I've been shopping around and no one near me will do Argon filled double pane and only one place will do a vacuum. The price seemed astronomically high considering I can buy the glass and the local hardware store (single pane 2x amount to make double pane) for ~1/10 of the cost. So ranting aside, what is the best way to make double pane glass / window inserts from single pane glass? I was thinking about using something easy like a few 1/4" plastic tile spacers to keep a uniform spacing with weight or light clamp then applying heavy silicone bead to everywhere but the spacers, coming back later to fill in all but one or two of the spacer holes. Do a good inspection and cleaning if necessary, plug to have one hole left and then pulling a vacuum to ~7-10psi (~5 psi vacuum from ambient). Last hole (vacuum hole) will have to be plugged/corked with something else then silicone to ensure longevity.

My project calls for 24 ~8.5"x11" inserts, trying to weigh in my approx. time to build these and that I already have vacuum pump, I could have a 50% success rate and still save money so if it at all possible to do this at home/shop I'm going with that option.

  • 11
    Unless you're experienced in manufacturing and actually machine the spacer from a material that matches glass expansion and a sealant that will work for at least ten years, it's a total waste of time. The cobble method proposed is going to be a highly frustrating wheel reinvention attempt of an early design that was abandoned. Commented Mar 7, 2013 at 16:53
  • @FiascoLabs, the spacers are going to be removed hence I'm filling in the holes they leave behind.
    – Jason
    Commented Mar 7, 2013 at 16:54
  • 3
    In all the dual-pane windows I've worked with, the spacer is a permanent part of the installation. That is the professional way, and attention to that detail and the adhesive used determines success or failure. Silicone caulk isn't a structural material suited to be a glass separator. Commented Mar 7, 2013 at 18:11
  • 2
    You can't compete with professionally made double glazed unit, but you probably shouldn't try to; since you own a vacuum pump, one option you have available is to build a resealable unit or with one way valve and simply revacuum it every winter or so.
    – Lie Ryan
    Commented Jan 7, 2015 at 0:33
  • 9
    Make professional grade double pane glass at home? - Go to a glazier's shop and write down the model number of every machine they have, every bottle of chemicals they use, and then stand there making notes for a few years. Then you can go buy that +$100k worth of stuff and try it at home. TL:DR : No.
    – Mazura
    Commented Jul 16, 2016 at 0:37

14 Answers 14


Glazing manufacturers have spent decades perfecting a spacer system that does not eventually leak and condense. They still haven't completely perfected it, though they are much better than 20 years ago. There is no way you're going to put together a system that does not eventually leak, especially with a vacuum. You'll have a better chance with inert gas, but I'm not convinced even professional argon filled glazing stays argon filled years later. It's not that I doubt your fabrication skills, it's just that it's a very difficult problem to address.

For all the time and effort spent assembling a window system, it's worth buying professionally built glazing units. If you want to save some money, forgo the argon filled and simply get dual glazed units with a low-E coating. IMO, these offer decent thermal performance and good value.

  • 3
    +1 for the argon remark, professional fabrication of an Argon IG unit is generally done cost effectively by creating a regular unit and drilling two holes. Argon is pumped into the inlet and the air is pushed out the outlet until an argon detector reaches it's limit. These holes are then filled with a sealant and become the weakest point of the unit and generally have leaks over time. The best units I have seen as far as seal quality are the old Andersen units where the seal is made by the glass itself (no longer manufactured). Commented Jan 12, 2014 at 6:40

You're effectively trying to create a hermetic seal. I would suggest doing a little permeability research for starters. Holding a vacuum short term is no problem but when you have 5-10 years for gasses to seep or diffuse through, permeability rates are very important.

A quick search on silicone:

"They have high gas permeability: at room temperature (25 °C), the permeability of silicone rubber for such gases as oxygen is approximately 400 times[citation needed] that of butyl rubber, making silicone useful for medical applications in which increased aeration is desired. Consequently, silicone rubbers cannot be used where gas-tight seals are necessary."

