Many of us are lucky enough to live in a period or possibly listed property. These come with there own little idiosyncrasies – small doors, unusual room layouts and features which would never pass modern building regulations. Among the more standard features are windows which come in a range of types including centrally pivoting sashes, sliding sash windows and traditional flush casement windows.
The Sliding sash window that most of us recognise is standard fitting on Georgian town houses and is instantly recognisable by 6 small panes above the central meeting rail and 6 below. There is a “horn” detail which is a decorative flourish on the sash style.
Sash windows are a thing of beauty which complement the look of the older property but the originals are prone to several problems.
The sashes are renowned for being stiff and difficult to lift, often due to years of over painting. They tend to rattle in the frame due to wood shrinkage and do not operate smoothly.The gaps around the sashes also allow cold draughts to enter the building. The original glass is often single glazed and is both thermally inefficient and has poor acoustics. The paint finish on older properties may also contain lead which needs to be treated with care when being removed.
“SO” I hear you say, “What can we do about these problems?”
Well, there are several options depending on budget, listed status and personal preference.
1. If you have a listed property, it is likely that you will be required to replace the windows like for like. The frame will need to be increased in depth due to the “pocket” required for the sash weights. For single glazed units a frame depth of 135mm is quite typical and for more modern double glazed units this will be increased to around 170mm. The glazing bars often associated with “Georgian” type properties will need to be solid bars which are mortice and tenoned into the frame for strength. It is not unusual for single glazed units to be specified by the listed officer as they are original features.
2. The more modern equivalent of the weights/ sash cord is the spring or turbo balance. These perform the same action as the original weights but are less obtrusive due to there size. They are normally set into a groove in the frame or can be face fixed. The springs themselves are housed in a protective outer case which helps keep them free from dust and dirt. Colours include white and brown.
3. The third and most cost effective replacement is the “Mock Sash” which from the outside appears to be a standard sliding sash complete with individual panes of glass and decorative horns. the main difference is when you come to open the window- it opens on friction hinges similar to a standard casement window. There is also the option to replace the solid glazing bars with “Plant on ” bars which come as a frame ready to fit after glazing. This gives the illusion of separate panes of glass but means that a single double glazed unit can be utilised. They are also a very good choice where a fire escape window has been specified
The choice of timber is also of importance when it comes to windows which need to withstand the rigours of the weather.
Hardwood is the best choice for durability but comes with a higher price tag. If the house is yours and you intend to live in it for a long time the extra investment is certainly worthwhile. Todays modern engineered timbers are far superior to the timber previously used and with a little TLC they should last for years.
If budget is a major consideration then softwood frames with a hardwood cill is the next best choice. A complete softwood frame is the lease expensive choice but it is unlikely to weather well and should be avoided if possible.
A timber such as Sapele which is part of the Mahogany family is a very popular choice as the close grain will result in a smooth finish if applying stain or paint.Due to the way it grows, there are no lower branches and so high grade Sapele will be knotless and again results in a superior wood finish. The vast majority of these type of windows are painted so it is unlikely that paying the extra for a timber such as Oak would be justified.
Modern paint systems have also improved to the point where a 3 coat system – primer/undercoat-2 top coats will protect the timber and leave it looking good for many years. If hardwood windows are chosen then these can be repainted and repaired as necessary. If softwood is chosen, then rot is more likely in the long term especially at the cill and then whole window sections will probably need to be changed.
The glazing is also of paramount importance. If the building is listed then single glazing may be the only choice. There are slim versions of double glazed units now available and these are sometimes acceptable, although they are generally more expensive than standard double glazed units.
If new windows are being manufactured and double glazed units such as 24mm can be used, incorporating “K” glass on the inner leaf to comply with building regulations, these are a good choice. The “U” value of double or even triple glazed units will be around 1.0 but can be as low as 0.8
The windows are an important feature on any house and getting the right look can make the difference between so so and the WOW factor.
Choose your joinery manufacturer carefully and make sure you visit them to see the quality of work being produced before you start signing cheques!!