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Replacing Glass in French Door

Posted by DHam007 (My Page) on
Fri, Mar 7, 14 at 22:39

Hello, my wife and I are looking at replacing some old windows in our house, and we've done some searching and found an installer and brand we like at a fair price. Our question is related to our French Doors.

We have 4 sets of double french doors (with 48" total span) on the front of our house. Evidently, this is a pretty rare and expensive fix. It will cost us 2-3 times the cost of all the windows in the house to replace these doors. I want to make clear that I realize you have to pay a fair price if you want a good installer and a good product. This comes down to we just don't think we can afford to do the doors with the windows, and we're likely to do the windows first as they are probably a bigger source of energy savings.

As the doors themselves are all in good condition we were wondering if it was possible to replace just the glass with a higher efficiency glass (they are all single pane at the moment, and we'd like to go to double pane and as efficient as we can get). If it is possible, would this be likely to save any money over a whole door/jam set up? More importantly would it make the door appreciably more energy efficient? The door is currently a wood door, with no drafts around it as it has "seal" foam strips to prevent this. I realize it won't be as good as a new door, but if we could get significant benefit over the single pane at a reduced cost, then it would be something we'd consider. ALternatively, if this doesn't work, as a stop gap until we can afford the switch, do the insulating window dressings really make any difference? I'd appreciate any advice we can get on a way that we could approach this for the doors.


Follow-Up Postings:

RE: Replacing Glass in French Door

If they are quality doors, it may be worth your while to do it. If you have true divided lites probably not as it is questionable as to whether the an insulated glass unit would fit in the rabbetted glazing pocket.
If these are one lite doors, have a reputable glass company come by and assess whether it can be done. Tempered glass as required in doors is expensive. New glazing stops would also be needed.

RE: Replacing Glass in French Door

Hi Eastbay10,

Thanks for the information. If I'm understanding what you are saying, I doubt it would make sense for us, or even be possible. Our doors are presumably old, and I'm relatively sure they are multiple not single lite. That said, I'm no expert, so I'll get a reputable glass company to come over and give us a look.

I know it won't make any difference in my particular case as price will depend on what is done and on quality of materials and work (and rightfully so), but is there a ball park for what we'd expect if it were one lite? (I mean very rough, are we looking at $500/door? 2000/door? etc). I just want to make sure I have some idea of what we're dealing with.

RE: Replacing Glass in French Door

I don't get involved in retail glass replacement so I can't help. There is probably someone else on the board that can give you some idea.
From what you said with the doors being old and multiple lites, it doesn't sound cost effective.
Another idea would be to reframe the openings and turn them into four foot wide windows. Those would be significantly less than new French doors or maybe leave one a door and turn the other two into windows. Just a thought without seeing it.

RE: Replacing Glass in French Door

Is the current glass safety glass( tempered or laminated).
If doing new tempered low e argon double panes is to costly perhaps you can add storm panels neither glazed with tempered low e or acrylic, till you can get the doors replaced.
Andersen makes 4' French doors, that where I would start if replacing.


RE: Replacing Glass in French Door

Just curious, but is your only consideration in replacing those doors (and windows) to save energy/money, or are there other reasons as well?

RE: Replacing Glass in French Door

Energy almost entirely, though I suppose there may be some aesthetic value gain. No leaks or issues like that. Our windows are just so inefficient it isn't funny. The doors (I think) are somewhat less so, but the repayment period on the doors might be above what we're willing to commit to the house (and above our means at the moment). Why do you ask?

Also, thought I posted replies yesterday that don't appear. I'll look into Andersen doors, and we thought of the idea of windows, but really like the doors. THanks for the ideas.

RE: Replacing Glass in French Door

The right windows and doors are going to save energy, no question about that, but partly depending on where you live, replacing doors and windows strictly for the energy savings may not be quite the great idea that it appears at first glance.

If saving money on your energy costs is your primary motivator, I would suggest that there are better ways to do so than replacig windows.

If you want to improve comfort, because the living room is freezing all winter and boiling all summer, while you are taxing your mechanicals all year around and they just can't keep up, then that could definitely be a valid reason for replacement. If the doors and windows are pretty much junk then obviously thats a no-brainer.

Heck if you have double-hungs and you want casements, that would be a good reason too. But once again, if it is ONLY for potential energy and/or money savings, I would recommend that you might consider a home energy audit before jumping into window and door replacement.

