How-To : Home Improvement

Every year, usually in January, we (Builders Architectural – a top Chicago-based window contractor) receive phone calls from customers who complain of sudden condensation on their windows.

This condensation can be surprising because of its sudden onset and large volume. Condensation is widely misunderstood but actually it is quite simple.

Think of a glass of cold beer on a muggy summer day when you are outdoors. The glass in your hand is dripping water on its outer surface to such extent you might almost think the liquid is actually leaking through the glass.

Unless you are drinking from a practical joker’s dribble glass, leaking glass is probably not the cause. The real cause is airborne water vapor(a gas) converting to liquid when it cools while contacting the cold glass. The water vapor has cooled to its “dew point” and condensed into a liquid.

This happens on your windows during a winter cold snap in the exactly same way.

Lets say you live in Chicago and so far the winter has been moderate. Your humidifier is set at 35-40% relative humidity(RH). One day the outside temperature drops from +30F to +10F.

Suddenly your windows are fogged. In extreme cases water drips down the face of the windows. Left unattended, water can damage window frames and finishes.

Then you call your favorite window contractor and complain that your windows are defective. Chances are they are not. The elevated humidity in your home has come in contact with very cold glass surfaces. The water vapor within the air has changed to a liquid form and is now visible on your windows.

Generally, most windows which are “thermal”- meaning they have insulated glass and either wood frames or aluminum frames with thermal breaks – are designed to function well to a range of +10F exterior and +70F interior, with an interior relative humidity (RH) of 25-30%. If any of these variables change, condensation may result.

Window treatment should help, shouldn’t they?

One of the most surprising aspects of condensation can be that it frequently take place behind fixed, insulated, or tightly fitting window treatments such as heavy drapes or honeycomb-style window treatments.

This is not what one would expect. We correctly think of these treatments as adding insulating value to the house. Why would condensation take place here?

The answer is simple. While it is true that window treatments can reduce the flow of heat through a window opening, there is an unfortunate by-product:

Window treatment prevents the flow of roomside heat from warming the glass surface. Glass surface temperature will cool. An environment may be created for condensation.

While window treatments retard the flow of heat, they don’t do much for retarding the flow of water vapor. You need a fully taped foil or plastic vapor barrier for that.

Remember osmosis and diffusion from high school biology? Of course you do. These forces of nature are playing themselves out on your windows and draperies. To refresh your memory:

Osmosis: The force in nature wherein water naturally migrates from a place of greater concentration to a place of lesser concentration. This is your roomside humidity equally dispersing itself throughout your house.

Diffusion: Osmosis through a semi-permeable membrane. The membrane is your window treatment. Diffusion is also known as “vapor drive”.

What can be done in my home?
# Wipe off the condensation. By doing this, you are physically reducing roomside humidity.

# Open the windows an inch or so. The dry outside air will mix with humid inside air and reduce roomside humidity.

# Lower your humidifier settings to 25% or below.

# Open up your blinds and drapes to a level which will allow the roomside heat to warm the glass surfaces.

# Use exhaust fans during and after showering and cooking.

# If you are painting or drywall taping open the windows to allow moisture to dissipate.

# Look at your clothes dryer. Make sure it vents to the exterior. “Vent-less” clothing dryers can bring large amounts of moisture into living spaces.

It could be the windows too

After excluding non-window sources, look for these possibilities on the windows themselves:

# Weather-stripping not tightly compressed allowing air infiltration into the space. Although we know that air infiltration can actually reduce interior humidity, it can also focus a cold spot on a metal window or glass edge. If there is a cold spot you could see condensation or even frost which could be window related.

# There could be a similar cold spot where caulk is missing at the perimeter of the window.

# Your windows could be single-glazed, where only one layer of glass, rather than two, separates you from the exterior.

Deal with humidity first

Good strategy would be to deal with the living space issues first. If you attack them as we describe above, condensation can disappear in 24-48 hours.

If condensation persists, look to the windows and caulking.

Mark Meshulam is Executive Vice President and Director of Engineering for Builders Architectural, a top Chicago-based window contractor. http://www.buildersarch.com

[tags]window condensation, frost on windows[/tags]

With the price of gas and electricity on a seemingly endless series of climbs, now is a good time to take a look around your home and see where you can make some energy savings.

Over 20% of the heat lost from your home goes straight out of the roof, so it’s important that you have the attic properly insulated. Even if your attic was insulated when the house was built or any time before the last couple of years, it may not have the right amount of insulation.

Recent government recommendations have almost doubled the suggested amount of insulation, and a minimum thickness of 200-250 mm (8 – 10 inches) is now suggested in temperate areas.

If you do need to top up your attic insulation, it’s easy to do it yourself in a few hours if you are reasonably good at DIY. You don’t need any special tools or skills and it can be much cheaper than paying someone else to do it – as long as you don’t put your foot through the ceiling!

But check before you start as grants may be available to help with part or all of the cost of insulation, especially for the elderly or those on a low income or benefit. If you do decide on the DIY route, remember that some types of insulation are irritants so wear suitable clothing, including gloves, goggles and a facemask when you are laying the insulating material.

Make sure you carefully follow the instructions that come with the insulation, and in particular ensure that you don’t block ventilators or air inlets. Leave a gap around the eaves as well to prevent condensation.

