Simple foam door

[Gabriel Bergeron]

Hi there,

Long long time reader here but never registered. So thanks for all the help thus far...
For this first post I have this odd little project.

I have this shed outside and it is well insulated apart from the door. I'd like to do some work in there in the winter so I wanted to get a door that was more appropriate. (I live in Canada and winters here can be... you know)

I was thinking of building a really simple insulated door but was wondering what you guys thought.

Essentially exterior doors nowadays have a foam core (polyurethane most of the time I think) with a metal/fiberglass skin and a wooden outer frame.
So my idea is to simply get a polyurethane rigid foam sheet, make an outer wooden frame and veneer that with some wood.

For your information this is a shed in the woods, doesn't have to be locked and be extremely solid to counter thiefs or bears. Just well insulated and look nice.

Of course I could just buy/make a wooden door but these are expensive and not that well insulated. And steel/fiberglass door just won't go with the look of the place which is all wood.

What do you think? Am I oversimplifying things? The way I see it, It's just a foam core with an outer skin.

If you think it’s not a fool idea, I have these little concerns:
- what’s the best glue to use for this to glue the wood to the sheets? The urethane sheets I’m getting have foil on one side and some plastic on the other side. Will the glue they sell for foam (so it won’t melt) work well here?
- What do you think is the best weatherstripping solution for wood doors? (can make adjustments to frame)

I thought it would be an odd and fun thing to do
Cheers,
Gabriel

[David G Baker]

I think it is a great idea. I have a sliding door on one of my out buildings that is made from 2x4's and the exterior is covered with metal siding. I filled every available space on the door interior with 1 inch rigid foam board and will eventually skin the door with luan underlayment. It isn't pretty but it works.

[Buck Williams]

Gabe,

I have done something similar, had to replace a basement door that led to stairs that exited to a Bilco cellar door. The existing opening made a custom sized door a necessity. The rails and stiles of the door were made of 3 - 3/4" thick pieces of pine. The two outer pieces were somewhat wider than the inner piece, so that a 3/4" thick piece of foam insulation slid right into the space left in the middle, much like a panel floats in a frame and panel door. I skinned that foam panel with some 1/4" plywood rabbetted into the rails and stiles, and a center stile, and came up with a pretty traditional looking door that had some R value. You could go "rustic" and not have to worry about gluing the foam to anything, it'll just float inside the frame.

[David Christopher]

first off, welcome to the creek.

I think a foam door would be great but I dont think you will need foam glue..build the frame and cut the foam to fit tight then veneer and it should be fine

[Tom Godley]

I have an opening 8'x8' in my outbuilding -- the builder made the frame of the doors out of 2x4s -- he made a torsion box. Each door is 4' x 8'


Inside and outside door skin is 1/4 plywood -- with the 3.5" interior filled with foam board cut to fit. He then drywalled the interior to match the walls and installed ball bearing hinges into shop made 2x6 frames.

The door has been up for more than ten years and works surprisingly well. I for one would not have thought that the 1/4 plywood would have held up to the weather - but it has.

[Wayne Cannon]

I have found foil-faced foam sheets often have a light oil-like contamination that prevents adhesion. A wipe-down with paint thinner solves the problem.

[Gabriel Bergeron]

Hey guys!

Thanks for your replies and suggestions.
I'd really like to veneer to replicate the look of a solid wood door look which the plywood option wouldn't really allow.

Plus I will need to glue the foam sheets together since I was only able to find 1" thick polyurethane sheets around here up until now. (If you guys by any chance know of any suppliers or distributors that would carry more options in the Montreal area...)

What adhesive would you suggest, knowing the foam has foil and plastic (polyethylene?) on the surface.

Thanks Wayne concerning the wipe-down tip! Great to know.


And about weatherstripping. I don't know which yields the best performance and if they're all the same...

I was thinking of getting this for the sides and top
http://www.mdteam.com/products.php?category=214

and this for the bottom
http://www.mdteam.com/products.php?category=1801
Not "rustic" like but I wasn't able to find anything else.

Any input or suggestions?

