Mylar Blankets- Inside or Outside?

[B-urban83]

I have been trying to find answers to this on the internet and sites only cover the basics regarding reflecting heat.
I am curious if mylar (space) blankets will still serve their purpose in a shelter if they are covered by pine or other insulating materials.

Since these blankets are cheap and not the best option for long term survival, they obviously wouldn't be ideal for a long term shelter.
IF this were necessary, i.e. bugging out turned into a longer term scenario and the mylar blanket was in your pack, would you place it on the inside of your shelter or the outer layer?

I know they reflect heat and can help trap heat, but is this reduced if you were to cover the blankets with an outer layer, whether it be a dense layer of pine or some other form of cover.

[Rick]

Anything that you place as a first layer is not only going to reflect but capture or contain your heat. I'm assuming you are talking about a debris shelter or lean-to or similar. They also have the added benefit of shedding water. This is really important if your debris is snow and/or ice covered. As it warms up it will begin to melt into your shelter unless you have a barrier in place. The added insulation in terms of debris or evergreen boughs or grass (whatever environ you are in) will increase your heat retention. Poking holes in the blanket is really your only concern.

[B-urban83]

Anything that you place as a first layer is not only going to reflect but capture or contain your heat. I'm assuming you are talking about a debris shelter or lean-to or similar. They also have the added benefit of shedding water. This is really important if your debris is snow and/or ice covered. As it warms up it will begin to melt into your shelter unless you have a barrier in place. The added insulation in terms of debris or evergreen boughs or grass (whatever environ you are in) will increase your heat retention. Poking holes in the blanket is really your only concern.

So layering overtop of the mylar won't lose effectiveness when trapping heat.
That is good to know. My base layer of the lean-to or makeshift shelter would probably be a thick plastic or possibly a tarp (don't currently have a tarp though, takes up a lot of space, and the cost of a decent one that is not so bulky is not in my current budget), then the mylar, followed by whatever nature provides.
(Just had our first baby, and he's 9 months old, so backpacking is going to be a fun adventure for both of us, and I'm gathering all info I can now).

[Rick]

Layering on top of the mylar will increase its effectiveness. The more insulation you add the warmer the shelter, excluding the cooling effects of wind that can blow inside the lean-to, which is why you want the back of the lean-to to face the wind.