While glass is hermetic many materials are not. You're going to need to be cautious about what you use for a sealer if you want your double panes to last. Again I would suggest capitalizing on all the research that has been done by scientist on how to form a hermetic seal. They have a variety of techniques that are considered quite effective.

Good Luck


It's possible to make them yourself if you get the right materials. For spacers search in Amazon for "Dual Seal Aluminum Spacer".

For the sealer use a PIB Primary seal tape that wraps around the top, outside edge, and bottom of the spacer. Search in Amazon for "CRL Polyisobutylene Primary Seal". This stuff remains flexible and is very tacky.

The pros seal the glass with some pressure at about 140 °F. Perhaps you can apply some weight and use a hot van in the summer sun?

Good Luck!


I would look for a supplier that would ship you the bare panes and build the frames yourself. I doubt you could manage a proper seal. Look how many tries Edison went through developing a vacuum light bulb. Although, even just air insulated double glass would be better than single pane. Unless it stays sealed, condensation will be a problem

You may have to order thermal panes from a glass shop, who then gets them from a manufacturer, Should still be cheaper than buying complete replacement windows.

  • I've been pondering investigating this myself, for the window frames which are still in good condition. I'm not sure it would actually be a lot cheaper than a full replacement, but since I'm going to have to reglaze at some point anyway...
    – keshlam
    Commented Nov 19, 2014 at 14:24
  • 1
    Spoke with a gkass shop. The greater thickness of ths insulated glass systems makes the retrofit difficult (you need to rout a deeper recess) and more fragile than a sash manufactured for the purpose. Not recommended.
    – keshlam
    Commented Nov 21, 2015 at 23:47

Why do you want/need a vacuum? This negative pressure will actually be a force constantly trying to suck outside air in. Build your two pane system on a dry hot day, seal it well, but before you do, throw in some silica gel beads to absorb any moisture that might get in.


If you look at the manufacturers of these units they use specialized equipment to wash the glass and seal the units together it is not an amateur job. And i am kinda dumb founded who would expect a professional to let people bring them sashes so they can have that window professional track down the information so the homeowner can do it themselves? You might have better results bringing the sash to a shop so it can be measured and asking for an in shop install price. Saving the house call. But expect a two week wait for the replacement to arrive.


Thermal conductivity of Argon vs Air:

Air, atmosphere (gas) 0.024 Argon (gas) 0.016

meaning if I am right, that there is not much difference as low thermal conductivity means good insulation.

metals are good conductor of heat have high thermal conductivity. example: Aluminium 205

PVC even has bigger conductivity than air Polyvinylchloride, PVC 0.19

so , why would you want to fill the space in glazing by Argon?

No gas in between makes sense. But air and argon? can't see the difference to be much of much!!??

  • 1
    "not much difference" -- I wouldn't call a 3:2 ratio "not much difference"; depending on which side you view it from, air is 50% worse or argon is 33% better. It adds up over the surface area.
    – keshlam
    Commented Nov 20, 2014 at 1:24

If you use Butyl Rubber around perimeter except a small part and use a heat lamp to heat interior section, then seal the short part, it will be like canning tomatoes. When it cools, a vacuum will be formed !


Creating glass to non-glass seals is a non-trivial problem. The problem scales as the window gets bigger. Making a 6" x 6" seal is pretty easy. Making a 6' x 6' is hard. Normal steel flexes more than you would suspect. You can't just glue two panes together without any support because they will flex and leak.

To make 8.5" x 11" panes is not too hard as long as you can do metal working. You just make a steel frame with slots, epoxy the slots with aquarium sealant and slide the panes in. The vacuum fitting has to be in the metal part of the frame. The frame generally needs to be welded together because unless you are an expert machinist it will not be air tight.

Needless to say, doing this will be insanely expensive compared to just buying double-pane glass.

