I can't afford to replace all the windows in my house with new ones. The wooden ones I have are rotting and are only single-paned. I'd like to construct my own double-paned double-hung windows.

I have a chop saw, table saw, and router which I believe I can correctly mill all the wood pieces with. I have some good experience with cutting and installing panes as well. The part I am not familiar with is the double-paned part.

I've been able to find a few things out: the panes should be spaced apart 5/8" for optimum energy efficiency; silicone caulking should be used to create a seal between the panes; and a desiccant should be used between the panes to reduced condensation.

Does anyone see any preceivable pitfalls in my project? The first two items are easy enough, but I have never worked with desiccants before. Has anyone out there? What type would you recommend and how would I use it in this application?

Thanks for any help you could lend out.

 

Pretty ambitious project you're envisioning there. My initial thought is that you should be sure you price out your materials properly before you begin the process.... with the price of glass being what it is at retail, you could end up being able to purchase vinyl double hung double pane windows and installing them yourself. I'll leave it to the true window experts to tell you why your project will - or will not make sense....

Also, keep in mind the federal tax credit (yes, credit) that you get for installing new energy efficient windows. I installed 8 windows last year - and the resulting credit paid for two of them....

 

Thanks Zster. Didn't know about the federal tax credit. I need to look into that.

About the price difference:
I estimated my job to be on the higher end of $5000 for just the windows I need - 36. If I do it myself, just the window only and forgetting that my time is valuable, the cost of everything comes to roughly $1000 - $800 for glass, $100 for wood, $100 for primer/paint/caulk, and $20 for clothesline. I have all the weights from my old windows, and I'm negating everything else because both options need the same things.

However I do plan on using plain glass, regular 2x3s, standard paint/primer, and silicone caulk. Are these product choices poor or is something else recommended?

 

I found a type of desiccant silica gel formed into 12"x12" paper at http://www.sorbentsystems.com/dessic_paper.html that perhaps I can use to absorb the humidity between the panes. Seems easy enough to cut up into strips and edging the gap - probably best to put on top of the caulk instead of within it. Another site claims that silica gel will take up to 40% of the water out of the air if enough is used.

Anyone know if a 40% reduction in humidity is enough for a double-pane window or have any comments on this method?

 

I've been in the glass and window business for 40 years. DON'T DO IT!!!! You will never be able to construct the window sashes with the strength and accuracy that's required. The glass is another problem. Even companies that manufacturer insulating glass units have units that fail in time. The desiccant is poured into aluminum spacers that are specially designed with tiny opening to absorb the moisture. Silicone is not the choice of sealants. If you really want to undertake this project I suggest you make one sample window first.

 

Nice reply, Johnam. I've been mulling how to respond for hours now.


krgoks, I'm impressed by your enthusiasm for this project, but I'd advise you to (metaphorically) set the gun down and slowly back away.

If you want some more specifics on why NOT to attempt this, there are multiple reasons.

First off, even if you could attempt this, your estimate is a little off. You need to make 72 sashes, and you think you can do that for $1000, or $13.88 per sash, complete????? Something is wrong with that picture.

As mentioned, silicone is NOT the sealant of choice when it comes to sealing insulating glass units (IGU's). Also, special spacers are needed between the panes, usually hollow aluminum extrusions that are filled with tiny beads of dessicant (not paper strips!) Correct me if I'm wrong, Johnam, but in factories where IGU's are made, the glass is first cleaned so that it's spotless (hard to clean it once you put it together) then once assembled, the IGU's are baked in an oven and slightly pressed- the baking activates the dessicant. If you tried to make your own IGU using your own ideas, I would guess it would fog up within 1 year at the most, if not 1 week, or whenever the sun shines on it... whichever comes first.

The glazing of the windows is an issue. You would not put the glass into a dado, trapping it inside the sash. You would need to make the glass removable, held in with wooden trim on one side. IGU's usually need space around the glass, and 1/8" rubber setting blocks are usually used around an IGU to cushion it and to shim the surrounding frame so that it stays just as square as the glass is.

If you have not done mortise and tenon joinery, you should forget even attempting this project. The sashes will not hold up unless you build them that way.

The species and quality of wood you plan to use is probably not the best choice.

Even if you would succeed in building the sashes, they would still be drafty old wooden windows with no weatherstripping.

IMO, your $1000 would be better spent removing your existing sashes, patching them up with bondo, scraping, priming and painting them, fixing the existing counterweight ropes, reglazing the perimeter of the glass as needed, replacing broken glass, reinstalling them and maybe if you feel adventurous, maybe you could attempt to build some simple, wooden, single pane storm windows to fit on the outside which would tighten up the window a little, and provide you with that 2nd pane of glass you are wanting.

Even then, I think you'll find that you're over budget. Johnam's suggestion to build one window is a sensible idea. It will give you an idea of what you're attempting to bite off.

 

Thanks guys, appreciate the dose of reality. I'd love to save the money, but I'd rather not invest into something that may only last a year. You're right XSleeper, I need to just repair what I can and replace what I can't. Eventually I guess I'll get them all replaced: I just have to wait.

 

BTW - check the tax code closely.... Last year the maximum credit was $400, regardless of the amount spent on new windows..... I'm assuming (you know what that word means) that, if you spread out the replacements from year to year - you could get the same credit multiple times, reducing your overall costs....

 

The tax credit is not that simple; it may not apply and it may be over. Here are the facts: http://www.energystar.gov/index.cfm?....pr_taxcredits

 

Good link Johnam.... which is why I suggested checking the tax code closely... those darned rules change every year....