Channel Grating

New Channel Grating

After years of research and hundreds of requests from architects and period property developers, we’re delighted to introduce our latest innovation – an elegant and simply stunning cast iron channel grille combined with a modern interlocking channel system.

The Quatrefoil linear drainage channel, also known as channel gratings or French drainage channels are specifically suitable for removing surface water in domestic period properties and pedestrian areas in conservation areas. The system can be installed for light vehicular use on driveways, patios and paths with block and flag stone paving or tarmac or concrete.

The Quatrefoil grilles are 108mm wide and 10mm thick and are available in a variety of lengths up to 1000mm long with a choice of bare metal or painted black finish. For those wishing to create their own channel or use an existing channel or indeed use the Quatrefoil grille as a vent or internal floor grille they are available with or without the plastic channel.

Quatrefoil grilles purchased with the channel will be supplied fully assembled with screws.

It is no accident that we chose the Quatrefoil design for our grille. We wanted our grille to appeal to conservationists and period property restorers alike and to enhance walkways and driveways in the simplest home or grandest mansion. For such a grille, we needed a design with class, history and elegance and the Quatrefoil has all three in abundance. The design can still be seen today in windows of Norman churches in England and throughout many Gothic London properties. Although used predominantly in churches, it’s earliest use can be traced back 1000 years to an English penny from the London mint. The design is used extensively throughout Europe featuring most notably in Notre Dame, cathedral in Paris and also in Renaissance buildings in Venice, Milan and Florence and is sure to look good in the grounds and along the paving of homes in the 21st century.

A standard length is 1 metre long (1000mm) although it is possible to have shorter lengths to allow the channel to fit almost any situation. Shorter lengths available are 155mm, 300mm, 440mm, 580mm, 720mm and 855mm. Whilst the 1 metre long version has four screw holes ( a pair at each end as per photo), all shortened versions of the Quatrefoil grille are supplied with only two holes at one end.

More details on the Quatrefoil Channel Grating

Please Note:-

Estimated delivery time 2-3 weeks bare metal, 3-4 weeks painted

titanic deck vents

Cellar, Fresh Air Inlets and Sewer Vents

It sounds as if we’re describing three different types of vent here but the cellar vent, fresh air inlet and sewer vent are all the same vent. I’m sure you’ll want to know what on earth a picture of the Titanic has to do with all this but please read on…

These rather splendid looking angled vents have two uses, to ventilate cellars and below ground rooms or to allow fresh air into the sewer pipes to prevent loss of the water trap in WCs. If used as the former they are normally fitted with mesh, whilst for sewers the mesh is replaced with a flap non return valve that prevents any smells escaping.  Because many WCs were outside period properties, these vents, used as fresh air inlets were more commonly used towards the rear of the property some distance from the building – generally around knee high ( to save on expensive cast iron pipework)

You would be pressed to notice a sewer vent nowadays installed in a modern sewer system. Unsurprisingly, they’re tucked away, with the cost of plastic sewer pipes being relatively inexpensive they’re placed at a significant distance from windows and more commonly above the rainwater gutters around the roof eaves.

Another use, with a mesh front is to ventilate below pavements. There angled profile allows air to be piped below the floor level without rain water and puddles being drained into the basement – an ingenious and most attractive method of subterranean ventilation.

I’m sure that mariners, seafarers and filmgoers alike will suggest that this very same principle is very similar to the structure on the deck of steam ships that gathered fresh air from the upper deck to divert it below to cool the machinery and men working below. Our cellar vent although diminutive in size has very much the same purpose as the deck vents of ocean liners (also known as Dorade vents), but more to the point…

which came first ?

castle drogo

National Trust Restoration, Castle Drogo

This weekend we went along to see some of the conservation work being carried out at Castle Drogo, Chagford in Devon, England.  The castle is owned by the National Trust and the restoration work is a huge undertaking, likely to cost around £12 million. The scaffolding completely encloses the castle which is dwarfed inside by a huge marquee suspended on the scaffolding structure – currently, the largest scaffolding structure in Europe.

Work progressing at the moment includes removal of the windows, replacing the pointing and replacement of the roofing material to waterproof the property. Despite it’s looks, Castle Drogo is in fact a 20th Century building having been completed in 1930. The architect Edwin Lutyens was keen to build a Norman style castle without rainwater gutters, down pipes or window ledges and with a flat roof which, over the last 80 years or so, has proved difficult to keep waterproof. That has been, and still is, especially true in rural Devon, hence the need to enclose the restoration work with a tent.

Whilst the work is most impressive, what sets this project out from the norm is the lengths at which the National Trust have gone to make it accessible to the general public. Donning high viz jackets and hard hats to scale the ladder tower is the highlight of the visit and is sure to inspire many in the field of restoration and conservation work. Castle Drogo is a must visit at any time but be sure to visit it while the restoration work is ongoing – it’s a revelation!