RE: Replacing Glass in French Door

Hi Oberon,

Okay fair points. I suppose we could look at that, and I think I was including our level of comfort within the energy savings portion :). Our rooms are big rooms are quite cold when it's cold and our AC runs a lot when it's hot, we're in Louisiana. I don't know that the windows and doors are junk necessarily (again not an expert), but our windows are single panes with aluminum frames from the 1980s (I assume original to the house, but I can't say for sure).

You do make a good point though there might be easier ways to improve our efficiency. I don't think the house was really built with efficiency in mind, so there might be a lot of easy things I don't know about. For example we have closets on the outside walls that are saunas in the summer and frigid in the winter (well relatively as far as LA gets frigid...). I wonder if there's even insulation in the walls it's so bad. Short of pulling the sheetrock though, is there anyway to install (cost effectively) insulation in existing walls?

Anyhow, so many questions, and I apologize for my naivtee. I'm happy to get any insight I can get, and perhaps the energy audit is the most logical first step.
Thanks again.

RE: Replacing Glass in French Door

It just so happens that there is an home energy rater from Louisiana who happens to hang out in these forums.

She goes by the name ERLA (go figure)...

I might suggest that if you are interested you can title a post in the building a home forum with ERLA in the title and ask her to drop in here and participate in your thread.

She is good, trust me on that one.

RE: Replacing Glass in French Door

lots of things have a bigger effect on comfort
and energy savings than window/door change outs.
here in La. window/door change outs have a long payback
and small energy savings (about 15%).

tell me more about your house.
single story or multi story
on slab or on piers
what sq ft is the living space
what size &type hvac system
where are ducts located
where is heating system located

what are interior walls..sheetrock or paneling

along with the dozen questions to answer..think about this.
back in the 1980's homes were not built tightly, and have a lot
of areas where air leaks into the house.
if you seal the air leaks, then it is less costly to heat/cool
and comfort is achieved. insulation slows temp transfer
but it doesn't stop air movement.
sealing leakage sites is your best bang for your buck.

sealing leaks in ductwork/returns is the next biggest
bang for your buck.
both require inexpensive materials, but lots of labor.

that the central runs a lot in the summer isn't a bad thing.
it is the oversized units that run 10 minutes on & off all day
that cost you money & comfort.

blower door testing the house to find leakage sites,
and testing duct work for leaks is not uncommon here in La.
do some googling of these testing methods & we'll talk more.

its been a LONG someone's attic all morning, &
then under their house sealing ducts & gaps in floors all
afternoon. achy, tired & not thinking well enough to explain
better just yet. but I will...just work on my questions &
do a little self education ...we will go from there.

btw in what area of La. are you located?

best of luck.

(Hey ya doing? I forget gw has a window
forum..but if you are here...everyone is in good hands!)

RE: Replacing Glass in French Door I chopped liver....?

Just kidding.


You will find that we have very few inquiries as it pertains to people changing out their windows on the basis of efficiency only and given the fact that the two most significant contributors on the windows side (Me and HomeSealed) are both BPI (envelope and analyst) certified, we steer people in the right direction.

Just like you would argue that you need to know more about the home prior to making an assessment, I would also argue that the "company line" of only saving "X" on windows is also a bit outdated.

We see homes that show massive tightness improvements when we change out the window and the savings far exceed what you are referencing above.

Usually and to a larger extent because of the envelope tightness improvements, but, as you said, every home is different.

Glad to have your contribution.

RE: Replacing Glass in French Door

I stand by my numbers as I have run them many times in my arch energy software used by people in my resnet field.
the numbers may change in other climates, but here in my state...the 15% savings is accuarate.

locally we have window companies promoting 40% savings..
which just isn't happening. I usually get called after the big bucks have been spent on windows...and by tightning the home,
reducing duct leakage and specific to that home upgrades
achieve 50% savings in existing homes.

kudos to you & your company for involving building envelope
& bpi training,,,here in La. your company would be the exception,,,
not the norm.

there is a La. based window company that installs good quality
windows for a very fair price..and I recommend them often...but
not at inflated savings or reduced payback of investment.

didn't intend to slight you..just Oberon & I go way way back...
glad to see that the two of you have this forum covered.
I'll have to visit more often to be more familiar with your postings.

RE: Replacing Glass in French Door


I am not saying that any guaranteed saving rate is acceptable and whatever company is doing that better watch their arse if they are doing that.