Don’t cover electrical cables and keep insulation away from items such as recessed light fittings that may require airflow to prevent overheating – check if you’re not sure.

The attic will be a lot colder once it’s insulated so make sure that pipes are lagged and water tanks are insulated. Don’t insulate under tanks though – leaving a clear area underneath will allow heat from below to rise and help stop them freezing. Finally don’t forget to insulate and draft proof the access hatch.

Now that the attic is snug, it’s time to look at some of the other areas that you can work on to cut down on the heating bills.

Double glazing your windows is most effective at retaining heat, but if you don’t want to replace your old sash windows just yet, you can save energy by stopping drafts. Seal or caulk any gaps around the frame using a sealant gun and cartridge – your local DIY or hardware store should be able to advise you on the best type for your needs. But whatever sealant you use, first ensure that all the surfaces are clean and dry and that there is no loose or flaking paint which could prevent the sealant adhering.

Fit weather strips to opening windows and doors – these come in many shapes and sizes ranging from cheap and easy to fit self-adhesive foam rubber strips to more expensive but durable plastic or metal weather stripping. Prevent drafts under doors by installing an adjustable threshold or brush type strip at the bottom of the door.

Once the frames are weatherproofed, you can look at reducing heat loss through the window glass itself. The cheapest way of doing this is to use a clear film plastic sheeting which is stuck to the window frame with tape and then warmed with a hairdryer. This causes the plastic film to shrink and tighten removing wrinkles and creases. This type of secondary glazing – while low priced – has to be renewed if you need to access the window, and so is unsuitable for windows which you want to open before spring!

More expensive are secondary glazing panels. These are made from rigid clear plastic and can either be fixed to the wooden frame with magnetic tape, or plastic channel which can be left in place. In both these cases, the panels can usually be removed for ventilation and cleaning.

Don’t forget that when you’re draft proofing your home that it’s vital to ensure that you have adequate ventilation in rooms where there is a heater, fire, boiler or any other appliance that needs air for combustion and make sure you never block up air bricks or vents.

Now that you’ve reduced the amount of energy that it takes to keep your home warm, you can turn down the heating. Even a small 1 or 2 degree C reduction on your thermostat can reduce your heating bill significantly. If you can also set your heating to fire up a little later and switch off a little earlier, you’ll find that even a difference of a few minutes a day can add up to a big saving over a year.

There’s only space here to give you a couple of ideas but there is a wealth of further information available both on and off-line on how you can economise on energy use.
Once you start to think about saving energy, you’ll be surprised how it soon becomes second nature and before you know it, you’ll have a greener and more energy efficient home with big benefits for your wallet and the planet.

Russ Grimble helps to run http://www.national-double-glazing.co.uk an online resource with hints and tips on saving energy, insulating your home and useful information on choosing Double glazing or replacement windows.

The smiling friendly salesman comes out to give you an estimate…and yes, that is a diamond inset into his front tooth. It really sparkles when he smiles.

And he still smiles-even after he hands you your estimate and you are choking and gagging at the estimate-$20.000 dollars…for windows?

“Yes”…he smiles bigger ..(Fast, smooth talking mode on).”But…it is not expensive at all, when you consider the enormous benefits of much lower utility bills and the satisfaction knowing you are going to be comfortable and secure in your own home…and don’t forget fuel costs are going up every year…why, the saving on fuel costs will easily offset the installation cost in just a few years.”

Your eyes began to settle back into their sockets. “Really” you say, thinking about your last fuel bill.

“Sure…it’s a no brainier…I can show you the figures if you want.”

Not wanting to be classified as stupid, you say “…uh…no, that’s not necessary.”

He licks his lips. “…And think about this…when you sell your home …I mean, you’ll want to upgrade to new larger home real soon …right.”

“…uh..Maybe.”

“Well, there you go….any agent will tell you the ROI on replacement windows is almost %100…maybe more as costs go up. You can’t loose…its win-win all the way.”

“I didn’t know that…”

“It’s true…and one more thing…” He looks around and moves closer. “If the boss finds out about this, he’ll kill me …I’m sure we have your windows in stock. That means I’m charging your windows out at the old price.”

“…The old price?”

“That’s right…you see, nobody keeps windows in stock…and before an install, we always order from the factory…but last week, we had a guy cancel and I’m sure the windows are the same as yours.”

“No kidding…you would do that…how much can I save?” You ask.

“A lot…you know, that price I gave you is just an estimate.”

“OH …REALLY?”

“Sure …everybody does it like that now a days…any additional costs like fuel surcharges….destination charges …would be added to that …I mean the way things are going up…how can we do it any other way. The margin is so small; we would be out of business in a short time. See, it says that right here” Pointing to a small blob of print on the estimate.

“I guess I need some glasses.”

“Don’t we all…but, I’ll tell you I can lock you in at that price today and you won’t have to worry about it at all …if you know what I mean.” He winks. “The boss doesn’t have to know about our special deal…just sign right here.”

“Okay…here?”

“That’s it…” He extends his hand, the diamond in his front tooth shining like a freight train headlight.” I want to thank you…uh..Mr. Fish…for giving me the opportunity to save you some money…It really makes me feel good to help someone.”

Jim McDonald is a retired general contractor and liscened real estate home inspector. Read more about your home at these websites.

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