# Hollow core door-insulation



## no1hustler (Aug 11, 2010)

Ok, this is going to be a stupid question. Our house needs two doors replaced. The back entry door and the door from the garage to the kitchen. The back door is original from 1954 so its really inefficient. The garage door is an interior door and the garage is an unheated space. Our luck has it, both doors are custom sizes. The rear door comes to almost $500 (wholesale) and the garage is under $400. We decided to replace the back door first. In the mean time, I'm considering removing on of the skins from the hollow core door so I can replace the honeycomb with 1" rigid insulation. Is this a stupid idea? Hollow core doors have roughly an R value of 2. Solid wood doors are about 3. 1" rigid foam is 5. 

Can it be done?


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## Ron6519 (Mar 28, 2007)

Neither one of these doors should be a hollow core door. The garage door should be a fire rated door in a fire rated frame.
Please detail a, "Custom door". What sizes do you have now and why can't you change the openings to fit a, "non custom" door?
Ron


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## no1hustler (Aug 11, 2010)

Ron6519 said:


> Neither one of these doors should be a hollow core door. The garage door should be a fire rated door in a fire rated frame.
> Please detail a, "Custom door". What sizes do you have now and why can't you change the openings to fit a, "non custom" door?
> Ron



The rear door isn't hollow core. That is solid wood with single pane glass. 

The door to the garage is obviously wrong. The person that owned the house before us put that in when replacing all of the other interior doors. It even had an interior door knob and the garage wasn't lockable at the time of purchase. Some people really do cheap out. 

I don't have the sizes in front of me anymore but I want to say they were skinnier than normal. Perhaps it was a "special order" and not custom size. lol

The house is brick so the rear door can't be made any larger. The garage door can be made larger but I don't want to because it will create problems with the existing tile on the kitchen walls. I don't have a problem paying the money for the door. I am going to do it, just not at the same time. So this idea was only a temp solution to help reduce my heating bill. Basically, a shot in the dark. I went all last winter with these two crappy doors.


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## Thurman (Feb 9, 2009)

I'm with Ron. I've done too many of these replacements. The door to the garage _should be_ a solid-type fire rated door. Unless the back door is under some type of cover preventing direct contact with rain--I would highly recommend a fiberglass or metal-clad door at this location. Please- before you go buy anything, measure each door-the actual doors width and height and post here. No one is doubting you, but there is a chance they may not be "custom" sizes. Taking a hollow core door apart to change out the "honey-comb" for insulation would only lower the structural integrity of the door. The "honeycomb" material is structural, not there for insulation.


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## concretemasonry (Oct 10, 2006)

Also, measure the existing door thickness. It might rear its ugly head if you are rehanging a door and not using a prehung door with a frame.

Dick


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## kwikfishron (Mar 11, 2010)

You can pick up solid door slabs for about $80, and you cut to fit.

Your local lumber yard usually will get you a better price on customs.

The box stores ding you hard when it comes to customs.


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## no1hustler (Aug 11, 2010)

Thurman said:


> I'm with Ron. I've done too many of these replacements. The door to the garage _should be_ a solid-type fire rated door. Unless the back door is under some type of cover preventing direct contact with rain--I would highly recommend a fiberglass or metal-clad door at this location. Please- before you go buy anything, measure each door-the actual doors width and height and post here. No one is doubting you, but there is a chance they may not be "custom" sizes. Taking a hollow core door apart to change out the "honey-comb" for insulation would only lower the structural integrity of the door. The "honeycomb" material is structural, not there for insulation.



Haha, guys, I know what _should_ be where. The garage door will be fire-rated once it gets replaced in a month or two. The rear is going to be a fiberglass door. You don't need to worry about my measuring, my brother did it who happens to be a reputable contractor. He ordered the door from a local lumber yard, not a apron store. 

I understand that the honey-comb is not intended to be used for insulation. The plan was just going to be a 2 month stop gap until the other door was replaced. 

BTW, the garage doesn't get a car parked in it so the chances of a fire starting in their is not different than any other part of the house. 

Sounds like my idea won't work out (not surprised) so I'll probably just scrap it. 

Thanks folks!


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## Ron6519 (Mar 28, 2007)

As a temporary thermal solution, you could just apply the foam on the inswing side of the door. Cover it with a piece of paneling.
Ron


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## no1hustler (Aug 11, 2010)

Thought about that but it would look pretty stupid. But so would my attempt to remove the door panel and put it back on.


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