Cast Iron Air Bricks vs Clay Air Bricks

Cast Iron Air Bricks vs Clay Air Bricks 

In the photograph above we’re comparing our GRID6 9×6 air brick with a similar sized clay air brick. If we take, for example, the corresponding 9×6 clay air brick in the photograph top right (middle of the 3 air bricks shown in buff) and compare the free air flow we can see a huge difference in ventilation supplied between these two products.

The clay air brick is inefficient as a ventilator because it requires a substantial amount of material to prevent it from deteriorating during winter months and succumbing to frost damage which leaves little room for holes – the main purpose of an air brick! We can see that the clay 9×6 air brick has small 8mm square holes in just four rows  and nine columns which allows for a free area in mm2 of 8x8x4x9 = 2304mm2

The cast iron air brick, however, isn’t affected by frost and therefore can be made with much larger holes, smaller ribs and narrower borders therefore allowing for substantially more ventilation holes and creating a very efficient vent. The cast iron 9×6 air brick has larger 11mm square holes, in twice as many rows (eight) and an impressive thirteen columns which allows a free area of 11x11x8x13 = 12,584mm2

The standard cast iron air brick provides more than 5 times the ventilation of the same size clay or terracotta air brick . If even more ventilation is required, our MAX6 maximum flow air brick of the same size will provide 18,000mm2 free area – an even more impressive vent!

Ventilation Faults in Period Homes – Condensation Part3

We’ve already seen ways of reducing condensation and also how period properties were originally built to avoid condensation but now let’s turn our attention to faults with the ventilation in period properties.  It should be noted that these “faults” weren’t part of the original build but have been introduced either by the occupants actions or inaction over the 100 years or so of the buildings life.

Previously we discussed about how draughts played a huge part in ventilating period homes. Look carefully at the modern period property and many of these draughts have been sealed up. Here are a few more errors that lead to more condensation and how to improve them:-

  • Blocked up fireplaces. These fires used to allow air to vent up the chimney but when blocked the room and the chimney will become less ventilated. This leads to more condensation in the room and also inside the chimney which may show itself as dampness on the internal chimney breast walls. Remedy is to either open the fireplace back up or fit and internal 9×6 cast iron vent were the open fire used to be.
  • Sash windows. Created small but steady ventilation through gaps in sashes. If these are sealed up consider removing sealant/draught excluder or partially opening secondary glazing. Were they have been replaced with UPVC double glazed units, ensure the new units have trickle vents fitted.
  • Increased ground levels. As previously mentioned consideration must be given to lowering outside ground levels to original levels. This often occurs were slabs and pavements have been built up by placing new pavements over existing ones. The idea is that this will reduce flooding but what really happens is vents become partially submerged and damp proof courses are breached. If pavements have been raised along public high streets at the front of period properties consideration should be given to removing air bricks and relaying higher up with periscope vent ducts.

Condensation in Period Homes – Condensation Part 2

We’ve already looked in our previous blog at the sources of condensation, but now let’s turn our attention to how its controlled in period properties. By looking at how our fore fathers controlled moisture in their homes, we should be able to find clues as to how we can alleviate condensation in the same properties in the 21st century.

What may come as a surprise, is that condensation is a modern problem and it’s highly likely that our fore fathers never found it a problem. We’ve talked about ventilation being a key deterrent in the battle against condensation in our previous blog and it is the reason why it was never a problem in homes prior to the 1950s. Not only were older properties extremely draughty with sash or ill fitted windows but they were heated, in the main by open fires drawing a considerable amount of air into to the property for combustion. This air helped to ventilate and keep moisture levels in main rooms lower but it’s not just the higher levels of ventilation that helped period homes stay condensation free. The lifestyle of our pre war home owners was significantly different than modern times and contributed to reducing the occurrence of condensation. The kitchen and the laundry were most often in annexes or set back rather than being a central part of the house, clothes were hung outside on a washing line and if it were necessary to dry indoors, then clothes would have been placed in front of a fire which would draw the moisture out of the room and up the chimney, bathing was kept to a minimum and showers and tumble dryers hadn’t been invented. We touched briefly on sash windows earlier but the existence of draughts in the period property helped considerably preventing condensation. Draughts occurred were ever there was a fireplace, even when unlit, chimneys drew air naturally out of the room and up the chimney. It is quite likely for even a small 2 or 3 bedroom period property to have 3 or 4 fireplaces so ventilation would be very efficient in these rooms, combined with ill fitting floor boards and bare floors.

