Wire balloon – Lets start with the galvanized wire balloon, otherwise known as the ‘bird cage’. Whilst this isn’t strictly a cowl, it will keep the birds out of a chimney pot and not alter the function of the flue. They are often cheaper to buy than a cowl, but as a downside they can rot prematurely depending on quality, be pressed into a pot by a heavy bird or blow out it the fit isnt perfect, which it often isn’t.
Anti Bird CowlTo stop bird entry – Birds can not only be a nuisance and enter the house through open fireplaces potentially damaging decorations and furnishing at great cost, but can also be hazardous when blocking the free flowing escape of deadly carbon monoxide gases from gas fires. The rotting corpses of dead birds trapped unseen behind a gas fire can also cause unpleasant smells and a plague of flies as the maggots develop. ( shudder )
Rain proof chimney cowlTo stop rain entry – Sometimes rainfall can create damp patches on chimney breasts inside the home. These are generally noticed in upstairs bedrooms and are even more common where the loft space has been converted, or the height of the roof between the apex and the ceiling is lower than other properties. A bungalow or a house with a shallow pitched roof are prime examples, often a homeowner with this type of problem will report the problem being worse when the wind is in a certain direction.
Increase updraughtTo increase updraft – There are a variety of conditions where you may find that a chimney may not suck the fumes up the chimney flue as well as it should, this suction is often referred to as the ‘draw’. If the draw is too little two common methods of fixing this are with a ‘spinning’ cowl or alternatively a ‘self adjusting’ cowl, often called ‘wind directional’ cowl. Read more on this further down the article…
Anti DowndraftTo stop downdraught – Down draught is normally a sporadic problem often caused by wind direction ( most often the North ). Tell tale signs with solid fuel chimneys like coal or wood are puffs of air / smoke being blown back down again. With gas fires it can make them flicker or occasionally be blown out, often the cure here can be to fit and ‘anti downdraught’ cowl, more on this further down the page.
Spark arrestor cowlThe spark arrestor – As the name suggests, the function here is to stop sparks and embers being blow onto thatched roofs and other highly combustable sources. Although specified by some insurance companies extreme caution is also required, regular cleaning is absolutely essential to ensure it remains very clean. A buildup of deposits on a spark arrester chimney cowl is potentially more dangerous than not having one at all, for that reason lots of insurance companies are moving away from recommending them.
Fitting a chimney Cowl
Unless you think you need specialist advice you can actually fit your own chimney cowls quite easily as long as you work safe, ( correct access equipment ) and are competent to do so. Before attempting any chimney cowl installation, I would however recommend you watch my video on chimney flue identification and pot size estimation further down the page.
fitting an all purpose cowlChimney cowl install – In this video I show you how to fit three common all purpose cowls. Often this would be to stop birds and rain, whilst being suitable for multi fuel types.
The best chimney cowls
By far the most common chimney cowls I’m asked to fit are dual function, firstly to stop birds falling down the chimney and secondly to stop the rain blowing down the flue. A low cost example of this would be the Mad Cowl or similar, and if you’re looking for the best chimney cowl to stop birds and rain it’s a good low cost solution. There are a number of unobtrusive solutions on the market for this same purpose, and some of them are also ‘multi fuel’ meaning should you wish to change your fire to burn a different type of fuel you will not need to change the cowl again. A good example, and a firm favorite in the roofing yards is the Colt Top or Colt Top 2 which is considered by some to be one of the best chimney cowls to stop downdraught, birds and rain as an all in one package.
Multifuel Chimney Cowl
Chimney Cowl – This is a standard low cost chimney cowl, these are commonly used for active chimney flues, chimney ventilation, stopping rain water, and bird ingress. Most commonly available in the ‘strap fix’ pictured, but also pressure bolt versions, see picture below.