Westminster design

Prototype Quatrefoil Channel Gratings

Our varied selection of 3 feet long gratings have always been a favourite for those wanting to replace ugly plastic and pressed tin grilles on top of channel gratings (also known as Ako drains) , with decorative cast iron grilles  Unfortunately, at 3 feet long, our grilles are not a perfect fit for sitting on top of the metric, 1000mm channels and our customers have either had to compromise or add a smaller extension grille to make up the difference. As many of our regular customers know, we’re not comfortable with asking our customers to compromise, so we’re now working on a solution. A very beautiful, ornate solution, with a design of cast iron grille based on the medieval, architectural, four circles known as the Quatrefoil, commonly used in windows of Norman churches and throughout Victorian period properties. This new grille will be ideal to enhance already installed channel gratings and provide architects and landscapers with stunning cast iron grilles to finish off there most prestigious projects and gardens.

Introducing item  Q1000 – 1metre long Quatrefoil pattern cast iron grille

“Estimated availability October 2014″

This new channel grating will be supplied with a plastic channel and on top, an integral decorative cast iron grille with screwed fittings to secure it to the channel below. It will be ideal for pedestrian use and driveways in period properties and contemporary, high end builds. The Q1000 can also be connected to a four way square grille end plate complete with cast iron grille + channel (item Q4) to allow the channel to be laid in an L, T or X layout.

The Q1000 can also be supplied in shorter lengths to enable almost any length of channel to be formed. Exact lengths of the extension channels complete with shorter lengths of cast iron grille are not known at this early design stage but are likely to be around the following lengths 150mm, 300mm, 450mm, 550mm, 700mm and 850mm


Made to Measure cast iron grilles

Made to Measure

We have been making square hole gratings in a wide range of sizes for many years. It’s been a bespoke service and we have measured grilles for customers as and when they enquire and worked out the free area in mm2 that can be achieved for ventilation.

While it started out with us making the occasional grille, it’s now very much a part of our manufacturing and so we’ve now got a guide featuring all the sizes and dimensions. We hope this new guide will prove especially useful to architects and designers looking for both external and interior grilles for projects and buildings

Made to Measure Cast Iron Gratings


Charles Rennie Mackintosh

DSCF3068 willow tea rooms chair charles rennie mackintosh

In November last year we spent a few days in Glasgow, looking for inspiration for new products and air bricks in listed buildings and period properties. Throughout the city are hundreds and hundreds of wonderful buildings and it wasn’t too long before we stumbled upon the works of the world renowned architect Charles Rennie Mackintosh.

We visited many of his properties including “The Lighthouse”, “Glasgow School of Art” and of course “Willow Tea Rooms” which were all very inspiring but none more so than the latter. For it was in the tea rooms that we came across a fabulous semi circular chair, a copy perhaps but certainly a chair designed by Mackintosh (shown middle photograph above) . The design is very simple but beautifully elegant with its symmetrical square and every increasing slot design.

The Willow Tea Room chair is the inspiration behind our newest and most elegant cast iron creation – a high air flow 9×6 inch cast iron air brick with over 20,000mm2 of free area. This air brick will undoubtedly suit ventilating high end building projects and is particularly suitable for inclusion in homes of discerning clients with a keen eye for design and symmetry .

The Mackintosh 9×6 (item code CRM6) air brick will be available soon from here

Blocked Air Brick

What’s wrong here?

We’re often asked for advice on installation from customers and the trade so it’s always useful to see a photograph of the work proposed.

Taking a look at the picture above, we saw a number of problems, here’s our thoughts and later a solution …….

  • The air vent appears to be blocked in a number of holes, especially the bottom row which is below the ground level and should have been cleaned regularly.
  • The air brick has been painted over, time and time again reducing the size of the vent holes.
  • The ground level has been built up and the stones are blocking the lower holes.  This is one of the biggest causes of damp and reduced ventilation under floor boards of period homes and can lead to increased levels of condensation inside the home, formation of wet rot and dry rot and reduced  air in properties for combustion of open fires and combustion appliances.
  • The air brick shown in the photo is a clay/terracotta air brick and even when new wouldn’t have allowed very much air in for ventilation,  see previous blog (clay vs cast iron comparison). Consideration must be given to upgrading clay and terracotta air bricks if the mm2 surface area of the holes is especially low and the vent is used to keep sub floors from rotting , reducing condensation or providing air for combustion appliances.


The priority here is to lower the ground level on the outside of the property. If the outside floor level has breached a damp proof course it will create damp along inside walls and floors which would also encourage the formation of dry and wet rot.

If the outside floor level cannot be lowered then we would suggest removing the clay 9×6 air brick and replacing it with a 9×3 brick along the lower course and mortaring in a 9×3 cast iron air brick with a minimum free area of 4500mm2 on top. Care should be taken to ensure the ventilation duct fashioned using mortar from the air brick and into the property is clear. If the ventilation path is required to direct air below floor boards inside the property then plastic ducting may be used within the wall either by drilling a core hole and inserting plastic tube or installing a periscope vent combined with the air brick.

It is essential that surface water is directed away from the property so the air brick doesn’t create entrance holes allowing water to run into basements or below interior floors. If the outside floor levels can be lowered it may still be worth considering replacing the clay air brick for a more efficient vent as once cleaned, the air brick in the photograph would only  provide a free area for ventilation of 8x8x6x4 = 1536mm2.

All our 9s3 cast iron air bricks have a free area of at least 4500mm2


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!

Blocked up Fireplace

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.