Just looking carefully through the previous paragraph it is easy to see that the period property from the Georgian, Victorian and Edwardian times couldn’t have suffered from condensation when they were built and first occupied. The same period properties in the 21st century that suffer from condensation must do so because of the occupants lifestyle (which we looked at in part1 of this feature) or perhaps have had something in the fabric of the property that has changed to retain moisture in the home. We’ll look more closely at these possible changes in period properties in part 3 on Condensation coming up next.

Condensation – Top Tips



Autumn is approaching and it’s that time of the year again – yes condensation is back!

Here are some simple tips to reduce condensation……….


  • When taking a shower or a bath, keep the bathroom door closed and if there is an extractor  fitted, make sure it’s on.
  • Don’t forget to pull the plug and drain the water out of the bath as soon as you’ve finished!
  • Drying clothes on radiators generates plenty of moisture, it will reduce condensation considerably if you use a tumble dryer instead and extract the moist air outside.
  • Modern windows have trickle vents fitted to allow a little air to keep condensation down, if these aren’t fitted, opening the window just a tiny bit will help reduce condensation
  • Hob extractors are great for removing moisture but only if they are set up to extract to an outside wall and they’re used every time the oven or hob is on. If they’re the recirc type then they won’t remove any moisture, just smells – consideration should be given to extracting outside if condensation is a problem in kitchens.
  • People generate moisture just by breathing so the more people in the property the more likely condensation will be a problem – public houses, village halls, community centres, offices and properties with large families are particularly vulnerable so ensure ventilation is adequate.
  • Fix leaks – Check inside the house to make sure there are no plumbing leaks. Particular attention should be given to overflows , double check that overflow pipework is connected to the outside and works. Checks drains aren’t leaking under the sink and under the bath.
  • Fix leaks – Check outside that rainwater gutters are clear and downpipes are connected and not blocked. When its raining hard, go outside and take a look to ensure the rainwater is flowing away from the property and not soaking into outside walls.
  • Put the heating on – warm air holds considerably more moisture than cold air but don’t be tempted to seal up the house by closing every window, see next tip……..
  • vent vent vent vent vent – we can’t stress this enough but ventilation is the key to reducing condensation, combined with improving insulation, reducing damp and heating the property.

Shipping All Over the World

After many years of supplying cast iron vents and drainage gratings it will come as no surprise to hear we ship all over the world.  One of our more remote deliveries has to be to Mr Chins House in Borneo, Malaysia. It was an order we especially remember because Mr Chin sent us a link to his blog showing the property and you can see from the picture above, what a surprise it was! Quite often we get photographs from customers and builders asking were they should put the vent or how to install it but normally the property isn’t at such an early stage as Mr Chins. It was very interesting looking at the way properties are built in the Jungle of Malaysia but what sounds so familiar is even in such a remote area Mr Chin had quite a job with the planners. Interesting but no matter were you are in the world, legislation is never far away!

One of the benefits of our new website has been the automation of global shipping rates. It has seen a significant increase in the number of overseas customers buying our British made products.

Throughout the website we showcase some of these customers and their properties including a wine cellar in Hungary and a windmill in Sweden as well as the many splendid properties at home in the UK.

To date our overseas customers include clients in Canada, Australia, New Zealand, Norway, Netherlands, Italy, Sweden, Hungary, Ireland, France, Spain, Germany, Switzerland and a substantial number of customers in many of the states in USA including Idaho, New Jersey, New Hampshire, Texas, Florida, Maine and Massachusetts.

Cast iron used for bridges, steps and walkways

Cast Iron for Steps, Bridges and Walkways

Cast iron has been used for centuries in properties for ventilation and drainage but it’s original use would have undoubtedly been in castles as covers for wells and as walkways and bridges. In more modern times, Georgians and Victorians used cast iron grilles along pavements to allow light through to the basement below and as bridges over streams and to create steps into properties.

