated and moves (convects) to the other surface, where the medium gives up its heat to the cooler surface.  Think heat rising in a chimney.

In the baked potatoe example, all three modes of heat transfer are in play. 

1...The potatoe is resting on a hot surface.

2...The potatoe is getting radiant heat from the oven walls and heating element. 

3...The potatoe is getting heat from the hot air in the oven.  This is likely the most heat transfered.  Consider how fast a convection oven cooks.

Microwave cooking is a variation of radiant heat transfer since the microwave is radio frequency radiation.

In a horse trailer roof, Mechanical considerations are more important than insulating value.  In a 1" space, I would rather have it filled with rigid foam than have an air space+ 1/2" radiant barrier.  If the ceiling is pushed upward... the foam board will collapse into the air space and the ceiling will have a permanent dent.  The full thickness foam will be more resistant to the dent.

Rigid insulation can be placed directly against the outside trailer skin, or have any type of surface attached to the inner LQ side. The rigid foam can be surfaced with one or two sides of foil. The rigid foam board and its thickness, will determine the amount of "R" value and its resulting ability to insulate. The more of it you can install in a given space, the more insulating value it will have. The foil facing (s) can restrict the heat loss or gain by redirecting radiating heat, the sun on the roof or interior heat trying to get out. The foil isn't necessary, but will help and doesn't take any additional time to install.

The most important installation step is to make sure the interior surface is completely sealed with tape. The surface of the board will act as a vapor barrier, and should be completely sealed with tape before any material is placed over it.

Many people have insulated their trailers with unfaced foam boards, with very good results. To include the foil would depend on your needs and the availability of the products. Even large LQs can be heated with a single ceramic heater, when insulated with only foam board. If you live in extreme environments, you might want to consider the foil, other wise you may not need it.

I chose to put in 1" insulation with the foil facing inward.  The rigid foam board fills the cavity completely.  With careful measurement and cutting, I got a very snug fit and did not have to fill in any little gaps.

I noticed that when the sun is shining directly on the trailer, the insulation is barely warm, and the studs are so hot that I could fry an egg on them.  I will be putting 1/2" furring strips on the wall and covering the studs (between the furring strips) with additional unfaced insulation (about 3" wide) - esentially filling the gap between the studs and the wallboard and providing additional support in those areas.  There will still be a 1/2" gap between the foil-faced walls and the wallboard.