Thanks again
Gabriel

[Tony Bilello]

"What do you think? Am I oversimplifying things? The way I see it, It's just a foam core with an outer skin."

It's refreshing to see simple solutions to simple problems. So many people end up overcomplicating things.
Go for it.

Regards.

[David G Baker]

Gabriel,
Make sure you use the right type of glue for the foam board, construction glue will melt the foam. I use 100% silicone if I don't have foam board adhesive on hand.

[Jamie Buxton]

When you say "veneer", do you intend to use commercial sliced veneer? That is, the stuff that is .025" thick, before you sand it? If you apply that to foam, I think you'd have a situation like a pond with a thin layer of ice on it. The ice looks solid, but it doesn't take much to punch through it. Doors occasionally get hit with pointy objects. I'd be concerned about punching through the veneer.

Heck, if the foam core has any irregularities on its surface which are larger than the veneer thickness, you'll likely sand through the veneer while you've making the door.

Covering the foam with 1/8" ply would be much stronger. Most interior doors are covered with this stuff, so you can look at them to see how un-obvious it is.

[Gabriel Bergeron]

*
--> I really have trouble finding polyurethane rigid foam sheets here in Canada (I live in the Montreal area) Any ideas?? I wanted to get the higher R-value material...
Do you guys in the US readily have access to this material?

Gabriel,
Make sure you use the right type of glue for the foam board, construction glue will melt the foam. I use 100% silicone if I don't have foam board adhesive on hand.

Yes this is why I was asking what adhesive I should be using. Also considering that neither face is covered with the foam itself - either plastic or foil.


Jamie, yes I should have specified. I don't plan to veneer with the .025" thick material but rather 1/8" wood I have here.

[Jamie Buxton]

Jamie, yes I should have specified. I don't plan to veneer with the .025" thick material but rather 1/8" wood I have here.

Good.

1/8" veneer raises an interesting issue, and I don't know the answer. When I glue shop-sawn veneer to plywood (or any veneer, for that matter), I'm expecting the substrate's strength to hold the veneer edges together. The plywood is strong enough that it prevents the veneer from expanding or contracting with changes in ambient humidity. Will foam (faced with plastic or foil) have the same ability? I don't know. I'd kinda be tempted to include a cross-banding layer under the face veneer. This would be a layer of standard sliced veneer, with the grain direction running across the grain of the face veneer.

I know, I know, this was supposed to be a simple project. Maybe you should just build it without the cross-banding and see what happens.

[Wayne Cannon]

Polyurethane (Gorilla) glue works very well on the foil face (I used it to glue a flanged 2x4 insert into the edge and adjoining foil face of a foil-faced rigid foam panel to support a hook for my spray gun). Most glues do not adhere well to polyethylene without heat. Double-stick tape works pretty well for polyethylene.

[Gabriel Bergeron]

Good.

1/8" veneer raises an interesting issue, and I don't know the answer. When I glue shop-sawn veneer to plywood (or any veneer, for that matter), I'm expecting the substrate's strength to hold the veneer edges together. The plywood is strong enough that it prevents the veneer from expanding or contracting with changes in ambient humidity. Will foam (faced with plastic or foil) have the same ability? I don't know. I'd kinda be tempted to include a cross-banding layer under the face veneer. This would be a layer of standard sliced veneer, with the grain direction running across the grain of the face veneer.

I know, I know, this was supposed to be a simple project. Maybe you should just build it without the cross-banding and see what happens.

Yes... I was pushing this thought away in the back of my mind since it complicates things. Usually those kinds of exterior door have a steel skeleton covered by the wood skin which would then be held in place I assume because of the strong "bone".

I could do this but it complicated things a bit...
I'll see what I'll do.
If you guys have any other suggestion for this problem...


Thanks Wayne for the glue advice.
What would be the best adhesive to glue wood to steel?

[Randy Cohen]

There is a factory near here that makes the EPS cores for steel entry doors. The EPS is 1 3/4" thick (i think). They have a pile of rejects that they sell real cheap. I used 3 layers of that to insulate the roof on my house. They are rejected because they were cut a little wrong. You could try to find a factory like that near to where you live.
The one around here is Radva.