We now find an increasing number of architects specifying not just the utilitarian square hole gratings  for steps and bridges but also the more decorative, Ecclesiastical and English Scroll  gratings for more elaborate projects.

Below, we feature an installation of gratings used as steps and a bridge over a small stream.  It’s an unusual combination, clients would normally require a step into a property or a walkway over a stream but not often both, but it illustrates the possibilities and the opportunities and benefits of using cast iron gratings.

Measuring for installation of cast iron gratings

The brick pillars or risers, when weathered, will blend in with the brick used around the window reveals of this stone outbuilding.

Cast iron used for bridges, steps and walkways

And then the gratings are fitted into the cast iron bearers onto the risers……….

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In this example, the bearers are screwed into the steps and then covered with hardwood (below). Drilling is not always required, quite often, bearers are simply mortared in place – every installation is different! We have seen clients slot the gratings into rebates cut with a disc cutter into stone slabs or into existing concrete paths without using the bearers which is very effective.

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Cast Iron Air Brick Outlet in Sweden

We’re proud to announce our cast iron air bricks and vents are soon to be available to property restorers and architects in Sweden.
Last week we were very excited to welcome a visit from Henrik Ulin, the owner and founder of Gamla Majeriet, the online building materials company based just south of Malmo, Sweden.

Henriks company specialises in quality building materials for the discerning property owner in Sweden and features many British made products. As well as our British made Conservation vents and Heritage vents, Gamla Majeriet also stock Thomas Crapper toilets, Drummond bath tubs (photographed) and various cast iron products including rainwater goods, bollards and radiators.

Of course it’s not the first time we’ve supplied to Swedish companies, our first Swedish customer were the owners of the wonderful Stavik lighthouse at Karlstad a number of years ago, but Gamla Majeriet will be our first retail outlet in Scandinavia.


British manufacturing – The New Micro Foundries

The Cast Iron Air Brick Company have been champions of UK made products for years. Our products are made in foundries of all shapes and sizes across the country from Somerset to Scotland. Many of these foundries have been producing iron castings since the 19th century, but our newest foundry is, by far, the most interesting. Situated in a tiny unit on an industrial estate, the little “micro foundry” supplies us with the 4″ and 5″ cowled cast iron Conservation vents. Our photograph (attached) features the entire workforce (yes both of them) turning out a crucible of molten iron to cast four of our Conservation vents.

To see more on the “micro foundry” and our vents being cast see the full story in pictures on Youtube, or view our foundry art section on Pinterest.

Supplying Windsor Air Bricks to Celebrity homes

In the 10 years or so we’ve been supplying cast iron vents and drainage gratings, we’ve supplied vents for all sorts of homes and they’ve been installed in “celebrity houses” such as Mrs Thatchers house, the colleges at Oxford and Cambridge, the PMs residence at Chequers and even Buckingham Palace!

We’re always thrilled when our vents are installed in these wonderful period properties and in the nations famous buildings.But there’s nothing to compare with our latest order for more than fifty of our beautiful Windsor air bricks (show picture of WIN3 ).

Our vents are not only going to be installed in one celebrity home, they’re being installed in an entire street of them! Around 40 homes in total and everyone of these homes is (and has been in the past) occupied by some of Britains most famous people (or should that be “Characters”). Where can it be?

Well, were else than Britains favourite street featured in Britains favourite TV programme, Coronation Street.

Read the latest on the restoration from The Daily Mail here and view the news as released in Westcountry newspaper, Western morning News here.


Conservation Vents – Before and After

Our cast iron Conservation vents are known as conservation vents for a reason. They’re ideal for use in conservation areas and especially suited to installation on listed buildings*. They can be used for outlets for extracted air from tumble dryers or fan outlets from bathrooms, kitchens and hobs or to supply air (up to 8000mm2) into a property for combustion appliances such as log burners and boilers. They are available in two spigot sizes either 4″, 100mm (7200mm2) or 5″, 125mm (8000mm2) diameters.

The picture before and after (attached) illustrates just what an impact our vents have in improving the look of ventilation outlets. Although especially suited to brick properties, our CON4 installed on this very tricky slatted wooden wall looks fantastic.

See more on the Conservation Cowled vent here