Why do you want to put argon in it? Argon is not an insulator you know. People use it in welding because it prevents oxygen from reacting with the work metal.

  • 1
    Unfortunately, the steel frame will become an excellent thermal conductor, negating significant portions of the benefit of the double glazing.
    – FreeMan
    Commented Jul 6, 2021 at 12:08

Kind of tangential here but file this away as another approach: I built a skylight 40 years ago out of acrylic sheets ("Plexiglass") using acrylic solvent to bond the edges of the double-paned center portion. It's still sealed after all these years. I didn't take all the precautions that were possible - leak testing and using adhesive where leaks existed; back filling with Argon; inserting gel to soak up moisture etc etc.


You're only talking about 15 square feet of surface area.

I would just use some thick single-pane low-e glass and be done with it.

Use the time and money to improve your house's energy efficiency in some more cost effective way, like adding some caulk somewhere or some better weather stripping around a couple doors.


Pella windows uses an installed window and then a panel that is installed like a storm window on the inside. The sides of the window has vents on each side high and low. No fogging with insulating qualities. The windows I had never fogged. If you have tools and some skills this could be attempted. Their gap was near 3/4" but some insulating qualities could still be achieved in the space used for insulated panels.

  • 1
    A vented storm window doesn't seem to answer the question of how to build a double pane argon filled window.
    – BMitch
    Commented Sep 8, 2015 at 12:38

Its much easy than here people saying. U should use normal glass(no plastic), professional hardware (spacers) and filling urethane compound. Forget about argon, vacuum etc: it doesn't meter for final window quality: u will never see a difference unless u will test your glass in the lab with professional equipment. U will never notice difference in your home with argon/vacuum filled and your hand made window.

What u need to have else:

  1. putty knife
  2. 2 glass cut in size
  3. miter saw (with aluminium cut blade, but u can replace it with other blade with tiny teeth)
  4. pice of clean fabric and glass cleaning fluid


  1. Measure your old glass dimensions, total thickness, spacer thickness, single glass thickness and space from glass edge to spacer edge (internal). Measure spacers dimensions (inside).
  2. order all listed above
  3. cut the spacer with miter saw exactly like u measured in #1. If u don't have that saw, use just hand saw for metal cut.
  4. Assemble the spacer frame. U need to use inserts-corners to hold peaces together. Be sure spacer frame is square, easiest way to check 2 diagonals.
  5. using glass cleaner clean glass. Important!
  6. put big pice of cloth on the table and put ypur glass, put frame on top, check diagonals again and put top glass part
  7. now take putty knife and fill black stuffing. it is very sticky be careful, when it harden u will not able to clean it, so do not put more than to fill a gap, and immediately clean what is extra. important to fill it fully: if u don't see a bubbles you seal it good. if you will not seal good - u will have a fog at winter time.
  8. wait 24h to make it harden, take a blade and clean glass if needed. Done! u get your glass and now it's ready to install.
  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Commented Feb 3, 2020 at 4:10

I used my Dremal with a 3/16" round diamond coated bit (Harbor Freight) and ground in a hole at the bottom left and upper right INSIDE pane. Grind at an angle till you break through. Then take a triangle bit and in a rotary motion open the hole to no more than 1/4". Be careful to not let the bits get jammed in the glass (Crack!). I then used a hair dryer to heat the inside. That got rid of the fogging. Normal air flow between the holes should keep the inside dry. I have done this to 5 windows and have not had a problem. The loss of insulation in my mind is minimal and not a big issue. I think the sealing chemicals they use today (thank the EPA), probably have little solvent if any) are breaking down sooner because they don't bind as well. My Caradco window panes from 1988 are still fine but my Capital window panes from 2004 are failing!

  • Not sure how this answers the question of "how to build a double-glazed window unit". This sounds more like "how to destroy the insulating qualities of a double-glazed window unit".
    – FreeMan
    Commented Jul 6, 2021 at 12:07

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