LA being a much more CDD vs. HDD dominated climate would support that idea that savings will be mitigated. It is cheaper to cool your home as compared to cool it from the outset.

It largely depends on window types and application as well. We have a bunch of steel casement, steel pan, single pane glass in the older sections. Between the terrible seal, thermal rating and hollow cavities behind the jambs, the saving can easily approach 30% on a smaller home with a good amount of glass.

I have done test in and test out on home where we just did windows and dropped +30% on the blower door number. We wound up tightening the home so much with the 2nd phase window project (full air sealing and insulation was first) that we had to have an ERV installed.

Thanks again for posting and I was just busting your chops about chopped liver.

If you hand around long will learn very quickly that I have a sense of humor and am usually joking.


RE: Replacing Glass in French Door

So clearly, I have to research this blower test, but ERLA, I have to ask, can you direct me toward this reasonable LA based window company so I can get some idea of whether the quotes I've seen are reasonable? Price wise, they both seemed okay, but from what I read one company's windows are not good and the other's are (based on the expert opinions on this board, and I just can't tell the difference).

RE: Replacing Glass in French Door

  • Posted by oberon north central (My Page) on
    Fri, Mar 14, 14 at 21:55

Hiya ERLA, ltns!!

I hope that you are doing well!

LOL WoW!! I grew up eating "chopped liver" - otherwise known as either liverwurst or braunschweiger. Loved the stuff as a kid; haven't had it for awhile, but would probably still enjoy it I assume.

I thoroughly enjoyed reading the back and forth between the two of you (and btw to both, you were discussing with one of the friendliest, most knowledgeable, and very best people that it has been my pleasure and privilege to have met online in all the years that I have been doing this...enjoy!!).

DHam, the purpose of my questions was simply to give you a few alternatives to consider before you spent a bundle of money.

I was not suggesting that replacing your windows would be a bad idea, just that you had all the details before you made the final decision.

I would strongly suggest however that you are getting some great advice from a couple of absolute top-of-the-line professionals, advice that you would be hard pressed to get for free out of here. For you as well, enjoy!

To ERLA and WoW, I would never suggest that air sealing wasn't an absolute necessity when dealing with energy performance and savings, but I would suggest that as important as air sealing is, don't discount the effects of the glazing when considering window performance.

In a heating dominated climate I would suggest that the greater the delta V the more important is the glass make-up, and in a cooling dominated climate I would suggest that stopping solar heat gain is a pretty significant factor in energy performance.

RE: Replacing Glass in French Door

Hi Oberon,

I didn't take it in a bad way. I'm all ears for more economical ways to save the same amount of heating and cooling costs. If the sealing helps as much or more for smaller cost, great. If the cost is small enough we might be able to do both. I was once an engineering in construction (though not residential) and my dad was in code enforcement for a while, so I'm familiar at least vaguely with most of the terms, but very novice in their application. More than happy to listen to experts to get the best bang for the buck.

I think we did some easy things, like redoing our kitchen nook which was a bit "drafty". We realized this was because the nails that were supposed to anchor into the toe plate missed and we literally could look straight to the outside... That made that area significantly better. Then we installed some doors on the fireplace which was drafty. Since it's gas, my recollection is the code requires a spacer to keep the flue open a bit at all times... that's also a bit warmer now. However aside from rather obvious huge issues like that, I probably wouldn't know that we had an issue. I'm not sure how bad our current windows are our our bill is in comparison to other homes. Perhaps I should look at that I guess. Is there a standard for what is good for heating (gas) and cooling (electric) in my area that I could reference? That is can I say that my average bill is x, and compare to some standard y to see how well (or more likely how badly) we are doing? I assume there's also a standard that would come into play for the right amount of attic insulation, right? I looked a bit into energy audits briefly today. I saw an add for about $100 audit that was usually $400, supposedly. Is that a fair going price? I have no idea what a reasonable charge is for that service, and I'm cautious about believing the level of discount without further exploration.

I'll try to do some further research on some of the topics mentioned this weekend. THanks.

RE: Replacing Glass in French Door


I love liverwurst. Good stuff. My dad raised me on stuff like that, pigs feet, gefilte fish, etc.

RE: Replacing Glass in French Door

DHam, no offense taken in any way. Good luck on the project!

WoW, I have never had either pigs feet or geflite fish...not sure what to make of either of them.

I prefer my fish raw and either wrapped in sticky rice and seaweed or else on top of sticky rice and seaweed, depending on my mood at the time!

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